add volatile sources support in libapt-pkg

Sources are usually defined in sources.list (and co) and are pretty
stable, but once in a while a frontend might want to add an additional
"source" like a local .deb file to install this package (No support for
'real' sources being added this way as this is a multistep process).

We had a hack in place to allow apt-get and apt to pull this of for a
short while now, but other frontends are either left in the cold by this
and/or the code for it looks dirty with FIXMEs plastering it and has on
top of this also some problems (like including these 'volatile' sources
in the srcpkgcache.bin file).

So the biggest part in this commit is actually the rewrite of the cache
generation as it is now potentially a three step process. The biggest
problem with adding support now through is that this makes a bunch of
previously mostly unusable by externs and therefore hidden classes
public, so a bit of further tuneing on this now public API is in order…

1 files changed, 11 insertions, 16 deletions

diff --git a/apt-pkg/deb/debindexfile.cc b/apt-pkg/deb/debindexfile.cc
index 972feba7f..e67233e5f 100644
--- a/apt-pkg/deb/debindexfile.cc
+++ b/apt-pkg/deb/debindexfile.cc
@@ -339,18 +339,16 @@ APT_CONST bool debStatusIndex::Exists() const
 }
 									/*}}}*/
 
-// debDebPkgFile - Single .deb file					/*{{{*/
-debDebPkgFileIndex::debDebPkgFileIndex(std::string DebFile)
+// debDebPkgFileIndex - Single .deb file				/*{{{*/
+debDebPkgFileIndex::debDebPkgFileIndex(std::string const &DebFile)
    : pkgIndexFile(true), d(NULL), DebFile(DebFile)
 {
    DebFileFullPath = flAbsPath(DebFile);
 }
-
 std::string debDebPkgFileIndex::ArchiveURI(std::string /*File*/) const
 {
    return "file:" + DebFileFullPath;
 }
-
 bool debDebPkgFileIndex::Exists() const
 {
    return FileExists(DebFile);
@@ -403,6 +401,8 @@ bool debDebPkgFileIndex::Merge(pkgCacheGenerator& Gen, OpProgress* Prog) const
    if (GetContent(content, DebFile) == false)
       return false;
    std::string const contentstr = content.str();
+   if (contentstr.empty())
+      return true;
    DebControl->Write(contentstr.c_str(), contentstr.length());
    // rewind for the listparser
    DebControl->Seek(0);
@@ -431,7 +431,7 @@ pkgCache::PkgFileIterator debDebPkgFileIndex::FindInCache(pkgCache &Cache) const
 
        return File;
    }
-   
+
    return File;
 }
 unsigned long debDebPkgFileIndex::Size() const
@@ -443,12 +443,11 @@ unsigned long debDebPkgFileIndex::Size() const
 }
 									/*}}}*/
 
-// debDscFileIndex stuff
-debDscFileIndex::debDscFileIndex(std::string &DscFile) 
+// debDscFileIndex - a .dsc file					/*{{{*/
+debDscFileIndex::debDscFileIndex(std::string const &DscFile)
    : pkgIndexFile(true), d(NULL), DscFile(DscFile)
 {
 }
-
 bool debDscFileIndex::Exists() const
 {
    return FileExists(DscFile);
@@ -461,8 +460,6 @@ unsigned long debDscFileIndex::Size() const
       return buf.st_size;
    return 0;
 }
-
-// DscFileIndex::CreateSrcParser - Get a parser for the .dsc file	/*{{{*/
 pkgSrcRecords::Parser *debDscFileIndex::CreateSrcParser() const
 {
    if (!FileExists(DscFile))
@@ -471,18 +468,17 @@ pkgSrcRecords::Parser *debDscFileIndex::CreateSrcParser() const
    return new debDscRecordParser(DscFile,this);
 }
 									/*}}}*/
+
 // Index File types for Debian						/*{{{*/
 class APT_HIDDEN debIFTypeSrc : public pkgIndexFile::Type
 {
    public:
-   
    debIFTypeSrc() {Label = "Debian Source Index";};
 };
 class APT_HIDDEN debIFTypePkg : public pkgIndexFile::Type
 {
    public:
-   
-   virtual pkgRecords::Parser *CreatePkgParser(pkgCache::PkgFileIterator File) const APT_OVERRIDE 
+   virtual pkgRecords::Parser *CreatePkgParser(pkgCache::PkgFileIterator File) const APT_OVERRIDE
    {
       return new debRecordParser(File.FileName(),*File.Cache());
    };
@@ -496,8 +492,7 @@ class APT_HIDDEN debIFTypeTrans : public debIFTypePkg
 class APT_HIDDEN debIFTypeStatus : public pkgIndexFile::Type
 {
    public:
-   
-   virtual pkgRecords::Parser *CreatePkgParser(pkgCache::PkgFileIterator File) const APT_OVERRIDE 
+   virtual pkgRecords::Parser *CreatePkgParser(pkgCache::PkgFileIterator File) const APT_OVERRIDE
    {
       return new debRecordParser(File.FileName(),*File.Cache());
    };
@@ -506,7 +501,7 @@ class APT_HIDDEN debIFTypeStatus : public pkgIndexFile::Type
 class APT_HIDDEN debIFTypeDebPkgFile : public pkgIndexFile::Type
 {
    public:
-   virtual pkgRecords::Parser *CreatePkgParser(pkgCache::PkgFileIterator File) const APT_OVERRIDE 
+   virtual pkgRecords::Parser *CreatePkgParser(pkgCache::PkgFileIterator File) const APT_OVERRIDE
    {
       return new debDebFileRecordParser(File.FileName());
    };