glibc/debug/asprintf_chk.c
Frédéric Bérat 505c884aeb stdio: Ensure *_chk routines have their hidden builtin definition available
If libc_hidden_builtin_{def,proto} isn't properly set for *_chk routines,
there are unwanted PLT entries in libc.so.

There is a special case with __asprintf_chk:
If ldbl_* macros are used for asprintf, ABI gets broken on s390x,
if it isn't, ppc64le isn't building due to multiple asm redirections.

This is due to the inclusion of bits/stdio-lbdl.h for ppc64le whereas it
isn't for s390x. This header creates redirections, which are not
compatible with the ones generated using libc_hidden_def.
Yet, we can't use libc_hidden_ldbl_proto on s390x since it will not
create a simple strong alias (e.g. as done on x86_64), but a versioned
alias, leading to ABI breakage.

This results in errors on s390x:
/usr/bin/ld: glibc/iconv/../libio/bits/stdio2.h:137: undefined reference
to `__asprintf_chk'

Original __asprintf_chk symbols:
00000000001395b0 T __asprintf_chk
0000000000177e90 T __nldbl___asprintf_chk

__asprintf_chk symbols with ldbl_* macros:
000000000012d590 t ___asprintf_chk
000000000012d590 t __asprintf_chk@@GLIBC_2.4
000000000012d590 t __GI___asprintf_chk
000000000012d590 t __GL____asprintf_chk___asprintf_chk
0000000000172240 T __nldbl___asprintf_chk

__asprintf_chk symbols with the patch:
000000000012d590 t ___asprintf_chk
000000000012d590 T __asprintf_chk
000000000012d590 t __GI___asprintf_chk
0000000000172240 T __nldbl___asprintf_chk

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
2023-07-05 16:59:48 +02:00

55 lines
2.0 KiB
C

/* Copyright (C) 1991-2023 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <stdarg.h>
#include <libio/libioP.h>
/* Write formatted output from FORMAT to a string which is
allocated with malloc and stored in *STRING_PTR. */
int
___asprintf_chk (char **result_ptr, int flag, const char *format, ...)
{
/* For flag > 0 (i.e. __USE_FORTIFY_LEVEL > 1) request that %n
can only come from read-only format strings. */
unsigned int mode = (flag > 0) ? PRINTF_FORTIFY : 0;
va_list ap;
int ret;
va_start (ap, format);
ret = __vasprintf_internal (result_ptr, format, ap, mode);
va_end (ap);
return ret;
}
#if defined __LDBL_COMPAT || __LDOUBLE_REDIRECTS_TO_FLOAT128_ABI == 1
/* This is needed since <bits/stdio-lbdl.h> is included in this case, leading to
* multiple asm redirection of the same symbol
*/
ldbl_hidden_def (___asprintf_chk, __asprintf_chk)
ldbl_strong_alias (___asprintf_chk, __asprintf_chk)
#else
/* On some systems introduction of ldbl_* macros lead to ABI breakage due to the
* long_double_symbol aliasing, e.g. on s390x:
* /usr/bin/ld: glibc/iconv/../libio/bits/stdio2.h:137: undefined reference to
* `__asprintf_chk'
* Due to __asprintf_chk@@GLIBC_2.4 alias replacing __asprintf_chk.
*/
strong_alias (___asprintf_chk, __asprintf_chk)
libc_hidden_def (__asprintf_chk)
#endif