]> git.saurik.com Git - apt.git/blobdiff - apt-pkg/acquire-item.cc
report warnings&errors consistently in edit-sources
[apt.git] / apt-pkg / acquire-item.cc
index e92ccc08b68efef8df5c7c8247f61067556aa230..208b84c64cb95ac4b198a212ef46596b810a7680 100644 (file)
 #include <apt-pkg/error.h>
 #include <apt-pkg/strutl.h>
 #include <apt-pkg/fileutl.h>
-#include <apt-pkg/sha1.h>
 #include <apt-pkg/tagfile.h>
-#include <apt-pkg/indexrecords.h>
+#include <apt-pkg/metaindex.h>
 #include <apt-pkg/acquire.h>
 #include <apt-pkg/hashes.h>
 #include <apt-pkg/indexfile.h>
 #include <apt-pkg/pkgcache.h>
 #include <apt-pkg/cacheiterators.h>
 #include <apt-pkg/pkgrecords.h>
+#include <apt-pkg/gpgv.h>
 
+#include <algorithm>
 #include <stddef.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
 #include <errno.h>
 #include <string>
-#include <sstream>
 #include <stdio.h>
 #include <ctime>
+#include <sstream>
+#include <numeric>
 
 #include <apti18n.h>
                                                                        /*}}}*/
 
 using namespace std;
 
-static void printHashSumComparision(std::string const &URI, HashStringList const &Expected, HashStringList const &Actual) /*{{{*/
+static void printHashSumComparison(std::string const &URI, HashStringList const &Expected, HashStringList const &Actual) /*{{{*/
 {
    if (_config->FindB("Debug::Acquire::HashSumMismatch", false) == false)
       return;
@@ -79,20 +81,19 @@ static std::string GetFinalFileNameFromURI(std::string const &uri)  /*{{{*/
    return _config->FindDir("Dir::State::lists") + URItoFileName(uri);
 }
                                                                        /*}}}*/
-static std::string GetCompressedFileName(std::string const &URI, std::string const &Name, std::string const &Ext) /*{{{*/
+static std::string GetKeepCompressedFileName(std::string file, IndexTarget const &Target)/*{{{*/
 {
-   if (Ext.empty() || Ext == "uncompressed")
-      return Name;
+   if (Target.KeepCompressed == false)
+      return file;
 
-   // do not reverify cdrom sources as apt-cdrom may rewrite the Packages
-   // file when its doing the indexcopy
-   if (URI.substr(0,6) == "cdrom:")
-      return Name;
-
-   // adjust DestFile if its compressed on disk
-   if (_config->FindB("Acquire::GzipIndexes",false) == true)
-      return Name + '.' + Ext;
-   return Name;
+   std::string const KeepCompressedAs = Target.Option(IndexTarget::KEEPCOMPRESSEDAS);
+   if (KeepCompressedAs.empty() == false)
+   {
+      std::string const ext = KeepCompressedAs.substr(0, KeepCompressedAs.find(' '));
+      if (ext != "uncompressed")
+        file.append(".").append(ext);
+   }
+   return file;
 }
                                                                        /*}}}*/
 static std::string GetMergeDiffsPatchFileName(std::string const &Final, std::string const &Patch)/*{{{*/
@@ -107,23 +108,178 @@ static std::string GetDiffsPatchFileName(std::string const &Final)       /*{{{*/
    return Final + ".ed";
 }
                                                                        /*}}}*/
+static std::string GetExistingFilename(std::string const &File)                /*{{{*/
+{
+   if (RealFileExists(File))
+      return File;
+   for (auto const &type : APT::Configuration::getCompressorExtensions())
+   {
+      std::string const Final = File + type;
+      if (RealFileExists(Final))
+        return Final;
+   }
+   return "";
+}
+                                                                       /*}}}*/
+static std::string GetDiffIndexFileName(std::string const &Name)       /*{{{*/
+{
+   return Name + ".diff/Index";
+}
+                                                                       /*}}}*/
+static std::string GetDiffIndexURI(IndexTarget const &Target)          /*{{{*/
+{
+   return Target.URI + ".diff/Index";
+}
+                                                                       /*}}}*/
+
+static void ReportMirrorFailureToCentral(pkgAcquire::Item const &I, std::string const &FailCode, std::string const &Details)/*{{{*/
+{
+   // we only act if a mirror was used at all
+   if(I.UsedMirror.empty())
+      return;
+#if 0
+   std::cerr << "\nReportMirrorFailure: "
+            << UsedMirror
+            << " Uri: " << DescURI()
+            << " FailCode: "
+            << FailCode << std::endl;
+#endif
+   string const report = _config->Find("Methods::Mirror::ProblemReporting",
+                                "/usr/lib/apt/apt-report-mirror-failure");
+   if(!FileExists(report))
+      return;
+
+   std::vector<char const*> const Args = {
+      report.c_str(),
+      I.UsedMirror.c_str(),
+      I.DescURI().c_str(),
+      FailCode.c_str(),
+      Details.c_str(),
+      NULL
+   };
+
+   pid_t pid = ExecFork();
+   if(pid < 0)
+   {
+      _error->Error("ReportMirrorFailure Fork failed");
+      return;
+   }
+   else if(pid == 0)
+   {
+      execvp(Args[0], (char**)Args.data());
+      std::cerr << "Could not exec " << Args[0] << std::endl;
+      _exit(100);
+   }
+   if(!ExecWait(pid, "report-mirror-failure"))
+      _error->Warning("Couldn't report problem to '%s'", report.c_str());
+}
+                                                                       /*}}}*/
+
+static APT_NONNULL(2) bool MessageInsecureRepository(bool const isError, char const * const msg, std::string const &repo)/*{{{*/
+{
+   std::string m;
+   strprintf(m, msg, repo.c_str());
+   if (isError)
+   {
+      _error->Error("%s", m.c_str());
+      _error->Notice("%s", _("Updating from such a repository can't be done securely, and is therefore disabled by default."));
+   }
+   else
+   {
+      _error->Warning("%s", m.c_str());
+      _error->Notice("%s", _("Data from such a repository can't be authenticated and is therefore potentially dangerous to use."));
+   }
+   _error->Notice("%s", _("See apt-secure(8) manpage for repository creation and user configuration details."));
+   return false;
+}
+                                                                       /*}}}*/
+// AllowInsecureRepositories                                           /*{{{*/
+enum class InsecureType { UNSIGNED, WEAK, NORELEASE };
+static bool TargetIsAllowedToBe(IndexTarget const &Target, InsecureType const type)
+{
+   if (_config->FindB("Acquire::AllowInsecureRepositories"))
+      return true;
+
+   if (Target.OptionBool(IndexTarget::ALLOW_INSECURE))
+      return true;
 
-static bool AllowInsecureRepositories(indexRecords const * const MetaIndexParser, pkgAcqMetaBase * const TransactionManager, pkgAcquire::Item * const I) /*{{{*/
+   switch (type)
+   {
+      case InsecureType::UNSIGNED: break;
+      case InsecureType::NORELEASE: break;
+      case InsecureType::WEAK:
+        if (_config->FindB("Acquire::AllowWeakRepositories"))
+           return true;
+        if (Target.OptionBool(IndexTarget::ALLOW_WEAK))
+           return true;
+        break;
+   }
+   return false;
+}
+static bool APT_NONNULL(3, 4, 5) AllowInsecureRepositories(InsecureType const msg, std::string const &repo,
+      metaIndex const * const MetaIndexParser, pkgAcqMetaClearSig * const TransactionManager, pkgAcquire::Item * const I)
 {
-   if(MetaIndexParser->IsAlwaysTrusted() || _config->FindB("Acquire::AllowInsecureRepositories") == true)
+   // we skip weak downgrades as its unlikely that a repository gets really weaker –
+   // its more realistic that apt got pickier in a newer version
+   if (msg != InsecureType::WEAK)
+   {
+      std::string const FinalInRelease = TransactionManager->GetFinalFilename();
+      std::string const FinalReleasegpg = FinalInRelease.substr(0, FinalInRelease.length() - strlen("InRelease")) + "Release.gpg";
+      if (RealFileExists(FinalReleasegpg) || RealFileExists(FinalInRelease))
+      {
+        char const * msgstr = nullptr;
+        switch (msg)
+        {
+           case InsecureType::UNSIGNED: msgstr = _("The repository '%s' is no longer signed."); break;
+           case InsecureType::NORELEASE: msgstr = _("The repository '%s' does no longer have a Release file."); break;
+           case InsecureType::WEAK: /* unreachable */ break;
+        }
+        if (_config->FindB("Acquire::AllowDowngradeToInsecureRepositories") ||
+              TransactionManager->Target.OptionBool(IndexTarget::ALLOW_DOWNGRADE_TO_INSECURE))
+        {
+           // meh, the users wants to take risks (we still mark the packages
+           // from this repository as unauthenticated)
+           _error->Warning(msgstr, repo.c_str());
+           _error->Warning(_("This is normally not allowed, but the option "
+                    "Acquire::AllowDowngradeToInsecureRepositories was "
+                    "given to override it."));
+        } else {
+           MessageInsecureRepository(true, msgstr, repo);
+           TransactionManager->AbortTransaction();
+           I->Status = pkgAcquire::Item::StatError;
+           return false;
+        }
+      }
+   }
+
+   if(MetaIndexParser->GetTrusted() == metaIndex::TRI_YES)
+      return true;
+
+   char const * msgstr = nullptr;
+   switch (msg)
+   {
+      case InsecureType::UNSIGNED: msgstr = _("The repository '%s' is not signed."); break;
+      case InsecureType::NORELEASE: msgstr = _("The repository '%s' does not have a Release file."); break;
+      case InsecureType::WEAK: msgstr = _("The repository '%s' provides only weak security information."); break;
+   }
+
+   if (TargetIsAllowedToBe(TransactionManager->Target, msg) == true)
+   {
+      MessageInsecureRepository(false, msgstr, repo);
       return true;
+   }
 
-   _error->Error(_("Use --allow-insecure-repositories to force the update"));
+   MessageInsecureRepository(true, msgstr, repo);
    TransactionManager->AbortTransaction();
    I->Status = pkgAcquire::Item::StatError;
    return false;
 }
                                                                        /*}}}*/
-static HashStringList GetExpectedHashesFromFor(indexRecords * const Parser, std::string const MetaKey)/*{{{*/
+static HashStringList GetExpectedHashesFromFor(metaIndex * const Parser, std::string const &MetaKey)/*{{{*/
 {
    if (Parser == NULL)
       return HashStringList();
-   indexRecords::checkSum * const R = Parser->Lookup(MetaKey);
+   metaIndex::checkSum * const R = Parser->Lookup(MetaKey);
    if (R == NULL)
       return HashStringList();
    return R->Hashes;
@@ -143,7 +299,20 @@ APT_CONST bool pkgAcqTransactionItem::HashesRequired() const
       we can at least trust them for integrity of the download itself.
       Only repositories without a Release file can (obviously) not have
       hashes – and they are very uncommon and strongly discouraged */
-   return TransactionManager->MetaIndexParser != NULL;
+   if (TransactionManager->MetaIndexParser->GetLoadedSuccessfully() != metaIndex::TRI_YES)
+      return false;
+   if (TargetIsAllowedToBe(Target, InsecureType::WEAK))
+   {
+      /* If we allow weak hashes, we check that we have some (weak) and then
+         declare hashes not needed. That will tip us in the right direction
+        as if hashes exist, they will be used, even if not required */
+      auto const hsl = GetExpectedHashes();
+      if (hsl.usable())
+        return true;
+      if (hsl.empty() == false)
+        return false;
+   }
+   return true;
 }
 HashStringList pkgAcqTransactionItem::GetExpectedHashes() const
 {
@@ -162,12 +331,12 @@ HashStringList pkgAcqMetaBase::GetExpectedHashes() const
 
 APT_CONST bool pkgAcqIndexDiffs::HashesRequired() const
 {
-   /* We don't always have the diff of the downloaded pdiff file.
-      What we have for sure is hashes for the uncompressed file,
-      but rred uncompresses them on the fly while parsing, so not handled here.
-      Hashes are (also) checked while searching for (next) patch to apply. */
+   /* We can't check hashes of rred result as we don't know what the
+      hash of the file will be. We just know the hash of the patch(es),
+      the hash of the file they will apply on and the hash of the resulting
+      file. */
    if (State == StateFetchDiff)
-      return available_patches[0].download_hashes.empty() == false;
+      return true;
    return false;
 }
 HashStringList pkgAcqIndexDiffs::GetExpectedHashes() const
@@ -183,7 +352,7 @@ APT_CONST bool pkgAcqIndexMergeDiffs::HashesRequired() const
       we can check the rred result after all patches are applied as
       we know the expected result rather than potentially apply more patches */
    if (State == StateFetchDiff)
-      return patch.download_hashes.empty() == false;
+      return true;
    return State == StateApplyDiff;
 }
 HashStringList pkgAcqIndexMergeDiffs::GetExpectedHashes() const
@@ -191,7 +360,7 @@ HashStringList pkgAcqIndexMergeDiffs::GetExpectedHashes() const
    if (State == StateFetchDiff)
       return patch.download_hashes;
    else if (State == StateApplyDiff)
-      return GetExpectedHashesFor(Target->MetaKey);
+      return GetExpectedHashesFor(Target.MetaKey);
    return HashStringList();
 }
 
@@ -227,14 +396,34 @@ bool pkgAcquire::Item::QueueURI(pkgAcquire::ItemDesc &Item)
    for a hashsum mismatch to happen which helps nobody) */
 bool pkgAcqTransactionItem::QueueURI(pkgAcquire::ItemDesc &Item)
 {
+   if (TransactionManager->State != TransactionStarted)
+   {
+      if (_config->FindB("Debug::Acquire::Transaction", false))
+        std::clog << "Skip " << Target.URI << " as transaction was already dealt with!" << std::endl;
+      return false;
+   }
    std::string const FinalFile = GetFinalFilename();
-   if (TransactionManager != NULL && TransactionManager->IMSHit == true &&
-        FileExists(FinalFile) == true)
+   if (TransactionManager->IMSHit == true && FileExists(FinalFile) == true)
    {
       PartialFile = DestFile = FinalFile;
       Status = StatDone;
       return false;
    }
+   // If we got the InRelease file via a mirror, pick all indexes directly from this mirror, too
+   if (TransactionManager->BaseURI.empty() == false &&
+        URI::SiteOnly(Item.URI) != URI::SiteOnly(TransactionManager->BaseURI))
+   {
+      // this ensures we rewrite only once and only the first step
+      auto const OldBaseURI = Target.Option(IndexTarget::BASE_URI);
+      if (OldBaseURI.empty() == false && APT::String::Startswith(Item.URI, OldBaseURI))
+      {
+        auto const ExtraPath = Item.URI.substr(OldBaseURI.length());
+        Item.URI = flCombine(TransactionManager->BaseURI, ExtraPath);
+        UsedMirror = TransactionManager->UsedMirror;
+        if (Item.Description.find(" ") != string::npos)
+           Item.Description.replace(0, Item.Description.find(" "), UsedMirror);
+      }
+   }
    return pkgAcquire::Item::QueueURI(Item);
 }
 /* The transition manager InRelease itself (or its older sisters-in-law
@@ -257,29 +446,29 @@ bool pkgAcqDiffIndex::QueueURI(pkgAcquire::ItemDesc &Item)
 // Acquire::Item::GetFinalFilename and specialisations for child classes       /*{{{*/
 std::string pkgAcquire::Item::GetFinalFilename() const
 {
+   // Beware: Desc.URI is modified by redirections
    return GetFinalFileNameFromURI(Desc.URI);
 }
 std::string pkgAcqDiffIndex::GetFinalFilename() const
 {
-   // the logic we inherent from pkgAcqBaseIndex isn't what we need here
-   return pkgAcquire::Item::GetFinalFilename();
+   return GetFinalFileNameFromURI(GetDiffIndexURI(Target));
 }
 std::string pkgAcqIndex::GetFinalFilename() const
 {
-   std::string const FinalFile = GetFinalFileNameFromURI(Target->URI);
-   return GetCompressedFileName(Target->URI, FinalFile, CurrentCompressionExtension);
+   std::string const FinalFile = GetFinalFileNameFromURI(Target.URI);
+   return GetKeepCompressedFileName(FinalFile, Target);
 }
 std::string pkgAcqMetaSig::GetFinalFilename() const
 {
-   return GetFinalFileNameFromURI(Target->URI);
+   return GetFinalFileNameFromURI(Target.URI);
 }
 std::string pkgAcqBaseIndex::GetFinalFilename() const
 {
-   return GetFinalFileNameFromURI(Target->URI);
+   return GetFinalFileNameFromURI(Target.URI);
 }
 std::string pkgAcqMetaBase::GetFinalFilename() const
 {
-   return GetFinalFileNameFromURI(DataTarget.URI);
+   return GetFinalFileNameFromURI(Target.URI);
 }
 std::string pkgAcqArchive::GetFinalFilename() const
 {
@@ -289,17 +478,17 @@ std::string pkgAcqArchive::GetFinalFilename() const
 // pkgAcqTransactionItem::GetMetaKey and specialisations for child classes     /*{{{*/
 std::string pkgAcqTransactionItem::GetMetaKey() const
 {
-   return Target->MetaKey;
+   return Target.MetaKey;
 }
 std::string pkgAcqIndex::GetMetaKey() const
 {
    if (Stage == STAGE_DECOMPRESS_AND_VERIFY || CurrentCompressionExtension == "uncompressed")
-      return Target->MetaKey;
-   return Target->MetaKey + "." + CurrentCompressionExtension;
+      return Target.MetaKey;
+   return Target.MetaKey + "." + CurrentCompressionExtension;
 }
 std::string pkgAcqDiffIndex::GetMetaKey() const
 {
-   return Target->MetaKey + ".diff/Index";
+   return GetDiffIndexFileName(Target.MetaKey);
 }
                                                                        /*}}}*/
 //pkgAcqTransactionItem::TransactionState and specialisations for child classes        /*{{{*/
@@ -308,6 +497,7 @@ bool pkgAcqTransactionItem::TransactionState(TransactionStates const state)
    bool const Debug = _config->FindB("Debug::Acquire::Transaction", false);
    switch(state)
    {
+      case TransactionStarted: _error->Fatal("Item %s changed to invalid transaction start state!", Target.URI.c_str()); break;
       case TransactionAbort:
         if(Debug == true)
            std::clog << "  Cancel: " << DestFile << std::endl;
@@ -318,16 +508,66 @@ bool pkgAcqTransactionItem::TransactionState(TransactionStates const state)
         }
         break;
       case TransactionCommit:
-        if(PartialFile != "")
+        if(PartialFile.empty() == false)
         {
-           if(Debug == true)
-              std::clog << "mv " << PartialFile << " -> "<< DestFile << " # " << DescURI() << std::endl;
+           bool sameFile = (PartialFile == DestFile);
+           // we use symlinks on IMS-Hit to avoid copies
+           if (RealFileExists(DestFile))
+           {
+              struct stat Buf;
+              if (lstat(PartialFile.c_str(), &Buf) != -1)
+              {
+                 if (S_ISLNK(Buf.st_mode) && Buf.st_size > 0)
+                 {
+                    char partial[Buf.st_size + 1];
+                    ssize_t const sp = readlink(PartialFile.c_str(), partial, Buf.st_size);
+                    if (sp == -1)
+                       _error->Errno("pkgAcqTransactionItem::TransactionState-sp", _("Failed to readlink %s"), PartialFile.c_str());
+                    else
+                    {
+                       partial[sp] = '\0';
+                       sameFile = (DestFile == partial);
+                    }
+                 }
+              }
+              else
+                 _error->Errno("pkgAcqTransactionItem::TransactionState-stat", _("Failed to stat %s"), PartialFile.c_str());
+           }
+           if (sameFile == false)
+           {
+              // ensure that even without lists-cleanup all compressions are nuked
+              std::string FinalFile = GetFinalFileNameFromURI(Target.URI);
+              if (FileExists(FinalFile))
+              {
+                 if(Debug == true)
+                    std::clog << "rm " << FinalFile << " # " << DescURI() << std::endl;
+                 if (RemoveFile("TransactionStates-Cleanup", FinalFile) == false)
+                    return false;
+              }
+              for (auto const &ext: APT::Configuration::getCompressorExtensions())
+              {
+                 auto const Final = FinalFile + ext;
+                 if (FileExists(Final))
+                 {
+                    if(Debug == true)
+                       std::clog << "rm " << Final << " # " << DescURI() << std::endl;
+                    if (RemoveFile("TransactionStates-Cleanup", Final) == false)
+                       return false;
+                 }
+              }
+              if(Debug == true)
+                 std::clog << "mv " << PartialFile << " -> "<< DestFile << " # " << DescURI() << std::endl;
+              if (Rename(PartialFile, DestFile) == false)
+                 return false;
+           }
+           else if(Debug == true)
+              std::clog << "keep " << PartialFile << " # " << DescURI() << std::endl;
 
-           Rename(PartialFile, DestFile);
         } else {
            if(Debug == true)
               std::clog << "rm " << DestFile << " # " << DescURI() << std::endl;
-           unlink(DestFile.c_str());
+           if (RemoveFile("TransItem::TransactionCommit", DestFile) == false)
+              return false;
         }
         break;
    }
@@ -347,18 +587,19 @@ bool pkgAcqIndex::TransactionState(TransactionStates const state)
 
    switch (state)
    {
+      case TransactionStarted: _error->Fatal("AcqIndex %s changed to invalid transaction start state!", Target.URI.c_str()); break;
       case TransactionAbort:
         if (Stage == STAGE_DECOMPRESS_AND_VERIFY)
         {
            // keep the compressed file, but drop the decompressed
            EraseFileName.clear();
-           if (PartialFile.empty() == false && flExtension(PartialFile) == "decomp")
-              unlink(PartialFile.c_str());
+           if (PartialFile.empty() == false && flExtension(PartialFile) != CurrentCompressionExtension)
+              RemoveFile("TransactionAbort", PartialFile);
         }
         break;
       case TransactionCommit:
         if (EraseFileName.empty() == false)
-           unlink(EraseFileName.c_str());
+           RemoveFile("AcqIndex::TransactionCommit", EraseFileName);
         break;
    }
    return true;
@@ -370,11 +611,12 @@ bool pkgAcqDiffIndex::TransactionState(TransactionStates const state)
 
    switch (state)
    {
+      case TransactionStarted: _error->Fatal("Item %s changed to invalid transaction start state!", Target.URI.c_str()); break;
       case TransactionCommit:
         break;
       case TransactionAbort:
-        std::string const Partial = GetPartialFileNameFromURI(Target->URI);
-        unlink(Partial.c_str());
+        std::string const Partial = GetPartialFileNameFromURI(Target.URI);
+        RemoveFile("TransactionAbort", Partial);
         break;
    }
 
@@ -382,39 +624,71 @@ bool pkgAcqDiffIndex::TransactionState(TransactionStates const state)
 }
                                                                        /*}}}*/
 
-// IndexTarget - Constructor                                           /*{{{*/
-IndexTarget::IndexTarget(std::string const &MetaKey, std::string const &ShortDesc,
-      std::string const &LongDesc, std::string const &URI, bool const IsOptional,
-      std::map<std::string, std::string> const &Options) :
-   URI(URI), Description(LongDesc), ShortDesc(ShortDesc), MetaKey(MetaKey), IsOptional(IsOptional), Options(Options)
-{
-}
-                                                                       /*}}}*/
-
 class APT_HIDDEN NoActionItem : public pkgAcquire::Item                        /*{{{*/
 /* The sole purpose of this class is having an item which does nothing to
    reach its done state to prevent cleanup deleting the mentioned file.
    Handy in cases in which we know we have the file already, like IMS-Hits. */
 {
-   IndexTarget const * const Target;
+   IndexTarget const Target;
    public:
-   virtual std::string DescURI() const {return Target->URI;};
-   virtual HashStringList GetExpectedHashes()  const {return HashStringList();};
+   virtual std::string DescURI() const APT_OVERRIDE {return Target.URI;};
+   virtual HashStringList GetExpectedHashes()  const APT_OVERRIDE {return HashStringList();};
 
-   NoActionItem(pkgAcquire * const Owner, IndexTarget const * const Target) :
+   NoActionItem(pkgAcquire * const Owner, IndexTarget const &Target) :
+      pkgAcquire::Item(Owner), Target(Target)
+   {
+      Status = StatDone;
+      DestFile = GetFinalFileNameFromURI(Target.URI);
+   }
+   NoActionItem(pkgAcquire * const Owner, IndexTarget const &Target, std::string const &FinalFile) :
       pkgAcquire::Item(Owner), Target(Target)
    {
       Status = StatDone;
-      DestFile = GetFinalFileNameFromURI(Target->URI);
+      DestFile = FinalFile;
+   }
+};
+                                                                       /*}}}*/
+class APT_HIDDEN CleanupItem : public pkgAcqTransactionItem            /*{{{*/
+/* This class ensures that a file which was configured but isn't downloaded
+   for various reasons isn't kept in an old version in the lists directory.
+   In a way its the reverse of NoActionItem as it helps with removing files
+   even if the lists-cleanup is deactivated. */
+{
+   public:
+   virtual std::string DescURI() const APT_OVERRIDE {return Target.URI;};
+   virtual HashStringList GetExpectedHashes()  const APT_OVERRIDE {return HashStringList();};
+
+   CleanupItem(pkgAcquire * const Owner, pkgAcqMetaClearSig * const TransactionManager, IndexTarget const &Target) :
+      pkgAcqTransactionItem(Owner, TransactionManager, Target)
+   {
+      Status = StatDone;
+      DestFile = GetFinalFileNameFromURI(Target.URI);
+   }
+   bool TransactionState(TransactionStates const state) APT_OVERRIDE
+   {
+      switch (state)
+      {
+        case TransactionStarted:
+           break;
+        case TransactionAbort:
+           break;
+        case TransactionCommit:
+           if (_config->FindB("Debug::Acquire::Transaction", false) == true)
+              std::clog << "rm " << DestFile << " # " << DescURI() << std::endl;
+           if (RemoveFile("TransItem::TransactionCommit", DestFile) == false)
+              return false;
+           break;
+      }
+      return true;
    }
 };
                                                                        /*}}}*/
 
 // Acquire::Item::Item - Constructor                                   /*{{{*/
 APT_IGNORE_DEPRECATED_PUSH
-pkgAcquire::Item::Item(pkgAcquire * const Owner) :
-   FileSize(0), PartialSize(0), Mode(0), Complete(false), Local(false),
-    QueueCounter(0), ExpectedAdditionalItems(0), Owner(Owner)
+pkgAcquire::Item::Item(pkgAcquire * const owner) :
+   FileSize(0), PartialSize(0), Mode(0), ID(0), Complete(false), Local(false),
+    QueueCounter(0), ExpectedAdditionalItems(0), Owner(owner), d(NULL)
 {
    Owner->Add(this);
    Status = StatIdle;
@@ -446,6 +720,11 @@ APT_PURE pkgAcquire * pkgAcquire::Item::GetOwner() const           /*{{{*/
    return Owner;
 }
                                                                        /*}}}*/
+APT_CONST pkgAcquire::ItemDesc &pkgAcquire::Item::GetItemDesc()                /*{{{*/
+{
+   return Desc;
+}
+                                                                       /*}}}*/
 APT_CONST bool pkgAcquire::Item::IsTrusted() const                     /*{{{*/
 {
    return false;
@@ -457,9 +736,6 @@ APT_CONST bool pkgAcquire::Item::IsTrusted() const                  /*{{{*/
    fetch this object */
 void pkgAcquire::Item::Failed(string const &Message,pkgAcquire::MethodConfig const * const Cnf)
 {
-   if(ErrorText.empty())
-      ErrorText = LookupTag(Message,"Message");
-   UsedMirror =  LookupTag(Message,"UsedMirror");
    if (QueueCounter <= 1)
    {
       /* This indicates that the file is not available right now but might
@@ -490,16 +766,80 @@ void pkgAcquire::Item::Failed(string const &Message,pkgAcquire::MethodConfig con
    }
 
    string const FailReason = LookupTag(Message, "FailReason");
-   if (FailReason == "MaximumSizeExceeded")
-      RenameOnError(MaximumSizeExceeded);
+   enum { MAXIMUM_SIZE_EXCEEDED, HASHSUM_MISMATCH, WEAK_HASHSUMS, OTHER } failreason = OTHER;
+   if ( FailReason == "MaximumSizeExceeded")
+      failreason = MAXIMUM_SIZE_EXCEEDED;
+   else if ( FailReason == "WeakHashSums")
+      failreason = WEAK_HASHSUMS;
    else if (Status == StatAuthError)
-      RenameOnError(HashSumMismatch);
+      failreason = HASHSUM_MISMATCH;
+
+   if(ErrorText.empty())
+   {
+      if (Status == StatAuthError)
+      {
+        std::ostringstream out;
+        switch (failreason)
+        {
+           case HASHSUM_MISMATCH:
+              out << _("Hash Sum mismatch") << std::endl;
+              break;
+           case WEAK_HASHSUMS:
+              out << _("Insufficient information available to perform this download securely") << std::endl;
+              break;
+           case MAXIMUM_SIZE_EXCEEDED:
+           case OTHER:
+              out << LookupTag(Message, "Message") << std::endl;
+              break;
+        }
+        auto const ExpectedHashes = GetExpectedHashes();
+        if (ExpectedHashes.empty() == false)
+        {
+           out << "Hashes of expected file:" << std::endl;
+           for (auto const &hs: ExpectedHashes)
+           {
+              out << " - " << hs.toStr();
+              if (hs.usable() == false)
+                 out << " [weak]";
+              out << std::endl;
+           }
+        }
+        if (failreason == HASHSUM_MISMATCH)
+        {
+           out << "Hashes of received file:" << std::endl;
+           for (char const * const * type = HashString::SupportedHashes(); *type != NULL; ++type)
+           {
+              std::string const tagname = std::string(*type) + "-Hash";
+              std::string const hashsum = LookupTag(Message, tagname.c_str());
+              if (hashsum.empty() == false)
+              {
+                 auto const hs = HashString(*type, hashsum);
+                 out << " - " << hs.toStr();
+                 if (hs.usable() == false)
+                    out << " [weak]";
+                 out << std::endl;
+              }
+           }
+           out << "Last modification reported: " << LookupTag(Message, "Last-Modified", "<none>") << std::endl;
+        }
+        ErrorText = out.str();
+      }
+      else
+        ErrorText = LookupTag(Message,"Message");
+   }
+
+   switch (failreason)
+   {
+      case MAXIMUM_SIZE_EXCEEDED: RenameOnError(MaximumSizeExceeded); break;
+      case HASHSUM_MISMATCH: RenameOnError(HashSumMismatch); break;
+      case WEAK_HASHSUMS: break;
+      case OTHER: break;
+   }
 
-   // report mirror failure back to LP if we actually use a mirror
    if (FailReason.empty() == false)
-      ReportMirrorFailure(FailReason);
+      ReportMirrorFailureToCentral(*this, FailReason, ErrorText);
    else
-      ReportMirrorFailure(ErrorText);
+      ReportMirrorFailureToCentral(*this, ErrorText, ErrorText);
 
    if (QueueCounter > 1)
       Status = StatIdle;
@@ -517,24 +857,35 @@ void pkgAcquire::Item::Start(string const &/*Message*/, unsigned long long const
       FileSize = Size;
 }
                                                                        /*}}}*/
+// Acquire::Item::VerifyDone - check if Item was downloaded OK         /*{{{*/
+/* Note that hash-verification is 'hardcoded' in acquire-worker and has
+ * already passed if this method is called. */
+bool pkgAcquire::Item::VerifyDone(std::string const &Message,
+        pkgAcquire::MethodConfig const * const /*Cnf*/)
+{
+   std::string const FileName = LookupTag(Message,"Filename");
+   if (FileName.empty() == true)
+   {
+      Status = StatError;
+      ErrorText = "Method gave a blank filename";
+      return false;
+   }
+
+   return true;
+}
+                                                                       /*}}}*/
 // Acquire::Item::Done - Item downloaded OK                            /*{{{*/
-void pkgAcquire::Item::Done(string const &Message, HashStringList const &Hashes,
+void pkgAcquire::Item::Done(string const &/*Message*/, HashStringList const &Hashes,
                            pkgAcquire::MethodConfig const * const /*Cnf*/)
 {
    // We just downloaded something..
-   string FileName = LookupTag(Message,"Filename");
-   UsedMirror = LookupTag(Message,"UsedMirror");
-   unsigned long long const downloadedSize = Hashes.FileSize();
-   if (downloadedSize != 0)
+   if (FileSize == 0)
    {
-      if (Complete == false && !Local && FileName == DestFile)
+      unsigned long long const downloadedSize = Hashes.FileSize();
+      if (downloadedSize != 0)
       {
-        if (Owner->Log != 0)
-           Owner->Log->Fetched(Hashes.FileSize(),atoi(LookupTag(Message,"Resume-Point","0").c_str()));
+        FileSize = downloadedSize;
       }
-
-      if (FileSize == 0)
-        FileSize= downloadedSize;
    }
    Status = StatDone;
    ErrorText = string();
@@ -576,13 +927,10 @@ bool pkgAcquire::Item::RenameOnError(pkgAcquire::Item::RenameOnErrorState const
    {
       case HashSumMismatch:
         errtext = _("Hash Sum mismatch");
-        Status = StatAuthError;
-        ReportMirrorFailure("HashChecksumFailure");
         break;
       case SizeMismatch:
         errtext = _("Size mismatch");
         Status = StatAuthError;
-        ReportMirrorFailure("SizeFailure");
         break;
       case InvalidFormat:
         errtext = _("Invalid file format");
@@ -594,12 +942,11 @@ bool pkgAcquire::Item::RenameOnError(pkgAcquire::Item::RenameOnErrorState const
         Status = StatError;
         break;
       case NotClearsigned:
-        errtext = _("Does not start with a cleartext signature");
-        Status = StatError;
+        strprintf(errtext, _("Clearsigned file isn't valid, got '%s' (does the network require authentication?)"), "NOSPLIT");
+        Status = StatAuthError;
         break;
       case MaximumSizeExceeded:
         // the method is expected to report a good error for this
-        Status = StatError;
         break;
       case PDiffError:
         // no handling here, done by callers
@@ -617,47 +964,9 @@ void pkgAcquire::Item::SetActiveSubprocess(const std::string &subprocess)/*{{{*/
 }
                                                                        /*}}}*/
 // Acquire::Item::ReportMirrorFailure                                  /*{{{*/
-void pkgAcquire::Item::ReportMirrorFailure(string const &FailCode)
+void pkgAcquire::Item::ReportMirrorFailure(std::string const &FailCode)
 {
-   // we only act if a mirror was used at all
-   if(UsedMirror.empty())
-      return;
-#if 0
-   std::cerr << "\nReportMirrorFailure: " 
-            << UsedMirror
-            << " Uri: " << DescURI()
-            << " FailCode: " 
-            << FailCode << std::endl;
-#endif
-   string report = _config->Find("Methods::Mirror::ProblemReporting", 
-                                "/usr/lib/apt/apt-report-mirror-failure");
-   if(!FileExists(report))
-      return;
-
-   std::vector<char const*> Args;
-   Args.push_back(report.c_str());
-   Args.push_back(UsedMirror.c_str());
-   Args.push_back(DescURI().c_str());
-   Args.push_back(FailCode.c_str());
-   Args.push_back(NULL);
-
-   pid_t pid = ExecFork();
-   if(pid < 0)
-   {
-      _error->Error("ReportMirrorFailure Fork failed");
-      return;
-   }
-   else if(pid == 0)
-   {
-      execvp(Args[0], (char**)Args.data());
-      std::cerr << "Could not exec " << Args[0] << std::endl;
-      _exit(100);
-   }
-   if(!ExecWait(pid, "report-mirror-failure"))
-   {
-      _error->Warning("Couldn't report problem to '%s'",
-                     _config->Find("Methods::Mirror::ProblemReporting").c_str());
-   }
+   ReportMirrorFailureToCentral(*this, FailCode, FailCode);
 }
                                                                        /*}}}*/
 std::string pkgAcquire::Item::HashSum() const                          /*{{{*/
@@ -669,8 +978,8 @@ std::string pkgAcquire::Item::HashSum() const                               /*{{{*/
                                                                        /*}}}*/
 
 pkgAcqTransactionItem::pkgAcqTransactionItem(pkgAcquire * const Owner, /*{{{*/
-      pkgAcqMetaBase * const TransactionManager, IndexTarget const * const Target) :
-   pkgAcquire::Item(Owner), Target(Target), TransactionManager(TransactionManager)
+      pkgAcqMetaClearSig * const transactionManager, IndexTarget const &target) :
+   pkgAcquire::Item(Owner), d(NULL), Target(target), TransactionManager(transactionManager)
 {
    if (TransactionManager != this)
       TransactionManager->Add(this);
@@ -680,21 +989,44 @@ pkgAcqTransactionItem::~pkgAcqTransactionItem()                           /*{{{*/
 {
 }
                                                                        /*}}}*/
-HashStringList pkgAcqTransactionItem::GetExpectedHashesFor(std::string const MetaKey) const    /*{{{*/
+HashStringList pkgAcqTransactionItem::GetExpectedHashesFor(std::string const &MetaKey) const   /*{{{*/
 {
    return GetExpectedHashesFromFor(TransactionManager->MetaIndexParser, MetaKey);
 }
                                                                        /*}}}*/
 
+static void LoadLastMetaIndexParser(pkgAcqMetaClearSig * const TransactionManager, std::string const &FinalRelease, std::string const &FinalInRelease)/*{{{*/
+{
+   if (TransactionManager->IMSHit == true)
+      return;
+   if (RealFileExists(FinalInRelease) || RealFileExists(FinalRelease))
+   {
+      TransactionManager->LastMetaIndexParser = TransactionManager->MetaIndexParser->UnloadedClone();
+      if (TransactionManager->LastMetaIndexParser != NULL)
+      {
+        _error->PushToStack();
+        if (RealFileExists(FinalInRelease))
+           TransactionManager->LastMetaIndexParser->Load(FinalInRelease, NULL);
+        else
+           TransactionManager->LastMetaIndexParser->Load(FinalRelease, NULL);
+        // its unlikely to happen, but if what we have is bad ignore it
+        if (_error->PendingError())
+        {
+           delete TransactionManager->LastMetaIndexParser;
+           TransactionManager->LastMetaIndexParser = NULL;
+        }
+        _error->RevertToStack();
+      }
+   }
+}
+                                                                       /*}}}*/
+
 // AcqMetaBase - Constructor                                           /*{{{*/
 pkgAcqMetaBase::pkgAcqMetaBase(pkgAcquire * const Owner,
-      pkgAcqMetaBase * const TransactionManager,
-      std::vector<IndexTarget*> const * const IndexTargets,
-      IndexTarget const &DataTarget,
-      indexRecords * const MetaIndexParser)
-: pkgAcqTransactionItem(Owner, TransactionManager, NULL), DataTarget(DataTarget),
-   MetaIndexParser(MetaIndexParser), LastMetaIndexParser(NULL), IndexTargets(IndexTargets),
-   AuthPass(false), IMSHit(false)
+      pkgAcqMetaClearSig * const TransactionManager,
+      IndexTarget const &DataTarget)
+: pkgAcqTransactionItem(Owner, TransactionManager, DataTarget), d(NULL),
+   AuthPass(false), IMSHit(false), State(TransactionStarted)
 {
 }
                                                                        /*}}}*/
@@ -710,10 +1042,20 @@ void pkgAcqMetaBase::AbortTransaction()
    if(_config->FindB("Debug::Acquire::Transaction", false) == true)
       std::clog << "AbortTransaction: " << TransactionManager << std::endl;
 
+   switch (TransactionManager->State)
+   {
+      case TransactionStarted: break;
+      case TransactionAbort: _error->Fatal("Transaction %s was already aborted and is aborted again", TransactionManager->Target.URI.c_str()); return;
+      case TransactionCommit: _error->Fatal("Transaction %s was already aborted and is now committed", TransactionManager->Target.URI.c_str()); return;
+   }
+   TransactionManager->State = TransactionAbort;
+
    // ensure the toplevel is in error state too
    for (std::vector<pkgAcqTransactionItem*>::iterator I = Transaction.begin();
         I != Transaction.end(); ++I)
    {
+      if ((*I)->Status != pkgAcquire::Item::StatFetching)
+        Owner->Dequeue(*I);
       (*I)->TransactionState(TransactionAbort);
    }
    Transaction.clear();
@@ -743,6 +1085,14 @@ void pkgAcqMetaBase::CommitTransaction()
    if(_config->FindB("Debug::Acquire::Transaction", false) == true)
       std::clog << "CommitTransaction: " << this << std::endl;
 
+   switch (TransactionManager->State)
+   {
+      case TransactionStarted: break;
+      case TransactionAbort: _error->Fatal("Transaction %s was already committed and is now aborted", TransactionManager->Target.URI.c_str()); return;
+      case TransactionCommit: _error->Fatal("Transaction %s was already committed and is again committed", TransactionManager->Target.URI.c_str()); return;
+   }
+   TransactionManager->State = TransactionCommit;
+
    // move new files into place *and* remove files that are not
    // part of the transaction but are still on disk
    for (std::vector<pkgAcqTransactionItem*>::iterator I = Transaction.begin();
@@ -771,37 +1121,36 @@ void pkgAcqMetaBase::TransactionStageRemoval(pkgAcqTransactionItem * const I,
 }
                                                                        /*}}}*/
 // AcqMetaBase::GenerateAuthWarning - Check gpg authentication error   /*{{{*/
+/* This method is called from ::Failed handlers. If it returns true,
+   no fallback to other files or modi is performed */
 bool pkgAcqMetaBase::CheckStopAuthentication(pkgAcquire::Item * const I, const std::string &Message)
 {
-   // FIXME: this entire function can do now that we disallow going to
-   //        a unauthenticated state and can cleanly rollback
-
    string const Final = I->GetFinalFilename();
-   if(FileExists(Final))
+   std::string const GPGError = LookupTag(Message, "Message");
+   if (FileExists(Final))
    {
       I->Status = StatTransientNetworkError;
-      _error->Warning(_("An error occurred during the signature "
-                        "verification. The repository is not updated "
-                        "and the previous index files will be used. "
-                        "GPG error: %s: %s\n"),
-                      Desc.Description.c_str(),
-                      LookupTag(Message,"Message").c_str());
+      _error->Warning(_("An error occurred during the signature verification. "
+              "The repository is not updated and the previous index files will be used. "
+              "GPG error: %s: %s"),
+           Desc.Description.c_str(),
+           GPGError.c_str());
       RunScripts("APT::Update::Auth-Failure");
       return true;
    } else if (LookupTag(Message,"Message").find("NODATA") != string::npos) {
       /* Invalid signature file, reject (LP: #346386) (Closes: #627642) */
       _error->Error(_("GPG error: %s: %s"),
-                    Desc.Description.c_str(),
-                    LookupTag(Message,"Message").c_str());
-      I->Status = StatError;
+           Desc.Description.c_str(),
+           GPGError.c_str());
+      I->Status = StatAuthError;
       return true;
    } else {
       _error->Warning(_("GPG error: %s: %s"),
-                      Desc.Description.c_str(),
-                      LookupTag(Message,"Message").c_str());
+           Desc.Description.c_str(),
+           GPGError.c_str());
    }
    // gpgv method failed
-   ReportMirrorFailure("GPGFailure");
+   ReportMirrorFailureToCentral(*this, "GPGFailure", GPGError);
    return false;
 }
                                                                        /*}}}*/
@@ -816,10 +1165,9 @@ string pkgAcqMetaBase::Custom600Headers() const
    Header += MaximumSize;
 
    string const FinalFile = GetFinalFilename();
-
    struct stat Buf;
    if (stat(FinalFile.c_str(),&Buf) == 0)
-      Header += "\nLast-Modified: " + TimeRFC1123(Buf.st_mtime);
+      Header += "\nLast-Modified: " + TimeRFC1123(Buf.st_mtime, false);
 
    return Header;
 }
@@ -840,15 +1188,17 @@ bool pkgAcqMetaBase::CheckDownloadDone(pkgAcqTransactionItem * const I, const st
    // We have just finished downloading a Release file (it is not
    // verified yet)
 
-   string const FileName = LookupTag(Message,"Filename");
-   if (FileName.empty() == true)
+   // Save the final base URI we got this Release file from
+   if (I->UsedMirror.empty() == false && _config->FindB("Acquire::SameMirrorForAllIndexes", true))
    {
-      I->Status = StatError;
-      I->ErrorText = "Method gave a blank filename";
-      return false;
+      if (APT::String::Endswith(I->Desc.URI, "InRelease"))
+        TransactionManager->BaseURI = I->Desc.URI.substr(0, I->Desc.URI.length() - strlen("InRelease"));
+      else if (APT::String::Endswith(I->Desc.URI, "Release"))
+        TransactionManager->BaseURI = I->Desc.URI.substr(0, I->Desc.URI.length() - strlen("Release"));
    }
 
-   if (FileName != I->DestFile)
+   std::string const FileName = LookupTag(Message,"Filename");
+   if (FileName != I->DestFile && RealFileExists(I->DestFile) == false)
    {
       I->Local = true;
       I->Desc.URI = "copy:" + FileName;
@@ -865,7 +1215,7 @@ bool pkgAcqMetaBase::CheckDownloadDone(pkgAcqTransactionItem * const I, const st
       if (RealFileExists(FinalFile) && Hashes.VerifyFile(FinalFile) == true)
       {
         IMSHit = true;
-        unlink(I->DestFile.c_str());
+        RemoveFile("CheckDownloadDone", I->DestFile);
       }
    }
 
@@ -873,8 +1223,7 @@ bool pkgAcqMetaBase::CheckDownloadDone(pkgAcqTransactionItem * const I, const st
    {
       // for simplicity, the transaction manager is always InRelease
       // even if it doesn't exist.
-      if (TransactionManager != NULL)
-        TransactionManager->IMSHit = true;
+      TransactionManager->IMSHit = true;
       I->PartialFile = I->DestFile = I->GetFinalFilename();
    }
 
@@ -890,6 +1239,8 @@ bool pkgAcqMetaBase::CheckAuthDone(string const &Message)          /*{{{*/
    // valid signature from a key in the trusted keyring.  We
    // perform additional verification of its contents, and use them
    // to verify the indexes we are about to download
+   if (_config->FindB("Debug::pkgAcquire::Auth", false))
+      std::cerr << "Signature verification succeeded: " << DestFile << std::endl;
 
    if (TransactionManager->IMSHit == false)
    {
@@ -907,28 +1258,13 @@ bool pkgAcqMetaBase::CheckAuthDone(string const &Message)                /*{{{*/
         FinalInRelease = FinalFile.substr(0, FinalFile.length() - strlen("Release")) + "InRelease";
         FinalRelease = FinalFile;
       }
-      if (RealFileExists(FinalInRelease) || RealFileExists(FinalRelease))
-      {
-        TransactionManager->LastMetaIndexParser = new indexRecords;
-        _error->PushToStack();
-        if (RealFileExists(FinalInRelease))
-           TransactionManager->LastMetaIndexParser->Load(FinalInRelease);
-        else
-           TransactionManager->LastMetaIndexParser->Load(FinalRelease);
-        // its unlikely to happen, but if what we have is bad ignore it
-        if (_error->PendingError())
-        {
-           delete TransactionManager->LastMetaIndexParser;
-           TransactionManager->LastMetaIndexParser = NULL;
-        }
-        _error->RevertToStack();
-      }
+      LoadLastMetaIndexParser(TransactionManager, FinalRelease, FinalInRelease);
    }
 
-   if (TransactionManager->MetaIndexParser->Load(DestFile) == false)
+   bool const GoodAuth = TransactionManager->MetaIndexParser->Load(DestFile, &ErrorText);
+   if (GoodAuth == false && AllowInsecureRepositories(InsecureType::WEAK, Target.Description, TransactionManager->MetaIndexParser, TransactionManager, this) == false)
    {
       Status = StatAuthError;
-      ErrorText = TransactionManager->MetaIndexParser->ErrorText;
       return false;
    }
 
@@ -938,98 +1274,203 @@ bool pkgAcqMetaBase::CheckAuthDone(string const &Message)               /*{{{*/
       return false;
    }
 
-   if (_config->FindB("Debug::pkgAcquire::Auth", false))
-      std::cerr << "Signature verification succeeded: "
-                << DestFile << std::endl;
-
    // Download further indexes with verification
-   QueueIndexes(true);
+   TransactionManager->QueueIndexes(GoodAuth);
 
-   return true;
+   return GoodAuth;
 }
                                                                        /*}}}*/
-void pkgAcqMetaBase::QueueIndexes(bool const verify)                   /*{{{*/
+void pkgAcqMetaClearSig::QueueIndexes(bool const verify)                       /*{{{*/
 {
    // at this point the real Items are loaded in the fetcher
    ExpectedAdditionalItems = 0;
 
-   vector <IndexTarget*>::const_iterator Target;
-   for (Target = IndexTargets->begin();
-        Target != IndexTargets->end();
-        ++Target)
-   {
-      bool trypdiff = _config->FindB("Acquire::PDiffs", true);
-      if (verify == true)
+   std::set<std::string> targetsSeen;
+   bool const hasReleaseFile = TransactionManager->MetaIndexParser != NULL;
+   bool const metaBaseSupportsByHash = hasReleaseFile && TransactionManager->MetaIndexParser->GetSupportsAcquireByHash();
+   bool hasHashes = true;
+   auto IndexTargets = TransactionManager->MetaIndexParser->GetIndexTargets();
+   if (hasReleaseFile && verify == false)
+      hasHashes = std::any_of(IndexTargets.begin(), IndexTargets.end(),
+           [&](IndexTarget const &Target) { return TransactionManager->MetaIndexParser->Exists(Target.MetaKey); });
+   for (auto&& Target: IndexTargets)
+   {
+      // if we have seen a target which is created-by a target this one here is declared a
+      // fallback to, we skip acquiring the fallback (but we make sure we clean up)
+      if (targetsSeen.find(Target.Option(IndexTarget::FALLBACK_OF)) != targetsSeen.end())
       {
-        if (TransactionManager->MetaIndexParser->Exists((*Target)->MetaKey) == false)
-        {
-           // optional targets that we do not have in the Release file are skipped
-           if ((*Target)->IsOptional)
+        targetsSeen.emplace(Target.Option(IndexTarget::CREATED_BY));
+        new CleanupItem(Owner, TransactionManager, Target);
+        continue;
+      }
+      // all is an implementation detail. Users shouldn't use this as arch
+      // We need this support trickery here as e.g. Debian has binary-all files already,
+      // but arch:all packages are still in the arch:any files, so we would waste precious
+      // download time, bandwidth and diskspace for nothing, BUT Debian doesn't feature all
+      // in the set of supported architectures, so we can filter based on this property rather
+      // than invent an entirely new flag we would need to carry for all of eternity.
+      if (hasReleaseFile && Target.Option(IndexTarget::ARCHITECTURE) == "all")
+      {
+        if (TransactionManager->MetaIndexParser->IsArchitectureAllSupportedFor(Target) == false)
+        {
+           new CleanupItem(Owner, TransactionManager, Target);
+           continue;
+        }
+      }
+
+      bool trypdiff = Target.OptionBool(IndexTarget::PDIFFS);
+      if (hasReleaseFile == true)
+      {
+        if (TransactionManager->MetaIndexParser->Exists(Target.MetaKey) == false)
+        {
+           // optional targets that we do not have in the Release file are skipped
+           if (hasHashes == true && Target.IsOptional)
+           {
+              new CleanupItem(Owner, TransactionManager, Target);
               continue;
+           }
 
-           Status = StatAuthError;
-           strprintf(ErrorText, _("Unable to find expected entry '%s' in Release file (Wrong sources.list entry or malformed file)"), (*Target)->MetaKey.c_str());
-           return;
-        }
+           std::string const &arch = Target.Option(IndexTarget::ARCHITECTURE);
+           if (arch.empty() == false)
+           {
+              if (TransactionManager->MetaIndexParser->IsArchitectureSupported(arch) == false)
+              {
+                 new CleanupItem(Owner, TransactionManager, Target);
+                 _error->Notice(_("Skipping acquire of configured file '%s' as repository '%s' doesn't support architecture '%s'"),
+                       Target.MetaKey.c_str(), TransactionManager->Target.Description.c_str(), arch.c_str());
+                 continue;
+              }
+              // if the architecture is officially supported but currently no packages for it available,
+              // ignore silently as this is pretty much the same as just shipping an empty file.
+              // if we don't know which architectures are supported, we do NOT ignore it to notify user about this
+              if (hasHashes == true && TransactionManager->MetaIndexParser->IsArchitectureSupported("*undefined*") == false)
+              {
+                 new CleanupItem(Owner, TransactionManager, Target);
+                 continue;
+              }
+           }
 
-        if (RealFileExists(GetFinalFileNameFromURI((*Target)->URI)))
+           if (hasHashes == true)
+           {
+              Status = StatAuthError;
+              strprintf(ErrorText, _("Unable to find expected entry '%s' in Release file (Wrong sources.list entry or malformed file)"), Target.MetaKey.c_str());
+              return;
+           }
+           else
+           {
+              new pkgAcqIndex(Owner, TransactionManager, Target);
+              continue;
+           }
+        }
+        else if (verify)
         {
-           if (TransactionManager->LastMetaIndexParser != NULL)
+           auto const hashes = GetExpectedHashesFor(Target.MetaKey);
+           if (hashes.empty() == false)
            {
-              HashStringList const newFile = GetExpectedHashesFromFor(TransactionManager->MetaIndexParser, (*Target)->MetaKey);
-              HashStringList const oldFile = GetExpectedHashesFromFor(TransactionManager->LastMetaIndexParser, (*Target)->MetaKey);
-              if (newFile == oldFile)
+              if (hashes.usable() == false && TargetIsAllowedToBe(TransactionManager->Target, InsecureType::WEAK) == false)
+              {
+                 new CleanupItem(Owner, TransactionManager, Target);
+                 _error->Warning(_("Skipping acquire of configured file '%s' as repository '%s' provides only weak security information for it"),
+                       Target.MetaKey.c_str(), TransactionManager->Target.Description.c_str());
+                 continue;
+              }
+              // empty files are skipped as acquiring the very small compressed files is a waste of time
+              else if (hashes.FileSize() == 0)
               {
-                 // we have the file already, no point in trying to acquire it again
-                 new NoActionItem(Owner, *Target);
+                 new CleanupItem(Owner, TransactionManager, Target);
+                 targetsSeen.emplace(Target.Option(IndexTarget::CREATED_BY));
                  continue;
               }
            }
         }
+
+        // autoselect the compression method
+        std::vector<std::string> types = VectorizeString(Target.Option(IndexTarget::COMPRESSIONTYPES), ' ');
+        types.erase(std::remove_if(types.begin(), types.end(), [&](std::string const &t) {
+           if (t == "uncompressed")
+              return TransactionManager->MetaIndexParser->Exists(Target.MetaKey) == false;
+           std::string const MetaKey = Target.MetaKey + "." + t;
+           return TransactionManager->MetaIndexParser->Exists(MetaKey) == false;
+        }), types.end());
+        if (types.empty() == false)
+        {
+           std::ostringstream os;
+           // add the special compressiontype byhash first if supported
+           std::string const useByHashConf = Target.Option(IndexTarget::BY_HASH);
+           bool useByHash = false;
+           if(useByHashConf == "force")
+              useByHash = true;
+           else
+              useByHash = StringToBool(useByHashConf) == true && metaBaseSupportsByHash;
+           if (useByHash == true)
+              os << "by-hash ";
+           std::copy(types.begin(), types.end()-1, std::ostream_iterator<std::string>(os, " "));
+           os << *types.rbegin();
+           Target.Options["COMPRESSIONTYPES"] = os.str();
+        }
+        else
+           Target.Options["COMPRESSIONTYPES"].clear();
+
+        std::string filename = GetExistingFilename(GetFinalFileNameFromURI(Target.URI));
+        if (filename.empty() == false)
+        {
+           // if the Release file is a hit and we have an index it must be the current one
+           if (TransactionManager->IMSHit == true)
+              ;
+           else if (TransactionManager->LastMetaIndexParser != NULL)
+           {
+              // see if the file changed since the last Release file
+              // we use the uncompressed files as we might compress differently compared to the server,
+              // so the hashes might not match, even if they contain the same data.
+              HashStringList const newFile = GetExpectedHashesFromFor(TransactionManager->MetaIndexParser, Target.MetaKey);
+              HashStringList const oldFile = GetExpectedHashesFromFor(TransactionManager->LastMetaIndexParser, Target.MetaKey);
+              if (newFile != oldFile)
+                 filename.clear();
+           }
+           else
+              filename.clear();
+        }
         else
            trypdiff = false; // no file to patch
 
+        if (filename.empty() == false)
+        {
+           new NoActionItem(Owner, Target, filename);
+           std::string const idxfilename = GetFinalFileNameFromURI(GetDiffIndexURI(Target));
+           if (FileExists(idxfilename))
+              new NoActionItem(Owner, Target, idxfilename);
+           targetsSeen.emplace(Target.Option(IndexTarget::CREATED_BY));
+           continue;
+        }
+
         // check if we have patches available
-        trypdiff &= TransactionManager->MetaIndexParser->Exists((*Target)->MetaKey + ".diff/Index");
+        trypdiff &= TransactionManager->MetaIndexParser->Exists(GetDiffIndexFileName(Target.MetaKey));
+      }
+      else
+      {
+        // if we have no file to patch, no point in trying
+        trypdiff &= (GetExistingFilename(GetFinalFileNameFromURI(Target.URI)).empty() == false);
       }
-      // if we have no file to patch, no point in trying
-      trypdiff &= RealFileExists(GetFinalFileNameFromURI((*Target)->URI));
 
       // no point in patching from local sources
       if (trypdiff)
       {
-        std::string const proto = (*Target)->URI.substr(0, strlen("file:/"));
+        std::string const proto = Target.URI.substr(0, strlen("file:/"));
         if (proto == "file:/" || proto == "copy:/" || proto == "cdrom:")
            trypdiff = false;
       }
 
       // Queue the Index file (Packages, Sources, Translation-$foo, …)
+      targetsSeen.emplace(Target.Option(IndexTarget::CREATED_BY));
       if (trypdiff)
-         new pkgAcqDiffIndex(Owner, TransactionManager, *Target);
+         new pkgAcqDiffIndex(Owner, TransactionManager, Target);
       else
-         new pkgAcqIndex(Owner, TransactionManager, *Target);
+         new pkgAcqIndex(Owner, TransactionManager, Target);
    }
 }
                                                                        /*}}}*/
-bool pkgAcqMetaBase::VerifyVendor(string const &Message)               /*{{{*/
+bool pkgAcqMetaBase::VerifyVendor(string const &)                      /*{{{*/
 {
-   string::size_type pos;
-
-   // check for missing sigs (that where not fatal because otherwise we had
-   // bombed earlier)
-   string missingkeys;
-   string msg = _("There is no public key available for the "
-                 "following key IDs:\n");
-   pos = Message.find("NO_PUBKEY ");
-   if (pos != std::string::npos)
-   {
-      string::size_type start = pos+strlen("NO_PUBKEY ");
-      string Fingerprint = Message.substr(start, Message.find("\n")-start);
-      missingkeys += (Fingerprint);
-   }
-   if(!missingkeys.empty())
-      _error->Warning("%s", (msg + missingkeys).c_str());
-
    string Transformed = TransactionManager->MetaIndexParser->GetExpectedDist();
 
    if (Transformed == "../project/experimental")
@@ -1037,7 +1478,7 @@ bool pkgAcqMetaBase::VerifyVendor(string const &Message)          /*{{{*/
       Transformed = "experimental";
    }
 
-   pos = Transformed.rfind('/');
+   auto pos = Transformed.rfind('/');
    if (pos != string::npos)
    {
       Transformed = Transformed.substr(0, pos);
@@ -1048,19 +1489,19 @@ bool pkgAcqMetaBase::VerifyVendor(string const &Message)                /*{{{*/
       Transformed = "";
    }
 
-   if (_config->FindB("Acquire::Check-Valid-Until", true) == true &&
-       TransactionManager->MetaIndexParser->GetValidUntil() > 0) {
+   if (TransactionManager->MetaIndexParser->GetValidUntil() > 0)
+   {
       time_t const invalid_since = time(NULL) - TransactionManager->MetaIndexParser->GetValidUntil();
       if (invalid_since > 0)
       {
         std::string errmsg;
         strprintf(errmsg,
               // TRANSLATOR: The first %s is the URL of the bad Release file, the second is
-              // the time since then the file is invalid - formated in the same way as in
+              // the time since then the file is invalid - formatted in the same way as in
               // the download progress display (e.g. 7d 3h 42min 1s)
               _("Release file for %s is expired (invalid since %s). "
                  "Updates for this repository will not be applied."),
-              DataTarget.URI.c_str(), TimeToStr(invalid_since).c_str());
+              Target.URI.c_str(), TimeToStr(invalid_since).c_str());
         if (ErrorText.empty())
            ErrorText = errmsg;
         return _error->Error("%s", errmsg.c_str());
@@ -1073,16 +1514,18 @@ bool pkgAcqMetaBase::VerifyVendor(string const &Message)                /*{{{*/
         TransactionManager->LastMetaIndexParser->GetDate() > TransactionManager->MetaIndexParser->GetDate())
    {
       TransactionManager->IMSHit = true;
-      unlink(DestFile.c_str());
+      RemoveFile("VerifyVendor", DestFile);
       PartialFile = DestFile = GetFinalFilename();
-      delete TransactionManager->MetaIndexParser;
-      TransactionManager->MetaIndexParser = TransactionManager->LastMetaIndexParser;
+      // load the 'old' file in the 'new' one instead of flipping pointers as
+      // the new one isn't owned by us, while the old one is so cleanup would be confused.
+      TransactionManager->MetaIndexParser->swapLoad(TransactionManager->LastMetaIndexParser);
+      delete TransactionManager->LastMetaIndexParser;
       TransactionManager->LastMetaIndexParser = NULL;
    }
 
    if (_config->FindB("Debug::pkgAcquire::Auth", false)) 
    {
-      std::cerr << "Got Codename: " << TransactionManager->MetaIndexParser->GetDist() << std::endl;
+      std::cerr << "Got Codename: " << TransactionManager->MetaIndexParser->GetCodename() << std::endl;
       std::cerr << "Expecting Dist: " << TransactionManager->MetaIndexParser->GetExpectedDist() << std::endl;
       std::cerr << "Transformed Dist: " << Transformed << std::endl;
    }
@@ -1093,37 +1536,41 @@ bool pkgAcqMetaBase::VerifyVendor(string const &Message)                /*{{{*/
 //       Status = StatAuthError;
 //       ErrorText = "Conflicting distribution; expected "
 //          + MetaIndexParser->GetExpectedDist() + " but got "
-//          + MetaIndexParser->GetDist();
+//          + MetaIndexParser->GetCodename();
 //       return false;
       if (!Transformed.empty())
       {
          _error->Warning(_("Conflicting distribution: %s (expected %s but got %s)"),
                          Desc.Description.c_str(),
                          Transformed.c_str(),
-                         TransactionManager->MetaIndexParser->GetDist().c_str());
+                         TransactionManager->MetaIndexParser->GetCodename().c_str());
       }
    }
 
    return true;
 }
                                                                        /*}}}*/
+pkgAcqMetaBase::~pkgAcqMetaBase()
+{
+}
 
 pkgAcqMetaClearSig::pkgAcqMetaClearSig(pkgAcquire * const Owner,       /*{{{*/
       IndexTarget const &ClearsignedTarget,
       IndexTarget const &DetachedDataTarget, IndexTarget const &DetachedSigTarget,
-      const vector<IndexTarget*>* const IndexTargets,
-      indexRecords * const MetaIndexParser) :
-   pkgAcqMetaIndex(Owner, this, ClearsignedTarget, DetachedSigTarget, IndexTargets, MetaIndexParser),
-   ClearsignedTarget(ClearsignedTarget),
-   DetachedDataTarget(DetachedDataTarget), DetachedSigTarget(DetachedSigTarget)
+      metaIndex * const MetaIndexParser) :
+   pkgAcqMetaIndex(Owner, this, ClearsignedTarget, DetachedSigTarget),
+   d(NULL), DetachedDataTarget(DetachedDataTarget),
+   MetaIndexParser(MetaIndexParser), LastMetaIndexParser(NULL)
 {
    // index targets + (worst case:) Release/Release.gpg
-   ExpectedAdditionalItems = IndexTargets->size() + 2;
+   ExpectedAdditionalItems = std::numeric_limits<decltype(ExpectedAdditionalItems)>::max();
    TransactionManager->Add(this);
 }
                                                                        /*}}}*/
 pkgAcqMetaClearSig::~pkgAcqMetaClearSig()                              /*{{{*/
 {
+   if (LastMetaIndexParser != NULL)
+      delete LastMetaIndexParser;
 }
                                                                        /*}}}*/
 // pkgAcqMetaClearSig::Custom600Headers - Insert custom request headers        /*{{{*/
@@ -1131,9 +1578,33 @@ string pkgAcqMetaClearSig::Custom600Headers() const
 {
    string Header = pkgAcqMetaBase::Custom600Headers();
    Header += "\nFail-Ignore: true";
+   std::string const key = TransactionManager->MetaIndexParser->GetSignedBy();
+   if (key.empty() == false)
+      Header += "\nSigned-By: " + key;
+
    return Header;
 }
                                                                        /*}}}*/
+void pkgAcqMetaClearSig::Finished()                                    /*{{{*/
+{
+   if(_config->FindB("Debug::Acquire::Transaction", false) == true)
+      std::clog << "Finished: " << DestFile <<std::endl;
+   if(TransactionManager->State == TransactionStarted &&
+      TransactionManager->TransactionHasError() == false)
+      TransactionManager->CommitTransaction();
+}
+                                                                       /*}}}*/
+bool pkgAcqMetaClearSig::VerifyDone(std::string const &Message,                /*{{{*/
+        pkgAcquire::MethodConfig const * const Cnf)
+{
+   Item::VerifyDone(Message, Cnf);
+
+   if (FileExists(DestFile) && !StartsWithGPGClearTextSignature(DestFile))
+      return RenameOnError(NotClearsigned);
+
+   return true;
+}
+                                                                       /*}}}*/
 // pkgAcqMetaClearSig::Done - We got a file                            /*{{{*/
 void pkgAcqMetaClearSig::Done(std::string const &Message,
                               HashStringList const &Hashes,
@@ -1141,17 +1612,6 @@ void pkgAcqMetaClearSig::Done(std::string const &Message,
 {
    Item::Done(Message, Hashes, Cnf);
 
-   // if we expect a ClearTextSignature (InRelease), ensure that
-   // this is what we get and if not fail to queue a 
-   // Release/Release.gpg, see #346386
-   if (FileExists(DestFile) && !StartsWithGPGClearTextSignature(DestFile))
-   {
-      pkgAcquire::Item::Failed(Message, Cnf);
-      RenameOnError(NotClearsigned);
-      TransactionManager->AbortTransaction();
-      return;
-   }
-
    if(AuthPass == false)
    {
       if(CheckDownloadDone(this, Message, Hashes) == true)
@@ -1167,42 +1627,53 @@ void pkgAcqMetaClearSig::Done(std::string const &Message,
         // We got an InRelease file IMSHit, but we haven't one, which means
         // we had a valid Release/Release.gpg combo stepping in, which we have
         // to 'acquire' now to ensure list cleanup isn't removing them
-        new NoActionItem(Owner, &DetachedDataTarget);
-        new NoActionItem(Owner, &DetachedSigTarget);
+        new NoActionItem(Owner, DetachedDataTarget);
+        new NoActionItem(Owner, DetachedSigTarget);
       }
    }
+   else if (Status != StatAuthError)
+   {
+      string const FinalFile = GetFinalFileNameFromURI(DetachedDataTarget.URI);
+      string const OldFile = GetFinalFilename();
+      if (TransactionManager->IMSHit == false)
+        TransactionManager->TransactionStageCopy(this, DestFile, FinalFile);
+      else if (RealFileExists(OldFile) == false)
+        new NoActionItem(Owner, DetachedDataTarget);
+      else
+        TransactionManager->TransactionStageCopy(this, OldFile, FinalFile);
+   }
 }
                                                                        /*}}}*/
 void pkgAcqMetaClearSig::Failed(string const &Message,pkgAcquire::MethodConfig const * const Cnf) /*{{{*/
 {
    Item::Failed(Message, Cnf);
 
-   // we failed, we will not get additional items from this method
-   ExpectedAdditionalItems = 0;
-
    if (AuthPass == false)
    {
+      if (Status == StatAuthError || Status == StatTransientNetworkError)
+      {
+        // if we expected a ClearTextSignature (InRelease) but got a network
+        // error or got a file, but it wasn't valid, we end up here (see VerifyDone).
+        // As these is usually called by web-portals we do not try Release/Release.gpg
+        // as this is gonna fail anyway and instead abort our try (LP#346386)
+        TransactionManager->AbortTransaction();
+        return;
+      }
+
       // Queue the 'old' InRelease file for removal if we try Release.gpg
       // as otherwise the file will stay around and gives a false-auth
       // impression (CVE-2012-0214)
       TransactionManager->TransactionStageRemoval(this, GetFinalFilename());
       Status = StatDone;
 
-      new pkgAcqMetaIndex(Owner, TransactionManager, DetachedDataTarget, DetachedSigTarget, IndexTargets, TransactionManager->MetaIndexParser);
+      new pkgAcqMetaIndex(Owner, TransactionManager, DetachedDataTarget, DetachedSigTarget);
    }
    else
    {
       if(CheckStopAuthentication(this, Message))
          return;
 
-      _error->Warning(_("The data from '%s' is not signed. Packages "
-                        "from that repository can not be authenticated."),
-                      ClearsignedTarget.Description.c_str());
-
-      // No Release file was present, or verification failed, so fall
-      // back to queueing Packages files without verification
-      // only allow going further if the users explicitely wants it
-      if(AllowInsecureRepositories(TransactionManager->MetaIndexParser, TransactionManager, this) == true)
+      if(AllowInsecureRepositories(InsecureType::UNSIGNED, Target.Description, TransactionManager->MetaIndexParser, TransactionManager, this) == true)
       {
         Status = StatDone;
 
@@ -1214,46 +1685,24 @@ void pkgAcqMetaClearSig::Failed(string const &Message,pkgAcquire::MethodConfig c
         string const FinalInRelease = GetFinalFilename();
         Rename(DestFile, PartialRelease);
         TransactionManager->TransactionStageCopy(this, PartialRelease, FinalRelease);
-
-        if (RealFileExists(FinalReleasegpg) || RealFileExists(FinalInRelease))
-        {
-           // open the last Release if we have it
-           if (TransactionManager->IMSHit == false)
-           {
-              TransactionManager->LastMetaIndexParser = new indexRecords;
-              _error->PushToStack();
-              if (RealFileExists(FinalInRelease))
-                 TransactionManager->LastMetaIndexParser->Load(FinalInRelease);
-              else
-                 TransactionManager->LastMetaIndexParser->Load(FinalRelease);
-              // its unlikely to happen, but if what we have is bad ignore it
-              if (_error->PendingError())
-              {
-                 delete TransactionManager->LastMetaIndexParser;
-                 TransactionManager->LastMetaIndexParser = NULL;
-              }
-              _error->RevertToStack();
-           }
-        }
+        LoadLastMetaIndexParser(TransactionManager, FinalRelease, FinalInRelease);
 
         // we parse the indexes here because at this point the user wanted
         // a repository that may potentially harm him
-        if (TransactionManager->MetaIndexParser->Load(PartialRelease) == false || VerifyVendor(Message) == false)
+        if (TransactionManager->MetaIndexParser->Load(PartialRelease, &ErrorText) == false || VerifyVendor(Message) == false)
            /* expired Release files are still a problem you need extra force for */;
         else
-           QueueIndexes(true);
+           TransactionManager->QueueIndexes(true);
       }
    }
 }
                                                                        /*}}}*/
 
 pkgAcqMetaIndex::pkgAcqMetaIndex(pkgAcquire * const Owner,             /*{{{*/
-                                 pkgAcqMetaBase * const TransactionManager,
+                                 pkgAcqMetaClearSig * const TransactionManager,
                                 IndexTarget const &DataTarget,
-                                IndexTarget const &DetachedSigTarget,
-                                vector<IndexTarget*> const * const IndexTargets,
-                                indexRecords * const MetaIndexParser) :
-   pkgAcqMetaBase(Owner, TransactionManager, IndexTargets, DataTarget, MetaIndexParser),
+                                IndexTarget const &DetachedSigTarget) :
+   pkgAcqMetaBase(Owner, TransactionManager, DataTarget), d(NULL),
    DetachedSigTarget(DetachedSigTarget)
 {
    if(_config->FindB("Debug::Acquire::Transaction", false) == true)
@@ -1267,9 +1716,6 @@ pkgAcqMetaIndex::pkgAcqMetaIndex(pkgAcquire * const Owner,                /*{{{*/
    Desc.Owner = this;
    Desc.ShortDesc = DataTarget.ShortDesc;
    Desc.URI = DataTarget.URI;
-
-   // we expect more item
-   ExpectedAdditionalItems = IndexTargets->size();
    QueueURI(Desc);
 }
                                                                        /*}}}*/
@@ -1284,7 +1730,7 @@ void pkgAcqMetaIndex::Done(string const &Message,                 /*{{{*/
       // we have a Release file, now download the Signature, all further
       // verify/queue for additional downloads will be done in the
       // pkgAcqMetaSig::Done() code
-      new pkgAcqMetaSig(Owner, TransactionManager, &DetachedSigTarget, this);
+      new pkgAcqMetaSig(Owner, TransactionManager, DetachedSigTarget, this);
    }
 }
                                                                        /*}}}*/
@@ -1295,53 +1741,39 @@ void pkgAcqMetaIndex::Failed(string const &Message,
    pkgAcquire::Item::Failed(Message, Cnf);
    Status = StatDone;
 
-   _error->Warning(_("The repository '%s' does not have a Release file. "
-                     "This is deprecated, please contact the owner of the "
-                     "repository."), DataTarget.Description.c_str());
-
    // No Release file was present so fall
    // back to queueing Packages files without verification
-   // only allow going further if the users explicitely wants it
-   if(AllowInsecureRepositories(TransactionManager->MetaIndexParser, TransactionManager, this) == true)
+   // only allow going further if the user explicitly wants it
+   if(AllowInsecureRepositories(InsecureType::NORELEASE, Target.Description, TransactionManager->MetaIndexParser, TransactionManager, this) == true)
    {
       // ensure old Release files are removed
       TransactionManager->TransactionStageRemoval(this, GetFinalFilename());
-      delete TransactionManager->MetaIndexParser;
-      TransactionManager->MetaIndexParser = NULL;
 
       // queue without any kind of hashsum support
-      QueueIndexes(false);
+      TransactionManager->QueueIndexes(false);
    }
 }
                                                                        /*}}}*/
-void pkgAcqMetaIndex::Finished()                                       /*{{{*/
-{
-   if(_config->FindB("Debug::Acquire::Transaction", false) == true)
-      std::clog << "Finished: " << DestFile <<std::endl;
-   if(TransactionManager != NULL &&
-      TransactionManager->TransactionHasError() == false)
-      TransactionManager->CommitTransaction();
-}
-                                                                       /*}}}*/
 std::string pkgAcqMetaIndex::DescURI() const                           /*{{{*/
 {
-   return DataTarget.URI;
+   return Target.URI;
 }
                                                                        /*}}}*/
+pkgAcqMetaIndex::~pkgAcqMetaIndex() {}
 
 // AcqMetaSig::AcqMetaSig - Constructor                                        /*{{{*/
 pkgAcqMetaSig::pkgAcqMetaSig(pkgAcquire * const Owner,
-      pkgAcqMetaBase * const TransactionManager,
-      IndexTarget const * const Target,
+      pkgAcqMetaClearSig * const TransactionManager,
+      IndexTarget const &Target,
       pkgAcqMetaIndex * const MetaIndex) :
-   pkgAcqTransactionItem(Owner, TransactionManager, Target), MetaIndex(MetaIndex)
+   pkgAcqTransactionItem(Owner, TransactionManager, Target), d(NULL), MetaIndex(MetaIndex)
 {
-   DestFile = GetPartialFileNameFromURI(Target->URI);
+   DestFile = GetPartialFileNameFromURI(Target.URI);
 
    // remove any partial downloaded sig-file in partial/.
    // it may confuse proxies and is too small to warrant a
    // partial download anyway
-   unlink(DestFile.c_str());
+   RemoveFile("pkgAcqMetaSig", DestFile);
 
    // set the TransactionManager
    if(_config->FindB("Debug::Acquire::Transaction", false) == true)
@@ -1349,10 +1781,10 @@ pkgAcqMetaSig::pkgAcqMetaSig(pkgAcquire * const Owner,
                 << TransactionManager << std::endl;
 
    // Create the item
-   Desc.Description = Target->Description;
+   Desc.Description = Target.Description;
    Desc.Owner = this;
-   Desc.ShortDesc = Target->ShortDesc;
-   Desc.URI = Target->URI;
+   Desc.ShortDesc = Target.ShortDesc;
+   Desc.URI = Target.URI;
 
    // If we got a hit for Release, we will get one for Release.gpg too (or obscure errors),
    // so we skip the download step and go instantly to verification
@@ -1370,6 +1802,16 @@ pkgAcqMetaSig::pkgAcqMetaSig(pkgAcquire * const Owner,
                                                                        /*}}}*/
 pkgAcqMetaSig::~pkgAcqMetaSig()                                                /*{{{*/
 {
+}
+                                                                       /*}}}*/
+// pkgAcqMetaSig::Custom600Headers - Insert custom request headers     /*{{{*/
+std::string pkgAcqMetaSig::Custom600Headers() const
+{
+   std::string Header = pkgAcqTransactionItem::Custom600Headers();
+   std::string const key = TransactionManager->MetaIndexParser->GetSignedBy();
+   if (key.empty() == false)
+      Header += "\nSigned-By: " + key;
+   return Header;
 }
                                                                        /*}}}*/
 // AcqMetaSig::Done - The signature was downloaded/verified            /*{{{*/
@@ -1402,6 +1844,14 @@ void pkgAcqMetaSig::Done(string const &Message, HashStringList const &Hashes,
         TransactionManager->TransactionStageCopy(MetaIndex, MetaIndex->DestFile, MetaIndex->GetFinalFilename());
       }
    }
+   else if (MetaIndex->Status != StatAuthError)
+   {
+      std::string const FinalFile = MetaIndex->GetFinalFilename();
+      if (TransactionManager->IMSHit == false)
+        TransactionManager->TransactionStageCopy(MetaIndex, MetaIndex->DestFile, FinalFile);
+      else
+        TransactionManager->TransactionStageCopy(MetaIndex, FinalFile, FinalFile);
+   }
 }
                                                                        /*}}}*/
 void pkgAcqMetaSig::Failed(string const &Message,pkgAcquire::MethodConfig const * const Cnf)/*{{{*/
@@ -1412,74 +1862,28 @@ void pkgAcqMetaSig::Failed(string const &Message,pkgAcquire::MethodConfig const
    if (MetaIndex->AuthPass == true && MetaIndex->CheckStopAuthentication(this, Message))
          return;
 
-   string const FinalRelease = MetaIndex->GetFinalFilename();
-   string const FinalReleasegpg = GetFinalFilename();
-   string const FinalInRelease = TransactionManager->GetFinalFilename();
-
-   if (RealFileExists(FinalReleasegpg) || RealFileExists(FinalInRelease))
-   {
-      std::string downgrade_msg;
-      strprintf(downgrade_msg, _("The repository '%s' is no longer signed."),
-                MetaIndex->DataTarget.Description.c_str());
-      if(_config->FindB("Acquire::AllowDowngradeToInsecureRepositories"))
-      {
-         // meh, the users wants to take risks (we still mark the packages
-         // from this repository as unauthenticated)
-         _error->Warning("%s", downgrade_msg.c_str());
-         _error->Warning(_("This is normally not allowed, but the option "
-                           "Acquire::AllowDowngradeToInsecureRepositories was "
-                           "given to override it."));
-         Status = StatDone;
-      } else {
-         _error->Error("%s", downgrade_msg.c_str());
-        if (TransactionManager->IMSHit == false)
-           Rename(MetaIndex->DestFile, MetaIndex->DestFile + ".FAILED");
-        Item::Failed("Message: " + downgrade_msg, Cnf);
-         TransactionManager->AbortTransaction();
-         return;
-      }
-   }
-   else
-      _error->Warning(_("The data from '%s' is not signed. Packages "
-              "from that repository can not be authenticated."),
-           MetaIndex->DataTarget.Description.c_str());
-
    // ensures that a Release.gpg file in the lists/ is removed by the transaction
    TransactionManager->TransactionStageRemoval(this, DestFile);
 
-   // only allow going further if the users explicitely wants it
-   if(AllowInsecureRepositories(TransactionManager->MetaIndexParser, TransactionManager, this) == true)
+   // only allow going further if the user explicitly wants it
+   if (AllowInsecureRepositories(InsecureType::UNSIGNED, MetaIndex->Target.Description, TransactionManager->MetaIndexParser, TransactionManager, this) == true)
    {
-      if (RealFileExists(FinalReleasegpg) || RealFileExists(FinalInRelease))
-      {
-        // open the last Release if we have it
-        if (TransactionManager->IMSHit == false)
-        {
-           TransactionManager->LastMetaIndexParser = new indexRecords;
-           _error->PushToStack();
-           if (RealFileExists(FinalInRelease))
-              TransactionManager->LastMetaIndexParser->Load(FinalInRelease);
-           else
-              TransactionManager->LastMetaIndexParser->Load(FinalRelease);
-           // its unlikely to happen, but if what we have is bad ignore it
-           if (_error->PendingError())
-           {
-              delete TransactionManager->LastMetaIndexParser;
-              TransactionManager->LastMetaIndexParser = NULL;
-           }
-           _error->RevertToStack();
-        }
-      }
+      string const FinalRelease = MetaIndex->GetFinalFilename();
+      string const FinalInRelease = TransactionManager->GetFinalFilename();
+      LoadLastMetaIndexParser(TransactionManager, FinalRelease, FinalInRelease);
 
       // we parse the indexes here because at this point the user wanted
       // a repository that may potentially harm him
-      if (TransactionManager->MetaIndexParser->Load(MetaIndex->DestFile) == false || MetaIndex->VerifyVendor(Message) == false)
+      bool const GoodLoad = TransactionManager->MetaIndexParser->Load(MetaIndex->DestFile, &ErrorText);
+      if (MetaIndex->VerifyVendor(Message) == false)
         /* expired Release files are still a problem you need extra force for */;
       else
-        MetaIndex->QueueIndexes(true);
+        TransactionManager->QueueIndexes(GoodLoad);
 
-      TransactionManager->TransactionStageCopy(MetaIndex, MetaIndex->DestFile, MetaIndex->GetFinalFilename());
+      TransactionManager->TransactionStageCopy(MetaIndex, MetaIndex->DestFile, FinalRelease);
    }
+   else if (TransactionManager->IMSHit == false)
+      Rename(MetaIndex->DestFile, MetaIndex->DestFile + ".FAILED");
 
    // FIXME: this is used often (e.g. in pkgAcqIndexTrans) so refactor
    if (Cnf->LocalOnly == true ||
@@ -1494,12 +1898,28 @@ void pkgAcqMetaSig::Failed(string const &Message,pkgAcquire::MethodConfig const
 
 // AcqBaseIndex - Constructor                                          /*{{{*/
 pkgAcqBaseIndex::pkgAcqBaseIndex(pkgAcquire * const Owner,
-      pkgAcqMetaBase * const TransactionManager,
-      IndexTarget const * const Target)
-: pkgAcqTransactionItem(Owner, TransactionManager, Target)
+      pkgAcqMetaClearSig * const TransactionManager,
+      IndexTarget const &Target)
+: pkgAcqTransactionItem(Owner, TransactionManager, Target), d(NULL)
 {
 }
                                                                        /*}}}*/
+void pkgAcqBaseIndex::Failed(std::string const &Message,pkgAcquire::MethodConfig const * const Cnf)/*{{{*/
+{
+   pkgAcquire::Item::Failed(Message, Cnf);
+   if (Status != StatAuthError)
+      return;
+
+   ErrorText.append("Release file created at: ");
+   auto const timespec = TransactionManager->MetaIndexParser->GetDate();
+   if (timespec == 0)
+      ErrorText.append("<unknown>");
+   else
+      ErrorText.append(TimeRFC1123(timespec, true));
+   ErrorText.append("\n");
+}
+                                                                       /*}}}*/
+pkgAcqBaseIndex::~pkgAcqBaseIndex() {}
 
 // AcqDiffIndex::AcqDiffIndex - Constructor                            /*{{{*/
 // ---------------------------------------------------------------------
@@ -1509,16 +1929,19 @@ pkgAcqBaseIndex::pkgAcqBaseIndex(pkgAcquire * const Owner,
  * the original packages file
  */
 pkgAcqDiffIndex::pkgAcqDiffIndex(pkgAcquire * const Owner,
-                                 pkgAcqMetaBase * const TransactionManager,
-                                 IndexTarget const * const Target)
-   : pkgAcqBaseIndex(Owner, TransactionManager, Target)
+                                 pkgAcqMetaClearSig * const TransactionManager,
+                                 IndexTarget const &Target)
+   : pkgAcqBaseIndex(Owner, TransactionManager, Target), d(NULL), diffs(NULL)
 {
+   // FIXME: Magic number as an upper bound on pdiffs we will reasonably acquire
+   ExpectedAdditionalItems = 40;
+
    Debug = _config->FindB("Debug::pkgAcquire::Diffs",false);
 
    Desc.Owner = this;
-   Desc.Description = Target->Description + ".diff/Index";
-   Desc.ShortDesc = Target->ShortDesc;
-   Desc.URI = Target->URI + ".diff/Index";
+   Desc.Description = GetDiffIndexFileName(Target.Description);
+   Desc.ShortDesc = Target.ShortDesc;
+   Desc.URI = GetDiffIndexURI(Target);
 
    DestFile = GetPartialFileNameFromURI(Desc.URI);
 
@@ -1533,6 +1956,9 @@ pkgAcqDiffIndex::pkgAcqDiffIndex(pkgAcquire * const Owner,
 /* The only header we use is the last-modified header. */
 string pkgAcqDiffIndex::Custom600Headers() const
 {
+   if (TransactionManager->LastMetaIndexParser != NULL)
+      return "\nIndex-File: true";
+
    string const Final = GetFinalFilename();
 
    if(Debug)
@@ -1542,7 +1968,7 @@ string pkgAcqDiffIndex::Custom600Headers() const
    if (stat(Final.c_str(),&Buf) != 0)
       return "\nIndex-File: true";
    
-   return "\nIndex-File: true\nLast-Modified: " + TimeRFC1123(Buf.st_mtime);
+   return "\nIndex-File: true\nLast-Modified: " + TimeRFC1123(Buf.st_mtime, false);
 }
                                                                        /*}}}*/
 void pkgAcqDiffIndex::QueueOnIMSHit() const                            /*{{{*/
@@ -1554,6 +1980,7 @@ void pkgAcqDiffIndex::QueueOnIMSHit() const                               /*{{{*/
                                                                        /*}}}*/
 bool pkgAcqDiffIndex::ParseDiffIndex(string const &IndexDiffFile)      /*{{{*/
 {
+   ExpectedAdditionalItems = 0;
    // failing here is fine: our caller will take care of trying to
    // get the complete file if patching fails
    if(Debug)
@@ -1562,7 +1989,7 @@ bool pkgAcqDiffIndex::ParseDiffIndex(string const &IndexDiffFile) /*{{{*/
 
    FileFd Fd(IndexDiffFile,FileFd::ReadOnly);
    pkgTagFile TF(&Fd);
-   if (_error->PendingError() == true)
+   if (Fd.IsOpen() == false || Fd.Failed())
       return false;
 
    pkgTagSection Tags;
@@ -1572,6 +1999,7 @@ bool pkgAcqDiffIndex::ParseDiffIndex(string const &IndexDiffFile) /*{{{*/
    HashStringList ServerHashes;
    unsigned long long ServerSize = 0;
 
+   auto const &posix = std::locale("C.UTF-8");
    for (char const * const * type = HashString::SupportedHashes(); *type != NULL; ++type)
    {
       std::string tagname = *type;
@@ -1583,6 +2011,7 @@ bool pkgAcqDiffIndex::ParseDiffIndex(string const &IndexDiffFile) /*{{{*/
       string hash;
       unsigned long long size;
       std::stringstream ss(tmp);
+      ss.imbue(posix);
       ss >> hash >> size;
       if (unlikely(hash.empty() == true))
         continue;
@@ -1599,14 +2028,14 @@ bool pkgAcqDiffIndex::ParseDiffIndex(string const &IndexDiffFile)       /*{{{*/
       return false;
    }
 
-   std::string const CurrentPackagesFile = GetFinalFileNameFromURI(Target->URI);
-   HashStringList const TargetFileHashes = GetExpectedHashesFor(Target->MetaKey);
+   std::string const CurrentPackagesFile = GetFinalFileNameFromURI(Target.URI);
+   HashStringList const TargetFileHashes = GetExpectedHashesFor(Target.MetaKey);
    if (TargetFileHashes.usable() == false || ServerHashes != TargetFileHashes)
    {
       if (Debug == true)
       {
         std::clog << "pkgAcqDiffIndex: " << IndexDiffFile << ": Index has different hashes than parser, probably older, so fail pdiffing" << std::endl;
-         printHashSumComparision(CurrentPackagesFile, ServerHashes, TargetFileHashes);
+         printHashSumComparison(CurrentPackagesFile, ServerHashes, TargetFileHashes);
       }
       return false;
    }
@@ -1614,10 +2043,10 @@ bool pkgAcqDiffIndex::ParseDiffIndex(string const &IndexDiffFile)       /*{{{*/
    HashStringList LocalHashes;
    // try avoiding calculating the hash here as this is costly
    if (TransactionManager->LastMetaIndexParser != NULL)
-      LocalHashes = GetExpectedHashesFromFor(TransactionManager->LastMetaIndexParser, Target->MetaKey);
+      LocalHashes = GetExpectedHashesFromFor(TransactionManager->LastMetaIndexParser, Target.MetaKey);
    if (LocalHashes.usable() == false)
    {
-      FileFd fd(CurrentPackagesFile, FileFd::ReadOnly);
+      FileFd fd(CurrentPackagesFile, FileFd::ReadOnly, FileFd::Auto);
       Hashes LocalHashesCalc(ServerHashes);
       LocalHashesCalc.AddFD(fd);
       LocalHashes = LocalHashesCalc.GetHashStringList();
@@ -1636,10 +2065,18 @@ bool pkgAcqDiffIndex::ParseDiffIndex(string const &IndexDiffFile)       /*{{{*/
       std::clog << "Server-Current: " << ServerHashes.find(NULL)->toStr() << " and we start at "
         << CurrentPackagesFile << " " << LocalHashes.FileSize() << " " << LocalHashes.find(NULL)->toStr() << std::endl;
 
+   // historically, older hashes have more info than newer ones, so start
+   // collecting with older ones first to avoid implementing complicated
+   // information merging techniques… a failure is after all always
+   // recoverable with a complete file and hashes aren't changed that often.
+   std::vector<char const *> types;
+   for (char const * const * type = HashString::SupportedHashes(); *type != NULL; ++type)
+      types.push_back(*type);
+
    // parse all of (provided) history
    vector<DiffInfo> available_patches;
    bool firstAcceptedHashes = true;
-   for (char const * const * type = HashString::SupportedHashes(); *type != NULL; ++type)
+   for (auto type = types.crbegin(); type != types.crend(); ++type)
    {
       if (LocalHashes.find(*type) == NULL)
         continue;
@@ -1653,6 +2090,7 @@ bool pkgAcqDiffIndex::ParseDiffIndex(string const &IndexDiffFile) /*{{{*/
       string hash, filename;
       unsigned long long size;
       std::stringstream ss(tmp);
+      ss.imbue(posix);
 
       while (ss >> hash >> size >> filename)
       {
@@ -1697,7 +2135,7 @@ bool pkgAcqDiffIndex::ParseDiffIndex(string const &IndexDiffFile) /*{{{*/
       return false;
    }
 
-   for (char const * const * type = HashString::SupportedHashes(); *type != NULL; ++type)
+   for (auto type = types.crbegin(); type != types.crend(); ++type)
    {
       if (LocalHashes.find(*type) == NULL)
         continue;
@@ -1711,6 +2149,7 @@ bool pkgAcqDiffIndex::ParseDiffIndex(string const &IndexDiffFile) /*{{{*/
       string hash, filename;
       unsigned long long size;
       std::stringstream ss(tmp);
+      ss.imbue(posix);
 
       while (ss >> hash >> size >> filename)
       {
@@ -1737,7 +2176,7 @@ bool pkgAcqDiffIndex::ParseDiffIndex(string const &IndexDiffFile) /*{{{*/
       }
    }
 
-   for (char const * const * type = HashString::SupportedHashes(); *type != NULL; ++type)
+   for (auto type = types.crbegin(); type != types.crend(); ++type)
    {
       std::string tagname = *type;
       tagname.append("-Download");
@@ -1748,6 +2187,7 @@ bool pkgAcqDiffIndex::ParseDiffIndex(string const &IndexDiffFile) /*{{{*/
       string hash, filename;
       unsigned long long size;
       std::stringstream ss(tmp);
+      ss.imbue(posix);
 
       // FIXME: all of pdiff supports only .gz compressed patches
       while (ss >> hash >> size >> filename)
@@ -1799,6 +2239,17 @@ bool pkgAcqDiffIndex::ParseDiffIndex(string const &IndexDiffFile)        /*{{{*/
       return false;
    }
 
+   for (auto const &patch: available_patches)
+      if (patch.result_hashes.usable() == false ||
+           patch.patch_hashes.usable() == false ||
+           patch.download_hashes.usable() == false)
+      {
+        if (Debug)
+           std::clog << "pkgAcqDiffIndex: " << IndexDiffFile << ": provides no usable hashes for " << patch.file
+              << " so fallback to complete download" << std::endl;
+        return false;
+      }
+
    // patching with too many files is rather slow compared to a fast download
    unsigned long const fileLimit = _config->FindI("Acquire::PDiffs::FileLimit", 0);
    if (fileLimit != 0 && fileLimit < available_patches.size())
@@ -1810,18 +2261,37 @@ bool pkgAcqDiffIndex::ParseDiffIndex(string const &IndexDiffFile)       /*{{{*/
    }
 
    // calculate the size of all patches we have to get
-   // note that all sizes are uncompressed, while we download compressed files
-   unsigned long long patchesSize = 0;
-   for (std::vector<DiffInfo>::const_iterator cur = available_patches.begin();
-        cur != available_patches.end(); ++cur)
-      patchesSize += cur->patch_hashes.FileSize();
-   unsigned long long const sizeLimit = ServerSize * _config->FindI("Acquire::PDiffs::SizeLimit", 100);
-   if (sizeLimit > 0 && (sizeLimit/100) < patchesSize)
-   {
-      if (Debug)
-        std::clog << "Need " << patchesSize << " bytes (Limit is " << sizeLimit/100
-           << ") so fallback to complete download" << std::endl;
-      return false;
+   unsigned short const sizeLimitPercent = _config->FindI("Acquire::PDiffs::SizeLimit", 100);
+   if (sizeLimitPercent > 0)
+   {
+      unsigned long long downloadSize = std::accumulate(available_patches.begin(),
+           available_patches.end(), 0llu, [](unsigned long long const T, DiffInfo const &I) {
+           return T + I.download_hashes.FileSize();
+           });
+      if (downloadSize != 0)
+      {
+        unsigned long long downloadSizeIdx = 0;
+        auto const types = VectorizeString(Target.Option(IndexTarget::COMPRESSIONTYPES), ' ');
+        for (auto const &t : types)
+        {
+           std::string MetaKey = Target.MetaKey;
+           if (t != "uncompressed")
+              MetaKey += '.' + t;
+           HashStringList const hsl = GetExpectedHashesFor(MetaKey);
+           if (unlikely(hsl.usable() == false))
+              continue;
+           downloadSizeIdx = hsl.FileSize();
+           break;
+        }
+        unsigned long long const sizeLimit = downloadSizeIdx * sizeLimitPercent;
+        if ((sizeLimit/100) < downloadSize)
+        {
+           if (Debug)
+              std::clog << "Need " << downloadSize << " compressed bytes (Limit is " << (sizeLimit/100) << ", "
+                 << "original is " << downloadSizeIdx << ") so fallback to complete download" << std::endl;
+           return false;
+        }
+      }
    }
 
    // we have something, queue the diffs
@@ -1842,11 +2312,46 @@ bool pkgAcqDiffIndex::ParseDiffIndex(string const &IndexDiffFile)       /*{{{*/
       pdiff_merge = (precedence != "merged");
    }
 
+   // clean the plate
+   {
+      std::string const Final = GetExistingFilename(CurrentPackagesFile);
+      if (unlikely(Final.empty())) // because we wouldn't be called in such a case
+        return false;
+      std::string const PartialFile = GetPartialFileNameFromURI(Target.URI);
+      if (FileExists(PartialFile) && RemoveFile("Bootstrap-linking", PartialFile) == false)
+      {
+        if (Debug)
+           std::clog << "Bootstrap-linking for patching " << CurrentPackagesFile
+              << " by removing stale " << PartialFile << " failed!" << std::endl;
+        return false;
+      }
+      for (auto const &ext : APT::Configuration::getCompressorExtensions())
+      {
+        std::string const Partial = PartialFile + ext;
+        if (FileExists(Partial) && RemoveFile("Bootstrap-linking", Partial) == false)
+        {
+           if (Debug)
+              std::clog << "Bootstrap-linking for patching " << CurrentPackagesFile
+                 << " by removing stale " << Partial << " failed!" << std::endl;
+           return false;
+        }
+      }
+      std::string const Ext = Final.substr(CurrentPackagesFile.length());
+      std::string const Partial = PartialFile + Ext;
+      if (symlink(Final.c_str(), Partial.c_str()) != 0)
+      {
+        if (Debug)
+           std::clog << "Bootstrap-linking for patching " << CurrentPackagesFile
+              << " by linking " << Final << " to " << Partial << " failed!" << std::endl;
+        return false;
+      }
+   }
+
    if (pdiff_merge == false)
       new pkgAcqIndexDiffs(Owner, TransactionManager, Target, available_patches);
    else
    {
-      std::vector<pkgAcqIndexMergeDiffs*> *diffs = new std::vector<pkgAcqIndexMergeDiffs*>(available_patches.size());
+      diffs = new std::vector<pkgAcqIndexMergeDiffs*>(available_patches.size());
       for(size_t i = 0; i < available_patches.size(); ++i)
         (*diffs)[i] = new pkgAcqIndexMergeDiffs(Owner, TransactionManager,
                Target,
@@ -1862,8 +2367,9 @@ bool pkgAcqDiffIndex::ParseDiffIndex(string const &IndexDiffFile) /*{{{*/
                                                                        /*}}}*/
 void pkgAcqDiffIndex::Failed(string const &Message,pkgAcquire::MethodConfig const * const Cnf)/*{{{*/
 {
-   Item::Failed(Message,Cnf);
+   pkgAcqBaseIndex::Failed(Message,Cnf);
    Status = StatDone;
+   ExpectedAdditionalItems = 0;
 
    if(Debug)
       std::clog << "pkgAcqDiffIndex failed: " << Desc.URI << " with " << Message << std::endl
@@ -1902,6 +2408,11 @@ void pkgAcqDiffIndex::Done(string const &Message,HashStringList const &Hashes,   /
    return;
 }
                                                                        /*}}}*/
+pkgAcqDiffIndex::~pkgAcqDiffIndex()
+{
+   if (diffs != NULL)
+      delete diffs;
+}
 
 // AcqIndexDiffs::AcqIndexDiffs - Constructor                          /*{{{*/
 // ---------------------------------------------------------------------
@@ -1909,40 +2420,28 @@ void pkgAcqDiffIndex::Done(string const &Message,HashStringList const &Hashes,  /
  * for each diff and the index
  */
 pkgAcqIndexDiffs::pkgAcqIndexDiffs(pkgAcquire * const Owner,
-                                   pkgAcqMetaBase * const TransactionManager,
-                                   IndexTarget const * const Target,
+                                   pkgAcqMetaClearSig * const TransactionManager,
+                                   IndexTarget const &Target,
                                   vector<DiffInfo> const &diffs)
-   : pkgAcqBaseIndex(Owner, TransactionManager, Target),
+   : pkgAcqBaseIndex(Owner, TransactionManager, Target), d(NULL),
      available_patches(diffs)
 {
-   DestFile = GetPartialFileNameFromURI(Target->URI);
+   DestFile = GetKeepCompressedFileName(GetPartialFileNameFromURI(Target.URI), Target);
 
    Debug = _config->FindB("Debug::pkgAcquire::Diffs",false);
 
    Desc.Owner = this;
-   Description = Target->Description;
-   Desc.ShortDesc = Target->ShortDesc;
+   Description = Target.Description;
+   Desc.ShortDesc = Target.ShortDesc;
 
    if(available_patches.empty() == true)
    {
       // we are done (yeah!), check hashes against the final file
-      DestFile = GetFinalFileNameFromURI(Target->URI);
+      DestFile = GetKeepCompressedFileName(GetFinalFileNameFromURI(Target.URI), Target);
       Finish(true);
    }
    else
    {
-      // patching needs to be bootstrapped with the 'old' version
-      std::string const PartialFile = GetPartialFileNameFromURI(Target->URI);
-      if (RealFileExists(PartialFile) == false)
-      {
-        if (symlink(GetFinalFilename().c_str(), PartialFile.c_str()) != 0)
-        {
-           Failed("Link creation of " + PartialFile + " to " + GetFinalFilename() + " failed", NULL);
-           return;
-        }
-      }
-
-      // get the next diff
       State = StateFetchDiff;
       QueueNextDiff();
    }
@@ -1950,17 +2449,20 @@ pkgAcqIndexDiffs::pkgAcqIndexDiffs(pkgAcquire * const Owner,
                                                                        /*}}}*/
 void pkgAcqIndexDiffs::Failed(string const &Message,pkgAcquire::MethodConfig const * const Cnf)/*{{{*/
 {
-   Item::Failed(Message,Cnf);
+   pkgAcqBaseIndex::Failed(Message,Cnf);
    Status = StatDone;
 
+   DestFile = GetKeepCompressedFileName(GetPartialFileNameFromURI(Target.URI), Target);
    if(Debug)
       std::clog << "pkgAcqIndexDiffs failed: " << Desc.URI << " with " << Message << std::endl
-               << "Falling back to normal index file acquire" << std::endl;
-   DestFile = GetPartialFileNameFromURI(Target->URI);
+               << "Falling back to normal index file acquire " << std::endl;
    RenameOnError(PDiffError);
    std::string const patchname = GetDiffsPatchFileName(DestFile);
    if (RealFileExists(patchname))
-      rename(patchname.c_str(), std::string(patchname + ".FAILED").c_str());
+      Rename(patchname, patchname + ".FAILED");
+   std::string const UnpatchedFile = GetExistingFilename(GetPartialFileNameFromURI(Target.URI));
+   if (UnpatchedFile.empty() == false && FileExists(UnpatchedFile))
+      Rename(UnpatchedFile, UnpatchedFile + ".FAILED");
    new pkgAcqIndex(Owner, TransactionManager, Target);
    Finish();
 }
@@ -1977,7 +2479,8 @@ void pkgAcqIndexDiffs::Finish(bool allDone)
    // the file will be cleaned
    if(allDone)
    {
-      TransactionManager->TransactionStageCopy(this, DestFile, GetFinalFilename());
+      std::string const Final = GetKeepCompressedFileName(GetFinalFilename(), Target);
+      TransactionManager->TransactionStageCopy(this, DestFile, Final);
 
       // this is for the "real" finish
       Complete = true;
@@ -1987,6 +2490,8 @@ void pkgAcqIndexDiffs::Finish(bool allDone)
         std::clog << "\n\nallDone: " << DestFile << "\n" << std::endl;
       return;
    }
+   else
+      DestFile.clear();
 
    if(Debug)
       std::clog << "Finishing: " << Desc.URI << std::endl;
@@ -1999,30 +2504,28 @@ void pkgAcqIndexDiffs::Finish(bool allDone)
 bool pkgAcqIndexDiffs::QueueNextDiff()                                 /*{{{*/
 {
    // calc sha1 of the just patched file
-   std::string const FinalFile = GetPartialFileNameFromURI(Target->URI);
-
-   if(!FileExists(FinalFile))
+   std::string const PartialFile = GetExistingFilename(GetPartialFileNameFromURI(Target.URI));
+   if(unlikely(PartialFile.empty()))
    {
-      Failed("Message: No FinalFile " + FinalFile + " available", NULL);
+      Failed("Message: The file " + GetPartialFileNameFromURI(Target.URI) + " isn't available", NULL);
       return false;
    }
 
-   FileFd fd(FinalFile, FileFd::ReadOnly);
+   FileFd fd(PartialFile, FileFd::ReadOnly, FileFd::Extension);
    Hashes LocalHashesCalc;
    LocalHashesCalc.AddFD(fd);
    HashStringList const LocalHashes = LocalHashesCalc.GetHashStringList();
 
    if(Debug)
-      std::clog << "QueueNextDiff: " << FinalFile << " (" << LocalHashes.find(NULL)->toStr() << ")" << std::endl;
+      std::clog << "QueueNextDiff: " << PartialFile << " (" << LocalHashes.find(NULL)->toStr() << ")" << std::endl;
 
-   HashStringList const TargetFileHashes = GetExpectedHashesFor(Target->MetaKey);
+   HashStringList const TargetFileHashes = GetExpectedHashesFor(Target.MetaKey);
    if (unlikely(LocalHashes.usable() == false || TargetFileHashes.usable() == false))
    {
-      Failed("Local/Expected hashes are not usable", NULL);
+      Failed("Local/Expected hashes are not usable for " + PartialFile, NULL);
       return false;
    }
 
-
    // final file reached before all patches are applied
    if(LocalHashes == TargetFileHashes)
    {
@@ -2032,26 +2535,22 @@ bool pkgAcqIndexDiffs::QueueNextDiff()                                  /*{{{*/
 
    // remove all patches until the next matching patch is found
    // this requires the Index file to be ordered
-   for(vector<DiffInfo>::iterator I = available_patches.begin();
-       available_patches.empty() == false &&
-         I != available_patches.end() &&
-         I->result_hashes != LocalHashes;
-       ++I)
-   {
-      available_patches.erase(I);
-   }
+   available_patches.erase(available_patches.begin(),
+        std::find_if(available_patches.begin(), available_patches.end(), [&](DiffInfo const &I) {
+           return I.result_hashes == LocalHashes;
+           }));
 
    // error checking and falling back if no patch was found
    if(available_patches.empty() == true)
    {
-      Failed("No patches left to reach target", NULL);
+      Failed("No patches left to reach target for " + PartialFile, NULL);
       return false;
    }
 
    // queue the right diff
-   Desc.URI = Target->URI + ".diff/" + available_patches[0].file + ".gz";
+   Desc.URI = Target.URI + ".diff/" + available_patches[0].file + ".gz";
    Desc.Description = Description + " " + available_patches[0].file + string(".pdiff");
-   DestFile = GetPartialFileNameFromURI(Target->URI + ".diff/" + available_patches[0].file);
+   DestFile = GetKeepCompressedFileName(GetPartialFileNameFromURI(Target.URI + ".diff/" + available_patches[0].file), Target);
 
    if(Debug)
       std::clog << "pkgAcqIndexDiffs::QueueNextDiff(): " << Desc.URI << std::endl;
@@ -2064,55 +2563,51 @@ bool pkgAcqIndexDiffs::QueueNextDiff()                                  /*{{{*/
 void pkgAcqIndexDiffs::Done(string const &Message, HashStringList const &Hashes,       /*{{{*/
                            pkgAcquire::MethodConfig const * const Cnf)
 {
-   if(Debug)
+   if (Debug)
       std::clog << "pkgAcqIndexDiffs::Done(): " << Desc.URI << std::endl;
 
    Item::Done(Message, Hashes, Cnf);
 
-   std::string const FinalFile = GetPartialFileNameFromURI(Target->URI);
-   std::string const PatchFile = GetDiffsPatchFileName(FinalFile);
-
-   // success in downloading a diff, enter ApplyDiff state
-   if(State == StateFetchDiff)
-   {
-      Rename(DestFile, PatchFile);
-
-      if(Debug)
-        std::clog << "Sending to rred method: " << FinalFile << std::endl;
-
-      State = StateApplyDiff;
-      Local = true;
-      Desc.URI = "rred:" + FinalFile;
-      QueueURI(Desc);
-      SetActiveSubprocess("rred");
-      return;
-   }
+   std::string const UncompressedUnpatchedFile = GetPartialFileNameFromURI(Target.URI);
+   std::string const UnpatchedFile = GetExistingFilename(UncompressedUnpatchedFile);
+   std::string const PatchFile = GetDiffsPatchFileName(UnpatchedFile);
+   std::string const PatchedFile = GetKeepCompressedFileName(UncompressedUnpatchedFile, Target);
 
-   // success in download/apply a diff, queue next (if needed)
-   if(State == StateApplyDiff)
+   switch (State)
    {
-      // remove the just applied patch
-      available_patches.erase(available_patches.begin());
-      unlink(PatchFile.c_str());
-
-      // move into place
-      if(Debug)
-      {
-        std::clog << "Moving patched file in place: " << std::endl
-                  << DestFile << " -> " << FinalFile << std::endl;
-      }
-      Rename(DestFile,FinalFile);
-      chmod(FinalFile.c_str(),0644);
-
-      // see if there is more to download
-      if(available_patches.empty() == false) {
-        new pkgAcqIndexDiffs(Owner, TransactionManager, Target,
-                             available_patches);
-        return Finish();
-      } else 
-         // update
-         DestFile = FinalFile;
-        return Finish(true);
+      // success in downloading a diff, enter ApplyDiff state
+      case StateFetchDiff:
+        Rename(DestFile, PatchFile);
+        DestFile = GetKeepCompressedFileName(UncompressedUnpatchedFile + "-patched", Target);
+        if(Debug)
+           std::clog << "Sending to rred method: " << UnpatchedFile << std::endl;
+        State = StateApplyDiff;
+        Local = true;
+        Desc.URI = "rred:" + UnpatchedFile;
+        QueueURI(Desc);
+        SetActiveSubprocess("rred");
+        return;
+      // success in download/apply a diff, queue next (if needed)
+      case StateApplyDiff:
+        // remove the just applied patch and base file
+        available_patches.erase(available_patches.begin());
+        RemoveFile("pkgAcqIndexDiffs::Done", PatchFile);
+        RemoveFile("pkgAcqIndexDiffs::Done", UnpatchedFile);
+        if(Debug)
+           std::clog << "Moving patched file in place: " << std::endl
+              << DestFile << " -> " << PatchedFile << std::endl;
+        Rename(DestFile, PatchedFile);
+
+        // see if there is more to download
+        if(available_patches.empty() == false)
+        {
+           new pkgAcqIndexDiffs(Owner, TransactionManager, Target, available_patches);
+           Finish();
+        } else {
+           DestFile = PatchedFile;
+           Finish(true);
+        }
+        return;
    }
 }
                                                                        /*}}}*/
@@ -2128,26 +2623,25 @@ std::string pkgAcqIndexDiffs::Custom600Headers() const                  /*{{{*/
    return patchhashes.str();
 }
                                                                        /*}}}*/
+pkgAcqIndexDiffs::~pkgAcqIndexDiffs() {}
 
 // AcqIndexMergeDiffs::AcqIndexMergeDiffs - Constructor                        /*{{{*/
 pkgAcqIndexMergeDiffs::pkgAcqIndexMergeDiffs(pkgAcquire * const Owner,
-                                             pkgAcqMetaBase * const TransactionManager,
-                                             IndexTarget const * const Target,
+                                             pkgAcqMetaClearSig * const TransactionManager,
+                                             IndexTarget const &Target,
                                              DiffInfo const &patch,
                                              std::vector<pkgAcqIndexMergeDiffs*> const * const allPatches)
-  : pkgAcqBaseIndex(Owner, TransactionManager, Target),
+  : pkgAcqBaseIndex(Owner, TransactionManager, Target), d(NULL),
      patch(patch), allPatches(allPatches), State(StateFetchDiff)
 {
    Debug = _config->FindB("Debug::pkgAcquire::Diffs",false);
 
    Desc.Owner = this;
-   Description = Target->Description;
-   Desc.ShortDesc = Target->ShortDesc;
-
-   Desc.URI = Target->URI + ".diff/" + patch.file + ".gz";
-   Desc.Description = Description + " " + patch.file + string(".pdiff");
-
-   DestFile = GetPartialFileNameFromURI(Target->URI + ".diff/" + patch.file);
+   Description = Target.Description;
+   Desc.ShortDesc = Target.ShortDesc;
+   Desc.URI = Target.URI + ".diff/" + patch.file + ".gz";
+   Desc.Description = Description + " " + patch.file + ".pdiff";
+   DestFile = GetPartialFileNameFromURI(Desc.URI);
 
    if(Debug)
       std::clog << "pkgAcqIndexMergeDiffs: " << Desc.URI << std::endl;
@@ -2160,7 +2654,7 @@ void pkgAcqIndexMergeDiffs::Failed(string const &Message,pkgAcquire::MethodConfi
    if(Debug)
       std::clog << "pkgAcqIndexMergeDiffs failed: " << Desc.URI << " with " << Message << std::endl;
 
-   Item::Failed(Message,Cnf);
+   pkgAcqBaseIndex::Failed(Message,Cnf);
    Status = StatDone;
 
    // check if we are the first to fail, otherwise we are done here
@@ -2168,17 +2662,22 @@ void pkgAcqIndexMergeDiffs::Failed(string const &Message,pkgAcquire::MethodConfi
    for (std::vector<pkgAcqIndexMergeDiffs *>::const_iterator I = allPatches->begin();
         I != allPatches->end(); ++I)
       if ((*I)->State == StateErrorDiff)
+      {
+        State = StateErrorDiff;
         return;
+      }
 
    // first failure means we should fallback
    State = StateErrorDiff;
    if (Debug)
       std::clog << "Falling back to normal index file acquire" << std::endl;
-   DestFile = GetPartialFileNameFromURI(Target->URI);
    RenameOnError(PDiffError);
-   std::string const patchname = GetMergeDiffsPatchFileName(DestFile, patch.file);
-   if (RealFileExists(patchname))
-      rename(patchname.c_str(), std::string(patchname + ".FAILED").c_str());
+   if (RealFileExists(DestFile))
+      Rename(DestFile, DestFile + ".FAILED");
+   std::string const UnpatchedFile = GetExistingFilename(GetPartialFileNameFromURI(Target.URI));
+   if (UnpatchedFile.empty() == false && FileExists(UnpatchedFile))
+      Rename(UnpatchedFile, UnpatchedFile + ".FAILED");
+   DestFile.clear();
    new pkgAcqIndex(Owner, TransactionManager, Target);
 }
                                                                        /*}}}*/
@@ -2190,67 +2689,73 @@ void pkgAcqIndexMergeDiffs::Done(string const &Message, HashStringList const &Ha
 
    Item::Done(Message, Hashes, Cnf);
 
-   string const FinalFile = GetPartialFileNameFromURI(Target->URI);
-   if (State == StateFetchDiff)
+   if (std::any_of(allPatches->begin(), allPatches->end(),
+           [](pkgAcqIndexMergeDiffs const * const P) { return P->State == StateErrorDiff; }))
    {
-      Rename(DestFile, GetMergeDiffsPatchFileName(FinalFile, patch.file));
-
-      // check if this is the last completed diff
-      State = StateDoneDiff;
-      for (std::vector<pkgAcqIndexMergeDiffs *>::const_iterator I = allPatches->begin();
-           I != allPatches->end(); ++I)
-        if ((*I)->State != StateDoneDiff)
-        {
-           if(Debug)
-              std::clog << "Not the last done diff in the batch: " << Desc.URI << std::endl;
-           return;
-        }
-
-      // this is the last completed diff, so we are ready to apply now
-      State = StateApplyDiff;
-
-      // patching needs to be bootstrapped with the 'old' version
-      if (symlink(GetFinalFilename().c_str(), FinalFile.c_str()) != 0)
-      {
-        Failed("Link creation of " + FinalFile + " to " + GetFinalFilename() + " failed", NULL);
-        return;
-      }
-
       if(Debug)
-        std::clog << "Sending to rred method: " << FinalFile << std::endl;
-
-      Local = true;
-      Desc.URI = "rred:" + FinalFile;
-      QueueURI(Desc);
-      SetActiveSubprocess("rred");
+        std::clog << "Another patch failed already, no point in processing this one." << std::endl;
+      State = StateErrorDiff;
       return;
    }
-   // success in download/apply all diffs, clean up
-   else if (State == StateApplyDiff)
-   {
-      // move the result into place
-      std::string const Final = GetFinalFilename();
-      if(Debug)
-        std::clog << "Queue patched file in place: " << std::endl
-                  << DestFile << " -> " << Final << std::endl;
 
-      // queue for copy by the transaction manager
-      TransactionManager->TransactionStageCopy(this, DestFile, Final);
+   std::string const UncompressedUnpatchedFile = GetPartialFileNameFromURI(Target.URI);
+   std::string const UnpatchedFile = GetExistingFilename(UncompressedUnpatchedFile);
+   if (UnpatchedFile.empty())
+   {
+      _error->Fatal("Unpatched file %s doesn't exist (anymore)!", UncompressedUnpatchedFile.c_str());
+      State = StateErrorDiff;
+      return;
+   }
+   std::string const PatchFile = GetMergeDiffsPatchFileName(UnpatchedFile, patch.file);
+   std::string const PatchedFile = GetKeepCompressedFileName(UncompressedUnpatchedFile, Target);
 
-      // ensure the ed's are gone regardless of list-cleanup
-      for (std::vector<pkgAcqIndexMergeDiffs *>::const_iterator I = allPatches->begin();
-           I != allPatches->end(); ++I)
-      {
-        std::string const PartialFile = GetPartialFileNameFromURI(Target->URI);
-        std::string const patch = GetMergeDiffsPatchFileName(PartialFile, (*I)->patch.file);
-        unlink(patch.c_str());
-      }
-      unlink(FinalFile.c_str());
+   switch (State)
+   {
+      case StateFetchDiff:
+        Rename(DestFile, PatchFile);
 
-      // all set and done
-      Complete = true;
-      if(Debug)
-        std::clog << "allDone: " << DestFile << "\n" << std::endl;
+        // check if this is the last completed diff
+        State = StateDoneDiff;
+        for (std::vector<pkgAcqIndexMergeDiffs *>::const_iterator I = allPatches->begin();
+              I != allPatches->end(); ++I)
+           if ((*I)->State != StateDoneDiff)
+           {
+              if(Debug)
+                 std::clog << "Not the last done diff in the batch: " << Desc.URI << std::endl;
+              return;
+           }
+        // this is the last completed diff, so we are ready to apply now
+        DestFile = GetKeepCompressedFileName(UncompressedUnpatchedFile + "-patched", Target);
+        if(Debug)
+           std::clog << "Sending to rred method: " << UnpatchedFile << std::endl;
+        State = StateApplyDiff;
+        Local = true;
+        Desc.URI = "rred:" + UnpatchedFile;
+        QueueURI(Desc);
+        SetActiveSubprocess("rred");
+        return;
+      case StateApplyDiff:
+        // success in download & apply all diffs, finialize and clean up
+        if(Debug)
+           std::clog << "Queue patched file in place: " << std::endl
+              << DestFile << " -> " << PatchedFile << std::endl;
+
+        // queue for copy by the transaction manager
+        TransactionManager->TransactionStageCopy(this, DestFile, GetKeepCompressedFileName(GetFinalFilename(), Target));
+
+        // ensure the ed's are gone regardless of list-cleanup
+        for (std::vector<pkgAcqIndexMergeDiffs *>::const_iterator I = allPatches->begin();
+              I != allPatches->end(); ++I)
+           RemoveFile("pkgAcqIndexMergeDiffs::Done", GetMergeDiffsPatchFileName(UnpatchedFile, (*I)->patch.file));
+        RemoveFile("pkgAcqIndexMergeDiffs::Done", UnpatchedFile);
+
+        // all set and done
+        Complete = true;
+        if(Debug)
+           std::clog << "allDone: " << DestFile << "\n" << std::endl;
+        return;
+      case StateDoneDiff: _error->Fatal("Done called for %s which is in an invalid Done state", PatchFile.c_str()); break;
+      case StateErrorDiff: _error->Fatal("Done called for %s which is in an invalid Error state", PatchFile.c_str()); break;
    }
 }
                                                                        /*}}}*/
@@ -2272,71 +2777,79 @@ std::string pkgAcqIndexMergeDiffs::Custom600Headers() const             /*{{{*/
    return patchhashes.str();
 }
                                                                        /*}}}*/
+pkgAcqIndexMergeDiffs::~pkgAcqIndexMergeDiffs() {}
 
 // AcqIndex::AcqIndex - Constructor                                    /*{{{*/
 pkgAcqIndex::pkgAcqIndex(pkgAcquire * const Owner,
-                         pkgAcqMetaBase * const TransactionManager,
-                         IndexTarget const * const Target)
-   : pkgAcqBaseIndex(Owner, TransactionManager, Target)
+                         pkgAcqMetaClearSig * const TransactionManager,
+                         IndexTarget const &Target)
+   : pkgAcqBaseIndex(Owner, TransactionManager, Target), d(NULL), Stage(STAGE_DOWNLOAD),
+   CompressionExtensions(Target.Option(IndexTarget::COMPRESSIONTYPES))
 {
-   // autoselect the compression method
-   AutoSelectCompression();
-   Init(Target->URI, Target->Description, Target->ShortDesc);
+   Init(Target.URI, Target.Description, Target.ShortDesc);
 
    if(_config->FindB("Debug::Acquire::Transaction", false) == true)
       std::clog << "New pkgIndex with TransactionManager "
                 << TransactionManager << std::endl;
 }
                                                                        /*}}}*/
-// AcqIndex::AutoSelectCompression - Select compression                        /*{{{*/
-void pkgAcqIndex::AutoSelectCompression()
+// AcqIndex::Init - defered Constructor                                        /*{{{*/
+static void NextCompressionExtension(std::string &CurrentCompressionExtension, std::string &CompressionExtensions, bool const preview)
 {
-   std::vector<std::string> types = APT::Configuration::getCompressionTypes();
-   CompressionExtensions = "";
-   if (TransactionManager->MetaIndexParser != NULL && TransactionManager->MetaIndexParser->Exists(Target->MetaKey))
+   size_t const nextExt = CompressionExtensions.find(' ');
+   if (nextExt == std::string::npos)
    {
-      for (std::vector<std::string>::const_iterator t = types.begin();
-           t != types.end(); ++t)
-      {
-         std::string CompressedMetaKey = string(Target->MetaKey).append(".").append(*t);
-         if (*t == "uncompressed" ||
-             TransactionManager->MetaIndexParser->Exists(CompressedMetaKey) == true)
-            CompressionExtensions.append(*t).append(" ");
-      }
+      CurrentCompressionExtension = CompressionExtensions;
+      if (preview == false)
+        CompressionExtensions.clear();
    }
    else
    {
-      for (std::vector<std::string>::const_iterator t = types.begin(); t != types.end(); ++t)
-        CompressionExtensions.append(*t).append(" ");
+      CurrentCompressionExtension = CompressionExtensions.substr(0, nextExt);
+      if (preview == false)
+        CompressionExtensions = CompressionExtensions.substr(nextExt+1);
    }
-   if (CompressionExtensions.empty() == false)
-      CompressionExtensions.erase(CompressionExtensions.end()-1);
 }
-                                                                       /*}}}*/
-// AcqIndex::Init - defered Constructor                                        /*{{{*/
 void pkgAcqIndex::Init(string const &URI, string const &URIDesc,
                        string const &ShortDesc)
 {
    Stage = STAGE_DOWNLOAD;
 
    DestFile = GetPartialFileNameFromURI(URI);
+   NextCompressionExtension(CurrentCompressionExtension, CompressionExtensions, false);
 
-   size_t const nextExt = CompressionExtensions.find(' ');
-   if (nextExt == std::string::npos)
-   {
-      CurrentCompressionExtension = CompressionExtensions;
-      CompressionExtensions.clear();
-   }
-   else
-   {
-      CurrentCompressionExtension = CompressionExtensions.substr(0, nextExt);
-      CompressionExtensions = CompressionExtensions.substr(nextExt+1);
-   }
+   // store file size of the download to ensure the fetcher gives
+   // accurate progress reporting
+   FileSize = GetExpectedHashes().FileSize();
 
    if (CurrentCompressionExtension == "uncompressed")
    {
       Desc.URI = URI;
    }
+   else if (CurrentCompressionExtension == "by-hash")
+   {
+      NextCompressionExtension(CurrentCompressionExtension, CompressionExtensions, true);
+      if(unlikely(CurrentCompressionExtension.empty()))
+        return;
+      if (CurrentCompressionExtension != "uncompressed")
+      {
+        Desc.URI = URI + '.' + CurrentCompressionExtension;
+        DestFile = DestFile + '.' + CurrentCompressionExtension;
+      }
+
+      HashStringList const Hashes = GetExpectedHashes();
+      HashString const * const TargetHash = Hashes.find(NULL);
+      if (unlikely(TargetHash == nullptr))
+        return;
+      std::string const ByHash = "/by-hash/" + TargetHash->HashType() + "/" + TargetHash->HashValue();
+      size_t const trailing_slash = Desc.URI.find_last_of("/");
+      if (unlikely(trailing_slash == std::string::npos))
+        return;
+      Desc.URI = Desc.URI.replace(
+           trailing_slash,
+           Desc.URI.substr(trailing_slash+1).size()+1,
+           ByHash);
+   }
    else if (unlikely(CurrentCompressionExtension.empty()))
       return;
    else
@@ -2345,8 +2858,6 @@ void pkgAcqIndex::Init(string const &URI, string const &URIDesc,
       DestFile = DestFile + '.' + CurrentCompressionExtension;
    }
 
-   if(TransactionManager->MetaIndexParser != NULL)
-      InitByHashIfNeeded();
 
    Desc.Description = URIDesc;
    Desc.Owner = this;
@@ -2355,49 +2866,24 @@ void pkgAcqIndex::Init(string const &URI, string const &URIDesc,
    QueueURI(Desc);
 }
                                                                        /*}}}*/
-// AcqIndex::AdjustForByHash - modify URI for by-hash support          /*{{{*/
-void pkgAcqIndex::InitByHashIfNeeded()
-{
-   // TODO:
-   //  - (maybe?) add support for by-hash into the sources.list as flag
-   //  - make apt-ftparchive generate the hashes (and expire?)
-   std::string HostKnob = "APT::Acquire::" + ::URI(Desc.URI).Host + "::By-Hash";
-   if(_config->FindB("APT::Acquire::By-Hash", false) == true ||
-      _config->FindB(HostKnob, false) == true ||
-      TransactionManager->MetaIndexParser->GetSupportsAcquireByHash())
-   {
-      HashStringList const Hashes = GetExpectedHashes();
-      if(Hashes.usable())
-      {
-         // FIXME: should we really use the best hash here? or a fixed one?
-         HashString const * const TargetHash = Hashes.find("");
-         std::string const ByHash = "/by-hash/" + TargetHash->HashType() + "/" + TargetHash->HashValue();
-         size_t const trailing_slash = Desc.URI.find_last_of("/");
-         Desc.URI = Desc.URI.replace(
-            trailing_slash,
-            Desc.URI.substr(trailing_slash+1).size()+1,
-            ByHash);
-      } else {
-         _error->Warning(
-            "Fetching ByHash requested but can not find record for %s",
-            GetMetaKey().c_str());
-      }
-   }
-}
-                                                                       /*}}}*/
 // AcqIndex::Custom600Headers - Insert custom request headers          /*{{{*/
 // ---------------------------------------------------------------------
 /* The only header we use is the last-modified header. */
 string pkgAcqIndex::Custom600Headers() const
 {
-   string Final = GetFinalFilename();
 
    string msg = "\nIndex-File: true";
-   struct stat Buf;
-   if (stat(Final.c_str(),&Buf) == 0)
-      msg += "\nLast-Modified: " + TimeRFC1123(Buf.st_mtime);
 
-   if(Target->IsOptional)
+   if (TransactionManager->LastMetaIndexParser == NULL)
+   {
+      std::string const Final = GetFinalFilename();
+
+      struct stat Buf;
+      if (stat(Final.c_str(),&Buf) == 0)
+        msg += "\nLast-Modified: " + TimeRFC1123(Buf.st_mtime, false);
+   }
+
+   if(Target.IsOptional)
       msg += "\nFail-Ignore: true";
 
    return msg;
@@ -2406,39 +2892,25 @@ string pkgAcqIndex::Custom600Headers() const
 // AcqIndex::Failed - getting the indexfile failed                     /*{{{*/
 void pkgAcqIndex::Failed(string const &Message,pkgAcquire::MethodConfig const * const Cnf)
 {
-   Item::Failed(Message,Cnf);
+   pkgAcqBaseIndex::Failed(Message,Cnf);
 
    // authorisation matches will not be fixed by other compression types
    if (Status != StatAuthError)
    {
       if (CompressionExtensions.empty() == false)
       {
-        Init(Target->URI, Desc.Description, Desc.ShortDesc);
+        Init(Target.URI, Desc.Description, Desc.ShortDesc);
         Status = StatIdle;
         return;
       }
    }
 
-   if(Target->IsOptional && GetExpectedHashes().empty() && Stage == STAGE_DOWNLOAD)
+   if(Target.IsOptional && GetExpectedHashes().empty() && Stage == STAGE_DOWNLOAD)
       Status = StatDone;
    else
       TransactionManager->AbortTransaction();
 }
                                                                        /*}}}*/
-// AcqIndex::ReverifyAfterIMS - Reverify index after an ims-hit                /*{{{*/
-void pkgAcqIndex::ReverifyAfterIMS()
-{
-   // update destfile to *not* include the compression extension when doing
-   // a reverify (as its uncompressed on disk already)
-   DestFile = GetCompressedFileName(Target->URI, GetPartialFileNameFromURI(Target->URI), CurrentCompressionExtension);
-
-   // copy FinalFile into partial/ so that we check the hash again
-   string FinalFile = GetFinalFilename();
-   Stage = STAGE_DECOMPRESS_AND_VERIFY;
-   Desc.URI = "copy:" + FinalFile;
-   QueueURI(Desc);
-}
-                                                                       /*}}}*/
 // AcqIndex::Done - Finished a fetch                                   /*{{{*/
 // ---------------------------------------------------------------------
 /* This goes through a number of states.. On the initial fetch the
@@ -2455,99 +2927,95 @@ void pkgAcqIndex::Done(string const &Message,
    switch(Stage) 
    {
       case STAGE_DOWNLOAD:
-         StageDownloadDone(Message, Hashes, Cfg);
+         StageDownloadDone(Message);
          break;
       case STAGE_DECOMPRESS_AND_VERIFY:
-         StageDecompressDone(Message, Hashes, Cfg);
+         StageDecompressDone();
          break;
    }
 }
                                                                        /*}}}*/
 // AcqIndex::StageDownloadDone - Queue for decompress and verify       /*{{{*/
-void pkgAcqIndex::StageDownloadDone(string const &Message, HashStringList const &,
-                                    pkgAcquire::MethodConfig const * const)
+void pkgAcqIndex::StageDownloadDone(string const &Message)
 {
+   Local = true;
    Complete = true;
 
-   // Handle the unzipd case
-   string FileName = LookupTag(Message,"Alt-Filename");
-   if (FileName.empty() == false)
+   std::string const AltFilename = LookupTag(Message,"Alt-Filename");
+   std::string Filename = LookupTag(Message,"Filename");
+
+   // we need to verify the file against the current Release file again
+   // on if-modfied-since hit to avoid a stale attack against us
+   if(StringToBool(LookupTag(Message,"IMS-Hit"),false) == true)
    {
+      // copy FinalFile into partial/ so that we check the hash again
+      string const FinalFile = GetExistingFilename(GetFinalFileNameFromURI(Target.URI));
+      if (symlink(FinalFile.c_str(), DestFile.c_str()) != 0)
+        _error->WarningE("pkgAcqIndex::StageDownloadDone", "Symlinking final file %s back to %s failed", FinalFile.c_str(), DestFile.c_str());
+      else
+      {
+        EraseFileName = DestFile;
+        Filename = DestFile;
+      }
       Stage = STAGE_DECOMPRESS_AND_VERIFY;
-      Local = true;
-      DestFile += ".decomp";
-      Desc.URI = "copy:" + FileName;
+      Desc.URI = "store:" + Filename;
       QueueURI(Desc);
-      SetActiveSubprocess("copy");
+      SetActiveSubprocess(::URI(Desc.URI).Access);
       return;
    }
-
-   FileName = LookupTag(Message,"Filename");
-   if (FileName.empty() == true)
+   // methods like file:// give us an alternative (uncompressed) file
+   else if (Target.KeepCompressed == false && AltFilename.empty() == false)
    {
-      Status = StatError;
-      ErrorText = "Method gave a blank filename";
+      Filename = AltFilename;
+      EraseFileName.clear();
    }
-
    // Methods like e.g. "file:" will give us a (compressed) FileName that is
    // not the "DestFile" we set, in this case we uncompress from the local file
-   if (FileName != DestFile)
-      Local = true;
-   else
-      EraseFileName = FileName;
-
-   // we need to verify the file against the current Release file again
-   // on if-modfied-since hit to avoid a stale attack against us
-   if(StringToBool(LookupTag(Message,"IMS-Hit"),false) == true)
+   else if (Filename != DestFile && RealFileExists(DestFile) == false)
    {
-      // The files timestamp matches, reverify by copy into partial/
-      EraseFileName = "";
-      ReverifyAfterIMS();
-      return;
+      // symlinking ensures that the filename can be used for compression detection
+      // that is e.g. needed for by-hash which has no extension over file
+      if (symlink(Filename.c_str(),DestFile.c_str()) != 0)
+        _error->WarningE("pkgAcqIndex::StageDownloadDone", "Symlinking file %s to %s failed", Filename.c_str(), DestFile.c_str());
+      else
+      {
+        EraseFileName = DestFile;
+        Filename = DestFile;
+      }
    }
 
-   // If we have compressed indexes enabled, queue for hash verification
-   if (_config->FindB("Acquire::GzipIndexes",false))
-   {
-      DestFile = GetPartialFileNameFromURI(Target->URI + '.' + CurrentCompressionExtension);
-      EraseFileName = "";
-      Stage = STAGE_DECOMPRESS_AND_VERIFY;
-      Desc.URI = "copy:" + FileName;
-      QueueURI(Desc);
-      SetActiveSubprocess("copy");
-      return;
-    }
-
-   // get the binary name for your used compression type
-   string decompProg;
-   if(CurrentCompressionExtension == "uncompressed")
-      decompProg = "copy";
+   Stage = STAGE_DECOMPRESS_AND_VERIFY;
+   DestFile = GetKeepCompressedFileName(GetPartialFileNameFromURI(Target.URI), Target);
+   if (Filename != DestFile && flExtension(Filename) == flExtension(DestFile))
+      Desc.URI = "copy:" + Filename;
    else
-      decompProg = _config->Find(string("Acquire::CompressionTypes::").append(CurrentCompressionExtension),"");
-   if(decompProg.empty() == true)
+      Desc.URI = "store:" + Filename;
+   if (DestFile == Filename)
    {
-      _error->Error("Unsupported extension: %s", CurrentCompressionExtension.c_str());
-      return;
+      if (CurrentCompressionExtension == "uncompressed")
+        return StageDecompressDone();
+      DestFile = "/dev/null";
    }
 
+   if (EraseFileName.empty() && Filename != AltFilename)
+      EraseFileName = Filename;
+
    // queue uri for the next stage
-   Stage = STAGE_DECOMPRESS_AND_VERIFY;
-   DestFile += ".decomp";
-   Desc.URI = decompProg + ":" + FileName;
    QueueURI(Desc);
-   SetActiveSubprocess(decompProg);
+   SetActiveSubprocess(::URI(Desc.URI).Access);
 }
                                                                        /*}}}*/
 // AcqIndex::StageDecompressDone - Final verification                  /*{{{*/
-void pkgAcqIndex::StageDecompressDone(string const &,
-                                      HashStringList const &,
-                                      pkgAcquire::MethodConfig const * const)
+void pkgAcqIndex::StageDecompressDone()
 {
+   if (DestFile == "/dev/null")
+      DestFile = GetKeepCompressedFileName(GetPartialFileNameFromURI(Target.URI), Target);
+
    // Done, queue for rename on transaction finished
    TransactionManager->TransactionStageCopy(this, DestFile, GetFinalFilename());
-   return;
 }
                                                                        /*}}}*/
+pkgAcqIndex::~pkgAcqIndex() {}
 
 
 // AcqArchive::AcqArchive - Constructor                                        /*{{{*/
@@ -2557,7 +3025,7 @@ void pkgAcqIndex::StageDecompressDone(string const &,
 pkgAcqArchive::pkgAcqArchive(pkgAcquire * const Owner,pkgSourceList * const Sources,
                             pkgRecords * const Recs,pkgCache::VerIterator const &Version,
                             string &StoreFilename) :
-               Item(Owner), LocalSource(false), Version(Version), Sources(Sources), Recs(Recs),
+               Item(Owner), d(NULL), LocalSource(false), Version(Version), Sources(Sources), Recs(Recs),
                StoreFilename(StoreFilename), Vf(Version.FileList()),
               Trusted(false)
 {
@@ -2578,7 +3046,7 @@ pkgAcqArchive::pkgAcqArchive(pkgAcquire * const Owner,pkgSourceList * const Sour
    // Skip not source sources, they do not have file fields.
    for (; Vf.end() == false; ++Vf)
    {
-      if ((Vf.File()->Flags & pkgCache::Flag::NotSource) != 0)
+      if (Vf.File().Flagged(pkgCache::Flag::NotSource))
         continue;
       break;
    }
@@ -2646,14 +3114,14 @@ bool pkgAcqArchive::QueueNext()
    {
       pkgCache::PkgFileIterator const PkgF = Vf.File();
       // Ignore not source sources
-      if ((PkgF->Flags & pkgCache::Flag::NotSource) != 0)
+      if (PkgF.Flagged(pkgCache::Flag::NotSource))
         continue;
 
       // Try to cross match against the source list
       pkgIndexFile *Index;
       if (Sources->FindIndex(PkgF, Index) == false)
            continue;
-      LocalSource = (PkgF->Flags & pkgCache::Flag::LocalSource) == pkgCache::Flag::LocalSource;
+      LocalSource = PkgF.Flagged(pkgCache::Flag::LocalSource);
 
       // only try to get a trusted package from another source if that source
       // is also trusted
@@ -2696,7 +3164,7 @@ bool pkgAcqArchive::QueueNext()
         
         /* Hmm, we have a file and its size does not match, this means it is
            an old style mismatched arch */
-        unlink(FinalFile.c_str());
+        RemoveFile("pkgAcqArchive::QueueNext", FinalFile);
       }
 
       // Check it again using the new style output filenames
@@ -2715,7 +3183,7 @@ bool pkgAcqArchive::QueueNext()
         
         /* Hmm, we have a file and its size does not match, this shouldn't
            happen.. */
-        unlink(FinalFile.c_str());
+        RemoveFile("pkgAcqArchive::QueueNext", FinalFile);
       }
 
       DestFile = _config->FindDir("Dir::Cache::Archives") + "partial/" + flNotDir(StoreFilename);
@@ -2725,7 +3193,7 @@ bool pkgAcqArchive::QueueNext()
       {
         // Hmm, the partial file is too big, erase it
         if ((unsigned long long)Buf.st_size > Version->Size)
-           unlink(DestFile.c_str());
+           RemoveFile("pkgAcqArchive::QueueNext", DestFile);
         else
            PartialSize = Buf.st_size;
       }
@@ -2760,16 +3228,8 @@ void pkgAcqArchive::Done(string const &Message, HashStringList const &Hashes,
    Item::Done(Message, Hashes, Cfg);
 
    // Grab the output filename
-   string FileName = LookupTag(Message,"Filename");
-   if (FileName.empty() == true)
-   {
-      Status = StatError;
-      ErrorText = "Method gave a blank filename";
-      return;
-   }
-
-   // Reference filename
-   if (FileName != DestFile)
+   std::string const FileName = LookupTag(Message,"Filename");
+   if (DestFile !=  FileName && RealFileExists(DestFile) == false)
    {
       StoreFilename = DestFile = FileName;
       Local = true;
@@ -2845,13 +3305,272 @@ std::string pkgAcqArchive::ShortDesc() const                           /*{{{*/
    return Desc.ShortDesc;
 }
                                                                        /*}}}*/
+pkgAcqArchive::~pkgAcqArchive() {}
+
+// AcqChangelog::pkgAcqChangelog - Constructors                                /*{{{*/
+class pkgAcqChangelog::Private
+{
+   public:
+   std::string FinalFile;
+};
+pkgAcqChangelog::pkgAcqChangelog(pkgAcquire * const Owner, pkgCache::VerIterator const &Ver,
+      std::string const &DestDir, std::string const &DestFilename) :
+   pkgAcquire::Item(Owner), d(new pkgAcqChangelog::Private()), SrcName(Ver.SourcePkgName()), SrcVersion(Ver.SourceVerStr())
+{
+   Desc.URI = URI(Ver);
+   Init(DestDir, DestFilename);
+}
+// some parameters are char* here as they come likely from char* interfaces – which can also return NULL
+pkgAcqChangelog::pkgAcqChangelog(pkgAcquire * const Owner, pkgCache::RlsFileIterator const &RlsFile,
+      char const * const Component, char const * const SrcName, char const * const SrcVersion,
+      const string &DestDir, const string &DestFilename) :
+   pkgAcquire::Item(Owner), d(new pkgAcqChangelog::Private()), SrcName(SrcName), SrcVersion(SrcVersion)
+{
+   Desc.URI = URI(RlsFile, Component, SrcName, SrcVersion);
+   Init(DestDir, DestFilename);
+}
+pkgAcqChangelog::pkgAcqChangelog(pkgAcquire * const Owner,
+      std::string const &URI, char const * const SrcName, char const * const SrcVersion,
+      const string &DestDir, const string &DestFilename) :
+   pkgAcquire::Item(Owner), d(new pkgAcqChangelog::Private()), SrcName(SrcName), SrcVersion(SrcVersion)
+{
+   Desc.URI = URI;
+   Init(DestDir, DestFilename);
+}
+void pkgAcqChangelog::Init(std::string const &DestDir, std::string const &DestFilename)
+{
+   if (Desc.URI.empty())
+   {
+      Status = StatError;
+      // TRANSLATOR: %s=%s is sourcename=sourceversion, e.g. apt=1.1
+      strprintf(ErrorText, _("Changelog unavailable for %s=%s"), SrcName.c_str(), SrcVersion.c_str());
+      // Let the error message print something sensible rather than "Failed to fetch /"
+      if (DestFilename.empty())
+        DestFile = SrcName + ".changelog";
+      else
+        DestFile = DestFilename;
+      Desc.URI = "changelog:/" + DestFile;
+      return;
+   }
+
+   std::string DestFileName;
+   if (DestFilename.empty())
+      DestFileName = flCombine(DestFile, SrcName + ".changelog");
+   else
+      DestFileName = flCombine(DestFile, DestFilename);
+
+   std::string const SandboxUser = _config->Find("APT::Sandbox::User");
+   std::string const systemTemp = GetTempDir(SandboxUser);
+   char tmpname[1000];
+   snprintf(tmpname, sizeof(tmpname), "%s/apt-changelog-XXXXXX", systemTemp.c_str());
+   if (NULL == mkdtemp(tmpname))
+   {
+      _error->Errno("mkdtemp", "mkdtemp failed in changelog acquire of %s %s", SrcName.c_str(), SrcVersion.c_str());
+      Status = StatError;
+      return;
+   }
+   TemporaryDirectory = tmpname;
+
+   ChangeOwnerAndPermissionOfFile("Item::QueueURI", TemporaryDirectory.c_str(),
+        SandboxUser.c_str(), "root", 0700);
+
+   DestFile = flCombine(TemporaryDirectory, DestFileName);
+   if (DestDir.empty() == false)
+   {
+      d->FinalFile = flCombine(DestDir, DestFileName);
+      if (RealFileExists(d->FinalFile))
+      {
+        FileFd file1, file2;
+        if (file1.Open(DestFile, FileFd::WriteOnly | FileFd::Create | FileFd::Exclusive) &&
+              file2.Open(d->FinalFile, FileFd::ReadOnly) && CopyFile(file2, file1))
+        {
+           struct timeval times[2];
+           times[0].tv_sec = times[1].tv_sec = file2.ModificationTime();
+           times[0].tv_usec = times[1].tv_usec = 0;
+           utimes(DestFile.c_str(), times);
+        }
+      }
+   }
+
+   Desc.ShortDesc = "Changelog";
+   strprintf(Desc.Description, "%s %s %s Changelog", URI::SiteOnly(Desc.URI).c_str(), SrcName.c_str(), SrcVersion.c_str());
+   Desc.Owner = this;
+   QueueURI(Desc);
+}
+                                                                       /*}}}*/
+std::string pkgAcqChangelog::URI(pkgCache::VerIterator const &Ver)     /*{{{*/
+{
+   std::string const confOnline = "Acquire::Changelogs::AlwaysOnline";
+   bool AlwaysOnline = _config->FindB(confOnline, false);
+   if (AlwaysOnline == false)
+      for (pkgCache::VerFileIterator VF = Ver.FileList(); VF.end() == false; ++VF)
+      {
+        pkgCache::PkgFileIterator const PF = VF.File();
+        if (PF.Flagged(pkgCache::Flag::NotSource) || PF->Release == 0)
+           continue;
+        pkgCache::RlsFileIterator const RF = PF.ReleaseFile();
+        if (RF->Origin != 0 && _config->FindB(confOnline + "::Origin::" + RF.Origin(), false))
+        {
+           AlwaysOnline = true;
+           break;
+        }
+      }
+   if (AlwaysOnline == false)
+   {
+      pkgCache::PkgIterator const Pkg = Ver.ParentPkg();
+      if (Pkg->CurrentVer != 0 && Pkg.CurrentVer() == Ver)
+      {
+        std::string const basename = std::string("/usr/share/doc/") + Pkg.Name() + "/changelog";
+        std::string const debianname = basename + ".Debian";
+        if (FileExists(debianname))
+           return "copy://" + debianname;
+        else if (FileExists(debianname + ".gz"))
+           return "gzip://" + debianname + ".gz";
+        else if (FileExists(basename))
+           return "copy://" + basename;
+        else if (FileExists(basename + ".gz"))
+           return "gzip://" + basename + ".gz";
+      }
+   }
+
+   char const * const SrcName = Ver.SourcePkgName();
+   char const * const SrcVersion = Ver.SourceVerStr();
+   // find the first source for this version which promises a changelog
+   for (pkgCache::VerFileIterator VF = Ver.FileList(); VF.end() == false; ++VF)
+   {
+      pkgCache::PkgFileIterator const PF = VF.File();
+      if (PF.Flagged(pkgCache::Flag::NotSource) || PF->Release == 0)
+        continue;
+      pkgCache::RlsFileIterator const RF = PF.ReleaseFile();
+      std::string const uri = URI(RF, PF.Component(), SrcName, SrcVersion);
+      if (uri.empty())
+        continue;
+      return uri;
+   }
+   return "";
+}
+std::string pkgAcqChangelog::URITemplate(pkgCache::RlsFileIterator const &Rls)
+{
+   if (Rls.end() == true || (Rls->Label == 0 && Rls->Origin == 0))
+      return "";
+   std::string const serverConfig = "Acquire::Changelogs::URI";
+   std::string server;
+#define APT_EMPTY_SERVER \
+   if (server.empty() == false) \
+   { \
+      if (server != "no") \
+        return server; \
+      return ""; \
+   }
+#define APT_CHECK_SERVER(X, Y) \
+   if (Rls->X != 0) \
+   { \
+      std::string const specialServerConfig = serverConfig + "::" + Y + #X + "::" + Rls.X(); \
+      server = _config->Find(specialServerConfig); \
+      APT_EMPTY_SERVER \
+   }
+   // this way e.g. Debian-Security can fallback to Debian
+   APT_CHECK_SERVER(Label, "Override::")
+   APT_CHECK_SERVER(Origin, "Override::")
+
+   if (RealFileExists(Rls.FileName()))
+   {
+      _error->PushToStack();
+      FileFd rf;
+      /* This can be costly. A caller wanting to get millions of URIs might
+        want to do this on its own once and use Override settings.
+        We don't do this here as Origin/Label are not as unique as they
+        should be so this could produce request order-dependent anomalies */
+      if (OpenMaybeClearSignedFile(Rls.FileName(), rf) == true)
+      {
+        pkgTagFile TagFile(&rf, rf.Size());
+        pkgTagSection Section;
+        if (TagFile.Step(Section) == true)
+           server = Section.FindS("Changelogs");
+      }
+      _error->RevertToStack();
+      APT_EMPTY_SERVER
+   }
+
+   APT_CHECK_SERVER(Label, "")
+   APT_CHECK_SERVER(Origin, "")
+#undef APT_CHECK_SERVER
+#undef APT_EMPTY_SERVER
+   return "";
+}
+std::string pkgAcqChangelog::URI(pkgCache::RlsFileIterator const &Rls,
+        char const * const Component, char const * const SrcName,
+        char const * const SrcVersion)
+{
+   return URI(URITemplate(Rls), Component, SrcName, SrcVersion);
+}
+std::string pkgAcqChangelog::URI(std::string const &Template,
+        char const * const Component, char const * const SrcName,
+        char const * const SrcVersion)
+{
+   if (Template.find("@CHANGEPATH@") == std::string::npos)
+      return "";
+
+   // the path is: COMPONENT/SRC/SRCNAME/SRCNAME_SRCVER, e.g. main/a/apt/1.1 or contrib/liba/libapt/2.0
+   std::string Src = SrcName;
+   std::string path = APT::String::Startswith(SrcName, "lib") ? Src.substr(0, 4) : Src.substr(0,1);
+   path.append("/").append(Src).append("/");
+   path.append(Src).append("_").append(StripEpoch(SrcVersion));
+   // we omit component for releases without one (= flat-style repositories)
+   if (Component != NULL && strlen(Component) != 0)
+      path = std::string(Component) + "/" + path;
+
+   return SubstVar(Template, "@CHANGEPATH@", path);
+}
+                                                                       /*}}}*/
+// AcqChangelog::Failed - Failure handler                              /*{{{*/
+void pkgAcqChangelog::Failed(string const &Message, pkgAcquire::MethodConfig const * const Cnf)
+{
+   Item::Failed(Message,Cnf);
+
+   std::string errText;
+   // TRANSLATOR: %s=%s is sourcename=sourceversion, e.g. apt=1.1
+   strprintf(errText, _("Changelog unavailable for %s=%s"), SrcName.c_str(), SrcVersion.c_str());
+
+   // Error is probably something techy like 404 Not Found
+   if (ErrorText.empty())
+      ErrorText = errText;
+   else
+      ErrorText = errText + " (" + ErrorText + ")";
+}
+                                                                       /*}}}*/
+// AcqChangelog::Done - Item downloaded OK                             /*{{{*/
+void pkgAcqChangelog::Done(string const &Message,HashStringList const &CalcHashes,
+                     pkgAcquire::MethodConfig const * const Cnf)
+{
+   Item::Done(Message,CalcHashes,Cnf);
+   if (d->FinalFile.empty() == false)
+   {
+      if (RemoveFile("pkgAcqChangelog::Done", d->FinalFile) == false ||
+           Rename(DestFile, d->FinalFile) == false)
+        Status = StatError;
+   }
+
+   Complete = true;
+}
+                                                                       /*}}}*/
+pkgAcqChangelog::~pkgAcqChangelog()                                    /*{{{*/
+{
+   if (TemporaryDirectory.empty() == false)
+   {
+      RemoveFile("~pkgAcqChangelog", DestFile);
+      rmdir(TemporaryDirectory.c_str());
+   }
+   delete d;
+}
+                                                                       /*}}}*/
 
 // AcqFile::pkgAcqFile - Constructor                                   /*{{{*/
 pkgAcqFile::pkgAcqFile(pkgAcquire * const Owner,string const &URI, HashStringList const &Hashes,
                       unsigned long long const Size,string const &Dsc,string const &ShortDesc,
                       const string &DestDir, const string &DestFilename,
                        bool const IsIndexFile) :
-                       Item(Owner), IsIndexFile(IsIndexFile), ExpectedHashes(Hashes)
+                       Item(Owner), d(NULL), IsIndexFile(IsIndexFile), ExpectedHashes(Hashes)
 {
    Retries = _config->FindI("Acquire::Retries",0);
 
@@ -2877,7 +3596,7 @@ pkgAcqFile::pkgAcqFile(pkgAcquire * const Owner,string const &URI, HashStringLis
    {
       // Hmm, the partial file is too big, erase it
       if ((Size > 0) && (unsigned long long)Buf.st_size > Size)
-        unlink(DestFile.c_str());
+        RemoveFile("pkgAcqFile", DestFile);
       else
         PartialSize = Buf.st_size;
    }
@@ -2891,14 +3610,7 @@ void pkgAcqFile::Done(string const &Message,HashStringList const &CalcHashes,
 {
    Item::Done(Message,CalcHashes,Cnf);
 
-   string FileName = LookupTag(Message,"Filename");
-   if (FileName.empty() == true)
-   {
-      Status = StatError;
-      ErrorText = "Method gave a blank filename";
-      return;
-   }
-
+   std::string const FileName = LookupTag(Message,"Filename");
    Complete = true;
 
    // The files timestamp matches
@@ -2906,7 +3618,7 @@ void pkgAcqFile::Done(string const &Message,HashStringList const &CalcHashes,
       return;
 
    // We have to copy it into place
-   if (FileName != DestFile)
+   if (RealFileExists(DestFile.c_str()) == false)
    {
       Local = true;
       if (_config->FindB("Acquire::Source-Symlinks",true) == false ||
@@ -2922,7 +3634,7 @@ void pkgAcqFile::Done(string const &Message,HashStringList const &CalcHashes,
       if (lstat(DestFile.c_str(),&St) == 0)
       {
         if (S_ISLNK(St.st_mode) != 0)
-           unlink(DestFile.c_str());
+           RemoveFile("pkgAcqFile::Done", DestFile);
       }
 
       // Symlink the file
@@ -2931,7 +3643,7 @@ void pkgAcqFile::Done(string const &Message,HashStringList const &CalcHashes,
         _error->PushToStack();
         _error->Errno("pkgAcqFile::Done", "Symlinking file %s failed", DestFile.c_str());
         std::stringstream msg;
-        _error->DumpErrors(msg);
+        _error->DumpErrors(msg, GlobalError::DEBUG, false);
         _error->RevertToStack();
         ErrorText = msg.str();
         Status = StatError;
@@ -2967,3 +3679,4 @@ string pkgAcqFile::Custom600Headers() const                               /*{{{*/
    return "";
 }
                                                                        /*}}}*/
+pkgAcqFile::~pkgAcqFile() {}