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[Qemu-devel] [6359] Avoid calling qemu_mallocz with zero size
From: |
malc |
Subject: |
[Qemu-devel] [6359] Avoid calling qemu_mallocz with zero size |
Date: |
Fri, 16 Jan 2009 22:32:34 +0000 |
Revision: 6359
http://svn.sv.gnu.org/viewvc/?view=rev&root=qemu&revision=6359
Author: malc
Date: 2009-01-16 22:32:33 +0000 (Fri, 16 Jan 2009)
Log Message:
-----------
Avoid calling qemu_mallocz with zero size
Currently qemu_mallocz calls malloc and handling of zero by malloc is
implementation defined behaviour:
http://www.opengroup.org/onlinepubs/7990989775/xsh/malloc.html
malloc(0) on AIX returns NULL[1] and qcow2 images without snapshots
are thus unusable
[1] Unless special Linux compatibility define is used when compiling
Modified Paths:
--------------
trunk/block-qcow2.c
Modified: trunk/block-qcow2.c
===================================================================
--- trunk/block-qcow2.c 2009-01-16 21:48:20 UTC (rev 6358)
+++ trunk/block-qcow2.c 2009-01-16 22:32:33 UTC (rev 6359)
@@ -1809,6 +1809,12 @@
int64_t offset;
uint32_t extra_data_size;
+ if (!s->nb_snapshots) {
+ s->snapshots = NULL;
+ s->snapshots_size = 0;
+ return 0;
+ }
+
offset = s->snapshots_offset;
s->snapshots = qemu_mallocz(s->nb_snapshots * sizeof(QCowSnapshot));
if (!s->snapshots)
@@ -2023,8 +2029,10 @@
snapshots1 = qemu_malloc((s->nb_snapshots + 1) * sizeof(QCowSnapshot));
if (!snapshots1)
goto fail;
- memcpy(snapshots1, s->snapshots, s->nb_snapshots * sizeof(QCowSnapshot));
- qemu_free(s->snapshots);
+ if (s->snapshots) {
+ memcpy(snapshots1, s->snapshots, s->nb_snapshots *
sizeof(QCowSnapshot));
+ qemu_free(s->snapshots);
+ }
s->snapshots = snapshots1;
s->snapshots[s->nb_snapshots++] = *sn;
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