glibc/debug/printf_chk.c
Zack Weinberg 4e2f43f842 Use PRINTF_FORTIFY instead of _IO_FLAGS2_FORTIFY (bug 11319)
The _chk variants of all of the printf functions become much simpler.
This is the last thing that we needed _IO_acquire_lock_clear_flags2
for, so it can go as well.  I took the opportunity to make the headers
included and the names of all local variables consistent across all the
affected files.

Since we ultimately want to get rid of __no_long_double as well, it
must be possible to get all of the nontrivial effects of the _chk
functions by calling the _internal functions with appropriate flags.
For most of the __(v)xprintf_chk functions, this is covered by
PRINTF_FORTIFY plus some up-front argument checks that can be
duplicated.  However, __(v)sprintf_chk installs a custom jump table so
that it can crash instead of overflowing the output buffer.  This
functionality is moved to __vsprintf_internal, which now has a
'maxlen' argument like __vsnprintf_internal; to get the unsafe
behavior of ordinary (v)sprintf, pass -1 for that argument.

obstack_printf_chk and obstack_vprintf_chk are no longer in the same
file.

As a side-effect of the unification of both fortified and non-fortified
vdprintf initialization, this patch fixes bug 11319 for __dprintf_chk
and __vdprintf_chk, which was previously fixed only for dprintf and
vdprintf by the commit

commit 7ca890b88e
Author: Ulrich Drepper <drepper@redhat.com>
Date:   Wed Feb 24 16:07:57 2010 -0800

    Fix reporting of I/O errors in *dprintf functions.

This patch adds a test case to avoid regressions.

Tested for powerpc and powerpc64le.
2018-12-05 18:15:43 -02:00

39 lines
1.3 KiB
C

/* Copyright (C) 1991-2018 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
<http://www.gnu.org/licenses/>. */
#include <stdarg.h>
#include <libio/libioP.h>
/* Write formatted output to stdout from the format string FORMAT. */
int
___printf_chk (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 = __vfprintf_internal (stdout, format, ap, mode);
va_end (ap);
return ret;
}
ldbl_strong_alias (___printf_chk, __printf_chk)