use the version id instead of the mmap offset as APT-ID

This leads to a small performance decrease as we need to build this
mapping now while interpreting the Response but a (buggy) solver can't
point us to dangerous memory locations anymore this way and VersionCount
remains useful for other mapping proposes

diff --git a/apt-pkg/edsp.cc b/apt-pkg/edsp.cc
index f8deef8..55bc0a0 100644 (file)
--- a/apt-pkg/edsp.cc
+++ b/apt-pkg/edsp.cc
@@ -39,7 +39,7 @@ bool EDSP::WriteScenario(pkgDepCache &Cache, FILE* output)
            fprintf(output, "Installed: yes\n");
         if (Pkg->SelectedState == pkgCache::State::Hold)
            fprintf(output, "Hold: yes\n");
-        fprintf(output, "APT-ID: %lu\n", Ver.Index());
+        fprintf(output, "APT-ID: %d\n", Ver->ID);
         fprintf(output, "Priority: %s\n", PrioMap[Ver->Priority]);
         if ((Pkg->Flags & pkgCache::Flag::Essential) == pkgCache::Flag::Essential)
            fprintf(output, "Essential: yes\n");
@@ -146,6 +146,17 @@ bool EDSP::ReadResponse(int const input, pkgDepCache &Cache) {
        in.OpenDescriptor(input, FileFd::ReadOnly);
        pkgTagFile response(&in);
        pkgTagSection section;
+
+       /* We build an map id to mmap offset here
+          In theory we could use the offset as ID, but then VersionCount
+          couldn't be used to create other versionmappings anymore and it
+          would be too easy for a (buggy) solver to segfault APT… */
+       unsigned long long const VersionCount = Cache.Head().VersionCount;
+       unsigned long VerIdx[VersionCount];
+       for (pkgCache::PkgIterator P = Cache.PkgBegin(); P.end() == false; ++P)
+               for (pkgCache::VerIterator V = P.VersionList(); V.end() == false; ++V)
+                       VerIdx[V->ID] = V.Index();
+
        while (response.Step(section) == true) {
                std::string type;
                if (section.Exists("Install") == true)
@@ -156,13 +167,16 @@ bool EDSP::ReadResponse(int const input, pkgDepCache &Cache) {
                else
                        continue;
 
-               size_t const index = section.FindULL(type.c_str(), 0);
-               if (index == 0) {
+               size_t const id = section.FindULL(type.c_str(), VersionCount);
+               if (id == VersionCount) {
                        _error->Warning("Unable to parse %s request with id value '%s'!", type.c_str(), section.FindS(type.c_str()).c_str());
                        continue;
+               } else if (id > Cache.Head().VersionCount) {
+                       _error->Warning("ID value '%s' in %s request stanza is to high to refer to a known version!", section.FindS(type.c_str()).c_str(), type.c_str());
+                       continue;
                }
 
-               pkgCache::VerIterator Ver(Cache.GetCache(), Cache.GetCache().VerP + index);
+               pkgCache::VerIterator Ver(Cache.GetCache(), Cache.GetCache().VerP + VerIdx[id]);
                Cache.SetCandidateVersion(Ver);
                if (type == "Install")
                        Cache.MarkInstall(Ver.ParentPkg(), false, false);