gl/freading.h

   1 /* Retrieve information about a FILE stream.
   2    Copyright (C) 2007-2023 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 2.1 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 <stdio.h>
  18
  19 /* Return true if the stream STREAM is opened read-only, or if the
  20    last operation on the stream was a read operation.  Return false if
  21    the stream is opened write-only or append-only, or if it supports
  22    writing and there is no current read operation (such as fgetc).
  23
  24    freading and fwriting will never both be true.  If STREAM supports
  25    both reads and writes, then:
  26      - both freading and fwriting might be false when the stream is first
  27        opened, after read encounters EOF, or after fflush,
  28      - freading might be false or true and fwriting might be false
  29        after repositioning (such as fseek, fsetpos, or rewind),
  30    depending on the underlying implementation.
  31
  32    STREAM must not be wide-character oriented.  */
  33
  34 #if HAVE___FREADING && (!defined __GLIBC__ || defined __UCLIBC__ || __GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 7))
  35 /* Solaris >= 7, UnixWare >= 7.1.4.MP4, Cygwin >= 1.7.34, Android API >= 29, not glibc >= 2.2, but glibc >= 2.7, or musl libc  */
  36
  37 # if HAVE_STDIO_EXT_H
  38 #  include <stdio_ext.h>
  39 # endif
  40 # define freading(stream) (__freading (stream) != 0)
  41
  42 #else
  43
  44 # ifdef __cplusplus
  45 extern "C" {
  46 # endif
  47
  48 extern bool freading (FILE *stream) _GL_ATTRIBUTE_PURE;
  49
  50 # ifdef __cplusplus
  51 }
  52 # endif
  53
  54 #endif