lib/fwriting.h

   1 /* Retrieve information about a FILE stream.
   2    Copyright (C) 2007, 2009-2024 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 /* This file uses _GL_ATTRIBUTE_PURE, HAVE___FWRITING, HAVE_STDIO_EXT_H.  */
  18 #if !_GL_CONFIG_H_INCLUDED
  19  #error "Please include config.h first."
  20 #endif
  21
  22 #include <stdio.h>
  23
  24 /* Return true if the stream STREAM is opened write-only or
  25    append-only, or if the last operation on the stream was a write
  26    operation.  Return false if the stream is opened read-only, or if
  27    it supports reading and there is no current write operation (such
  28    as fputc).
  29
  30    freading and fwriting will never both be true.  If STREAM supports
  31    both reads and writes, then:
  32      - both freading and fwriting might be false when the stream is first
  33        opened, after read encounters EOF, or after fflush,
  34      - freading might be false or true and fwriting might be false
  35        after repositioning (such as fseek, fsetpos, or rewind),
  36    depending on the underlying implementation.
  37
  38    STREAM must not be wide-character oriented.  */
  39
  40 #if HAVE___FWRITING
  41 /* glibc >= 2.2, Solaris >= 7, UnixWare >= 7.1.4.MP4, Cygwin >= 1.7.34, Android API >= 29, musl libc */
  42
  43 # if HAVE_STDIO_EXT_H
  44 #  include <stdio_ext.h>
  45 # endif
  46 # define fwriting(stream) (__fwriting (stream) != 0)
  47
  48 #else
  49
  50 # ifdef __cplusplus
  51 extern "C" {
  52 # endif
  53
  54 extern bool fwriting (FILE *stream) _GL_ATTRIBUTE_PURE;
  55
  56 # ifdef __cplusplus
  57 }
  58 # endif
  59
  60 #endif