On 01/20/2010 12:19 AM, Kirill A. Shutemov wrote:
On Wed, Jan 20, 2010 at 1:56 AM, Juan Quintela<quint...@redhat.com> wrote:
From: Kirill A. Shutemov<kir...@shutemov.name>
CC block/vvfat.o
cc1: warnings being treated as errors
block/vvfat.c: In function 'commit_one_file':
block/vvfat.c:2259: error: ignoring return value of 'ftruncate', declared with
attribute warn_unused_result
make: *** [block/vvfat.o] Error 1
CC block/vvfat.o
In file included from /usr/include/stdio.h:912,
from ./qemu-common.h:19,
from block/vvfat.c:27:
In function 'snprintf',
inlined from 'init_directories' at block/vvfat.c:871,
inlined from 'vvfat_open' at block/vvfat.c:1068:
/usr/include/bits/stdio2.h:65: error: call to __builtin___snprintf_chk will
always overflow destination buffer
make: *** [block/vvfat.o] Error 1
Signed-off-by: Kirill A. Shutemov<kir...@shutemov.name>
Signed-off-by: Juan Quintela<quint...@redhat.com>
---
block/vvfat.c | 9 +++++++--
1 files changed, 7 insertions(+), 2 deletions(-)
diff --git a/block/vvfat.c b/block/vvfat.c
index 063f731..df957e5 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -868,7 +868,8 @@ static int init_directories(BDRVVVFATState* s,
{
direntry_t* entry=array_get_next(&(s->directory));
entry->attributes=0x28; /* archive | volume label */
- snprintf((char*)entry->name,11,"QEMU VVFAT");
+ memcpy(entry->name,"QEMU VVF",8);
+ memcpy(entry->extension,"AT ",3);
}
Better to use
memcpy(entry->name, "QEMU VVFAT", 11);
memcpy() doesn't check bounds.
Relying on such things is bad form because it isn't obvious to a casual
reader what is happening. You have to know that entry->name is 8 chars
long and realize that it will overflow into extension. Since that info
is all the way in the structure definition, the result is difficult to
read code.
Any other discussions about whether the standards allow such a thing or
whether tools are "stupid" is irrelevant. It's a neat trick but it
results in more difficult to maintain code.
Regards,
Anthony Liguori
