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[apt.git] / apt-pkg / acquire-item.cc
index d6e9ccbe0461f127f77dccfd1864ddc50588968e..2180a5a41b118def9aaa9081a351a8f76cdad34d 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 +108,75 @@ 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 bool AllowInsecureRepositories(indexRecords const * const MetaIndexParser, pkgAcqMetaBase * const TransactionManager, pkgAcquire::Item * const I) /*{{{*/
+static bool MessageInsecureRepository(bool const isError, std::string const &msg)/*{{{*/
 {
-   if(MetaIndexParser->IsAlwaysTrusted() || _config->FindB("Acquire::AllowInsecureRepositories") == true)
+   if (isError)
+   {
+      _error->Error("%s", msg.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", msg.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;
+}
+static bool MessageInsecureRepository(bool const isError, char const * const msg, std::string const &repo)
+{
+   std::string m;
+   strprintf(m, msg, repo.c_str());
+   return MessageInsecureRepository(isError, m);
+}
+                                                                       /*}}}*/
+static bool AllowInsecureRepositories(char const * const msg, std::string const &repo,/*{{{*/
+      metaIndex const * const MetaIndexParser, pkgAcqMetaClearSig * const TransactionManager, pkgAcquire::Item * const I)
+{
+   if(MetaIndexParser->GetTrusted() == metaIndex::TRI_YES)
+      return true;
+
+   if (_config->FindB("Acquire::AllowInsecureRepositories") == true)
+   {
+      MessageInsecureRepository(false, msg, repo);
       return true;
+   }
 
-   _error->Error(_("Use --allow-insecure-repositories to force the update"));
+   MessageInsecureRepository(true, msg, 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 +196,8 @@ 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;
+   return TransactionManager->MetaIndexParser != NULL &&
+      TransactionManager->MetaIndexParser->GetLoadedSuccessfully() == metaIndex::TRI_YES;
 }
 HashStringList pkgAcqTransactionItem::GetExpectedHashes() const
 {
@@ -162,12 +216,12 @@ 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 +237,7 @@ 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
@@ -257,17 +311,17 @@ 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);
+   return GetKeepCompressedFileName(FinalFile, Target);
 }
 std::string pkgAcqMetaSig::GetFinalFilename() const
 {
@@ -299,7 +353,7 @@ std::string pkgAcqIndex::GetMetaKey() const
 }
 std::string pkgAcqDiffIndex::GetMetaKey() const
 {
-   return Target.MetaKey + ".diff/Index";
+   return GetDiffIndexFileName(Target.MetaKey);
 }
                                                                        /*}}}*/
 //pkgAcqTransactionItem::TransactionState and specialisations for child classes        /*{{{*/
@@ -318,16 +372,66 @@ 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("TransactionCommit", DestFile) == false)
+              return false;
         }
         break;
    }
@@ -352,13 +456,13 @@ bool pkgAcqIndex::TransactionState(TransactionStates const state)
         {
            // 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("TransactionCommit", EraseFileName);
         break;
    }
    return true;
@@ -374,7 +478,7 @@ bool pkgAcqDiffIndex::TransactionState(TransactionStates const state)
         break;
       case TransactionAbort:
         std::string const Partial = GetPartialFileNameFromURI(Target.URI);
-        unlink(Partial.c_str());
+        RemoveFile("TransactionAbort", Partial);
         break;
    }
 
@@ -389,23 +493,29 @@ class APT_HIDDEN NoActionItem : public pkgAcquire::Item                   /*{{{*/
 {
    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 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 = FinalFile;
+   }
 };
                                                                        /*}}}*/
 
 // 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;
@@ -437,6 +547,11 @@ 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;
@@ -450,7 +565,6 @@ void pkgAcquire::Item::Failed(string const &Message,pkgAcquire::MethodConfig con
 {
    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
@@ -508,24 +622,35 @@ 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();
@@ -585,8 +710,8 @@ 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
@@ -660,8 +785,8 @@ std::string pkgAcquire::Item::HashSum() const                               /*{{{*/
                                                                        /*}}}*/
 
 pkgAcqTransactionItem::pkgAcqTransactionItem(pkgAcquire * const Owner, /*{{{*/
-      pkgAcqMetaBase * const TransactionManager, IndexTarget 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);
@@ -671,7 +796,7 @@ pkgAcqTransactionItem::~pkgAcqTransactionItem()                             /*{{{*/
 {
 }
                                                                        /*}}}*/
-HashStringList pkgAcqTransactionItem::GetExpectedHashesFor(std::string const MetaKey) const    /*{{{*/
+HashStringList pkgAcqTransactionItem::GetExpectedHashesFor(std::string const &MetaKey) const   /*{{{*/
 {
    return GetExpectedHashesFromFor(TransactionManager->MetaIndexParser, MetaKey);
 }
@@ -679,12 +804,11 @@ HashStringList pkgAcqTransactionItem::GetExpectedHashesFor(std::string const Met
 
 // AcqMetaBase - Constructor                                           /*{{{*/
 pkgAcqMetaBase::pkgAcqMetaBase(pkgAcquire * const Owner,
-      pkgAcqMetaBase * const TransactionManager,
-      std::vector<IndexTarget> const IndexTargets,
-      IndexTarget const &DataTarget,
-      indexRecords * const MetaIndexParser)
-: pkgAcqTransactionItem(Owner, TransactionManager, DataTarget),
-   MetaIndexParser(MetaIndexParser), LastMetaIndexParser(NULL), IndexTargets(IndexTargets),
+      pkgAcqMetaClearSig * const TransactionManager,
+      std::vector<IndexTarget> const &IndexTargets,
+      IndexTarget const &DataTarget)
+: pkgAcqTransactionItem(Owner, TransactionManager, DataTarget), d(NULL),
+   IndexTargets(IndexTargets),
    AuthPass(false), IMSHit(false)
 {
 }
@@ -774,7 +898,7 @@ bool pkgAcqMetaBase::CheckStopAuthentication(pkgAcquire::Item * const I, const s
       _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"),
+                        "GPG error: %s: %s"),
                       Desc.Description.c_str(),
                       LookupTag(Message,"Message").c_str());
       RunScripts("APT::Update::Auth-Failure");
@@ -784,7 +908,7 @@ bool pkgAcqMetaBase::CheckStopAuthentication(pkgAcquire::Item * const I, const s
       _error->Error(_("GPG error: %s: %s"),
                     Desc.Description.c_str(),
                     LookupTag(Message,"Message").c_str());
-      I->Status = StatError;
+      I->Status = StatAuthError;
       return true;
    } else {
       _error->Warning(_("GPG error: %s: %s"),
@@ -807,7 +931,6 @@ 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);
@@ -831,15 +954,8 @@ 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)
-   {
-      I->Status = StatError;
-      I->ErrorText = "Method gave a blank filename";
-      return false;
-   }
-
-   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;
@@ -856,7 +972,7 @@ 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);
       }
    }
 
@@ -900,26 +1016,28 @@ bool pkgAcqMetaBase::CheckAuthDone(string const &Message)                /*{{{*/
       }
       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())
+        TransactionManager->LastMetaIndexParser = TransactionManager->MetaIndexParser->UnloadedClone();
+        if (TransactionManager->LastMetaIndexParser != NULL)
         {
-           delete TransactionManager->LastMetaIndexParser;
-           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();
         }
-        _error->RevertToStack();
       }
    }
 
-   if (TransactionManager->MetaIndexParser->Load(DestFile) == false)
+   if (TransactionManager->MetaIndexParser->Load(DestFile, &ErrorText) == false)
    {
       Status = StatAuthError;
-      ErrorText = TransactionManager->MetaIndexParser->ErrorText;
       return false;
    }
 
@@ -944,11 +1062,29 @@ void pkgAcqMetaBase::QueueIndexes(bool const verify)                     /*{{{*/
    // at this point the real Items are loaded in the fetcher
    ExpectedAdditionalItems = 0;
 
-   for (std::vector <IndexTarget>::const_iterator Target = IndexTargets.begin();
+  bool metaBaseSupportsByHash = false;
+  if (TransactionManager != NULL && TransactionManager->MetaIndexParser != NULL)
+     metaBaseSupportsByHash = TransactionManager->MetaIndexParser->GetSupportsAcquireByHash();
+
+   for (std::vector <IndexTarget>::iterator Target = IndexTargets.begin();
         Target != IndexTargets.end();
         ++Target)
    {
-      bool trypdiff = _config->FindB("Acquire::PDiffs", true);
+      // 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 (Target->Option(IndexTarget::ARCHITECTURE) == "all")
+      {
+        if (TransactionManager->MetaIndexParser->IsArchitectureSupported("all") == false)
+           continue;
+        if (TransactionManager->MetaIndexParser->IsArchitectureAllSupportedFor(*Target) == false)
+           continue;
+      }
+
+      bool trypdiff = Target->OptionBool(IndexTarget::PDIFFS);
       if (verify == true)
       {
         if (TransactionManager->MetaIndexParser->Exists(Target->MetaKey) == false)
@@ -957,33 +1093,103 @@ void pkgAcqMetaBase::QueueIndexes(bool const verify)                    /*{{{*/
            if (Target->IsOptional)
               continue;
 
+           std::string const &arch = Target->Option(IndexTarget::ARCHITECTURE);
+           if (arch.empty() == false)
+           {
+              if (TransactionManager->MetaIndexParser->IsArchitectureSupported(arch) == false)
+              {
+                 _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 (TransactionManager->MetaIndexParser->IsArchitectureSupported("*undefined*") == false)
+                 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;
         }
+        else
+        {
+           auto const hashes = GetExpectedHashesFor(Target->MetaKey);
+           if (hashes.usable() == false && hashes.empty() == false)
+           {
+              _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;
+           }
+        }
 
-        if (RealFileExists(GetFinalFileNameFromURI(Target->URI)))
+        // 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)
         {
-           if (TransactionManager->LastMetaIndexParser != NULL)
+           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)
-              {
-                 // we have the file already, no point in trying to acquire it again
-                 new NoActionItem(Owner, *Target);
-                 continue;
-              }
+              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);
+           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)
@@ -1038,15 +1244,15 @@ 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."),
@@ -1063,16 +1269,18 @@ 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;
    }
@@ -1083,29 +1291,33 @@ 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,
-      std::vector<IndexTarget> const IndexTargets,
-      indexRecords * const MetaIndexParser) :
-   pkgAcqMetaIndex(Owner, this, ClearsignedTarget, DetachedSigTarget, IndexTargets, MetaIndexParser),
-   ClearsignedTarget(ClearsignedTarget),
-   DetachedDataTarget(DetachedDataTarget), DetachedSigTarget(DetachedSigTarget)
+      std::vector<IndexTarget> const &IndexTargets,
+      metaIndex * const MetaIndexParser) :
+   pkgAcqMetaIndex(Owner, this, ClearsignedTarget, DetachedSigTarget, IndexTargets),
+   d(NULL), ClearsignedTarget(ClearsignedTarget),
+   DetachedDataTarget(DetachedDataTarget),
+   MetaIndexParser(MetaIndexParser), LastMetaIndexParser(NULL)
 {
    // index targets + (worst case:) Release/Release.gpg
    ExpectedAdditionalItems = IndexTargets.size() + 2;
@@ -1114,6 +1326,8 @@ pkgAcqMetaClearSig::pkgAcqMetaClearSig(pkgAcquire * const Owner,  /*{{{*/
                                                                        /*}}}*/
 pkgAcqMetaClearSig::~pkgAcqMetaClearSig()                              /*{{{*/
 {
+   if (LastMetaIndexParser != NULL)
+      delete LastMetaIndexParser;
 }
                                                                        /*}}}*/
 // pkgAcqMetaClearSig::Custom600Headers - Insert custom request headers        /*{{{*/
@@ -1121,9 +1335,24 @@ 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;
 }
                                                                        /*}}}*/
+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,
@@ -1131,17 +1360,6 @@ 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)
@@ -1172,27 +1390,33 @@ void pkgAcqMetaClearSig::Failed(string const &Message,pkgAcquire::MethodConfig c
 
    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, IndexTargets);
    }
    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)
+      // only allow going further if the user explicitly wants it
+      if(AllowInsecureRepositories(_("The repository '%s' is not signed."), ClearsignedTarget.Description, TransactionManager->MetaIndexParser, TransactionManager, this) == true)
       {
         Status = StatDone;
 
@@ -1210,25 +1434,28 @@ void pkgAcqMetaClearSig::Failed(string const &Message,pkgAcquire::MethodConfig c
            // 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())
+              TransactionManager->LastMetaIndexParser = TransactionManager->MetaIndexParser->UnloadedClone();
+              if (TransactionManager->LastMetaIndexParser != NULL)
               {
-                 delete TransactionManager->LastMetaIndexParser;
-                 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();
               }
-              _error->RevertToStack();
            }
         }
 
         // 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);
@@ -1238,12 +1465,11 @@ void pkgAcqMetaClearSig::Failed(string const &Message,pkgAcquire::MethodConfig c
                                                                        /*}}}*/
 
 pkgAcqMetaIndex::pkgAcqMetaIndex(pkgAcquire * const Owner,             /*{{{*/
-                                 pkgAcqMetaBase * const TransactionManager,
+                                 pkgAcqMetaClearSig * const TransactionManager,
                                 IndexTarget const &DataTarget,
                                 IndexTarget const &DetachedSigTarget,
-                                vector<IndexTarget> const IndexTargets,
-                                indexRecords * const MetaIndexParser) :
-   pkgAcqMetaBase(Owner, TransactionManager, IndexTargets, DataTarget, MetaIndexParser),
+                                vector<IndexTarget> const &IndexTargets) :
+   pkgAcqMetaBase(Owner, TransactionManager, IndexTargets, DataTarget), d(NULL),
    DetachedSigTarget(DetachedSigTarget)
 {
    if(_config->FindB("Debug::Acquire::Transaction", false) == true)
@@ -1285,19 +1511,13 @@ 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."), Target.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(_("The repository '%s' does not have a Release file."), 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);
@@ -1318,20 +1538,21 @@ std::string pkgAcqMetaIndex::DescURI() const                            /*{{{*/
    return Target.URI;
 }
                                                                        /*}}}*/
+pkgAcqMetaIndex::~pkgAcqMetaIndex() {}
 
 // AcqMetaSig::AcqMetaSig - Constructor                                        /*{{{*/
 pkgAcqMetaSig::pkgAcqMetaSig(pkgAcquire * const Owner,
-      pkgAcqMetaBase * const TransactionManager,
-      IndexTarget 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);
 
    // 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)
@@ -1360,6 +1581,16 @@ 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            /*{{{*/
@@ -1421,7 +1652,7 @@ void pkgAcqMetaSig::Failed(string const &Message,pkgAcquire::MethodConfig const
                            "given to override it."));
          Status = StatDone;
       } else {
-         _error->Error("%s", downgrade_msg.c_str());
+        MessageInsecureRepository(true, downgrade_msg);
         if (TransactionManager->IMSHit == false)
            Rename(MetaIndex->DestFile, MetaIndex->DestFile + ".FAILED");
         Item::Failed("Message: " + downgrade_msg, Cnf);
@@ -1429,44 +1660,44 @@ void pkgAcqMetaSig::Failed(string const &Message,pkgAcquire::MethodConfig const
          return;
       }
    }
-   else
-      _error->Warning(_("The data from '%s' is not signed. Packages "
-              "from that repository can not be authenticated."),
-           MetaIndex->Target.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(_("The repository '%s' is not signed."), 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())
+           TransactionManager->LastMetaIndexParser = TransactionManager->MetaIndexParser->UnloadedClone();
+           if (TransactionManager->LastMetaIndexParser != NULL)
            {
-              delete TransactionManager->LastMetaIndexParser;
-              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();
            }
-           _error->RevertToStack();
         }
       }
 
       // 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);
+        MetaIndex->QueueIndexes(GoodLoad);
 
       TransactionManager->TransactionStageCopy(MetaIndex, MetaIndex->DestFile, MetaIndex->GetFinalFilename());
    }
@@ -1484,12 +1715,13 @@ void pkgAcqMetaSig::Failed(string const &Message,pkgAcquire::MethodConfig const
 
 // AcqBaseIndex - Constructor                                          /*{{{*/
 pkgAcqBaseIndex::pkgAcqBaseIndex(pkgAcquire * const Owner,
-      pkgAcqMetaBase * const TransactionManager,
-      IndexTarget const Target)
-: pkgAcqTransactionItem(Owner, TransactionManager, Target)
+      pkgAcqMetaClearSig * const TransactionManager,
+      IndexTarget const &Target)
+: pkgAcqTransactionItem(Owner, TransactionManager, Target), d(NULL)
 {
 }
                                                                        /*}}}*/
+pkgAcqBaseIndex::~pkgAcqBaseIndex() {}
 
 // AcqDiffIndex::AcqDiffIndex - Constructor                            /*{{{*/
 // ---------------------------------------------------------------------
@@ -1499,16 +1731,16 @@ pkgAcqBaseIndex::pkgAcqBaseIndex(pkgAcquire * const Owner,
  * the original packages file
  */
 pkgAcqDiffIndex::pkgAcqDiffIndex(pkgAcquire * const Owner,
-                                 pkgAcqMetaBase * const TransactionManager,
-                                 IndexTarget const Target)
-   : pkgAcqBaseIndex(Owner, TransactionManager, Target)
+                                 pkgAcqMetaClearSig * const TransactionManager,
+                                 IndexTarget const &Target)
+   : pkgAcqBaseIndex(Owner, TransactionManager, Target), d(NULL), diffs(NULL)
 {
    Debug = _config->FindB("Debug::pkgAcquire::Diffs",false);
 
    Desc.Owner = this;
-   Desc.Description = Target.Description + ".diff/Index";
+   Desc.Description = GetDiffIndexFileName(Target.Description);
    Desc.ShortDesc = Target.ShortDesc;
-   Desc.URI = Target.URI + ".diff/Index";
+   Desc.URI = GetDiffIndexURI(Target);
 
    DestFile = GetPartialFileNameFromURI(Desc.URI);
 
@@ -1523,6 +1755,9 @@ 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)
@@ -1552,7 +1787,7 @@ 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;
@@ -1596,7 +1831,7 @@ bool pkgAcqDiffIndex::ParseDiffIndex(string const &IndexDiffFile) /*{{{*/
       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;
    }
@@ -1607,7 +1842,7 @@ bool pkgAcqDiffIndex::ParseDiffIndex(string const &IndexDiffFile) /*{{{*/
       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();
@@ -1626,10 +1861,18 @@ 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;
@@ -1687,7 +1930,7 @@ 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;
@@ -1727,7 +1970,7 @@ 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");
@@ -1789,6 +2032,17 @@ 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())
@@ -1800,18 +2054,37 @@ 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 && TransactionManager->MetaIndexParser != nullptr)
+   {
+      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
@@ -1832,11 +2105,46 @@ 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,
@@ -1892,6 +2200,11 @@ void pkgAcqDiffIndex::Done(string const &Message,HashStringList const &Hashes,   /
    return;
 }
                                                                        /*}}}*/
+pkgAcqDiffIndex::~pkgAcqDiffIndex()
+{
+   if (diffs != NULL)
+      delete diffs;
+}
 
 // AcqIndexDiffs::AcqIndexDiffs - Constructor                          /*{{{*/
 // ---------------------------------------------------------------------
@@ -1899,13 +2212,13 @@ 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 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);
 
@@ -1916,23 +2229,11 @@ pkgAcqIndexDiffs::pkgAcqIndexDiffs(pkgAcquire * const Owner,
    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();
    }
@@ -1943,14 +2244,17 @@ void pkgAcqIndexDiffs::Failed(string const &Message,pkgAcquire::MethodConfig con
    Item::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();
 }
@@ -1967,7 +2271,8 @@ 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;
@@ -1977,6 +2282,8 @@ 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;
@@ -1989,30 +2296,28 @@ 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);
    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)
    {
@@ -2022,26 +2327,22 @@ 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.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;
@@ -2054,55 +2355,51 @@ 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);
+   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 downloading a diff, enter ApplyDiff state
-   if(State == StateFetchDiff)
+   switch (State)
    {
-      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;
-   }
-
-   // success in download/apply a diff, queue next (if needed)
-   if(State == StateApplyDiff)
-   {
-      // 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;
    }
 }
                                                                        /*}}}*/
@@ -2118,14 +2415,15 @@ std::string pkgAcqIndexDiffs::Custom600Headers() const                  /*{{{*/
    return patchhashes.str();
 }
                                                                        /*}}}*/
+pkgAcqIndexDiffs::~pkgAcqIndexDiffs() {}
 
 // AcqIndexMergeDiffs::AcqIndexMergeDiffs - Constructor                        /*{{{*/
 pkgAcqIndexMergeDiffs::pkgAcqIndexMergeDiffs(pkgAcquire * const Owner,
-                                             pkgAcqMetaBase * const TransactionManager,
-                                             IndexTarget 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);
@@ -2133,11 +2431,9 @@ pkgAcqIndexMergeDiffs::pkgAcqIndexMergeDiffs(pkgAcquire * const Owner,
    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);
+   Desc.Description = Description + " " + patch.file + ".pdiff";
+   DestFile = GetPartialFileNameFromURI(Desc.URI);
 
    if(Debug)
       std::clog << "pkgAcqIndexMergeDiffs: " << Desc.URI << std::endl;
@@ -2158,17 +2454,22 @@ 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);
 }
                                                                        /*}}}*/
@@ -2180,67 +2481,73 @@ 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;
    }
 }
                                                                        /*}}}*/
@@ -2262,15 +2569,15 @@ std::string pkgAcqIndexMergeDiffs::Custom600Headers() const             /*{{{*/
    return patchhashes.str();
 }
                                                                        /*}}}*/
+pkgAcqIndexMergeDiffs::~pkgAcqIndexMergeDiffs() {}
 
 // AcqIndex::AcqIndex - Constructor                                    /*{{{*/
 pkgAcqIndex::pkgAcqIndex(pkgAcquire * const Owner,
-                         pkgAcqMetaBase * const TransactionManager,
-                         IndexTarget 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);
 
    if(_config->FindB("Debug::Acquire::Transaction", false) == true)
@@ -2278,55 +2585,63 @@ pkgAcqIndex::pkgAcqIndex(pkgAcquire * const Owner,
                 << 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(TransactionManager->MetaIndexParser == NULL || 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
@@ -2335,8 +2650,6 @@ void pkgAcqIndex::Init(string const &URI, string const &URIDesc,
       DestFile = DestFile + '.' + CurrentCompressionExtension;
    }
 
-   if(TransactionManager->MetaIndexParser != NULL)
-      InitByHashIfNeeded();
 
    Desc.Description = URIDesc;
    Desc.Owner = this;
@@ -2345,47 +2658,22 @@ 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 (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);
+   }
 
    if(Target.IsOptional)
       msg += "\nFail-Ignore: true";
@@ -2415,20 +2703,6 @@ void pkgAcqIndex::Failed(string const &Message,pkgAcquire::MethodConfig const *
       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
@@ -2445,99 +2719,96 @@ 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";
+      if (CurrentCompressionExtension != "uncompressed")
+        DestFile.erase(DestFile.length() - (CurrentCompressionExtension.length() + 1));
+      Filename = AltFilename;
    }
-
    // 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())
+      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                                        /*{{{*/
@@ -2547,7 +2818,7 @@ 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)
 {
@@ -2686,7 +2957,7 @@ 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
@@ -2705,7 +2976,7 @@ 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);
@@ -2715,7 +2986,7 @@ 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;
       }
@@ -2750,16 +3021,8 @@ 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;
@@ -2835,13 +3098,272 @@ 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);
 
@@ -2867,7 +3389,7 @@ 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;
    }
@@ -2881,14 +3403,7 @@ 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
@@ -2896,7 +3411,7 @@ 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 ||
@@ -2912,7 +3427,7 @@ 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
@@ -2921,7 +3436,7 @@ 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;
@@ -2957,3 +3472,4 @@ string pkgAcqFile::Custom600Headers() const                               /*{{{*/
    return "";
 }
                                                                        /*}}}*/
+pkgAcqFile::~pkgAcqFile() {}