glibc/libio/memstream.c
Szabolcs Nagy de895ddcd7 Disable single thread optimization for open_memstream
Single thread optimization is valid if at thread creation time the
optimization can be disabled.  This is in principle true for all
stream objects that user code can access (and thus needs locking),
using the same internal list as fflush(0) uses.  However in glibc
open_memstream is not on that list (BZ 21735) so the optimization
has to be disabled.

	* libio/memstream.c (__open_memstream): Set _IO_FLAGS2_NEED_LOCK.
	* libio/wmemstream.c (open_wmemstream): Likewise.
	* nptl/tst-memstream.c: New.
2017-07-14 16:09:56 +01:00

143 lines
4.0 KiB
C

/* Copyright (C) 1995-2017 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 "libioP.h"
#include "strfile.h"
#include <stdio.h>
#include <stdlib.h>
struct _IO_FILE_memstream
{
_IO_strfile _sf;
char **bufloc;
_IO_size_t *sizeloc;
};
static int _IO_mem_sync (_IO_FILE* fp) __THROW;
static void _IO_mem_finish (_IO_FILE* fp, int) __THROW;
static const struct _IO_jump_t _IO_mem_jumps libio_vtable =
{
JUMP_INIT_DUMMY,
JUMP_INIT (finish, _IO_mem_finish),
JUMP_INIT (overflow, _IO_str_overflow),
JUMP_INIT (underflow, _IO_str_underflow),
JUMP_INIT (uflow, _IO_default_uflow),
JUMP_INIT (pbackfail, _IO_str_pbackfail),
JUMP_INIT (xsputn, _IO_default_xsputn),
JUMP_INIT (xsgetn, _IO_default_xsgetn),
JUMP_INIT (seekoff, _IO_str_seekoff),
JUMP_INIT (seekpos, _IO_default_seekpos),
JUMP_INIT (setbuf, _IO_default_setbuf),
JUMP_INIT (sync, _IO_mem_sync),
JUMP_INIT (doallocate, _IO_default_doallocate),
JUMP_INIT (read, _IO_default_read),
JUMP_INIT (write, _IO_default_write),
JUMP_INIT (seek, _IO_default_seek),
JUMP_INIT (close, _IO_default_close),
JUMP_INIT (stat, _IO_default_stat),
JUMP_INIT(showmanyc, _IO_default_showmanyc),
JUMP_INIT(imbue, _IO_default_imbue)
};
/* Open a stream that writes into a malloc'd buffer that is expanded as
necessary. *BUFLOC and *SIZELOC are updated with the buffer's location
and the number of characters written on fflush or fclose. */
_IO_FILE *
__open_memstream (char **bufloc, _IO_size_t *sizeloc)
{
struct locked_FILE
{
struct _IO_FILE_memstream fp;
#ifdef _IO_MTSAFE_IO
_IO_lock_t lock;
#endif
struct _IO_wide_data wd;
} *new_f;
char *buf;
new_f = (struct locked_FILE *) malloc (sizeof (struct locked_FILE));
if (new_f == NULL)
return NULL;
#ifdef _IO_MTSAFE_IO
new_f->fp._sf._sbf._f._lock = &new_f->lock;
#endif
buf = calloc (1, _IO_BUFSIZ);
if (buf == NULL)
{
free (new_f);
return NULL;
}
_IO_init_internal (&new_f->fp._sf._sbf._f, 0);
_IO_JUMPS_FILE_plus (&new_f->fp._sf._sbf) = &_IO_mem_jumps;
_IO_str_init_static_internal (&new_f->fp._sf, buf, _IO_BUFSIZ, buf);
new_f->fp._sf._sbf._f._flags &= ~_IO_USER_BUF;
new_f->fp._sf._s._allocate_buffer = (_IO_alloc_type) malloc;
new_f->fp._sf._s._free_buffer = (_IO_free_type) free;
new_f->fp.bufloc = bufloc;
new_f->fp.sizeloc = sizeloc;
/* Disable single thread optimization. BZ 21735. */
new_f->fp._sf._sbf._f._flags2 |= _IO_FLAGS2_NEED_LOCK;
return (_IO_FILE *) &new_f->fp._sf._sbf;
}
libc_hidden_def (__open_memstream)
weak_alias (__open_memstream, open_memstream)
static int
_IO_mem_sync (_IO_FILE *fp)
{
struct _IO_FILE_memstream *mp = (struct _IO_FILE_memstream *) fp;
if (fp->_IO_write_ptr == fp->_IO_write_end)
{
_IO_str_overflow (fp, '\0');
--fp->_IO_write_ptr;
}
*mp->bufloc = fp->_IO_write_base;
*mp->sizeloc = fp->_IO_write_ptr - fp->_IO_write_base;
return 0;
}
static void
_IO_mem_finish (_IO_FILE *fp, int dummy)
{
struct _IO_FILE_memstream *mp = (struct _IO_FILE_memstream *) fp;
*mp->bufloc = (char *) realloc (fp->_IO_write_base,
fp->_IO_write_ptr - fp->_IO_write_base + 1);
if (*mp->bufloc != NULL)
{
(*mp->bufloc)[fp->_IO_write_ptr - fp->_IO_write_base] = '\0';
*mp->sizeloc = fp->_IO_write_ptr - fp->_IO_write_base;
fp->_IO_buf_base = NULL;
}
_IO_str_finish (fp, 0);
}