malloc_usable_size: Add implementation of the function

malloc_usable_size returns the size of the allocated chunk. We must provide
our own implementation as the size we allocated differs from what libc would
allocate.

Author: petris

duma.h

@@ -263,6 +263,8 @@ DUMA_EXTERN_C int _duma_posix_memalign(void **memptr, size_t alignment,
 DUMA_EXTERN_C void *_duma_realloc(void *baseAdr, size_t newSize,
                                   const char *filename, int lineno);
 DUMA_EXTERN_C void *_duma_valloc(size_t size, const char *filename, int lineno);
+DUMA_EXTERN_C size_t _duma_malloc_usable_size(void *ptr, const char *filename,
+                                              int lineno);
 DUMA_EXTERN_C char *_duma_strdup(const char *str, const char *filename,
                                  int lineno);
 DUMA_EXTERN_C void *_duma_memcpy(void *dest, const void *src, size_t size,
@@ -294,6 +296,7 @@ DUMA_EXTERN_C int _duma_posix_memalign(void **memptr, size_t alignment,
                                        size_t userSize);
 DUMA_EXTERN_C void *_duma_realloc(void *baseAdr, size_t newSize);
 DUMA_EXTERN_C void *_duma_valloc(size_t size);
+DUMA_EXTERN_C size_t _duma_malloc_usable_size(void *ptr);
 DUMA_EXTERN_C char *_duma_strdup(const char *str);
 DUMA_EXTERN_C void *_duma_memcpy(void *dest, const void *src, size_t size);
 DUMA_EXTERN_C void *_duma_memmove(void *dest, const void *src, size_t size);
@@ -318,6 +321,8 @@ DUMA_EXTERN_C char *_duma_strncat(char *dest, const char *src, size_t size);
 #define realloc(BASEADR, NEWSIZE)                                              \
   _duma_realloc(BASEADR, NEWSIZE, __FILE__, __LINE__)
 #define valloc(SIZE) _duma_valloc(SIZE, __FILE__, __LINE__)
+#define malloc_usable_size(PTR) \
+  _duma_malloc_usable_size(PTR, __FILE__, __LINE__)
 #define strdup(STR) _duma_strdup(STR, __FILE__, __LINE__)
 #define memcpy(DEST, SRC, SIZE)                                                \
   _duma_memcpy(DEST, SRC, SIZE, __FILE__, __LINE__)

dumadll/dumadll.cpp

@@ -46,6 +46,12 @@ void * duma_valloc(size_t size)
 }
 
 
+size_t duma_malloc_usable_size(void *ptr)
+{
+  return _duma_malloc_usable_size(ptr  DUMA_PARAMS_UK);
+}
+
+
 char * duma_strdup(const char * str)
 {
   return _duma_strdup(str  DUMA_PARAMS_UK);
@@ -88,4 +94,4 @@ char * duma_strncat(char *dest, const char *src, size_t size)
 }
 
 
-// end
+// end

dumadll/dumadll.def

@@ -7,6 +7,7 @@ EXPORTS
   duma_memalign
   duma_realloc
   duma_valloc
+  duma_malloc_usable_size
   duma_strdup
   duma_memcpy
   duma_memmove

noduma.h

@@ -77,6 +77,10 @@
 #undef valloc
 #endif
 
+#ifdef malloc_usable_size
+#undef malloc_usable_size
+#endif
+
 #ifdef strdup
 #undef strdup
 #endif

src/duma.c

@@ -2176,6 +2176,40 @@ void *_duma_valloc(size_t size DUMA_PARAMLIST_FL) {
                         DUMA_FAIL_ENV DUMA_PARAMS_FL);
 }
 
+/* Function: _duma_malloc_usable_size
+ *
+ * A version of malloc_usable_size.
+ */
+size_t _duma_malloc_usable_size(void *ptr DUMA_PARAMLIST_FL) {
+  struct _DUMA_Slot *slot;
+  size_t size;
+
+  if (0 == ptr || _duma_g.null_addr == ptr)
+    return 0;
+
+  if (0 == _duma_g.allocList) {
+#ifdef DUMA_DETOURS
+    /* Odd things happen with detours sometimes... */
+    DUMA_Print("DUMA_Warning: malloc_usable_size() called before first malloc().");
+    return 0;
+#else
+    DUMA_Abort("malloc_usable_size() called before first malloc().");
+#endif
+  }
+
+  Page_AllowAccess(_duma_g.allocList, _duma_s.allocListSize);
+
+  if (!(slot = slotForUserAddress(ptr))) {
+    DUMA_Abort("malloc_usable_size(%a): address not from malloc.",
+      (DUMA_ADDR)ptr);
+  }
+  size = slot->userSize;
+
+  Page_DenyAccess(_duma_g.allocList, _duma_s.allocListSize);
+
+  return size;
+}
+
 /* Function: _duma_strdup
  *
  * A version of strdup.
@@ -2451,6 +2485,10 @@ void *realloc(void *oldBuffer, size_t newSize) {
 
 void *valloc(size_t size) { return _duma_valloc(size DUMA_PARAMS_UK); }
 
+size_t malloc_usable_size(void *ptr) {
+  return _duma_malloc_usable_size(ptr DUMA_PARAMS_UK);
+}
+
 char *strdup(const char *str) { return _duma_strdup(str DUMA_PARAMS_UK); }
 
 void *memcpy(void *dest, const void *src, size_t size) {