lib/freading.c

   1 /* Retrieve information about a FILE stream.
   2    Copyright (C) 2007-2017 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program 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 General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  16
  17 #include <config.h>
  18
  19 /* Specification.  */
  20 #include "freading.h"
  21
  22 #include "stdio-impl.h"
  23
  24 /* Don't use glibc's __freading function in glibc < 2.7, see
  25    <http://sourceware.org/bugzilla/show_bug.cgi?id=4359>  */
  26 #if !(HAVE___FREADING && (!defined __GLIBC__ || defined __UCLIBC__ || __GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 7)))
  27
  28 bool
  29 freading (FILE *fp)
  30 {
  31   /* Most systems provide FILE as a struct and the necessary bitmask in
  32      <stdio.h>, because they need it for implementing getc() and putc() as
  33      fast macros.  */
  34 # if defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1 /* GNU libc, BeOS, Haiku, Linux libc5 */
  35   return ((fp->_flags & _IO_NO_WRITES) != 0
  36           || ((fp->_flags & (_IO_NO_READS | _IO_CURRENTLY_PUTTING)) == 0
  37               && fp->_IO_read_base != NULL));
  38 # elif defined __sferror || defined __DragonFly__ || defined __ANDROID__
  39   /* FreeBSD, NetBSD, OpenBSD, DragonFly, Mac OS X, Cygwin, Minix 3, Android */
  40   return (fp_->_flags & __SRD) != 0;
  41 # elif defined __EMX__               /* emx+gcc */
  42   return (fp->_flags & _IOREAD) != 0;
  43 # elif defined __minix               /* Minix */
  44   return (fp->_flags & _IOREADING) != 0;
  45 # elif defined _IOERR                /* AIX, HP-UX, IRIX, OSF/1, Solaris, OpenServer, mingw, MSVC, NonStop Kernel, OpenVMS */
  46 #  if defined __sun                  /* Solaris */
  47   return (fp_->_flag & _IOREAD) != 0 && (fp_->_flag & _IOWRT) == 0;
  48 #  else
  49   return (fp_->_flag & _IOREAD) != 0;
  50 #  endif
  51 # elif defined __UCLIBC__            /* uClibc */
  52   return (fp->__modeflags & (__FLAG_READONLY | __FLAG_READING)) != 0;
  53 # elif defined __QNX__               /* QNX */
  54   return ((fp->_Mode & 0x2 /* _MOPENW */) == 0
  55           || (fp->_Mode & 0x1000 /* _MREAD */) != 0);
  56 # elif defined __MINT__              /* Atari FreeMiNT */
  57   if (!fp->__mode.__write)
  58     return 1;
  59   if (!fp->__mode.__read)
  60     return 0;
  61 #  ifdef _IO_CURRENTLY_GETTING /* Flag added on 2009-02-28 */
  62   return (fp->__flags & _IO_CURRENTLY_GETTING) != 0;
  63 #  else
  64   return (fp->__buffer < fp->__get_limit /*|| fp->__bufp == fp->__put_limit ??*/);
  65 #  endif
  66 # elif defined EPLAN9                /* Plan9 */
  67   if (fp->state == 0 /* CLOSED */ || fp->state == 4 /* WR */)
  68     return 0;
  69   return (fp->state == 3 /* RD */ && (fp->bufl == 0 || fp->rp < fp->wp));
  70 # else
  71 #  error "Please port gnulib freading.c to your platform!"
  72 # endif
  73 }
  74
  75 #endif