1/* Copyright (C) 1993-2021 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 <https://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 <stdio.h>
28#include <fcntl.h>
29#include <stdlib.h>
30#include <unistd.h>
31
32#include <libioP.h>
33#include <fd_to_filename.h>
34#include <shlib-compat.h>
35
36FILE *
37freopen (const char *filename, const char *mode, FILE *fp)
38{
39 FILE *result = NULL;
40 struct fd_to_filename fdfilename;
41
42 CHECK_FILE (fp, NULL);
43
44 _IO_acquire_lock (fp);
45 /* First flush the stream (failure should be ignored). */
46 _IO_SYNC (fp);
47
48 if (!(fp->_flags & _IO_IS_FILEBUF))
49 goto end;
50
51 int fd = _IO_fileno (fp);
52 const char *gfilename
53 = filename != NULL ? filename : __fd_to_filename (fd, &fdfilename);
54
55 fp->_flags2 |= _IO_FLAGS2_NOCLOSE;
56#if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_1)
57 if (&_IO_stdin_used == NULL)
58 {
59 /* If the shared C library is used by the application binary which
60 was linked against the older version of libio, we just use the
61 older one even for internal use to avoid trouble since a pointer
62 to the old libio may be passed into shared C library and wind
63 up here. */
64 _IO_old_file_close_it (fp);
65 _IO_JUMPS_FUNC_UPDATE (fp, &_IO_old_file_jumps);
66 result = _IO_old_file_fopen (fp, gfilename, mode);
67 }
68 else
69#endif
70 {
71 _IO_file_close_it (fp);
72 _IO_JUMPS_FILE_plus (fp) = &_IO_file_jumps;
73 if (_IO_vtable_offset (fp) == 0 && fp->_wide_data != NULL)
74 fp->_wide_data->_wide_vtable = &_IO_wfile_jumps;
75 result = _IO_file_fopen (fp, gfilename, mode, 1);
76 if (result != NULL)
77 result = __fopen_maybe_mmap (result);
78 }
79 fp->_flags2 &= ~_IO_FLAGS2_NOCLOSE;
80 if (result != NULL)
81 {
82 /* unbound stream orientation */
83 result->_mode = 0;
84
85 if (fd != -1 && _IO_fileno (result) != fd)
86 {
87 /* At this point we have both file descriptors already allocated,
88 so __dup3 will not fail with EBADF, EINVAL, or EMFILE. But
89 we still need to check for EINVAL and, due Linux internal
90 implementation, EBUSY. It is because on how it internally opens
91 the file by splitting the buffer allocation operation and VFS
92 opening (a dup operation may run when a file is still pending
93 'install' on VFS). */
94 if (__dup3 (_IO_fileno (result), fd,
95 (result->_flags2 & _IO_FLAGS2_CLOEXEC) != 0
96 ? O_CLOEXEC : 0) == -1)
97 {
98 _IO_file_close_it (result);
99 result = NULL;
100 goto end;
101 }
102 __close (_IO_fileno (result));
103 _IO_fileno (result) = fd;
104 }
105 }
106 else if (fd != -1)
107 __close (fd);
108
109end:
110 _IO_release_lock (fp);
111 return result;
112}
113