glibc/libio/freopen.c

119 lines
3.5 KiB
C

/* Copyright (C) 1993-2017 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/>.
As a special exception, if you link the code in this file with
files compiled with a GNU compiler to produce an executable,
that does not cause the resulting executable to be covered by
the GNU Lesser General Public License. This exception does not
however invalidate any other reasons why the executable file
might be covered by the GNU Lesser General Public License.
This exception applies to code released by its copyright holders
in files containing the exception. */
#include "libioP.h"
#include "stdio.h"
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <shlib-compat.h>
#include <fd_to_filename.h>
#include <kernel-features.h>
FILE *
freopen (const char *filename, const char *mode, FILE *fp)
{
FILE *result;
CHECK_FILE (fp, NULL);
if (!(fp->_flags & _IO_IS_FILEBUF))
return NULL;
_IO_acquire_lock (fp);
int fd = _IO_fileno (fp);
const char *gfilename = (filename == NULL && fd >= 0
? fd_to_filename (fd) : filename);
fp->_flags2 |= _IO_FLAGS2_NOCLOSE;
#if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_1)
if (&_IO_stdin_used == NULL)
{
/* If the shared C library is used by the application binary which
was linked against the older version of libio, we just use the
older one even for internal use to avoid trouble since a pointer
to the old libio may be passed into shared C library and wind
up here. */
_IO_old_file_close_it (fp);
_IO_JUMPS_FILE_plus (fp) = &_IO_old_file_jumps;
result = _IO_old_file_fopen (fp, gfilename, mode);
}
else
#endif
{
_IO_file_close_it (fp);
_IO_JUMPS_FILE_plus (fp) = &_IO_file_jumps;
if (_IO_vtable_offset (fp) == 0 && fp->_wide_data != NULL)
fp->_wide_data->_wide_vtable = &_IO_wfile_jumps;
result = _IO_file_fopen (fp, gfilename, mode, 1);
if (result != NULL)
result = __fopen_maybe_mmap (result);
}
fp->_flags2 &= ~_IO_FLAGS2_NOCLOSE;
if (result != NULL)
{
/* unbound stream orientation */
result->_mode = 0;
if (fd != -1)
{
#ifdef O_CLOEXEC
# ifndef __ASSUME_DUP3
int newfd;
if (__have_dup3 < 0)
newfd = -1;
else
newfd =
# endif
__dup3 (_IO_fileno (result), fd,
(result->_flags2 & _IO_FLAGS2_CLOEXEC) != 0
? O_CLOEXEC : 0);
#else
# define newfd 1
#endif
#ifndef __ASSUME_DUP3
if (newfd < 0)
{
if (errno == ENOSYS)
__have_dup3 = -1;
__dup2 (_IO_fileno (result), fd);
if ((result->_flags2 & _IO_FLAGS2_CLOEXEC) != 0)
__fcntl (fd, F_SETFD, FD_CLOEXEC);
}
#endif
__close (_IO_fileno (result));
_IO_fileno (result) = fd;
}
}
else if (fd != -1)
__close (fd);
if (filename == NULL)
free ((char *) gfilename);
_IO_release_lock (fp);
return result;
}