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forked from pool/gc
gc/0001-Speedup-calloc-size-overflow-check-by-preventing-div.patch

35 lines
1.1 KiB
Diff

From 83231d0ab5ed60015797c3d1ad9056295ac3b2bb Mon Sep 17 00:00:00 2001
From: Hans Boehm <Hans.Boehm@hp.com>
Date: Thu, 15 Mar 2012 21:09:05 +0400
Subject: [PATCH] Speedup calloc size overflow check by preventing division if
small values
* malloc.c (GC_SQRT_SIZE_MAX): New macro.
* malloc.c (calloc): Add fast initial size overflow check to avoid
integer division for reasonably small values passed.
---
malloc.c | 5 ++++-
1 files changed, 4 insertions(+), 1 deletions(-)
diff --git a/malloc.c b/malloc.c
index cb49a5c..c9b9eb6 100644
--- a/malloc.c
+++ b/malloc.c
@@ -381,9 +381,12 @@ void * malloc(size_t lb)
# define GC_SIZE_MAX (~(size_t)0)
#endif
+#define GC_SQRT_SIZE_MAX ((1U << (WORDSZ / 2)) - 1)
+
void * calloc(size_t n, size_t lb)
{
- if (lb && n > GC_SIZE_MAX / lb)
+ if ((lb | n) > GC_SQRT_SIZE_MAX /* fast initial test */
+ && lb && n > GC_SIZE_MAX / lb)
return NULL;
# if defined(GC_LINUX_THREADS) /* && !defined(USE_PROC_FOR_LIBRARIES) */
/* libpthread allocated some memory that is only pointed to by */
--
1.7.7