string: Fix bug-strncat1 with fortify enabled

If fortify is enabled, the truncated output warning is issued by
the wrapper itself:

bug-strncat1.c: In function ‘main’:
bug-strncat1.c:14:3: error: ‘__builtin___strncat_chk’ output truncated
copying 1 byte from a string of length 2 [-Werror=stringop-truncation]
   14 |   strncat (d, "\5\6", 1);
      |   ^

Checked on x86_64-linux-gnu.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
This commit is contained in:
Adhemerval Zanella Netto 2023-07-21 09:18:16 -03:00 committed by Adhemerval Zanella
parent 2d472b4861
commit 85ac7edcdf

View File

@ -1,9 +1,16 @@
#undef __USE_STRING_INLINES
#define __USE_STRING_INLINES
#include <sys/cdefs.h>
#include <libc-diag.h>
#if __GNUC_PREREQ (8, 0)
/* GCC warns about strncat truncating output; this is deliberately
tested here. If fortify is enabled, it is also triggered by the
wrappers. */
DIAG_IGNORE_NEEDS_COMMENT (8, "-Wstringop-truncation");
#endif
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <libc-diag.h>
char d[3] = "\0\1\2";
@ -11,11 +18,6 @@ int
main (void)
{
DIAG_PUSH_NEEDS_COMMENT;
#if __GNUC_PREREQ (8, 0)
/* GCC 8 warns about strncat truncating output; this is deliberately
tested here. */
DIAG_IGNORE_NEEDS_COMMENT (8, "-Wstringop-truncation");
#endif
strncat (d, "\5\6", 1);
DIAG_POP_NEEDS_COMMENT;
if (d[0] != '\5')