Module Name: src
Committed By: kamil
Date: Thu Aug 20 22:27:49 UTC 2015
Modified Files:
src/lib/libc/stdlib: reallocarr.c
Log Message:
Minor alterations to reallocarr(3)
Add comment about division.
Mark error branches with __predict_false().
Reduce one branch with the OR trick.
To generate a diff of this commit:
cvs rdiff -u -r1.4 -r1.5 src/lib/libc/stdlib/reallocarr.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/lib/libc/stdlib/reallocarr.c
diff -u src/lib/libc/stdlib/reallocarr.c:1.4 src/lib/libc/stdlib/reallocarr.c:1.5
--- src/lib/libc/stdlib/reallocarr.c:1.4 Thu Aug 20 20:08:04 2015
+++ src/lib/libc/stdlib/reallocarr.c Thu Aug 20 22:27:49 2015
@@ -1,4 +1,4 @@
-/* $NetBSD: reallocarr.c,v 1.4 2015/08/20 20:08:04 joerg Exp $ */
+/* $NetBSD: reallocarr.c,v 1.5 2015/08/20 22:27:49 kamil Exp $ */
/*-
* Copyright (c) 2015 Joerg Sonnenberger <jo...@netbsd.org>.
@@ -34,7 +34,7 @@
#endif
#include <sys/cdefs.h>
-__RCSID("$NetBSD: reallocarr.c,v 1.4 2015/08/20 20:08:04 joerg Exp $");
+__RCSID("$NetBSD: reallocarr.c,v 1.5 2015/08/20 22:27:49 kamil Exp $");
#include "namespace.h"
#include <errno.h>
@@ -70,14 +70,20 @@ reallocarr(void *ptr, size_t number, siz
return 0;
}
- if ((number >= SQRT_SIZE_MAX || size >= SQRT_SIZE_MAX) &&
- number > SIZE_MAX / size) {
+ /*
+ * Try to avoid division here.
+ *
+ * It isn't possible to overflow during multiplication if neither
+ * operand uses any of the most significant half of the bits.
+ */
+ if (__predict_false((number|size) >= SQRT_SIZE_MAX &&
+ number > SIZE_MAX / size)) {
errno = saved_errno;
return EOVERFLOW;
}
nptr = realloc(optr, number * size);
- if (nptr == NULL) {
+ if (__predict_false(nptr == NULL)) {
result = errno;
} else {
result = 0;
