1 /* Retrieve information about a FILE stream.
2 Copyright (C) 2007, 2009-2021 Free Software Foundation, Inc.
3
4 This file is free software: you can redistribute it and/or modify
5 it under the terms of the GNU Lesser General Public License as
6 published by the Free Software Foundation; either version 3 of the
7 License, or (at your option) any later version.
8
9 This file 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
12 GNU Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public License
15 along with this program. If not, see <https://www.gnu.org/licenses/>. */
16
17 #include <stdbool.h>
18 #include <stdio.h>
19
20 /* Return true if the stream STREAM is opened write-only or
21 append-only, or if the last operation on the stream was a write
22 operation. Return false if the stream is opened read-only, or if
23 it supports reading and there is no current write operation (such
24 as fputc).
25
26 freading and fwriting will never both be true. If STREAM supports
27 both reads and writes, then:
28 - both freading and fwriting might be false when the stream is first
29 opened, after read encounters EOF, or after fflush,
30 - freading might be false or true and fwriting might be false
31 after repositioning (such as fseek, fsetpos, or rewind),
32 depending on the underlying implementation.
33
34 STREAM must not be wide-character oriented. */
35
36 #if HAVE___FWRITING
37 /* glibc >= 2.2, Solaris >= 7, UnixWare >= 7.1.4.MP4, Cygwin >= 1.7.34, Android API >= 29, musl libc */
38
39 # if HAVE_STDIO_EXT_H
40 # include <stdio_ext.h>
41 # endif
42 # define fwriting(stream) (__fwriting (stream) != 0)
43
44 #else
45
46 # ifdef __cplusplus
47 extern "C" {
48 # endif
49
50 extern bool fwriting (FILE *stream) _GL_ATTRIBUTE_PURE;
51
52 # ifdef __cplusplus
53 }
54 # endif
55
56 #endif