Jacques Caron wrote:
Hi,
At 14:40 12/06/2008, Cyril SCETBON wrote:
I've tested it on the host and did not get any error with a negative
value or a big value :
cat test_malloc.c
#include <stdlib.h>
#include <stdio.h>
int main()
{
printf("malloc(-4096)\n");
malloc(-4096);
printf("malloc(18446744073709547520)\n");
malloc(18446744073709547520);
return 0;
}
cc -g -w test_malloc.c -o test_malloc
./test_malloc
malloc(-4096)
malloc(18446744073709547520)
no segmentation fault
Quite normal, the malloc itself won't cause a segfault, it's the fact
that something later uses space requested via malloc that couldn't be
allocated (malloc then returned 0). What's the return value of the
malloc calls?
malloc returns NULL in the both cases
, and the strace command shows :
write(1, "malloc(-4096)\n", 14malloc(-4096)
) = 14
brk(0) = 0x501000
brk(0x521000) = 0x521000
mmap(NULL, 2097152, PROT_NONE,
MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = 0x2b78f91d1000
munmap(0x2b78f91d1000, 192512) = 0
munmap(0x2b78f9300000, 856064) = 0
mprotect(0x2b78f9200000, 131072, PROT_READ|PROT_WRITE) = 0
mmap(NULL, 2097152, PROT_NONE,
MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = 0x2b78f9300000
munmap(0x2b78f9400000, 1048576) = 0
mprotect(0x2b78f9300000, 131072, PROT_READ|PROT_WRITE) = 0
munmap(0x2b78f9300000, 1048576) = 0
write(1, "malloc(18446744073709547520)\n",
29malloc(18446744073709547520)
) = 29
mmap(NULL, 2097152, PROT_NONE,
MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = 0x2b78f9300000
munmap(0x2b78f9400000, 1048576) = 0
mprotect(0x2b78f9300000, 131072, PROT_READ|PROT_WRITE) = 0
munmap(0x2b78f9300000, 1048576) = 0
munmap(0x2b78f8e94000, 4096) = 0
exit_group(0) = ?
Process 15518 detached
- you'll notice that the mmap calls are the same for both calls (don't
quite know what malloc is really doing here, it seems to be allocating
more space then freeing up bits, probably trying to align on some
large size), though neither size matches the actual request (?)
ok
- the malloc-induced mmap is quite different from the one in your
original strace (see the flags). Is that the same box?
It's the same host
You must have some special compile flags or libraries in your slonik
compile that change malloc's behaviour. Was your slony-1 install
locally compiled or installed from binaries?
packaged (debian) from sources :
cc -g -Wall -O2 -Wall -Wmissing-prototypes -Wmissing-declarations
-I../.. -DPGSHARE="\"/usr/share/slony1\"" -I/usr/incl
ude/postgresql/8.2/server/ -I/usr/include/postgresql/ -c -o slonik.o
slonik.c
cc -g -Wall -O2 -Wall -Wmissing-prototypes -Wmissing-declarations
-I../.. -DPGSHARE="\"/usr/share/slony1\"" -I/usr/incl
ude/postgresql/8.2/server/ -I/usr/include/postgresql/ -c -o dbutil.o
dbutil.c
cc -g -Wall -O2 -Wall -Wmissing-prototypes -Wmissing-declarations
-I../.. -DPGSHARE="\"/usr/share/slony1\"" -I/usr/incl
ude/postgresql/8.2/server/ -I/usr/include/postgresql/ -c -o parser.o
parser.c
If the latter you might want to try a good old wget/tar/configure/make
to see if the result is the same...
Jacques.
--
Cyril SCETBON - Ingénieur bases de données
AUSY pour France Télécom - OPF/PORTAILS/DOP/HEBEX
Tél : +33 (0)4 97 12 87 60
Jabber : [EMAIL PROTECTED]
France Telecom - Orange
790 Avenue du Docteur Maurice Donat
Bâtiment Marco Polo C2 - Bureau 202
06250 Mougins
France
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