Fixed aliasing bug in Windows platform layer (thanks, Dennis!).

icculus · Mar 12, 2008 · 53a9169 · 53a9169
1 parent bdb7e2a
commit 53a9169
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Showing 3 changed files with 30 additions and 14 deletions.
diff --git a/CHANGELOG.txt b/CHANGELOG.txt
@@ -2,6 +2,7 @@
  * CHANGELOG.
  */
 
+03122008 - Fixed aliasing bug in Windows platform layer (thanks, Dennis!).
 03102008 - Changed some text files from ISO-8859-1 to UTF-8. Replaced all the
            translations with UTF-8 encoded equivalents.
 03082008 - Fixed compiler warnings in Windows platform layer (thanks, Dennis!).

diff --git a/physfs_internal.h b/physfs_internal.h
@@ -33,6 +33,13 @@
 extern "C" {
 #endif
 
+#ifdef __GNUC__
+#define PHYSFS_MINIMUM_GCC_VER(major, minor) \
+    ( ((__GNUC__ << 16) + __GNUC_MINOR__) >= (((major) << 16) + (minor)) )
+#else
+#define PHYSFS_MINIMUM_GCC_VER(major, minor) (0)
+#endif
+
 /*
  * Interface for small allocations. If you need a little scratch space for
  *  a throwaway buffer or string, use this. It will make small allocations
@@ -1020,6 +1027,7 @@ void __PHYSFS_sort(void *entries, PHYSFS_uint32 max,
 #define __PHYSFS_UI64(x) x
 #endif
 
+
 /*
  * Check if a ui64 will fit in the platform's address space.
  *  The initial sizeof check will optimize this macro out entirely on
@@ -1032,6 +1040,7 @@ void __PHYSFS_sort(void *entries, PHYSFS_uint32 max,
     ((s) > (__PHYSFS_UI64(0xFFFFFFFFFFFFFFFF) >> (64-(sizeof(size_t)*8)))) \
 )
 
+
 /*
  * This is a strcasecmp() or stricmp() replacement that expects both strings
  *  to be in UTF-8 encoding. It will do "case folding" to decide if the

diff --git a/platform/windows.c b/platform/windows.c
@@ -256,28 +256,34 @@ static HANDLE WINAPI fallbackCreateFileW(LPCWSTR fname,
 } /* fallbackCreateFileW */
 
 
-/* A blatant abuse of pointer casting... */
-static int symLookup(HMODULE dll, void **addr, const char *sym)
+#if (PHYSFS_MINIMUM_GCC_VERSION(3,3))
+    typedef FARPROC __attribute__((__may_alias__)) PHYSFS_FARPROC;
+#else
+    typedef FARPROC PHYSFS_FARPROC;
+#endif
+
+
+static void symLookup(HMODULE dll, PHYSFS_FARPROC *addr, const char *sym,
+                      int reallyLook, PHYSFS_FARPROC fallback)
 {
-    return( (*addr = GetProcAddress(dll, sym)) != NULL );
+    PHYSFS_FARPROC proc;
+    proc = (PHYSFS_FARPROC) ((reallyLook) ? GetProcAddress(dll, sym) : NULL);
+    if (proc == NULL)
+        proc = fallback;  /* may also be NULL. */
+    *addr = proc;
 } /* symLookup */
 
 
 static int findApiSymbols(void)
 {
     HMODULE dll = NULL;
 
-    #define LOOKUP_NOFALLBACK(x, reallyLook) { \
-        if (reallyLook) \
-            symLookup(dll, (void **) &p##x, #x); \
-        else \
-            p##x = NULL; \
-    }
-
-    #define LOOKUP(x, reallyLook) { \
-        if ((!reallyLook) || (!symLookup(dll, (void **) &p##x, #x))) \
-            p##x = fallback##x; \
-    }
+    #define LOOKUP_NOFALLBACK(x, reallyLook) \
+        symLookup(dll, (PHYSFS_FARPROC *) &p##x, #x, reallyLook, NULL)
+
+    #define LOOKUP(x, reallyLook) \
+        symLookup(dll, (PHYSFS_FARPROC *) &p##x, #x, \
+                  reallyLook, (PHYSFS_FARPROC) fallback##x)
 
     /* Apparently Win9x HAS the Unicode entry points, they just don't WORK. */
     /*  ...so don't look them up unless we're on NT+. (see osHasUnicode.) */