1/* Copyright (C) 1993-2018 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <http://www.gnu.org/licenses/>.
17
18 As a special exception, if you link the code in this file with
19 files compiled with a GNU compiler to produce an executable,
20 that does not cause the resulting executable to be covered by
21 the GNU Lesser General Public License. This exception does not
22 however invalidate any other reasons why the executable file
23 might be covered by the GNU Lesser General Public License.
24 This exception applies to code released by its copyright holders
25 in files containing the exception. */
26
27#include "libioP.h"
28#include "stdio.h"
29#include <fcntl.h>
30#include <stdlib.h>
31#include <unistd.h>
32
33#include <shlib-compat.h>
34#include <fd_to_filename.h>
35
36#include <kernel-features.h>
37
38FILE *
39freopen (const char *filename, const char *mode, FILE *fp)
40{
41 FILE *result;
42 CHECK_FILE (fp, NULL);
43 if (!(fp->_flags & _IO_IS_FILEBUF))
44 return NULL;
45 _IO_acquire_lock (fp);
46 int fd = _IO_fileno (fp);
47 const char *gfilename = (filename == NULL && fd >= 0
48 ? fd_to_filename (fd) : filename);
49 fp->_flags2 |= _IO_FLAGS2_NOCLOSE;
50#if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_1)
51 if (&_IO_stdin_used == NULL)
52 {
53 /* If the shared C library is used by the application binary which
54 was linked against the older version of libio, we just use the
55 older one even for internal use to avoid trouble since a pointer
56 to the old libio may be passed into shared C library and wind
57 up here. */
58 _IO_old_file_close_it (fp);
59 _IO_JUMPS_FILE_plus (fp) = &_IO_old_file_jumps;
60 result = _IO_old_file_fopen (fp, gfilename, mode);
61 }
62 else
63#endif
64 {
65 _IO_file_close_it (fp);
66 _IO_JUMPS_FILE_plus (fp) = &_IO_file_jumps;
67 if (_IO_vtable_offset (fp) == 0 && fp->_wide_data != NULL)
68 fp->_wide_data->_wide_vtable = &_IO_wfile_jumps;
69 result = _IO_file_fopen (fp, gfilename, mode, 1);
70 if (result != NULL)
71 result = __fopen_maybe_mmap (result);
72 }
73 fp->_flags2 &= ~_IO_FLAGS2_NOCLOSE;
74 if (result != NULL)
75 {
76 /* unbound stream orientation */
77 result->_mode = 0;
78
79 if (fd != -1 && _IO_fileno (result) != fd)
80 {
81 /* At this point we have both file descriptors already allocated,
82 so __dup3 will not fail with EBADF, EINVAL, or EMFILE. But
83 we still need to check for EINVAL and, due Linux internal
84 implementation, EBUSY. It is because on how it internally opens
85 the file by splitting the buffer allocation operation and VFS
86 opening (a dup operation may run when a file is still pending
87 'install' on VFS). */
88 if (__dup3 (_IO_fileno (result), fd,
89 (result->_flags2 & _IO_FLAGS2_CLOEXEC) != 0
90 ? O_CLOEXEC : 0) == -1)
91 {
92 _IO_file_close_it (result);
93 result = NULL;
94 goto end;
95 }
96 __close (_IO_fileno (result));
97 _IO_fileno (result) = fd;
98 }
99 }
100 else if (fd != -1)
101 __close (fd);
102
103end:
104 if (filename == NULL)
105 free ((char *) gfilename);
106
107 _IO_release_lock (fp);
108 return result;
109}
110