[devel] [PATCH for apt 2/2] Fix pointer arithmetics

[Aleksei Nikiforov <darktemplar@altlinux.org>]

This change should fix pointer arithmetic issues for e2k.
---
 apt/apt-pkg/Makefile.am          |  1 +
 apt/apt-pkg/cacheiterators.h     | 14 ++++++++------
 apt/apt-pkg/contrib/mmap.cc      |  8 +++++---
 apt/apt-pkg/pkgcachegen.cc       | 15 ++++++++-------
 apt/apt-pkg/rebase_pointer.h     | 16 ++++++++++++++++
 apt/apt-pkg/rpm/rpmlistparser.cc |  3 ++-
 6 files changed, 40 insertions(+), 17 deletions(-)
 create mode 100644 apt/apt-pkg/rebase_pointer.h

diff --git a/apt/apt-pkg/Makefile.am b/apt/apt-pkg/Makefile.am
index 4c0d234..d038d01 100644
--- a/apt/apt-pkg/Makefile.am
+++ b/apt/apt-pkg/Makefile.am
@@ -94,6 +94,7 @@ libapt_pkg_la_SOURCES = \
 	pkgsystem.h \
 	policy.cc \
 	policy.h \
+	rebase_pointer.h \
 	repository.cc \
 	repository.h \
 	scopeexit.h \
diff --git a/apt/apt-pkg/cacheiterators.h b/apt/apt-pkg/cacheiterators.h
index a4bf670..51f70c1 100644
--- a/apt/apt-pkg/cacheiterators.h
+++ b/apt/apt-pkg/cacheiterators.h
@@ -34,6 +34,8 @@
 #pragma interface "apt-pkg/cacheiterators.h"
 #endif 
 
+#include <apt-pkg/rebase_pointer.h>
+
 #include <set>
 
 // Package Iterator
@@ -89,7 +91,7 @@ class pkgCache::PkgIterator
    {
       if (Owner == 0 || Pkg == 0)
          return;
-      Pkg += static_cast<Package const *>(newMap) - static_cast<Package const *>(oldMap);
+      Pkg = RebasePointer(Pkg, oldMap, newMap);
    }
 
    // Constructors
@@ -151,7 +153,7 @@ class pkgCache::VerIterator
    {
       if (Owner == 0 || Ver == 0)
          return;
-      Ver += static_cast<Version const *>(newMap) - static_cast<Version const *>(oldMap);
+      Ver = RebasePointer(Ver, oldMap, newMap);
    }
 
    inline VerIterator() : Ver(0), Owner(0) {};   
@@ -224,7 +226,7 @@ class pkgCache::DepIterator
    {
       if (Owner == 0 || Dep == 0)
          return;
-      Dep += static_cast<Dependency const *>(newMap) - static_cast<Dependency const *>(oldMap);
+      Dep = RebasePointer(Dep, oldMap, newMap);
    }
 
    inline DepIterator(pkgCache &Owner,Dependency *Trg,Version * = 0) :
@@ -283,7 +285,7 @@ class pkgCache::PrvIterator
    {
       if (Owner == 0 || Prv == 0)
          return;
-      Prv += static_cast<Provides const *>(newMap) - static_cast<Provides const *>(oldMap);
+      Prv = RebasePointer(Prv, oldMap, newMap);
    }
 
    inline PrvIterator() : Prv(0), Type(PrvVer), Owner(0)  {};
@@ -346,7 +348,7 @@ class pkgCache::PkgFileIterator
    {
       if (Owner == 0 || File == 0)
          return;
-      File += static_cast<PackageFile const *>(newMap) - static_cast<PackageFile const *>(oldMap);
+      File = RebasePointer(File, oldMap, newMap);
    }
 
    // Constructors
@@ -387,7 +389,7 @@ class pkgCache::VerFileIterator
    {
       if (Owner == 0 || FileP == 0)
          return;
-      FileP += static_cast<VerFile const *>(newMap) - static_cast<VerFile const *>(oldMap);
+      FileP = RebasePointer(FileP, oldMap, newMap);
    }
 
    inline VerFileIterator() : Owner(0), FileP(0) {};
diff --git a/apt/apt-pkg/contrib/mmap.cc b/apt/apt-pkg/contrib/mmap.cc
index cf01be9..ddae2ff 100644
--- a/apt/apt-pkg/contrib/mmap.cc
+++ b/apt/apt-pkg/contrib/mmap.cc
@@ -30,6 +30,7 @@
 #include <apt-pkg/configuration.h>
 #include <apt-pkg/mmap.h>
 #include <apt-pkg/error.h>
+#include <apt-pkg/rebase_pointer.h>
 
 #include <apti18n.h>
 
@@ -301,7 +302,7 @@ std::experimental::optional<map_ptrloc> DynamicMMap::Allocate(unsigned long Item
       Pool* oldPools = Pools;
       auto idxResult = RawAllocate(I->Count*ItemSize,ItemSize);
       if (Pools != oldPools)
-         I += Pools - oldPools;
+         I = RebasePointer(I, oldPools, Pools);
 
       // Does the allocation failed ?
       if (!idxResult)
@@ -371,7 +372,7 @@ bool DynamicMMap::Grow(unsigned long long size)
       Fd->Write(&C,sizeof(C));
    }
 
-   unsigned long const poolOffset = Pools - ((Pool*) Base);
+   const void * const old_base = Base;
 
    if (Fd != 0)
    {
@@ -408,7 +409,8 @@ bool DynamicMMap::Grow(unsigned long long size)
       memset((char*)Base + WorkSpace, 0, newSize - WorkSpace);
    }
 
-   Pools = (Pool*) Base + poolOffset;
+   if (Base != old_base)
+      Pools = RebasePointer(Pools, old_base, Base);
    WorkSpace = newSize;
 
    return true;
diff --git a/apt/apt-pkg/pkgcachegen.cc b/apt/apt-pkg/pkgcachegen.cc
index 654c81c..10a0fd7 100644
--- a/apt/apt-pkg/pkgcachegen.cc
+++ b/apt/apt-pkg/pkgcachegen.cc
@@ -26,6 +26,7 @@
 #include <apt-pkg/strutl.h>
 #include <apt-pkg/sptr.h>
 #include <apt-pkg/pkgsystem.h>
+#include <apt-pkg/rebase_pointer.h>
 
 #include <apti18n.h>
 
@@ -116,11 +117,11 @@ void pkgCacheGenerator::ReMap(void const * const oldMap, void const * const newM
 
    Cache.ReMap(false);
 
-   CurrentFile += (pkgCache::PackageFile*) newMap - (pkgCache::PackageFile*) oldMap;
+   CurrentFile = RebasePointer(CurrentFile, oldMap, newMap);
 
    for (size_t i = 0; i < _count(UniqHash); ++i)
       if (UniqHash[i] != 0)
-         UniqHash[i] += (pkgCache::StringItem*) newMap - (pkgCache::StringItem*) oldMap;
+         UniqHash[i] = RebasePointer(UniqHash[i], oldMap, newMap);
 
    for (auto i = Dynamic<pkgCache::PkgIterator>::toReMap.begin();
         i != Dynamic<pkgCache::PkgIterator>::toReMap.end(); ++i)
@@ -271,7 +272,7 @@ bool pkgCacheGenerator::MergeList(ListParser &List,
 
       if (oldMap != Map.Data())
       {
-         Last += (map_ptrloc*) Map.Data() - (map_ptrloc*) oldMap;
+         Last = RebasePointer(Last, oldMap, Map.Data());
          oldMap = Map.Data();
       }
 
@@ -297,7 +298,7 @@ bool pkgCacheGenerator::MergeList(ListParser &List,
                               PackageName.c_str(), 1);
 
       if (oldMap != Map.Data())
-         Last += (map_ptrloc*) Map.Data() - (map_ptrloc*) oldMap;
+         Last = RebasePointer(Last, oldMap, Map.Data());
       *Last = *verindex;
 
       Ver->ParentPkg = Pkg.Index();
@@ -605,7 +606,7 @@ bool pkgCacheGenerator::ListParser::NewDepends(pkgCache::VerIterator &Ver,
 	 OldDepLast = &D->NextDepends;
       OldDepVer = Ver;
    } else if (oldMap != Owner->Map.Data())
-      OldDepLast += (map_ptrloc*) Owner->Map.Data() - (map_ptrloc*) oldMap;
+      OldDepLast = RebasePointer(OldDepLast, oldMap, Owner->Map.Data());
 
    // Is it a file dependency?
    if (PackageName[0] == '/')
@@ -747,8 +748,8 @@ std::experimental::optional<map_ptrloc> pkgCacheGenerator::WriteUniqString(const
 
    if (oldMap != Map.Data())
    {
-      Last += (map_ptrloc*) Map.Data() - (map_ptrloc*) oldMap;
-      I += (pkgCache::StringItem*) Map.Data() - (pkgCache::StringItem*) oldMap;
+      Last = RebasePointer(Last, oldMap, Map.Data());
+      I = RebasePointer(I, oldMap, Map.Data());
    }
 
    *Last = *Item;
diff --git a/apt/apt-pkg/rebase_pointer.h b/apt/apt-pkg/rebase_pointer.h
new file mode 100644
index 0000000..efc4074
--- /dev/null
+++ b/apt/apt-pkg/rebase_pointer.h
@@ -0,0 +1,16 @@
+#ifndef PKGLIB_REBASE_POINTER_H
+#define PKGLIB_REBASE_POINTER_H
+
+template <typename T>
+static inline T* RebasePointer(T *ptr, const void * const old_base, const void * const new_base)
+{
+   return reinterpret_cast<T*>(reinterpret_cast<char*>(ptr) + (reinterpret_cast<char const * const>(new_base) - reinterpret_cast<char const * const>(old_base)));
+}
+
+template <typename T>
+static inline const T* RebasePointer(const T *ptr, const void * const old_base, const void * const new_base)
+{
+   return reinterpret_cast<const T*>(reinterpret_cast<const char*>(ptr) + (reinterpret_cast<char const * const>(new_base) - reinterpret_cast<char const * const>(old_base)));
+}
+
+#endif
diff --git a/apt/apt-pkg/rpm/rpmlistparser.cc b/apt/apt-pkg/rpm/rpmlistparser.cc
index 9b2e9ad..84b6b8d 100644
--- a/apt/apt-pkg/rpm/rpmlistparser.cc
+++ b/apt/apt-pkg/rpm/rpmlistparser.cc
@@ -25,6 +25,7 @@
 #include <apt-pkg/strutl.h>
 #include <apt-pkg/crc-16.h>
 #include <apt-pkg/tagfile.h>
+#include <apt-pkg/rebase_pointer.h>
 
 #include <apti18n.h>
 
@@ -56,7 +57,7 @@ rpmListParser::rpmListParser(RPMHandler *Handler)
 
          for (auto iter: *SeenPackages)
          {
-            tmp.insert(iter + (static_cast<const char *>(newMap) - static_cast<const char *>(oldMap)));
+            tmp.insert(RebasePointer(iter, oldMap, newMap));
          }
 
          SeenPackages->swap(tmp);
-- 
2.24.0