1/* Copyright (C) 1993-2023 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
35FILE *
36freopen64 (const char *filename, const char *mode, FILE *fp)
37{
38 FILE *result = NULL;
39 struct fd_to_filename fdfilename;
40
41 CHECK_FILE (fp, NULL);
42
43 _IO_acquire_lock (fp);
44 /* First flush the stream (failure should be ignored). */
45 _IO_SYNC (fp);
46
47 if (!(fp->_flags & _IO_IS_FILEBUF))
48 goto end;
49
50 int fd = _IO_fileno (fp);
51 const char *gfilename
52 = filename != NULL ? filename : __fd_to_filename (fd, &fdfilename);
53
54 fp->_flags2 |= _IO_FLAGS2_NOCLOSE;
55 _IO_file_close_it (fp);
56 _IO_JUMPS_FILE_plus (fp) = &_IO_file_jumps;
57 if (_IO_vtable_offset (fp) == 0 && fp->_wide_data != NULL)
58 fp->_wide_data->_wide_vtable = &_IO_wfile_jumps;
59 result = _IO_file_fopen (fp, gfilename, mode, 0);
60 fp->_flags2 &= ~_IO_FLAGS2_NOCLOSE;
61 if (result != NULL)
62 result = __fopen_maybe_mmap (result);
63 if (result != NULL)
64 {
65 /* unbound stream orientation */
66 result->_mode = 0;
67
68 if (fd != -1 && _IO_fileno (result) != fd)
69 {
70 /* At this point we have both file descriptors already allocated,
71 so __dup3 will not fail with EBADF, EINVAL, or EMFILE. But
72 we still need to check for EINVAL and, due Linux internal
73 implementation, EBUSY. It is because on how it internally opens
74 the file by splitting the buffer allocation operation and VFS
75 opening (a dup operation may run when a file is still pending
76 'install' on VFS). */
77 if (__dup3 (_IO_fileno (result), fd,
78 (result->_flags2 & _IO_FLAGS2_CLOEXEC) != 0
79 ? O_CLOEXEC : 0) == -1)
80 {
81 _IO_file_close_it (result);
82 result = NULL;
83 goto end;
84 }
85 __close (_IO_fileno (result));
86 _IO_fileno (result) = fd;
87 }
88 }
89 else if (fd != -1)
90 __close (fd);
91
92end:
93 _IO_release_lock (fp);
94 return result;
95}
96