From a133f79c8766aee5b7d7811285e60b3d311d8473 Mon Sep 17 00:00:00 2001
From: David Kalnischkies <david@kalnischkies.de>
Date: Wed, 27 Jan 2016 00:15:12 +0100
Subject: deal better with (very) small apt::cache-start values
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It is a bit academic to support values which aren't big enough to fit even
the hashtables without resizing, but cleaning up ensures that we do the
right thing (aka not segfaulting) even if something goes wrong in these
deep layers. You still can't have very very small values through…

Git-Dch: Ignore
---
 apt-pkg/pkgcachegen.cc | 40 ++++++++++++++++++++++++----------------
 1 file changed, 24 insertions(+), 16 deletions(-)

(limited to 'apt-pkg/pkgcachegen.cc')

diff --git a/apt-pkg/pkgcachegen.cc b/apt-pkg/pkgcachegen.cc
index a48fe7946..639ad215c 100644
--- a/apt-pkg/pkgcachegen.cc
+++ b/apt-pkg/pkgcachegen.cc
@@ -57,6 +57,9 @@ using APT::StringView;
 pkgCacheGenerator::pkgCacheGenerator(DynamicMMap *pMap,OpProgress *Prog) :
 		    Map(*pMap), Cache(pMap,false), Progress(Prog),
 		     CurrentRlsFile(NULL), CurrentFile(NULL), d(NULL)
+{
+}
+bool pkgCacheGenerator::Start()
 {
    if (Map.Size() == 0)
    {
@@ -67,7 +70,9 @@ pkgCacheGenerator::pkgCacheGenerator(DynamicMMap *pMap,OpProgress *Prog) :
       bool const newError = _error->PendingError();
       _error->MergeWithStack();
       if (newError)
-	 return;
+	 return false;
+      if (Map.Size() <= 0)
+	 return false;
 
       Map.UsePools(*Cache.HeaderP->Pools,sizeof(Cache.HeaderP->Pools)/sizeof(Cache.HeaderP->Pools[0]));
 
@@ -76,16 +81,15 @@ pkgCacheGenerator::pkgCacheGenerator(DynamicMMap *pMap,OpProgress *Prog) :
 
       // make room for the hashtables for packages and groups
       if (Map.RawAllocate(2 * (Cache.HeaderP->GetHashTableSize() * sizeof(map_pointer_t))) == 0)
-	 return;
+	 return false;
 
       map_stringitem_t const idxVerSysName = WriteStringInMap(_system->VS->Label);
       if (unlikely(idxVerSysName == 0))
-	 return;
-      Cache.HeaderP->VerSysName = idxVerSysName;
+	 return false;
       map_stringitem_t const idxArchitecture = StoreString(MIXED, _config->Find("APT::Architecture"));
       if (unlikely(idxArchitecture == 0))
-	 return;
-      Cache.HeaderP->Architecture = idxArchitecture;
+	 return false;
+      map_stringitem_t idxArchitectures;
 
       std::vector<std::string> archs = APT::Configuration::getArchitectures();
       if (archs.size() > 1)
@@ -94,13 +98,17 @@ pkgCacheGenerator::pkgCacheGenerator(DynamicMMap *pMap,OpProgress *Prog) :
 	 std::string list = *a;
 	 for (++a; a != archs.end(); ++a)
 	    list.append(",").append(*a);
-	 map_stringitem_t const idxArchitectures = WriteStringInMap(list);
+	 idxArchitectures = WriteStringInMap(list);
 	 if (unlikely(idxArchitectures == 0))
-	    return;
-	 Cache.HeaderP->SetArchitectures(idxArchitectures);
+	    return false;
       }
       else
-	 Cache.HeaderP->SetArchitectures(idxArchitecture);
+	 idxArchitectures = idxArchitecture;
+
+      Cache.HeaderP = (pkgCache::Header *)Map.Data();
+      Cache.HeaderP->VerSysName = idxVerSysName;
+      Cache.HeaderP->Architecture = idxArchitecture;
+      Cache.HeaderP->SetArchitectures(idxArchitectures);
 
       // Calculate the hash for the empty map, so ReMap does not fail
       Cache.HeaderP->CacheFileSize = Cache.CacheHash();
@@ -112,14 +120,12 @@ pkgCacheGenerator::pkgCacheGenerator(DynamicMMap *pMap,OpProgress *Prog) :
       Cache.ReMap(); 
       Map.UsePools(*Cache.HeaderP->Pools,sizeof(Cache.HeaderP->Pools)/sizeof(Cache.HeaderP->Pools[0]));
       if (Cache.VS != _system->VS)
-      {
-	 _error->Error(_("Cache has an incompatible versioning system"));
-	 return;
-      }
+	 return _error->Error(_("Cache has an incompatible versioning system"));
    }
 
    Cache.HeaderP->Dirty = true;
    Map.Sync(0,sizeof(pkgCache::Header));
+   return true;
 }
 									/*}}}*/
 // CacheGenerator::~pkgCacheGenerator - Destructor 			/*{{{*/
@@ -1607,7 +1613,7 @@ static bool loadBackMMapFromFile(std::unique_ptr<pkgCacheGenerator> &Gen,
    if (CacheF.Read((unsigned char *)Map->Data() + alloc, CacheF.Size()) == false)
       return false;
    Gen.reset(new pkgCacheGenerator(Map.get(),Progress));
-   return true;
+   return Gen->Start();
 }
 bool pkgMakeStatusCache(pkgSourceList &List,OpProgress &Progress,
 			MMap **OutMap, bool AllowMem)
@@ -1713,6 +1719,8 @@ bool pkgCacheGenerator::MakeStatusCache(pkgSourceList &List,OpProgress *Progress
       if (Debug == true)
 	 std::clog << "srcpkgcache.bin is NOT valid - rebuild" << std::endl;
       Gen.reset(new pkgCacheGenerator(Map.get(),Progress));
+      if (Gen->Start() == false)
+	 return false;
 
       TotalSize += ComputeSize(&List, Files.begin(),Files.end());
       if (BuildCache(*Gen, Progress, CurrentSize, TotalSize, &List,
@@ -1790,7 +1798,7 @@ bool pkgCacheGenerator::MakeOnlyStatusCache(OpProgress *Progress,DynamicMMap **O
    if (Progress != NULL)
       Progress->OverallProgress(0,1,1,_("Reading package lists"));
    pkgCacheGenerator Gen(Map.get(),Progress);
-   if (_error->PendingError() == true)
+   if (Gen.Start() == false || _error->PendingError() == true)
       return false;
    if (BuildCache(Gen,Progress,CurrentSize,TotalSize, NULL,
 		  Files.begin(), Files.end()) == false)
-- 
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