add MEM_recallocN(), so bytes are ensured to be zero'd when growing.

3 files changed, 48 insertions, 5 deletions

diff --git a/intern/guardedalloc/MEM_guardedalloc.h b/intern/guardedalloc/MEM_guardedalloc.h
index ae8115a337e..149483e719f 100644
--- a/intern/guardedalloc/MEM_guardedalloc.h
+++ b/intern/guardedalloc/MEM_guardedalloc.h
@@ -111,6 +111,16 @@ extern "C" {
 	;
 
 	/**
+	 * A variant of realloc which zeros new bytes
+	 */
+	void *MEM_recallocN(void *vmemh, size_t len)
+#if MEM_GNU_ATTRIBUTES
+	__attribute__((warn_unused_result))
+	__attribute__((alloc_size(2)))
+#endif
+	;
+
+	/**
 	 * Allocate a block of memory of size len, with tag name str. The
 	 * memory is cleared. The name must be static, because only a
 	 * pointer to it is stored ! */
diff --git a/intern/guardedalloc/intern/mallocn.c b/intern/guardedalloc/intern/mallocn.c
index c4902e6aa5a..df6f4d59c7f 100644
--- a/intern/guardedalloc/intern/mallocn.c
+++ b/intern/guardedalloc/intern/mallocn.c
@@ -302,10 +302,45 @@ void *MEM_reallocN(void *vmemh, size_t len)
 
 		newp = MEM_mallocN(len, memh->name);
 		if (newp) {
-			if (len < memh->len)
+			if (len < memh->len) {
+				/* shrink */
 				memcpy(newp, vmemh, len);
-			else
+			}
+			else {
+				/* grow (or remain same size) */
+				memcpy(newp, vmemh, memh->len);
+			}
+		}
+
+		MEM_freeN(vmemh);
+	}
+
+	return newp;
+}
+
+void *MEM_recallocN(void *vmemh, size_t len)
+{
+	void *newp = NULL;
+
+	if (vmemh) {
+		MemHead *memh = vmemh;
+		memh--;
+
+		newp = MEM_mallocN(len, memh->name);
+		if (newp) {
+			if (len < memh->len) {
+				/* shrink */
+				memcpy(newp, vmemh, len);
+			}
+			else {
 				memcpy(newp, vmemh, memh->len);
+
+				if (len > memh->len) {
+					/* grow */
+					/* zero new bytes */
+					memset(((char *)newp) + memh->len, 0, len - memh->len);
+				}
+			}
 		}
 
 		MEM_freeN(vmemh);
diff --git a/source/blender/avi/intern/avi.c b/source/blender/avi/intern/avi.c
index 9d4704cf0f2..39424057faf 100644
--- a/source/blender/avi/intern/avi.c
+++ b/source/blender/avi/intern/avi.c
@@ -968,9 +968,7 @@ AviError AVI_write_frame(AviMovie *movie, int frame_num, ...)
 		const size_t entry_size = (movie->header->Streams + 1) * sizeof(AviIndexEntry);
 
 		if (movie->entries != NULL) {
-			temp = (AviIndexEntry *)MEM_reallocN(movie->entries, (frame_num + 1) * entry_size);
-			/* clear new bytes */
-			memset(&temp[movie->index_entries + 1], 0, (frame_num - movie->index_entries) * entry_size);
+			temp = (AviIndexEntry *)MEM_recallocN(movie->entries, (frame_num + 1) * entry_size);
 		}
 		else {
 			temp = (AviIndexEntry *) MEM_callocN((frame_num + 1) * entry_size, "newidxentry");