[FTFD] Fix malloc/realloc/free wrappers

On x64 malloc needs to return a 16 byte aligned buffer, the previous code used an 8 byte header, making the allocations unaligned. This is now fixed with an improved header structure. Also simplify realloc a bit and make it handle Object == NULL.

[FTFD] Fix malloc/realloc/free wrappers
On x64 malloc needs to return a 16 byte aligned buffer, the previous code used an 8 byte header, making the allocations unaligned. This is now fixed with an improved header structure. Also simplify realloc a bit and make it handle Object == NULL.
dca51942 · Timo Kreuzer · 91fadeb6 · dca51942
--- a/win32ss/drivers/font/ftfd/rosglue.c
+++ b/win32ss/drivers/font/ftfd/rosglue.c
@@ -36,43 +36,54 @@ DbgPrint(IN PCCH Format, IN ...)
 * buffer (need to copy the old contents to the new buffer). So, allocate
 * extra space for a size_t, store the allocated size in there and return
 * the address just past it as the allocated buffer.
+ * On win64 we need to align the allocation to 16 bytes, otherwise 8 bytes.
 */
+typedef struct _MALLOC_HEADER
+{
+    SIZE_T Size;
+    SIZE_T Alignment;
+} MALLOC_HEADER, * PMALLOC_HEADER;

 void *
 malloc(size_t Size)
 {
-    void *Object;
+    PMALLOC_HEADER Header;

-    Object = EngAllocMem(0, sizeof(size_t) + Size, TAG_FREETYPE);
-    if (Object != NULL)
+    Header = EngAllocMem(0, sizeof(MALLOC_HEADER) + Size, TAG_FREETYPE);
+    if (Header == NULL)
    {
-        *((size_t *)Object) = Size;
-        Object = (void *)((size_t *)Object + 1);
+        return NULL;
    }

-    return Object;
+    Header->Size = Size;
+    Header->Alignment = -1;
+    return (Header + 1);
 }

 void *
 realloc(void *Object, size_t Size)
 {
-    void *NewObject;
+    PVOID NewObject;
+    PMALLOC_HEADER OldHeader;
    size_t CopySize;

-    NewObject = EngAllocMem(0, sizeof(size_t) + Size, TAG_FREETYPE);
-    if (NewObject != NULL)
+    NewObject = malloc(Size);
+    if (NewObject == NULL)
    {
-        *((size_t *)NewObject) = Size;
-        NewObject = (void *)((size_t *)NewObject + 1);
-        CopySize = *((size_t *)Object - 1);
-        if (Size < CopySize)
-        {
-            CopySize = Size;
-        }
-        memcpy(NewObject, Object, CopySize);
-        EngFreeMem((size_t *)Object - 1);
+        return NULL;
    }

+    if (Object == NULL)
+    {
+        return NewObject;
+    }
+
+    OldHeader = (PMALLOC_HEADER)Object - 1;
+    CopySize = min(OldHeader->Size, Size);
+    memcpy(NewObject, Object, CopySize);
+
+    free(Object);
+
    return NewObject;
 }

@@ -81,7 +92,7 @@ free(void *Object)
 {
    if (Object != NULL)
    {
-        EngFreeMem((size_t *)Object - 1);
+        EngFreeMem((PMALLOC_HEADER)Object - 1);
    }
 }