* apt-pkg/pkgcachegen.{cc,h}:

  - make the used MMap moveable (and therefore dynamic resizeable) by
    applying (some) mad pointer magic (Closes: #195018)

8 files changed, 226 insertions, 77 deletions

diff --git a/apt-pkg/cacheiterators.h b/apt-pkg/cacheiterators.h
index dfe5707e1..eb8dee5e3 100644
--- a/apt-pkg/cacheiterators.h
+++ b/apt-pkg/cacheiterators.h
@@ -75,6 +75,12 @@ template<typename Str, typename Itr> class pkgCache::Iterator :
 	inline bool IsGood() const { return S && Owner && ! end();};
 	inline unsigned long Index() const {return S - OwnerPointer();};
 
+	void ReOwn(pkgCache &newOwner, void const * const oldMap, void const * const newMap) {
+		if (S == 0)
+			return;
+		S += (Str*)(newMap) - (Str*)(oldMap);
+	}
+
 	// Constructors - look out for the variable assigning
 	inline Iterator() : S(0), Owner(0) {};
 	inline Iterator(pkgCache &Owner,Str *T = 0) : S(T), Owner(&Owner) {};
diff --git a/apt-pkg/contrib/mmap.cc b/apt-pkg/contrib/mmap.cc
index d71066243..aa184b130 100644
--- a/apt-pkg/contrib/mmap.cc
+++ b/apt-pkg/contrib/mmap.cc
@@ -225,22 +225,22 @@ DynamicMMap::DynamicMMap(unsigned long Flags,unsigned long const &WorkSpace,
 
 	// disable Moveable if we don't grow
 	if (Grow == 0)
-		Flags &= ~Moveable;
+		this->Flags &= ~Moveable;
 
 #ifndef __linux__
 	// kfreebsd doesn't have mremap, so we use the fallback
-	if ((Flags & Moveable) == Moveable)
-		Flags |= Fallback;
+	if ((this->Flags & Moveable) == Moveable)
+		this->Flags |= Fallback;
 #endif
 
 #ifdef _POSIX_MAPPED_FILES
-	if ((Flags & Fallback) != Fallback) {
+	if ((this->Flags & Fallback) != Fallback) {
 		// Set the permissions.
 		int Prot = PROT_READ;
 		int Map = MAP_PRIVATE | MAP_ANONYMOUS;
-		if ((Flags & ReadOnly) != ReadOnly)
+		if ((this->Flags & ReadOnly) != ReadOnly)
 			Prot |= PROT_WRITE;
-		if ((Flags & Public) == Public)
+		if ((this->Flags & Public) == Public)
 			Map = MAP_SHARED | MAP_ANONYMOUS;
 
 		// use anonymous mmap() to get the memory
@@ -314,7 +314,7 @@ unsigned long DynamicMMap::Allocate(unsigned long ItemSize)
    // Look for a matching pool entry
    Pool *I;
    Pool *Empty = 0;
-   for (I = Pools; I != Pools + PoolCount; I++)
+   for (I = Pools; I != Pools + PoolCount; ++I)
    {
       if (I->ItemSize == 0)
 	 Empty = I;
@@ -342,7 +342,11 @@ unsigned long DynamicMMap::Allocate(unsigned long ItemSize)
    {
       const unsigned long size = 20*1024;
       I->Count = size/ItemSize;
+      Pool* oldPools = Pools;
       Result = RawAllocate(size,ItemSize);
+      if (Pools != oldPools)
+	 I += Pools - oldPools;
+
       // Does the allocation failed ?
       if (Result == 0 && _error->PendingError())
 	 return 0;
@@ -365,7 +369,7 @@ unsigned long DynamicMMap::WriteString(const char *String,
    if (Len == (unsigned long)-1)
       Len = strlen(String);
 
-   unsigned long Result = RawAllocate(Len+1,0);
+   unsigned long const Result = RawAllocate(Len+1,0);
 
    if (Result == 0 && _error->PendingError())
       return 0;
@@ -395,16 +399,20 @@ bool DynamicMMap::Grow() {
 		return _error->Error(_("Unable to increase the size of the MMap as the "
 		                       "limit of %lu bytes is already reached."), Limit);
 
-	unsigned long const newSize = WorkSpace + 1024*1024;
+	unsigned long const newSize = WorkSpace + GrowFactor;
 
 	if(Fd != 0) {
 		Fd->Seek(newSize - 1);
 		char C = 0;
 		Fd->Write(&C,sizeof(C));
 	}
+
+	unsigned long const poolOffset = Pools - ((Pool*) Base);
+
 	if ((Flags & Fallback) != Fallback) {
 #if defined(_POSIX_MAPPED_FILES) && defined(__linux__)
    #ifdef MREMAP_MAYMOVE
+
 		if ((Flags & Moveable) == Moveable)
 			Base = mremap(Base, WorkSpace, newSize, MREMAP_MAYMOVE);
 		else
@@ -425,6 +433,7 @@ bool DynamicMMap::Grow() {
 			return false;
 	}
 
+	Pools =(Pool*) Base + poolOffset;
 	WorkSpace = newSize;
 	return true;
 }
diff --git a/apt-pkg/deb/debindexfile.cc b/apt-pkg/deb/debindexfile.cc
index 6d9e99497..5e6db3f38 100644
--- a/apt-pkg/deb/debindexfile.cc
+++ b/apt-pkg/deb/debindexfile.cc
@@ -277,6 +277,7 @@ bool debPackagesIndex::Merge(pkgCacheGenerator &Gen,OpProgress *Prog) const
 
    // Store the IMS information
    pkgCache::PkgFileIterator File = Gen.GetCurFile();
+   pkgCacheGenerator::Dynamic<pkgCache::PkgFileIterator> DynFile(File);
    struct stat St;
    if (fstat(Pkg.Fd(),&St) != 0)
       return _error->Errno("fstat","Failed to stat");
diff --git a/apt-pkg/pkgcache.cc b/apt-pkg/pkgcache.cc
index 68aa83d0c..8af8ef7de 100644
--- a/apt-pkg/pkgcache.cc
+++ b/apt-pkg/pkgcache.cc
@@ -119,7 +119,7 @@ pkgCache::pkgCache(MMap *Map, bool DoMap) : Map(*Map)
 // Cache::ReMap - Reopen the cache file					/*{{{*/
 // ---------------------------------------------------------------------
 /* If the file is already closed then this will open it open it. */
-bool pkgCache::ReMap()
+bool pkgCache::ReMap(bool const &Errorchecks)
 {
    // Apply the typecasts.
    HeaderP = (Header *)Map.Data();
@@ -135,6 +135,9 @@ bool pkgCache::ReMap()
    StringItemP = (StringItem *)Map.Data();
    StrP = (char *)Map.Data();
 
+   if (Errorchecks == false)
+      return true;
+
    if (Map.Size() == 0 || HeaderP == 0)
       return _error->Error(_("Empty package cache"));
    
diff --git a/apt-pkg/pkgcache.h b/apt-pkg/pkgcache.h
index 426bb9f13..799521784 100644
--- a/apt-pkg/pkgcache.h
+++ b/apt-pkg/pkgcache.h
@@ -174,7 +174,7 @@ class pkgCache								/*{{{*/
    StringItem *StringItemP;
    char *StrP;
 
-   virtual bool ReMap();
+   virtual bool ReMap(bool const &Errorchecks = true);
    inline bool Sync() {return Map.Sync();};
    inline MMap &GetMap() {return Map;};
    inline void *DataEnd() {return ((unsigned char *)Map.Data()) + Map.Size();};
diff --git a/apt-pkg/pkgcachegen.cc b/apt-pkg/pkgcachegen.cc
index 62e457734..18bad6727 100644
--- a/apt-pkg/pkgcachegen.cc
+++ b/apt-pkg/pkgcachegen.cc
@@ -36,6 +36,7 @@
 #include <stdio.h>
 									/*}}}*/
 typedef vector<pkgIndexFile *>::iterator FileIterator;
+template <typename Iter> std::set<Iter*> pkgCacheGenerator::Dynamic<Iter>::toReMap;
 
 // CacheGenerator::pkgCacheGenerator - Constructor			/*{{{*/
 // ---------------------------------------------------------------------
@@ -61,8 +62,12 @@ pkgCacheGenerator::pkgCacheGenerator(DynamicMMap *pMap,OpProgress *Prog) :
 
       // Starting header
       *Cache.HeaderP = pkgCache::Header();
-      Cache.HeaderP->VerSysName = WriteStringInMap(_system->VS->Label);
-      Cache.HeaderP->Architecture = WriteStringInMap(_config->Find("APT::Architecture"));
+      map_ptrloc const idxVerSysName = WriteStringInMap(_system->VS->Label);
+      Cache.HeaderP->VerSysName = idxVerSysName;
+      map_ptrloc const idxArchitecture = WriteStringInMap(_config->Find("APT::Architecture"));
+      Cache.HeaderP->Architecture = idxArchitecture;
+      if (unlikely(idxVerSysName == 0 || idxArchitecture == 0))
+	 return;
       Cache.ReMap();
    }
    else
@@ -96,19 +101,65 @@ pkgCacheGenerator::~pkgCacheGenerator()
    Map.Sync(0,sizeof(pkgCache::Header));
 }
 									/*}}}*/
+void pkgCacheGenerator::ReMap(void const * const oldMap, void const * const newMap) {/*{{{*/
+   if (oldMap == newMap)
+      return;
+
+   Cache.ReMap(false);
+
+   CurrentFile += (pkgCache::PackageFile*) newMap - (pkgCache::PackageFile*) oldMap;
+
+   for (size_t i = 0; i < _count(UniqHash); ++i)
+      if (UniqHash[i] != 0)
+	 UniqHash[i] += (pkgCache::StringItem*) newMap - (pkgCache::StringItem*) oldMap;
+
+   for (std::set<pkgCache::GrpIterator*>::const_iterator i = Dynamic<pkgCache::GrpIterator>::toReMap.begin();
+	i != Dynamic<pkgCache::GrpIterator>::toReMap.end(); ++i)
+      (*i)->ReOwn(Cache, oldMap, newMap);
+   for (std::set<pkgCache::PkgIterator*>::const_iterator i = Dynamic<pkgCache::PkgIterator>::toReMap.begin();
+	i != Dynamic<pkgCache::PkgIterator>::toReMap.end(); ++i)
+      (*i)->ReOwn(Cache, oldMap, newMap);
+   for (std::set<pkgCache::VerIterator*>::const_iterator i = Dynamic<pkgCache::VerIterator>::toReMap.begin();
+	i != Dynamic<pkgCache::VerIterator>::toReMap.end(); ++i)
+      (*i)->ReOwn(Cache, oldMap, newMap);
+   for (std::set<pkgCache::DepIterator*>::const_iterator i = Dynamic<pkgCache::DepIterator>::toReMap.begin();
+	i != Dynamic<pkgCache::DepIterator>::toReMap.end(); ++i)
+      (*i)->ReOwn(Cache, oldMap, newMap);
+   for (std::set<pkgCache::DescIterator*>::const_iterator i = Dynamic<pkgCache::DescIterator>::toReMap.begin();
+	i != Dynamic<pkgCache::DescIterator>::toReMap.end(); ++i)
+      (*i)->ReOwn(Cache, oldMap, newMap);
+   for (std::set<pkgCache::PrvIterator*>::const_iterator i = Dynamic<pkgCache::PrvIterator>::toReMap.begin();
+	i != Dynamic<pkgCache::PrvIterator>::toReMap.end(); ++i)
+      (*i)->ReOwn(Cache, oldMap, newMap);
+   for (std::set<pkgCache::PkgFileIterator*>::const_iterator i = Dynamic<pkgCache::PkgFileIterator>::toReMap.begin();
+	i != Dynamic<pkgCache::PkgFileIterator>::toReMap.end(); ++i)
+      (*i)->ReOwn(Cache, oldMap, newMap);
+}									/*}}}*/
 // CacheGenerator::WriteStringInMap					/*{{{*/
-unsigned long pkgCacheGenerator::WriteStringInMap(const char *String,
+map_ptrloc pkgCacheGenerator::WriteStringInMap(const char *String,
 					const unsigned long &Len) {
-   return Map.WriteString(String, Len);
+   void const * const oldMap = Map.Data();
+   map_ptrloc const index = Map.WriteString(String, Len);
+   if (index != 0)
+      ReMap(oldMap, Map.Data());
+   return index;
 }
 									/*}}}*/
 // CacheGenerator::WriteStringInMap					/*{{{*/
-unsigned long pkgCacheGenerator::WriteStringInMap(const char *String) {
-   return Map.WriteString(String);
+map_ptrloc pkgCacheGenerator::WriteStringInMap(const char *String) {
+   void const * const oldMap = Map.Data();
+   map_ptrloc const index = Map.WriteString(String);
+   if (index != 0)
+      ReMap(oldMap, Map.Data());
+   return index;
 }
 									/*}}}*/
-unsigned long pkgCacheGenerator::AllocateInMap(const unsigned long &size) {/*{{{*/
-   return Map.Allocate(size);
+map_ptrloc pkgCacheGenerator::AllocateInMap(const unsigned long &size) {/*{{{*/
+   void const * const oldMap = Map.Data();
+   map_ptrloc const index = Map.Allocate(size);
+   if (index != 0)
+      ReMap(oldMap, Map.Data());
+   return index;
 }
 									/*}}}*/
 // CacheGenerator::MergeList - Merge the package list			/*{{{*/
@@ -142,6 +193,7 @@ bool pkgCacheGenerator::MergeList(ListParser &List,
       {
       // Get a pointer to the package structure
       pkgCache::PkgIterator Pkg;
+      Dynamic<pkgCache::PkgIterator> DynPkg(Pkg);
       if (NewPackage(Pkg, PackageName, *arch) == false)
 	 return _error->Error(_("Error occurred while processing %s (NewPackage)"),PackageName.c_str());
       Counter++;
@@ -158,6 +210,7 @@ bool pkgCacheGenerator::MergeList(ListParser &List,
 	 // (this has the bonus that we get MMap error when we run out
 	 //  of MMap space)
 	 pkgCache::VerIterator Ver(Cache);
+	 Dynamic<pkgCache::VerIterator> DynVer(Ver);
 	 if (List.UsePackage(Pkg, Ver) == false)
 	    return _error->Error(_("Error occurred while processing %s (UsePackage1)"),
 				 PackageName.c_str());
@@ -165,11 +218,11 @@ bool pkgCacheGenerator::MergeList(ListParser &List,
  	 // Find the right version to write the description
  	 MD5SumValue CurMd5 = List.Description_md5();
  	 Ver = Pkg.VersionList();
- 	 map_ptrloc *LastVer = &Pkg->VersionList;
 
-	 for (; Ver.end() == false; LastVer = &Ver->NextVer, Ver++)
+	 for (; Ver.end() == false; ++Ver)
  	 {
  	    pkgCache::DescIterator Desc = Ver.DescriptionList();
+	    Dynamic<pkgCache::DescIterator> DynDesc(Desc);
  	    map_ptrloc *LastDesc = &Ver->DescriptionList;
 	    bool duplicate=false;
 
@@ -189,7 +242,11 @@ bool pkgCacheGenerator::MergeList(ListParser &List,
  	       if (MD5SumValue(Desc.md5()) == CurMd5) 
                {
  		  // Add new description
- 		  *LastDesc = NewDescription(Desc, List.DescriptionLanguage(), CurMd5, *LastDesc);
+		  void const * const oldMap = Map.Data();
+		  map_ptrloc const descindex = NewDescription(Desc, List.DescriptionLanguage(), CurMd5, *LastDesc);
+		  if (oldMap != Map.Data())
+		     LastDesc += (map_ptrloc*) Map.Data() - (map_ptrloc*) oldMap;
+		  *LastDesc = descindex;
  		  Desc->ParentPkg = Pkg.Index();
 		  
 		  if ((*LastDesc == 0 && _error->PendingError()) || NewFileDesc(Desc,List) == false)
@@ -203,7 +260,9 @@ bool pkgCacheGenerator::MergeList(ListParser &List,
       }
 
       pkgCache::VerIterator Ver = Pkg.VersionList();
+      Dynamic<pkgCache::VerIterator> DynVer(Ver);
       map_ptrloc *LastVer = &Pkg->VersionList;
+      void const * oldMap = Map.Data();
       int Res = 1;
       unsigned long const Hash = List.VersionHash();
       for (; Ver.end() == false; LastVer = &Ver->NextVer, Ver++)
@@ -242,21 +301,28 @@ bool pkgCacheGenerator::MergeList(ListParser &List,
       }
 
       // Add a new version
-      *LastVer = NewVersion(Ver,Version,*LastVer);
+      map_ptrloc const verindex = NewVersion(Ver,Version,*LastVer);
+      if (verindex == 0 && _error->PendingError())
+	 return _error->Error(_("Error occurred while processing %s (NewVersion%d)"),
+			      PackageName.c_str(), 1);
+
+      if (oldMap != Map.Data())
+	 LastVer += (map_ptrloc*) Map.Data() - (map_ptrloc*) oldMap;
+      *LastVer = verindex;
       Ver->ParentPkg = Pkg.Index();
       Ver->Hash = Hash;
 
-      if ((*LastVer == 0 && _error->PendingError()) || List.NewVersion(Ver) == false)
-	 return _error->Error(_("Error occurred while processing %s (NewVersion1)"),
-			      PackageName.c_str());
+      if (List.NewVersion(Ver) == false)
+	 return _error->Error(_("Error occurred while processing %s (NewVersion%d)"),
+			      PackageName.c_str(), 2);
 
       if (List.UsePackage(Pkg,Ver) == false)
 	 return _error->Error(_("Error occurred while processing %s (UsePackage3)"),
 			      PackageName.c_str());
       
       if (NewFileVer(Ver,List) == false)
-	 return _error->Error(_("Error occurred while processing %s (NewVersion2)"),
-			      PackageName.c_str());
+	 return _error->Error(_("Error occurred while processing %s (NewVersion%d)"),
+			      PackageName.c_str(), 3);
 
       // Read only a single record and return
       if (OutVer != 0)
@@ -269,13 +335,18 @@ bool pkgCacheGenerator::MergeList(ListParser &List,
       /* Record the Description data. Description data always exist in
 	 Packages and Translation-* files. */
       pkgCache::DescIterator Desc = Ver.DescriptionList();
+      Dynamic<pkgCache::DescIterator> DynDesc(Desc);
       map_ptrloc *LastDesc = &Ver->DescriptionList;
-      
+
       // Skip to the end of description set
       for (; Desc.end() == false; LastDesc = &Desc->NextDesc, Desc++);
 
       // Add new description
-      *LastDesc = NewDescription(Desc, List.DescriptionLanguage(), List.Description_md5(), *LastDesc);
+      oldMap = Map.Data();
+      map_ptrloc const descindex = NewDescription(Desc, List.DescriptionLanguage(), List.Description_md5(), *LastDesc);
+      if (oldMap != Map.Data())
+	 LastDesc += (map_ptrloc*) Map.Data() - (map_ptrloc*) oldMap;
+      *LastDesc = descindex;
       Desc->ParentPkg = Pkg.Index();
 
       if ((*LastDesc == 0 && _error->PendingError()) || NewFileDesc(Desc,List) == false)
@@ -322,6 +393,7 @@ bool pkgCacheGenerator::MergeFileProvides(ListParser &List)
 	 continue;
       
       pkgCache::PkgIterator Pkg = Cache.FindPkg(PackageName);
+      Dynamic<pkgCache::PkgIterator> DynPkg(Pkg);
       if (Pkg.end() == true)
 	 return _error->Error(_("Error occurred while processing %s (FindPkg)"),
 				PackageName.c_str());
@@ -331,6 +403,7 @@ bool pkgCacheGenerator::MergeFileProvides(ListParser &List)
 
       unsigned long Hash = List.VersionHash();
       pkgCache::VerIterator Ver = Pkg.VersionList();
+      Dynamic<pkgCache::VerIterator> DynVer(Ver);
       for (; Ver.end() == false; Ver++)
       {
 	 if (Ver->Hash == Hash && Version.c_str() == Ver.VerStr())
@@ -358,14 +431,15 @@ bool pkgCacheGenerator::NewGroup(pkgCache::GrpIterator &Grp, const string &Name)
       return true;
 
    // Get a structure
-   unsigned long const Group = AllocateInMap(sizeof(pkgCache::Group));
+   map_ptrloc const Group = AllocateInMap(sizeof(pkgCache::Group));
    if (unlikely(Group == 0))
       return false;
 
    Grp = pkgCache::GrpIterator(Cache, Cache.GrpP + Group);
-   Grp->Name = WriteStringInMap(Name);
-   if (unlikely(Grp->Name == 0))
+   map_ptrloc const idxName = WriteStringInMap(Name);
+   if (unlikely(idxName == 0))
       return false;
+   Grp->Name = idxName;
 
    // Insert it into the hash table
    unsigned long const Hash = Cache.Hash(Name);
@@ -382,6 +456,7 @@ bool pkgCacheGenerator::NewGroup(pkgCache::GrpIterator &Grp, const string &Name)
 bool pkgCacheGenerator::NewPackage(pkgCache::PkgIterator &Pkg,const string &Name,
 					const string &Arch) {
    pkgCache::GrpIterator Grp;
+   Dynamic<pkgCache::GrpIterator> DynGrp(Grp);
    if (unlikely(NewGroup(Grp, Name) == false))
       return false;
 
@@ -390,7 +465,7 @@ bool pkgCacheGenerator::NewPackage(pkgCache::PkgIterator &Pkg,const string &Name
 	 return true;
 
    // Get a structure
-   unsigned long const Package = AllocateInMap(sizeof(pkgCache::Package));
+   map_ptrloc const Package = AllocateInMap(sizeof(pkgCache::Package));
    if (unlikely(Package == 0))
       return false;
    Pkg = pkgCache::PkgIterator(Cache,Cache.PkgP + Package);
@@ -416,9 +491,10 @@ bool pkgCacheGenerator::NewPackage(pkgCache::PkgIterator &Pkg,const string &Name
    // Set the name, arch and the ID
    Pkg->Name = Grp->Name;
    Pkg->Group = Grp.Index();
-   Pkg->Arch = WriteUniqString(Arch.c_str());
-   if (unlikely(Pkg->Arch == 0))
+   map_ptrloc const idxArch = WriteUniqString(Arch.c_str());
+   if (unlikely(idxArch == 0))
       return false;
+   Pkg->Arch = idxArch;
    Pkg->ID = Cache.HeaderP->PackageCount++;
 
    return true;
@@ -434,7 +510,7 @@ bool pkgCacheGenerator::NewFileVer(pkgCache::VerIterator &Ver,
       return true;
    
    // Get a structure
-   unsigned long VerFile = AllocateInMap(sizeof(pkgCache::VerFile));
+   map_ptrloc const VerFile = AllocateInMap(sizeof(pkgCache::VerFile));
    if (VerFile == 0)
       return 0;
    
@@ -465,7 +541,7 @@ unsigned long pkgCacheGenerator::NewVersion(pkgCache::VerIterator &Ver,
 					    unsigned long Next)
 {
    // Get a structure
-   unsigned long Version = AllocateInMap(sizeof(pkgCache::Version));
+   map_ptrloc const Version = AllocateInMap(sizeof(pkgCache::Version));
    if (Version == 0)
       return 0;
    
@@ -473,9 +549,10 @@ unsigned long pkgCacheGenerator::NewVersion(pkgCache::VerIterator &Ver,
    Ver = pkgCache::VerIterator(Cache,Cache.VerP + Version);
    Ver->NextVer = Next;
    Ver->ID = Cache.HeaderP->VersionCount++;
-   Ver->VerStr = WriteStringInMap(VerStr);
-   if (Ver->VerStr == 0)
+   map_ptrloc const idxVerStr = WriteStringInMap(VerStr);
+   if (unlikely(idxVerStr == 0))
       return 0;
+   Ver->VerStr = idxVerStr;
    
    return Version;
 }
@@ -490,7 +567,7 @@ bool pkgCacheGenerator::NewFileDesc(pkgCache::DescIterator &Desc,
       return true;
    
    // Get a structure
-   unsigned long DescFile = AllocateInMap(sizeof(pkgCache::DescFile));
+   map_ptrloc const DescFile = AllocateInMap(sizeof(pkgCache::DescFile));
    if (DescFile == 0)
       return false;
 
@@ -523,7 +600,7 @@ map_ptrloc pkgCacheGenerator::NewDescription(pkgCache::DescIterator &Desc,
 					    map_ptrloc Next)
 {
    // Get a structure
-   map_ptrloc Description = AllocateInMap(sizeof(pkgCache::Description));
+   map_ptrloc const Description = AllocateInMap(sizeof(pkgCache::Description));
    if (Description == 0)
       return 0;
 
@@ -531,10 +608,12 @@ map_ptrloc pkgCacheGenerator::NewDescription(pkgCache::DescIterator &Desc,
    Desc = pkgCache::DescIterator(Cache,Cache.DescP + Description);
    Desc->NextDesc = Next;
    Desc->ID = Cache.HeaderP->DescriptionCount++;
-   Desc->language_code = WriteStringInMap(Lang);
-   Desc->md5sum = WriteStringInMap(md5sum.Value());
-   if (Desc->language_code == 0 || Desc->md5sum == 0)
+   map_ptrloc const idxlanguage_code = WriteStringInMap(Lang);
+   map_ptrloc const idxmd5sum = WriteStringInMap(md5sum.Value());
+   if (unlikely(idxlanguage_code == 0 || idxmd5sum == 0))
       return 0;
+   Desc->language_code = idxlanguage_code;
+   Desc->md5sum = idxmd5sum;
 
    return Description;
 }
@@ -550,15 +629,22 @@ bool pkgCacheGenerator::FinishCache(OpProgress *Progress)
    if (archs.size() > 1)
    {
       // Create Conflicts in between the group
-      for (pkgCache::GrpIterator G = GetCache().GrpBegin(); G.end() != true; G++)
+      pkgCache::GrpIterator G = GetCache().GrpBegin();
+      Dynamic<pkgCache::GrpIterator> DynG(G);
+      for (; G.end() != true; G++)
       {
 	 string const PkgName = G.Name();
-	 for (pkgCache::PkgIterator P = G.PackageList(); P.end() != true; P = G.NextPkg(P))
+	 pkgCache::PkgIterator P = G.PackageList();
+	 Dynamic<pkgCache::PkgIterator> DynP(P);
+	 for (; P.end() != true; P = G.NextPkg(P))
 	 {
 	    if (strcmp(P.Arch(),"all") == 0)
 	       continue;
 	    pkgCache::PkgIterator allPkg;
-	    for (pkgCache::VerIterator V = P.VersionList(); V.end() != true; V++)
+	    Dynamic<pkgCache::PkgIterator> DynallPkg(allPkg);
+	    pkgCache::VerIterator V = P.VersionList();
+	    Dynamic<pkgCache::VerIterator> DynV(V);
+	    for (; V.end() != true; V++)
 	    {
 	       string const Arch = V.Arch(true);
 	       map_ptrloc *OldDepLast = NULL;
@@ -578,6 +664,7 @@ bool pkgCacheGenerator::FinishCache(OpProgress *Progress)
 		     per group, therefore each group member conflicts
 		     with all other group members */
 		  pkgCache::PkgIterator D = G.FindPkg(*A);
+		  Dynamic<pkgCache::PkgIterator> DynD(D);
 		  if (D.end() == true)
 		     continue;
 		  if (coInstall == true)
@@ -622,13 +709,15 @@ bool pkgCacheGenerator::NewDepends(pkgCache::PkgIterator &Pkg,
 				   unsigned int const &Type,
 				   map_ptrloc *OldDepLast)
 {
+   void const * const oldMap = Map.Data();
    // Get a structure
-   unsigned long const Dependency = AllocateInMap(sizeof(pkgCache::Dependency));
+   map_ptrloc const Dependency = AllocateInMap(sizeof(pkgCache::Dependency));
    if (unlikely(Dependency == 0))
       return false;
    
    // Fill it in
    pkgCache::DepIterator Dep(Cache,Cache.DepP + Dependency);
+   Dynamic<pkgCache::DepIterator> DynDep(Dep);
    Dep->ParentVer = Ver.Index();
    Dep->Type = Type;
    Dep->CompareOp = Op;
@@ -640,9 +729,12 @@ bool pkgCacheGenerator::NewDepends(pkgCache::PkgIterator &Pkg,
 /*      for (pkgCache::DepIterator I = Pkg.RevDependsList(); I.end() == false; I++)
 	 if (I->Version != 0 && I.TargetVer() == Version)
 	    Dep->Version = I->Version;*/
-      if (Dep->Version == 0)
-	 if (unlikely((Dep->Version = WriteStringInMap(Version)) == 0))
+      if (Dep->Version == 0) {
+	 map_ptrloc const index = WriteStringInMap(Version);
+	 if (unlikely(index == 0))
 	    return false;
+	 Dep->Version = index;
+      }
    }
 
    // Link it to the package
@@ -656,7 +748,8 @@ bool pkgCacheGenerator::NewDepends(pkgCache::PkgIterator &Pkg,
       OldDepLast = &Ver->DependsList;
       for (pkgCache::DepIterator D = Ver.DependsList(); D.end() == false; D++)
 	 OldDepLast = &D->NextDepends;
-   }
+   } else if (oldMap != Map.Data())
+      OldDepLast += (map_ptrloc*) Map.Data() - (map_ptrloc*) oldMap;
 
    Dep->NextDepends = *OldDepLast;
    *OldDepLast = Dep.Index();
@@ -677,11 +770,13 @@ bool pkgCacheGenerator::ListParser::NewDepends(pkgCache::VerIterator &Ver,
 					       unsigned int Type)
 {
    pkgCache::GrpIterator Grp;
+   Dynamic<pkgCache::GrpIterator> DynGrp(Grp);
    if (unlikely(Owner->NewGroup(Grp, PackageName) == false))
       return false;
 
    // Locate the target package
    pkgCache::PkgIterator Pkg = Grp.FindPkg(Arch);
+   Dynamic<pkgCache::PkgIterator> DynPkg(Pkg);
    if (Pkg.end() == true) {
       if (unlikely(Owner->NewPackage(Pkg, PackageName, Arch) == false))
 	 return false;
@@ -715,13 +810,14 @@ bool pkgCacheGenerator::ListParser::NewProvides(pkgCache::VerIterator &Ver,
       return true;
    
    // Get a structure
-   unsigned long const Provides = Owner->AllocateInMap(sizeof(pkgCache::Provides));
+   map_ptrloc const Provides = Owner->AllocateInMap(sizeof(pkgCache::Provides));
    if (unlikely(Provides == 0))
       return false;
    Cache.HeaderP->ProvidesCount++;
    
    // Fill it in
    pkgCache::PrvIterator Prv(Cache,Cache.ProvideP + Provides,Cache.PkgP);
+   Dynamic<pkgCache::PrvIterator> DynPrv(Prv);
    Prv->Version = Ver.Index();
    Prv->NextPkgProv = Ver->ProvidesList;
    Ver->ProvidesList = Prv.Index();
@@ -730,6 +826,7 @@ bool pkgCacheGenerator::ListParser::NewProvides(pkgCache::VerIterator &Ver,
    
    // Locate the target package
    pkgCache::PkgIterator Pkg;
+   Dynamic<pkgCache::PkgIterator> DynPkg(Pkg);
    if (unlikely(Owner->NewPackage(Pkg,PkgName, PkgArch) == false))
       return false;
    
@@ -750,24 +847,29 @@ bool pkgCacheGenerator::SelectFile(const string &File,const string &Site,
 				   unsigned long Flags)
 {
    // Get some space for the structure
-   CurrentFile = Cache.PkgFileP + AllocateInMap(sizeof(*CurrentFile));
-   if (CurrentFile == Cache.PkgFileP)
+   map_ptrloc const idxFile = AllocateInMap(sizeof(*CurrentFile));
+   if (unlikely(idxFile == 0))
       return false;
-   
+   CurrentFile = Cache.PkgFileP + idxFile;
+
    // Fill it in
-   CurrentFile->FileName = WriteStringInMap(File);
-   CurrentFile->Site = WriteUniqString(Site);
+   map_ptrloc const idxFileName = WriteStringInMap(File);
+   map_ptrloc const idxSite = WriteUniqString(Site);
+   if (unlikely(idxFileName == 0 || idxSite == 0))
+      return false;
+   CurrentFile->FileName = idxFileName;
+   CurrentFile->Site = idxSite;
    CurrentFile->NextFile = Cache.HeaderP->FileList;
    CurrentFile->Flags = Flags;
    CurrentFile->ID = Cache.HeaderP->PackageFileCount;
-   CurrentFile->IndexType = WriteUniqString(Index.GetType()->Label);
+   map_ptrloc const idxIndexType = WriteUniqString(Index.GetType()->Label);
+   if (unlikely(idxIndexType == 0))
+      return false;
+   CurrentFile->IndexType = idxIndexType;
    PkgFileName = File;
    Cache.HeaderP->FileList = CurrentFile - Cache.PkgFileP;
    Cache.HeaderP->PackageFileCount++;
 
-   if (CurrentFile->FileName == 0)
-      return false;
-   
    if (Progress != 0)
       Progress->SubProgress(Index.Size());
    return true;
@@ -807,18 +909,25 @@ unsigned long pkgCacheGenerator::WriteUniqString(const char *S,
    }
    
    // Get a structure
-   unsigned long Item = AllocateInMap(sizeof(pkgCache::StringItem));
+   void const * const oldMap = Map.Data();
+   map_ptrloc const Item = AllocateInMap(sizeof(pkgCache::StringItem));
    if (Item == 0)
       return 0;
 
+   map_ptrloc const idxString = WriteStringInMap(S,Size);
+   if (unlikely(idxString == 0))
+      return 0;
+   if (oldMap != Map.Data()) {
+      Last += (map_ptrloc*) Map.Data() - (map_ptrloc*) oldMap;
+      I += (pkgCache::StringItem*) Map.Data() - (pkgCache::StringItem*) oldMap;
+   }
+   *Last = Item;
+
    // Fill in the structure
    pkgCache::StringItem *ItemP = Cache.StringItemP + Item;
    ItemP->NextItem = I - Cache.StringItemP;
-   *Last = Item;
-   ItemP->String = WriteStringInMap(S,Size);
-   if (ItemP->String == 0)
-      return 0;
-   
+   ItemP->String = idxString;
+
    Bucket = ItemP;
    return ItemP->String;
 }
@@ -1072,7 +1181,7 @@ bool pkgCacheGenerator::MakeStatusCache(pkgSourceList &List,OpProgress *Progress
       unlink(CacheFile.c_str());
       CacheF = new FileFd(CacheFile,FileFd::WriteEmpty);
       fchmod(CacheF->Fd(),0644);
-      Map = new DynamicMMap(*CacheF,MMap::Public,MapSize);
+      Map = new DynamicMMap(*CacheF,MMap::Public | MMap::Moveable, MapSize);
       if (_error->PendingError() == true)
 	 return false;
       if (Debug == true)
@@ -1081,7 +1190,7 @@ bool pkgCacheGenerator::MakeStatusCache(pkgSourceList &List,OpProgress *Progress
    else
    {
       // Just build it in memory..
-      Map = new DynamicMMap(0,MapSize);
+      Map = new DynamicMMap(MMap::Moveable, MapSize);
       if (Debug == true)
 	 std::clog << "Open memory Map (not filebased)" << std::endl;
    }
@@ -1194,7 +1303,7 @@ bool pkgCacheGenerator::MakeOnlyStatusCache(OpProgress *Progress,DynamicMMap **O
    if (_system->AddStatusFiles(Files) == false)
       return false;
    
-   SPtr<DynamicMMap> Map = new DynamicMMap(0,MapSize);
+   SPtr<DynamicMMap> Map = new DynamicMMap(MMap::Moveable, MapSize);
    unsigned long CurrentSize = 0;
    unsigned long TotalSize = 0;
    
diff --git a/apt-pkg/pkgcachegen.h b/apt-pkg/pkgcachegen.h
index 8f7739165..3bee1f958 100644
--- a/apt-pkg/pkgcachegen.h
+++ b/apt-pkg/pkgcachegen.h
@@ -23,6 +23,8 @@
 #include <apt-pkg/pkgcache.h>
 #include <apt-pkg/md5.h>
 
+#include <set>
+
 class pkgSourceList;
 class OpProgress;
 class MMap;
@@ -33,18 +35,32 @@ class pkgCacheGenerator							/*{{{*/
    private:
 
    pkgCache::StringItem *UniqHash[26];
-   unsigned long WriteStringInMap(std::string const &String) { return WriteStringInMap(String.c_str()); };
-   unsigned long WriteStringInMap(const char *String);
-   unsigned long WriteStringInMap(const char *String, const unsigned long &Len);
-   unsigned long AllocateInMap(const unsigned long &size);
+   map_ptrloc WriteStringInMap(std::string const &String) { return WriteStringInMap(String.c_str()); };
+   map_ptrloc WriteStringInMap(const char *String);
+   map_ptrloc WriteStringInMap(const char *String, const unsigned long &Len);
+   map_ptrloc AllocateInMap(const unsigned long &size);
 
    public:
    
    class ListParser;
    friend class ListParser;
-   
+
+   template<typename Iter> class Dynamic {
+      Iter *I;
+
+      public:
+      static std::set<Iter*> toReMap;
+      Dynamic(Iter &It) : I(&It) {
+	 toReMap.insert(I);
+      }
+
+      ~Dynamic() {
+	 toReMap.erase(I);
+      }
+   };
+
    protected:
-   
+
    DynamicMMap &Map;
    pkgCache Cache;
    OpProgress *Progress;
@@ -86,6 +102,8 @@ class pkgCacheGenerator							/*{{{*/
 			MMap **OutMap = 0,bool AllowMem = false);
    static bool MakeOnlyStatusCache(OpProgress *Progress,DynamicMMap **OutMap);
 
+   void ReMap(void const * const oldMap, void const * const newMap);
+
    pkgCacheGenerator(DynamicMMap *Map,OpProgress *Progress);
    ~pkgCacheGenerator();
 };
diff --git a/debian/changelog b/debian/changelog
index 878d5238a..dab703c6b 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -37,6 +37,9 @@ apt (0.7.26~exp8) UNRELEASED; urgency=low
   * apt-pkg/policy.h:
     - add another round of const& madness as the previous round accidentally
       NOT overrides the virtual GetCandidateVer() method (Closes: #587725)
+  * apt-pkg/pkgcachegen.{cc,h}:
+    - make the used MMap moveable (and therefore dynamic resizeable) by
+      applying (some) mad pointer magic (Closes: #195018)
 
   [ Julian Andres Klode ]
   * methods/ftp.h: