lib/freading.c

   1 /* Retrieve information about a FILE stream.
   2    Copyright (C) 2007-2024 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 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 <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    <https://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_EOF_SEEN || defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1
  35   /* GNU libc, BeOS, Haiku, Linux libc5 */
  36   return ((fp->_flags & _IO_NO_WRITES) != 0
  37           || ((fp->_flags & (_IO_NO_READS | _IO_CURRENTLY_PUTTING)) == 0
  38               && fp->_IO_read_base != NULL));
  39 # elif defined __sferror || defined __DragonFly__ || defined __ANDROID__
  40   /* FreeBSD, NetBSD, OpenBSD, DragonFly, Mac OS X, Cygwin < 1.7.34, Minix 3, Android */
  41   return (fp_->_flags & __SRD) != 0;
  42 # elif defined __EMX__               /* emx+gcc */
  43   return (fp->_flags & _IOREAD) != 0;
  44 # elif defined __minix               /* Minix */
  45   return (fp->_flags & _IOREADING) != 0;
  46 # elif defined _IOERR                /* AIX, HP-UX, IRIX, OSF/1, Solaris, OpenServer, UnixWare, mingw, MSVC, NonStop Kernel, OpenVMS */
  47 #  if defined __sun                  /* Solaris */
  48   return (fp_->_flag & _IOREAD) != 0 && (fp_->_flag & _IOWRT) == 0;
  49 #  else
  50   return (fp_->_flag & _IOREAD) != 0;
  51 #  endif
  52 # elif defined __UCLIBC__            /* uClibc */
  53   return (fp->__modeflags & (__FLAG_READONLY | __FLAG_READING)) != 0;
  54 # elif defined __QNX__               /* QNX */
  55   return ((fp->_Mode & 0x2 /* _MOPENW */) == 0
  56           || (fp->_Mode & 0x1000 /* _MREAD */) != 0);
  57 # elif defined __MINT__              /* Atari FreeMiNT */
  58   if (!fp->__mode.__write)
  59     return 1;
  60   if (!fp->__mode.__read)
  61     return 0;
  62 #  ifdef _IO_CURRENTLY_GETTING /* Flag added on 2009-02-28 */
  63   return (fp->__flags & _IO_CURRENTLY_GETTING) != 0;
  64 #  else
  65   return (fp->__buffer < fp->__get_limit /*|| fp->__bufp == fp->__put_limit ??*/);
  66 #  endif
  67 # elif defined EPLAN9                /* Plan9 */
  68   if (fp->state == 0 /* CLOSED */ || fp->state == 4 /* WR */)
  69     return 0;
  70   return (fp->state == 3 /* RD */ && (fp->bufl == 0 || fp->rp < fp->wp));
  71 # else
  72 #  error "Please port gnulib freading.c to your platform!"
  73 # endif
  74 }
  75
  76 #endif