Add a Acquire::CompressionTypes config variable from there the

acquire-items choose which compression file they should (try first to)
download to easily add new or change the order of the compression types.
And because it is easy now we directly add builtin lzma support.

The compression ratio is better than bzip2 but we prefer the later for now
as no (official) mirror uses lzma, so this would only generate useless
hits on the servers. Maybe sometime in the future lzma will be the default...

[apt-pkg/acquire-item.cc]
- use configsettings for dynamic compression type use and order.
  Based on a patch by Jyrki Muukkonen, thanks! (LP: #71746)
[apt-pkg/init.cc]
- add default configuration for compression types and add lzma
  support. Order is now bzip2, lzma, gzip, none (Closes: #510526)
[ftparchive/writer.cc]
- add lzma support also here, patch for this (and inspiration for
  the one above) by Robert Millan, thanks!

1 files changed, 49 insertions, 30 deletions

diff --git a/apt-pkg/acquire-item.cc b/apt-pkg/acquire-item.cc
index 39ae327cb..ffbe66d7d 100644
--- a/apt-pkg/acquire-item.cc
+++ b/apt-pkg/acquire-item.cc
@@ -551,13 +551,24 @@ pkgAcqIndex::pkgAcqIndex(pkgAcquire *Owner,
    if(comprExt.empty()) 
    {
       // autoselect the compression method
-      if(FileExists("/bin/bzip2")) 
-	 CompressionExtension = ".bz2";
-      else 
-	 CompressionExtension = ".gz";
-   } else {
-      CompressionExtension = (comprExt == "plain" ? "" : comprExt);
+      Configuration::Item const *Opts = _config->Tree("Acquire::CompressionTypes");
+      if (Opts != 0)
+	 Opts = Opts->Child;
+
+      const char dirBin[] = "Dir::Bin::";
+      for (; Opts != 0; Opts = Opts->Next)
+      {
+	 if (Opts->Tag.empty() == true || Opts->Value.empty() == true)
+	    continue;
+	 const string bin = _config->FindFile(string(dirBin).append(Opts->Value).c_str(),"");
+	 if (bin != "" && !FileExists(bin))
+	    continue;
+	 comprExt = '.' + Opts->Tag;
+	 break;
+      }
    }
+   CompressionExtension = ((comprExt == "plain" || comprExt == ".") ? "" : comprExt);
+
    Desc.URI = URI + CompressionExtension;
 
    Desc.Description = URIDesc;
@@ -584,24 +595,32 @@ string pkgAcqIndex::Custom600Headers()
 									/*}}}*/
 void pkgAcqIndex::Failed(string Message,pkgAcquire::MethodConfig *Cnf)	/*{{{*/
 {
-   bool descChanged = false;
-   // no .bz2 found, retry with .gz
-   if(Desc.URI.substr(Desc.URI.size()-3) == "bz2") {
-      Desc.URI = Desc.URI.substr(0,Desc.URI.size()-3) + "gz";
-
-      new pkgAcqIndex(Owner, RealURI, Desc.Description,Desc.ShortDesc,
-		      ExpectedHash, string(".gz"));
-	  descChanged = true;
-   }
-   // no .gz found, retry with uncompressed
-   else if(Desc.URI.substr(Desc.URI.size()-2) == "gz") {
-      Desc.URI = Desc.URI.substr(0,Desc.URI.size()-2);
+   Configuration::Item const *Opts = _config->Tree("Acquire::CompressionTypes");
+   if (Opts != 0)
+      Opts = Opts->Child;
+
+   const char dirBin[] = "Dir::Bin::";
+   for (; Opts != 0; Opts = Opts->Next)
+   {
+      if (Opts->Tag.empty() == true || Opts->Value.empty() == true)
+	 continue;
+
+      // jump over all already checked compression types
+      const unsigned int nameLen = Desc.URI.size() - Opts->Tag.size();
+      if(Desc.URI.substr(nameLen) != Opts->Tag || Opts->Next == 0)
+	 continue;
+
+      // check if we need an external binary for this compression type
+      const string bin = _config->FindFile(string(dirBin).append(Opts->Next->Value).c_str(),"");
+      if (bin != "" && !FileExists(bin))
+	 continue;
+
+      // retry with the next extension
+      Desc.URI = Desc.URI.substr(0, nameLen) + Opts->Next->Tag;
+
+      new pkgAcqIndex(Owner, RealURI, Desc.Description, Desc.ShortDesc,
+			ExpectedHash, string(".").append(Opts->Next->Tag));
 
-      new pkgAcqIndex(Owner, RealURI, Desc.Description,Desc.ShortDesc,
-		      ExpectedHash, string("plain"));
-	  descChanged = true;
-   }
-   if (descChanged) {
       Status = StatDone;
       Complete = false;
       Dequeue();
@@ -698,11 +717,11 @@ void pkgAcqIndex::Done(string Message,unsigned long Size,string Hash,
       Local = true;
    
    string compExt = flExtension(flNotDir(URI(Desc.URI).Path));
-   const char *decompProg;
-   if(compExt == "bz2") 
-      decompProg = "bzip2";
-   else if(compExt == "gz") 
-      decompProg = "gzip";
+   string decompProg;
+
+   // get the binary name for your used compression type
+   decompProg = _config->Find(string("Acquire::CompressionTypes::").append(compExt),"");
+   if(decompProg.empty() == false);
    // flExtensions returns the full name if no extension is found
    // this is why we have this complicated compare operation here
    // FIMXE: add a new flJustExtension() that return "" if no
@@ -717,9 +736,9 @@ void pkgAcqIndex::Done(string Message,unsigned long Size,string Hash,
 
    Decompression = true;
    DestFile += ".decomp";
-   Desc.URI = string(decompProg) + ":" + FileName;
+   Desc.URI = decompProg + ":" + FileName;
    QueueURI(Desc);
-   Mode = decompProg;
+   Mode = decompProg.c_str();
 }
 									/*}}}*/
 // AcqIndexTrans::pkgAcqIndexTrans - Constructor			/*{{{*/