Add debug mode to gssapi_alloc.h

Because the gssalloc macros are normally equivalent to malloc and free
on Unix, we cannot use the full test suite to find cases where we
allocate with malloc and free with gssalloc_free or vice versa.
Provide a way to test for this kind of bug (if only in a special build
configuration) by supporting a DEBUG_GSSALLOC symbol, which causes the
gssalloc wrappers to be deliberately incompatible with malloc and
free.

1 files changed, 77 insertions, 21 deletions

diff --git a/src/lib/gssapi/generic/gssapi_alloc.h b/src/lib/gssapi/generic/gssapi_alloc.h
index 9c0f340b1..9a5cd9892 100644
--- a/src/lib/gssapi/generic/gssapi_alloc.h
+++ b/src/lib/gssapi/generic/gssapi_alloc.h
@@ -9,54 +9,110 @@
 
 #ifdef _WIN32
 #include "winbase.h"
-#define USE_HEAPALLOC 1
-#else
-#define USE_HEAPALLOC 0
 #endif
 #include <string.h>
 
+#if defined(_WIN32)
+
 static inline void
-gssalloc_free(void * value)
+gssalloc_free(void *value)
 {
-    if (value) {
-#if USE_HEAPALLOC
+    if (value)
         HeapFree(GetProcessHeap(), 0, value);
-#else
-        free(value);
-#endif
-    }
 }
 
 static inline void *
 gssalloc_malloc(size_t size)
 {
-#if USE_HEAPALLOC
     return HeapAlloc(GetProcessHeap(), 0, size);
-#else
-    return malloc(size);
-#endif
 }
 
 static inline void *
 gssalloc_calloc(size_t count, size_t size)
 {
-#if USE_HEAPALLOC
     return HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, count * size);
-#else
-    return calloc(count, size);
-#endif
 }
 
 static inline void *
 gssalloc_realloc(void *value, size_t size)
 {
-#if USE_HEAPALLOC
     return HeapReAlloc(GetProcessHeap(), 0, value, size);
-#else
+}
+
+#elif defined(DEBUG_GSSALLOC)
+
+/* Be deliberately incompatible with malloc and free, to allow us to detect
+ * mismatched malloc/gssalloc usage on Unix. */
+
+static inline void
+gssalloc_free(void *value)
+{
+    char *p = (char *)value - 8;
+
+    if (value == NULL)
+        return;
+    if (memcmp(p, "gssalloc", 8) != 0)
+        abort();
+    free(p);
+}
+
+static inline void *
+gssalloc_malloc(size_t size)
+{
+    char *p = calloc(size + 8, 1);
+
+    memcpy(p, "gssalloc", 8);
+    return p + 8;
+}
+
+static inline void *
+gssalloc_calloc(size_t count, size_t size)
+{
+    return gssalloc_malloc(count * size);
+}
+
+static inline void *
+gssalloc_realloc(void *value, size_t size)
+{
+    char *p = (char *)value - 8;
+
+    if (value == NULL)
+        return gssalloc_malloc(size);
+    if (memcmp(p, "gssalloc", 8) != 0)
+        abort();
+    return (char *)realloc(p, size) + 8;
+}
+
+#else /* not _WIN32 or DEBUG_GSSALLOC */
+
+/* Normal Unix case, just use free/malloc/calloc/realloc. */
+
+static inline void
+gssalloc_free(void *value)
+{
+    free(value);
+}
+
+static inline void *
+gssalloc_malloc(size_t size)
+{
+    return malloc(size);
+}
+
+static inline void *
+gssalloc_calloc(size_t count, size_t size)
+{
+    return calloc(count, size);
+}
+
+static inline void *
+gssalloc_realloc(void *value, size_t size)
+{
     return realloc(value, size);
-#endif
 }
 
+#endif /* not _WIN32 or DEBUG_GSSALLOC */
+
 static inline char *
 gssalloc_strdup(const char *str)
 {