debrecords: Do not reparse if given same location

The TagFile parser will have already parsed further and can't go
back so it needs to reopen the file if compressed.

Closes: #1067440

2 files changed, 14 insertions, 3 deletions

diff --git a/apt-pkg/deb/debrecords.cc b/apt-pkg/deb/debrecords.cc
index b9d1b6e2f..438b147bd 100644
--- a/apt-pkg/deb/debrecords.cc
+++ b/apt-pkg/deb/debrecords.cc
@@ -31,9 +31,13 @@
 
 using std::string;
 
+struct debRecordParser::Private {
+   unsigned long long Offset = -1;
+};
+
 // RecordParser::debRecordParser - Constructor				/*{{{*/
 debRecordParser::debRecordParser(string FileName,pkgCache &Cache) :
-   debRecordParserBase(), d(NULL), File(FileName, FileFd::ReadOnly, FileFd::Extension),
+   debRecordParserBase(), d(new Private), File(FileName, FileFd::ReadOnly, FileFd::Extension),
    Tags(&File, std::max(Cache.Head().MaxVerFileSize, Cache.Head().MaxDescFileSize) + 200)
 {
 }
@@ -41,18 +45,24 @@ debRecordParser::debRecordParser(string FileName,pkgCache &Cache) :
 // RecordParser::Jump - Jump to a specific record			/*{{{*/
 bool debRecordParser::Jump(pkgCache::VerFileIterator const &Ver)
 {
+   if (d->Offset == Ver->Offset)
+      return true;
    if (Ver.end() == true)
       return false;
+   d->Offset = Ver->Offset;
    return Tags.Jump(Section,Ver->Offset);
 }
 bool debRecordParser::Jump(pkgCache::DescFileIterator const &Desc)
 {
+   if (d->Offset == Desc->Offset)
+      return true;
    if (Desc.end() == true)
       return false;
+   d->Offset = Desc->Offset;
    return Tags.Jump(Section,Desc->Offset);
 }
 									/*}}}*/
-debRecordParser::~debRecordParser() {}
+debRecordParser::~debRecordParser() { delete d; }
 
 debRecordParserBase::debRecordParserBase() : Parser(), d(NULL) {}
 // RecordParserBase::FileName - Return the archive filename on the site	/*{{{*/
diff --git a/apt-pkg/deb/debrecords.h b/apt-pkg/deb/debrecords.h
index 10ef91768..d81bdf08f 100644
--- a/apt-pkg/deb/debrecords.h
+++ b/apt-pkg/deb/debrecords.h
@@ -53,7 +53,8 @@ class APT_HIDDEN debRecordParserBase : public pkgRecords::Parser
 
 class APT_HIDDEN debRecordParser : public debRecordParserBase
 {
-   void * const d;
+   struct Private;
+   Private *d;
  protected:
    FileFd File;
    pkgTagFile Tags;