libio: Flush stream at freopen (BZ#21037)

As POSIX states [1] a freopen call should first flush the stream as if by a
call fflush.  C99 (n1256) and C11 (n1570) only states the function should
first close any file associated with the specific stream.  Although current
implementation only follow C specification, current BSD and other libc
implementation (musl) are in sync with POSIX and fflush the stream.

This patch change freopen{64} to fflush the stream before actually reopening
it (or returning if the stream does not support reopen).  It also changes the
Linux implementation to avoid a dynamic allocation on 'fd_to_filename'.

Checked on x86_64-linux-gnu.

	[BZ #21037]
	* libio/Makefile (tests): Add tst-memstream4 and tst-wmemstream4.
	* libio/freopen.c (freopen): Sync stream before reopen and adjust to
	new fd_to_filename interface.
	* libio/freopen64.c (freopen64): Likewise.
	* libio/tst-memstream.h: New file.
	* libio/tst-memstream4.c: Likewise.
	* libio/tst-wmemstream4.c: Likewise.
	* sysdeps/generic/fd_to_filename.h (fd_to_filename): Change signature.
	* sysdeps/unix/sysv/linux/fd_to_filename.h (fd_to_filename): Likewise
	and remove internal dynamic allocation.

[1] http://pubs.opengroup.org/onlinepubs/9699919799/
This commit is contained in:
Adhemerval Zanella 2017-07-13 16:43:24 -03:00
parent d0e91e8c4e
commit 0b727ed4d6
9 changed files with 213 additions and 48 deletions

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@ -1,3 +1,17 @@
2018-10-02 Adhemerval Zanella <adhemerval.zanella@linaro.org>
[BZ #21037]
* libio/Makefile (tests): Add tst-memstream4 and tst-wmemstream4.
* libio/freopen.c (freopen): Sync stream before reopen and adjust to
new fd_to_filename interface.
* libio/freopen64.c (freopen64): Likewise.
* libio/tst-memstream.h: New file.
* libio/tst-memstream4.c: Likewise.
* libio/tst-wmemstream4.c: Likewise.
* sysdeps/generic/fd_to_filename.h (fd_to_filename): Change signature.
* sysdeps/unix/sysv/linux/fd_to_filename.h (fd_to_filename): Likewise
and remove internal dynamic allocation.
2018-10-01 Joseph Myers <joseph@codesourcery.com>
* sysdeps/unix/sysv/linux/bits/mman-linux.h [__USE_GNU]

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@ -59,8 +59,8 @@ tests = tst_swprintf tst_wprintf tst_swscanf tst_wscanf tst_getwc tst_putwc \
tst-mmap-eofsync tst-mmap-fflushsync bug-mmap-fflush \
tst-mmap2-eofsync tst-mmap-offend bug-fopena+ bug-wfflush \
bug-ungetc2 bug-ftell bug-ungetc3 bug-ungetc4 tst-fopenloc2 \
tst-memstream1 tst-memstream2 tst-memstream3 \
tst-wmemstream1 tst-wmemstream2 tst-wmemstream3 \
tst-memstream1 tst-memstream2 tst-memstream3 tst-memstream4 \
tst-wmemstream1 tst-wmemstream2 tst-wmemstream3 tst-wmemstream4 \
bug-memstream1 bug-wmemstream1 \
tst-setvbuf1 tst-popen1 tst-fgetwc bug-wsetpos tst-fseek \
tst-fwrite-error tst-ftell-partial-wide tst-ftell-active-handler \

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@ -24,28 +24,34 @@
This exception applies to code released by its copyright holders
in files containing the exception. */
#include "libioP.h"
#include "stdio.h"
#include <stdio.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <shlib-compat.h>
#include <libioP.h>
#include <fd_to_filename.h>
#include <kernel-features.h>
#include <shlib-compat.h>
FILE *
freopen (const char *filename, const char *mode, FILE *fp)
{
FILE *result;
FILE *result = NULL;
char fdfilename[FD_TO_FILENAME_SIZE];
CHECK_FILE (fp, NULL);
if (!(fp->_flags & _IO_IS_FILEBUF))
return NULL;
_IO_acquire_lock (fp);
/* First flush the stream (failure should be ignored). */
_IO_SYNC (fp);
if (!(fp->_flags & _IO_IS_FILEBUF))
goto end;
int fd = _IO_fileno (fp);
const char *gfilename = (filename == NULL && fd >= 0
? fd_to_filename (fd) : filename);
const char *gfilename
= filename != NULL ? filename : fd_to_filename (fd, fdfilename);
fp->_flags2 |= _IO_FLAGS2_NOCLOSE;
#if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_1)
if (&_IO_stdin_used == NULL)
@ -101,9 +107,6 @@ freopen (const char *filename, const char *mode, FILE *fp)
__close (fd);
end:
if (filename == NULL)
free ((char *) gfilename);
_IO_release_lock (fp);
return result;
}

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@ -24,27 +24,33 @@
This exception applies to code released by its copyright holders
in files containing the exception. */
#include "libioP.h"
#include "stdio.h"
#include <stdio.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <libioP.h>
#include <fd_to_filename.h>
#include <kernel-features.h>
FILE *
freopen64 (const char *filename, const char *mode, FILE *fp)
{
FILE *result;
FILE *result = NULL;
char fdfilename[FD_TO_FILENAME_SIZE];
CHECK_FILE (fp, NULL);
if (!(fp->_flags & _IO_IS_FILEBUF))
return NULL;
_IO_acquire_lock (fp);
/* First flush the stream (failure should be ignored). */
_IO_SYNC (fp);
if (!(fp->_flags & _IO_IS_FILEBUF))
goto end;
int fd = _IO_fileno (fp);
const char *gfilename = (filename == NULL && fd >= 0
? fd_to_filename (fd) : filename);
const char *gfilename
= filename != NULL ? filename : fd_to_filename (fd, fdfilename);
fp->_flags2 |= _IO_FLAGS2_NOCLOSE;
_IO_file_close_it (fp);
_IO_JUMPS_FILE_plus (fp) = &_IO_file_jumps;
@ -84,8 +90,6 @@ freopen64 (const char *filename, const char *mode, FILE *fp)
__close (fd);
end:
if (filename == NULL)
free ((char *) gfilename);
_IO_release_lock (fp);
return result;
}

68
libio/tst-memstream.h Normal file
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@ -0,0 +1,68 @@
/* Common definitions for open_memstream tests.
Copyright (C) 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 <mcheck.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <errno.h>
#include <support/check.h>
#ifdef TEST_WCHAR
# include <wchar.h>
/* Straighforward implementation so tst-memstream3 could use check
fwrite on open_memstream. */
static size_t __attribute__ ((used))
fwwrite (const void *ptr, size_t size, size_t nmemb, FILE *arq)
{
const wchar_t *wcs = (const wchar_t*) (ptr);
for (size_t s = 0; s < size; s++)
{
for (size_t n = 0; n < nmemb; n++)
if (fputwc (wcs[n], arq) == WEOF)
return n;
}
return size * nmemb;
}
# define CHAR_T wchar_t
# define W(o) L##o
# define OPEN_MEMSTREAM open_wmemstream
# define PRINTF wprintf
# define FWRITE fwwrite
# define FPUTC fputwc
# define FPUTS fputws
# define STRCMP wcscmp
# define STRLEN wcslen
#else
# define CHAR_T char
# define W(o) o
# define OPEN_MEMSTREAM open_memstream
# define PRINTF printf
# define FWRITE fwrite
# define FPUTC fputc
# define FPUTS fputs
# define STRCMP strcmp
# define STRLEN strlen
#endif
#define S(s) S1 (s)
#define S1(s) #s

64
libio/tst-memstream4.c Normal file
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@ -0,0 +1,64 @@
/* Test for open_memstream BZ #21037.
Copyright (C) 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 "tst-memstream.h"
static void
mcheck_abort (enum mcheck_status ev)
{
printf ("mecheck failed with status %d\n", (int) ev);
exit (1);
}
static int
do_test (void)
{
mcheck_pedantic (mcheck_abort);
/* Check if freopen proper fflush the stream. */
{
CHAR_T old[] = W("old");
CHAR_T *buf = old;
size_t size;
FILE *fp = OPEN_MEMSTREAM (&buf, &size);
TEST_VERIFY_EXIT (fp != NULL);
FPUTS (W("new"), fp);
/* The stream buffer pointer should be updated with only a fflush or
fclose. */
TEST_COMPARE (STRCMP (buf, old), 0);
/* The old stream should be fflush the stream, even for an invalid
streams. */
FILE *nfp = freopen ("invalid-file", "r", fp);
TEST_VERIFY_EXIT (nfp == NULL);
TEST_VERIFY (STRCMP (buf, W("new")) == 0);
TEST_COMPARE_BLOB (buf, STRLEN (buf) * sizeof (CHAR_T),
W("new"), STRLEN (W("new")) * sizeof (CHAR_T));
TEST_COMPARE (fclose (fp), 0);
free (buf);
}
return 0;
}
#include <support/test-driver.c>

20
libio/tst-wmemstream4.c Normal file
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@ -0,0 +1,20 @@
/* Test for open_wmemstream BZ #21037.
Copyright (C) 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/>. */
#define TEST_WCHAR
#include <libio/tst-memstream4.c>

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@ -16,10 +16,12 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#define FD_TO_FILENAME_SIZE 0
/* In general there is no generic way to query filename for an open
file descriptor. */
static inline const char *
fd_to_filename (int fd)
fd_to_filename (int fd, char *buf)
{
return NULL;
}

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@ -16,30 +16,20 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <_itoa.h>
#define FD_TO_FILENAME_SIZE ((sizeof ("/proc/self/fd/") - 1) \
+ (sizeof ("4294967295") - 1) + 1)
static inline const char *
fd_to_filename (int fd)
fd_to_filename (unsigned int fd, char *buf)
{
char *ret = malloc (30);
*_fitoa_word (fd, __stpcpy (buf, "/proc/self/fd/"), 10, 0) = '\0';
if (ret != NULL)
{
struct stat64 st;
*_fitoa_word (fd, __stpcpy (ret, "/proc/self/fd/"), 10, 0) = '\0';
/* We must make sure the file exists. */
if (__lxstat64 (_STAT_VER, ret, &st) < 0)
{
/* /proc is not mounted or something else happened. Don't
return the file name. */
free (ret);
ret = NULL;
}
}
return ret;
/* We must make sure the file exists. */
struct stat64 st;
if (__lxstat64 (_STAT_VER, buf, &st) < 0)
/* /proc is not mounted or something else happened. */
return NULL;
return buf;
}