]> git.saurik.com Git - apt.git/blobdiff - apt-pkg/acquire-worker.cc
handle site-changing redirects as mirror changes
[apt.git] / apt-pkg / acquire-worker.cc
index 4a357bdab884df1e2e1e4f1e8ff0ab3bf5427fc7..dc03a8870a0a4360a104f0d348831c0b6b2a7c65 100644 (file)
@@ -34,6 +34,9 @@
 #include <signal.h>
 #include <stdio.h>
 #include <errno.h>
+#include <sys/types.h>
+#include <pwd.h>
+#include <grp.h>
 
 #include <apti18n.h>
                                                                        /*}}}*/
@@ -44,7 +47,7 @@ using namespace std;
 // ---------------------------------------------------------------------
 /* */
 pkgAcquire::Worker::Worker(Queue *Q,MethodConfig *Cnf,
-                          pkgAcquireStatus *Log) : Log(Log)
+                          pkgAcquireStatus *log) : d(NULL), Log(log)
 {
    OwnerQ = Q;
    Config = Cnf;
@@ -52,23 +55,18 @@ pkgAcquire::Worker::Worker(Queue *Q,MethodConfig *Cnf,
    CurrentItem = 0;
    TotalSize = 0;
    CurrentSize = 0;
-   
-   Construct();   
+
+   Construct();
 }
                                                                        /*}}}*/
 // Worker::Worker - Constructor for method config startup              /*{{{*/
 // ---------------------------------------------------------------------
 /* */
-pkgAcquire::Worker::Worker(MethodConfig *Cnf)
+pkgAcquire::Worker::Worker(MethodConfig *Cnf) : d(NULL), OwnerQ(NULL), Config(Cnf),
+                                               Access(Cnf->Access), CurrentItem(NULL),
+                                               CurrentSize(0), TotalSize(0)
 {
-   OwnerQ = 0;
-   Config = Cnf;
-   Access = Cnf->Access;
-   CurrentItem = 0;
-   TotalSize = 0;
-   CurrentSize = 0;
-   
-   Construct();   
+   Construct();
 }
                                                                        /*}}}*/
 // Worker::Construct - Constructor helper                              /*{{{*/
@@ -133,7 +131,7 @@ bool pkgAcquire::Worker::Start()
    }
    for (int I = 0; I != 4; I++)
       SetCloseExec(Pipes[I],true);
-   
+
    // Fork off the process
    Process = ExecFork();
    if (Process == 0)
@@ -142,9 +140,9 @@ bool pkgAcquire::Worker::Start()
       dup2(Pipes[1],STDOUT_FILENO);
       dup2(Pipes[2],STDIN_FILENO);
       SetCloseExec(STDOUT_FILENO,false);
-      SetCloseExec(STDIN_FILENO,false);      
+      SetCloseExec(STDIN_FILENO,false);
       SetCloseExec(STDERR_FILENO,false);
-      
+
       const char *Args[2];
       Args[0] = Method.c_str();
       Args[1] = 0;
@@ -162,7 +160,7 @@ bool pkgAcquire::Worker::Start()
    close(Pipes[2]);
    OutReady = false;
    InReady = true;
-   
+
    // Read the configuration data
    if (WaitFd(InFd) == false ||
        ReadMessages() == false)
@@ -171,7 +169,7 @@ bool pkgAcquire::Worker::Start()
    RunMessages();
    if (OwnerQ != 0)
       SendConfiguration();
-   
+
    return true;
 }
                                                                        /*}}}*/
@@ -198,7 +196,7 @@ bool pkgAcquire::Worker::RunMessages()
 
       if (Debug == true)
         clog << " <- " << Access << ':' << QuoteString(Message,"\n") << endl;
-      
+
       // Fetch the message number
       char *End;
       int Number = strtol(Message.c_str(),&End,10);
@@ -206,21 +204,24 @@ bool pkgAcquire::Worker::RunMessages()
         return _error->Error("Invalid message from method %s: %s",Access.c_str(),Message.c_str());
 
       string URI = LookupTag(Message,"URI");
-      pkgAcquire::Queue::QItem *Itm = 0;
+      pkgAcquire::Queue::QItem *Itm = NULL;
       if (URI.empty() == false)
         Itm = OwnerQ->FindItem(URI,this);
 
-      // update used mirror
-      string UsedMirror = LookupTag(Message,"UsedMirror", "");
-      if (!UsedMirror.empty() && 
-          Itm && 
-          Itm->Description.find(" ") != string::npos) 
+      if (Itm != NULL)
       {
-         Itm->Description.replace(0, Itm->Description.find(" "), UsedMirror);
-         // FIXME: will we need this as well?
-         //Itm->ShortDesc = UsedMirror;
+        // update used mirror
+        string UsedMirror = LookupTag(Message,"UsedMirror", "");
+        if (UsedMirror.empty() == false)
+        {
+           for (pkgAcquire::Queue::QItem::owner_iterator O = Itm->Owners.begin(); O != Itm->Owners.end(); ++O)
+              (*O)->UsedMirror = UsedMirror;
+
+           if (Itm->Description.find(" ") != string::npos)
+              Itm->Description.replace(0, Itm->Description.find(" "), UsedMirror);
+        }
       }
-      
+
       // Determine the message number and dispatch
       switch (Number)
       {
@@ -229,18 +230,18 @@ bool pkgAcquire::Worker::RunMessages()
         if (Capabilities(Message) == false)
            return _error->Error("Unable to process Capabilities message from %s",Access.c_str());
         break;
-        
+
         // 101 Log
         case 101:
         if (Debug == true)
            clog << " <- (log) " << LookupTag(Message,"Message") << endl;
         break;
-        
+
         // 102 Status
         case 102:
         Status = LookupTag(Message,"Message");
         break;
-           
+
          // 103 Redirect
          case 103:
          {
@@ -249,27 +250,49 @@ bool pkgAcquire::Worker::RunMessages()
                _error->Error("Method gave invalid 103 Redirect message");
                break;
             }
-            string NewURI = LookupTag(Message,"New-URI",URI.c_str());
+
+           std::string const NewURI = LookupTag(Message,"New-URI",URI.c_str());
             Itm->URI = NewURI;
 
            ItemDone();
 
-           pkgAcquire::Item *Owner = Itm->Owner;
-           pkgAcquire::ItemDesc Desc = *Itm;
-
            // Change the status so that it can be dequeued
-           Owner->Status = pkgAcquire::Item::StatIdle;
+           for (pkgAcquire::Queue::QItem::owner_iterator O = Itm->Owners.begin(); O != Itm->Owners.end(); ++O)
+              (*O)->Status = pkgAcquire::Item::StatIdle;
            // Mark the item as done (taking care of all queues)
            // and then put it in the main queue again
+           std::vector<Item*> const ItmOwners = Itm->Owners;
            OwnerQ->ItemDone(Itm);
-           OwnerQ->Owner->Enqueue(Desc);
-
-           if (Log != 0)
-              Log->Done(Desc);
+           Itm = NULL;
+           for (pkgAcquire::Queue::QItem::owner_iterator O = ItmOwners.begin(); O != ItmOwners.end(); ++O)
+           {
+              pkgAcquire::Item *Owner = *O;
+              pkgAcquire::ItemDesc &desc = Owner->GetItemDesc();
+              // if we change site, treat it as a mirror change
+              if (URI::SiteOnly(NewURI) != URI::SiteOnly(desc.URI))
+              {
+                 std::string const OldSite = desc.Description.substr(0, desc.Description.find(" "));
+                 if (likely(APT::String::Startswith(desc.URI, OldSite)))
+                 {
+                    std::string const OldExtra = desc.URI.substr(OldSite.length() + 1);
+                    if (likely(APT::String::Endswith(NewURI, OldExtra)))
+                    {
+                       std::string const NewSite = NewURI.substr(0, NewURI.length() - OldExtra.length());
+                       Owner->UsedMirror = URI::ArchiveOnly(NewSite);
+                       if (desc.Description.find(" ") != string::npos)
+                          desc.Description.replace(0, desc.Description.find(" "), Owner->UsedMirror);
+                    }
+                 }
+              }
+              desc.URI = NewURI;
+              OwnerQ->Owner->Enqueue(desc);
+
+              if (Log != 0)
+                 Log->Done(desc);
+           }
             break;
          }
-   
+
         // 200 URI Start
         case 200:
         {
@@ -278,23 +301,27 @@ bool pkgAcquire::Worker::RunMessages()
               _error->Error("Method gave invalid 200 URI Start message");
               break;
            }
-           
+
            CurrentItem = Itm;
            CurrentSize = 0;
            TotalSize = strtoull(LookupTag(Message,"Size","0").c_str(), NULL, 10);
            ResumePoint = strtoull(LookupTag(Message,"Resume-Point","0").c_str(), NULL, 10);
-           Itm->Owner->Start(Message,strtoull(LookupTag(Message,"Size","0").c_str(), NULL, 10));
+           for (pkgAcquire::Queue::QItem::owner_iterator O = Itm->Owners.begin(); O != Itm->Owners.end(); ++O)
+           {
+              (*O)->Start(Message, TotalSize);
 
-           // Display update before completion
-           if (Log != 0 && Log->MorePulses == true)
-              Log->Pulse(Itm->Owner->GetOwner());
-           
-           if (Log != 0)
-              Log->Fetch(*Itm);
+              // Display update before completion
+              if (Log != 0)
+              {
+                 if (Log->MorePulses == true)
+                    Log->Pulse((*O)->GetOwner());
+                 Log->Fetch((*O)->GetItemDesc());
+              }
+           }
 
            break;
         }
-        
+
         // 201 URI Done
         case 201:
         {
@@ -303,69 +330,113 @@ bool pkgAcquire::Worker::RunMessages()
               _error->Error("Method gave invalid 201 URI Done message");
               break;
            }
-           
-           pkgAcquire::Item *Owner = Itm->Owner;
-           pkgAcquire::ItemDesc Desc = *Itm;
-           
+
+           PrepareFiles("201::URIDone", Itm);
+
            // Display update before completion
            if (Log != 0 && Log->MorePulses == true)
-              Log->Pulse(Owner->GetOwner());
-           
-           OwnerQ->ItemDone(Itm);
-           unsigned long long const ServerSize = strtoull(LookupTag(Message,"Size","0").c_str(), NULL, 10);
-            bool isHit = StringToBool(LookupTag(Message,"IMS-Hit"),false) ||
-                         StringToBool(LookupTag(Message,"Alt-IMS-Hit"),false);
-            // Using the https method the server might return 200, but the
-            // If-Modified-Since condition is not satsified, libcurl will
-            // discard the download. In this case, however, TotalSize will be
-            // set to the actual size of the file, while ServerSize will be set
-            // to 0. Therefore, if the item is marked as a hit and the
-            // downloaded size (ServerSize) is 0, we ignore TotalSize.
-           if (TotalSize != 0 && (!isHit || ServerSize != 0) && ServerSize != TotalSize)
-              _error->Warning("Size of file %s is not what the server reported %s %llu",
-                              Owner->DestFile.c_str(), LookupTag(Message,"Size","0").c_str(),TotalSize);
-
-           // see if there is a hash to verify
-           HashStringList RecivedHashes;
-           HashStringList expectedHashes = Owner->HashSums();
-           for (HashStringList::const_iterator hs = expectedHashes.begin(); hs != expectedHashes.end(); ++hs)
-           {
-              std::string const tagname = hs->HashType() + "-Hash";
-              std::string const hashsum = LookupTag(Message, tagname.c_str());
-              if (hashsum.empty() == false)
-                 RecivedHashes.push_back(HashString(hs->HashType(), hashsum));
-           }
+              for (pkgAcquire::Queue::QItem::owner_iterator O = Itm->Owners.begin(); O != Itm->Owners.end(); ++O)
+                 Log->Pulse((*O)->GetOwner());
 
-           if(_config->FindB("Debug::pkgAcquire::Auth", false) == true)
+           std::string const filename = LookupTag(Message, "Filename", Itm->Owner->DestFile.c_str());
+           HashStringList ReceivedHashes;
            {
-              std::clog << "201 URI Done: " << Owner->DescURI() << endl
-                 << "RecivedHash:" << endl;
-              for (HashStringList::const_iterator hs = RecivedHashes.begin(); hs != RecivedHashes.end(); ++hs)
-                 std::clog <<  "\t- " << hs->toStr() << std::endl;
-              std::clog << "ExpectedHash:" << endl;
-              for (HashStringList::const_iterator hs = expectedHashes.begin(); hs != expectedHashes.end(); ++hs)
-                 std::clog <<  "\t- " << hs->toStr() << std::endl;
-              std::clog << endl;
+              // see if we got hashes to verify
+              for (char const * const * type = HashString::SupportedHashes(); *type != NULL; ++type)
+              {
+                 std::string const tagname = std::string(*type) + "-Hash";
+                 std::string const hashsum = LookupTag(Message, tagname.c_str());
+                 if (hashsum.empty() == false)
+                    ReceivedHashes.push_back(HashString(*type, hashsum));
+              }
+              // not all methods always sent Hashes our way
+              if (ReceivedHashes.usable() == false)
+              {
+                 HashStringList const ExpectedHashes = Itm->GetExpectedHashes();
+                 if (ExpectedHashes.usable() == true && RealFileExists(filename))
+                 {
+                    Hashes calc(ExpectedHashes);
+                    FileFd file(filename, FileFd::ReadOnly, FileFd::None);
+                    calc.AddFD(file);
+                    ReceivedHashes = calc.GetHashStringList();
+                 }
+              }
            }
-           Owner->Done(Message, ServerSize, RecivedHashes, Config);
-           ItemDone();
 
-           // Log that we are done
-           if (Log != 0)
+           // only local files can refer other filenames and counting them as fetched would be unfair
+           if (Log !=  NULL && filename != Itm->Owner->DestFile)
+              Log->Fetched(ReceivedHashes.FileSize(),atoi(LookupTag(Message,"Resume-Point","0").c_str()));
+
+           std::vector<Item*> const ItmOwners = Itm->Owners;
+           OwnerQ->ItemDone(Itm);
+           Itm = NULL;
+
+           bool const isIMSHit = StringToBool(LookupTag(Message,"IMS-Hit"),false) ||
+              StringToBool(LookupTag(Message,"Alt-IMS-Hit"),false);
+           for (pkgAcquire::Queue::QItem::owner_iterator O = ItmOwners.begin(); O != ItmOwners.end(); ++O)
            {
-              if (isHit)
+              pkgAcquire::Item * const Owner = *O;
+              HashStringList const ExpectedHashes = Owner->GetExpectedHashes();
+              if(_config->FindB("Debug::pkgAcquire::Auth", false) == true)
+              {
+                 std::clog << "201 URI Done: " << Owner->DescURI() << endl
+                    << "ReceivedHash:" << endl;
+                 for (HashStringList::const_iterator hs = ReceivedHashes.begin(); hs != ReceivedHashes.end(); ++hs)
+                    std::clog <<  "\t- " << hs->toStr() << std::endl;
+                 std::clog << "ExpectedHash:" << endl;
+                 for (HashStringList::const_iterator hs = ExpectedHashes.begin(); hs != ExpectedHashes.end(); ++hs)
+                    std::clog <<  "\t- " << hs->toStr() << std::endl;
+                 std::clog << endl;
+              }
+
+              // decide if what we got is what we expected
+              bool consideredOkay = false;
+              if (ExpectedHashes.usable())
+              {
+                 if (ReceivedHashes.usable() == false)
+                 {
+                    /* IMS-Hits can't be checked here as we will have uncompressed file,
+                       but the hashes for the compressed file. What we have was good through
+                       so all we have to ensure later is that we are not stalled. */
+                    consideredOkay = isIMSHit;
+                 }
+                 else if (ReceivedHashes == ExpectedHashes)
+                    consideredOkay = true;
+                 else
+                    consideredOkay = false;
+
+              }
+              else if (Owner->HashesRequired() == true)
+                 consideredOkay = false;
+              else
+                 consideredOkay = true;
+
+              if (consideredOkay == true)
               {
-                 /* Hide 'hits' for local only sources - we also manage to
-                    hide gets */
-                 if (Config->LocalOnly == false)
-                    Log->IMSHit(Desc);
-              }               
+                 Owner->Done(Message, ReceivedHashes, Config);
+
+                 // Log that we are done
+                 if (Log != 0)
+                 {
+                    if (isIMSHit)
+                       Log->IMSHit(Owner->GetItemDesc());
+                    else
+                       Log->Done(Owner->GetItemDesc());
+                 }
+              }
               else
-                 Log->Done(Desc);
+              {
+                 Owner->Status = pkgAcquire::Item::StatAuthError;
+                 Owner->Failed(Message,Config);
+
+                 if (Log != 0)
+                    Log->Fail(Owner->GetItemDesc());
+              }
            }
+           ItemDone();
            break;
-        }       
-        
+        }
+
         // 400 URI Failure
         case 400:
         {
@@ -376,40 +447,46 @@ bool pkgAcquire::Worker::RunMessages()
               break;
            }
 
+           PrepareFiles("400::URIFailure", Itm);
+
            // Display update before completion
            if (Log != 0 && Log->MorePulses == true)
-              Log->Pulse(Itm->Owner->GetOwner());
-           
-           pkgAcquire::Item *Owner = Itm->Owner;
-           pkgAcquire::ItemDesc Desc = *Itm;
+              for (pkgAcquire::Queue::QItem::owner_iterator O = Itm->Owners.begin(); O != Itm->Owners.end(); ++O)
+                 Log->Pulse((*O)->GetOwner());
+
+           std::vector<Item*> const ItmOwners = Itm->Owners;
            OwnerQ->ItemDone(Itm);
+           Itm = NULL;
+
+           for (pkgAcquire::Queue::QItem::owner_iterator O = ItmOwners.begin(); O != ItmOwners.end(); ++O)
+           {
+              // set some status
+              if(LookupTag(Message,"FailReason") == "Timeout" ||
+                    LookupTag(Message,"FailReason") == "TmpResolveFailure" ||
+                    LookupTag(Message,"FailReason") == "ResolveFailure" ||
+                    LookupTag(Message,"FailReason") == "ConnectionRefused")
+                 (*O)->Status = pkgAcquire::Item::StatTransientNetworkError;
 
-           // set some status
-           if(LookupTag(Message,"FailReason") == "Timeout" || 
-              LookupTag(Message,"FailReason") == "TmpResolveFailure" ||
-              LookupTag(Message,"FailReason") == "ResolveFailure" ||
-              LookupTag(Message,"FailReason") == "ConnectionRefused") 
-              Owner->Status = pkgAcquire::Item::StatTransientNetworkError;
+              (*O)->Failed(Message,Config);
 
-           Owner->Failed(Message,Config);
+              if (Log != 0)
+                 Log->Fail((*O)->GetItemDesc());
+           }
            ItemDone();
 
-           if (Log != 0)
-              Log->Fail(Desc);
-
            break;
-        }       
-        
+        }
+
         // 401 General Failure
         case 401:
         _error->Error("Method %s General failure: %s",Access.c_str(),LookupTag(Message,"Message").c_str());
         break;
-        
+
         // 403 Media Change
         case 403:
-        MediaChange(Message); 
+        MediaChange(Message);
         break;
-      }      
+      }
    }
    return true;
 }
@@ -422,7 +499,7 @@ bool pkgAcquire::Worker::Capabilities(string Message)
 {
    if (Config == 0)
       return true;
-   
+
    Config->Version = LookupTag(Message,"Version");
    Config->SingleInstance = StringToBool(LookupTag(Message,"Single-Instance"),false);
    Config->Pipeline = StringToBool(LookupTag(Message,"Pipeline"),false);
@@ -437,13 +514,13 @@ bool pkgAcquire::Worker::Capabilities(string Message)
       clog << "Configured access method " << Config->Access << endl;
       clog << "Version:" << Config->Version <<
              " SingleInstance:" << Config->SingleInstance <<
-             " Pipeline:" << Config->Pipeline << 
-             " SendConfig:" << Config->SendConfig << 
-             " LocalOnly: " << Config->LocalOnly << 
-             " NeedsCleanup: " << Config->NeedsCleanup << 
+             " Pipeline:" << Config->Pipeline <<
+             " SendConfig:" << Config->SendConfig <<
+             " LocalOnly: " << Config->LocalOnly <<
+             " NeedsCleanup: " << Config->NeedsCleanup <<
              " Removable: " << Config->Removable << endl;
    }
-   
+
    return true;
 }
                                                                        /*}}}*/
@@ -453,10 +530,10 @@ bool pkgAcquire::Worker::Capabilities(string Message)
 bool pkgAcquire::Worker::MediaChange(string Message)
 {
    int status_fd = _config->FindI("APT::Status-Fd",-1);
-   if(status_fd > 0) 
+   if(status_fd > 0)
    {
       string Media = LookupTag(Message,"Media");
-      string Drive = LookupTag(Message,"Drive"); 
+      string Drive = LookupTag(Message,"Drive");
       ostringstream msg,status;
       ioprintf(msg,_("Please insert the disc labeled: "
                     "'%s' "
@@ -526,22 +603,43 @@ bool pkgAcquire::Worker::QueueItem(pkgAcquire::Queue::QItem *Item)
 {
    if (OutFd == -1)
       return false;
-   
+
    string Message = "600 URI Acquire\n";
    Message.reserve(300);
    Message += "URI: " + Item->URI;
    Message += "\nFilename: " + Item->Owner->DestFile;
-   HashStringList const hsl = Item->Owner->HashSums();
+
+   HashStringList const hsl = Item->GetExpectedHashes();
    for (HashStringList::const_iterator hs = hsl.begin(); hs != hsl.end(); ++hs)
       Message += "\nExpected-" + hs->HashType() + ": " + hs->HashValue();
-   Message += Item->Owner->Custom600Headers();
+
+   if (hsl.FileSize() == 0)
+   {
+      unsigned long long FileSize = Item->GetMaximumSize();
+      if(FileSize > 0)
+      {
+        string MaximumSize;
+        strprintf(MaximumSize, "%llu", FileSize);
+        Message += "\nMaximum-Size: " + MaximumSize;
+      }
+   }
+
+   Item->SyncDestinationFiles();
+   Message += Item->Custom600Headers();
    Message += "\n\n";
-   
+
+   if (RealFileExists(Item->Owner->DestFile))
+   {
+      std::string SandboxUser = _config->Find("APT::Sandbox::User");
+      ChangeOwnerAndPermissionOfFile("Item::QueueURI", Item->Owner->DestFile.c_str(),
+                                     SandboxUser.c_str(), "root", 0600);
+   }
+
    if (Debug == true)
       clog << " -> " << Access << ':' << QuoteString(Message,"\n") << endl;
    OutQueue += Message;
    OutReady = true;
-   
+
    return true;
 }
                                                                        /*}}}*/
@@ -563,7 +661,7 @@ bool pkgAcquire::Worker::OutFdReady()
    OutQueue.erase(0,Res);
    if (OutQueue.empty() == true)
       OutReady = false;
-   
+
    return true;
 }
                                                                        /*}}}*/
@@ -585,7 +683,7 @@ bool pkgAcquire::Worker::InFdReady()
 bool pkgAcquire::Worker::MethodFailure()
 {
    _error->Error("Method %s has died unexpectedly!",Access.c_str());
-   
+
    // do not reap the child here to show meaningfull error to the user
    ExecWait(Process,Access.c_str(),false);
    Process = -1;
@@ -597,26 +695,22 @@ bool pkgAcquire::Worker::MethodFailure()
    InReady = false;
    OutQueue = string();
    MessageQueue.erase(MessageQueue.begin(),MessageQueue.end());
-   
+
    return false;
 }
                                                                        /*}}}*/
-// Worker::Pulse - Called periodically                                         /*{{{*/
+// Worker::Pulse - Called periodically                                 /*{{{*/
 // ---------------------------------------------------------------------
 /* */
 void pkgAcquire::Worker::Pulse()
 {
    if (CurrentItem == 0)
       return;
+
    struct stat Buf;
    if (stat(CurrentItem->Owner->DestFile.c_str(),&Buf) != 0)
       return;
    CurrentSize = Buf.st_size;
-   
-   // Hmm? Should not happen...
-   if (CurrentSize > TotalSize && TotalSize != 0)
-      TotalSize = CurrentSize;
 }
                                                                        /*}}}*/
 // Worker::ItemDone - Called when the current item is finished         /*{{{*/
@@ -630,3 +724,33 @@ void pkgAcquire::Worker::ItemDone()
    Status = string();
 }
                                                                        /*}}}*/
+void pkgAcquire::Worker::PrepareFiles(char const * const caller, pkgAcquire::Queue::QItem const * const Itm)/*{{{*/
+{
+   if (RealFileExists(Itm->Owner->DestFile))
+   {
+      ChangeOwnerAndPermissionOfFile(caller, Itm->Owner->DestFile.c_str(), "root", "root", 0644);
+      std::string const filename = Itm->Owner->DestFile;
+      for (pkgAcquire::Queue::QItem::owner_iterator O = Itm->Owners.begin(); O != Itm->Owners.end(); ++O)
+      {
+        pkgAcquire::Item const * const Owner = *O;
+        if (Owner->DestFile == filename)
+           continue;
+        unlink(Owner->DestFile.c_str());
+        if (link(filename.c_str(), Owner->DestFile.c_str()) != 0)
+        {
+           // different mounts can't happen for us as we download to lists/ by default,
+           // but if the system is reused by others the locations can potentially be on
+           // different disks, so use symlink as poor-men replacement.
+           // FIXME: Real copying as last fallback, but that is costly, so offload to a method preferable
+           if (symlink(filename.c_str(), Owner->DestFile.c_str()) != 0)
+              _error->Error("Can't create (sym)link of file %s to %s", filename.c_str(), Owner->DestFile.c_str());
+        }
+      }
+   }
+   else
+   {
+      for (pkgAcquire::Queue::QItem::owner_iterator O = Itm->Owners.begin(); O != Itm->Owners.end(); ++O)
+        unlink((*O)->DestFile.c_str());
+   }
+}
+                                                                       /*}}}*/