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!

3 files changed, 75 insertions, 38 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			/*{{{*/
diff --git a/apt-pkg/acquire-item.h b/apt-pkg/acquire-item.h
index 36a926a0f..3f073de5b 100644
--- a/apt-pkg/acquire-item.h
+++ b/apt-pkg/acquire-item.h
@@ -540,7 +540,9 @@ class pkgAcqIndex : public pkgAcquire::Item
     *
     *  \param compressExt The compression-related extension with which
     *  this index file should be downloaded, or "" to autodetect
-    *  (".bz2" is used if bzip2 is installed, ".gz" otherwise).
+    *  Compression types can be set with config Acquire::CompressionTypes,
+    *  default is ".lzma" or ".bz2" (if the needed binaries are present)
+    *  fallback is ".gz" or none.
     */
    pkgAcqIndex(pkgAcquire *Owner,string URI,string URIDesc,
 	       string ShortDesc, HashString ExpectedHash, string compressExt="");
@@ -569,12 +571,6 @@ class pkgAcqIndexTrans : public pkgAcqIndex
     *  \param URIDesc A "URI-style" description of this index file.
     *
     *  \param ShortDesc A brief description of this index file.
-    *
-    *  \param ExpectedHash The expected hashsum of this index file.
-    *
-    *  \param compressExt The compression-related extension with which
-    *  this index file should be downloaded, or "" to autodetect
-    *  (".bz2" is used if bzip2 is installed, ".gz" otherwise).
     */
    pkgAcqIndexTrans(pkgAcquire *Owner,string URI,string URIDesc,
 		    string ShortDesc);
diff --git a/apt-pkg/init.cc b/apt-pkg/init.cc
index 63caade36..46017bf0c 100644
--- a/apt-pkg/init.cc
+++ b/apt-pkg/init.cc
@@ -103,7 +103,29 @@ bool pkgInitConfig(Configuration &Cnf)
 
    if (Res == false)
       return false;
-   
+
+   // we load all config files, now check the configs and setup post-defaults:
+   // * check for CompressionTypes setup
+   {
+      Configuration::Item const *Opts = _config->Tree("Acquire::CompressionTypes");
+      if (Opts != 0)
+	 Opts = Opts->Child;
+      bool foundLzma=false, foundBzip2=false, foundGzip=false;
+      for (; Opts != 0; Opts = Opts->Next)
+      {
+	 if (Opts->Value == "lzma") foundLzma = true;
+	 else if (Opts->Value == "bz2") foundBzip2 = true;
+	 else if (Opts->Value == "gz") foundGzip = true;
+      }
+      if (!foundBzip2) Cnf.Set("Acquire::CompressionTypes::bz2","bzip2");
+      if (!foundLzma) Cnf.Set("Acquire::CompressionTypes::lzma","lzma");
+      if (!foundGzip) Cnf.Set("Acquire::CompressionTypes::gz","gzip");
+      Cnf.CndSet("Dir::Bin::lzma", "/usr/bin/lzma");
+      Cnf.CndSet("Dir::Bin::bzip2", "/bin/bzip2");
+   }
+
+
+
    if (Cnf.FindB("Debug::pkgInitConfig",false) == true)
       Cnf.Dump();