5 Jul
2011
5 Jul
'11
1:40 p.m.
Hi,
strcmp() returns 0 if both are parameters NULL, but segfaults if one of the parameters is NULL.
Is this a known behaviour ? man page says nothing about NULL parameters. I ask because, vdr checks for NULL parameter(s) to strcmp() sometimes.
Check for one or both parameters: epg.c:692: if (shortText && strcmp(title, shortText) == 0) { epg.c:742: if (shortText && description && strcmp(shortText, description) == 0) {
No check for null parameter: channels.c:227: bool nn = strcmp(name, Name) != 0; channels.c:228: bool ns = strcmp(shortName, ShortName) != 0;
--
Thanks,
Sundararaj
$ /lib/libc.so.6
GNU C Library (Ubuntu EGLIBC 2.11.1-0ubuntu7.7) stable release version
2.11.1, by Roland McGrath et al.
...
Compiled by GNU CC version 4.4.3.
Compiled on a Linux >>2.6.24-28-server<< system on 2011-01-11.
Available extensions:
crypt add-on version 2.1 by Michael Glad and others
GNU Libidn by Simon Josefsson
Native POSIX Threads Library by Ulrich Drepper et al
BIND-8.2.3-T5B
/*---------------------------------------------------------------*/
#include <string.h>
#include <stdio.h>
int main()
{
int nn;
printf("trying strcmp(NULL,NULL)\n");
nn = strcmp(NULL, NULL); /* no segfault */
printf("trying strcmp("non null string",NULL)\n");
nn = strcmp("non null string", NULL); /* segfault */
printf("does not reach here\n");
return 0;
} /* main() */
/*-------------------------------------------------------------------*/
in gdb I get this backtrace
#0 __strcmp_ia32 () at ../sysdeps/i386/i686/multiarch/../strcmp.S:40