new module 'fwritable'

[Bruno Haible]

This makes '__fwritable' from Solaris and glibc portable.

2007-04-13  Bruno Haible  <address@hidden>

        * modules/fwritable: New file.
        * lib/fwritable.h: New file.
        * lib/fwritable.c: New file.
        * m4/fwritable.m4: New file.

============================== modules/fwritable ==============================
Description:
fwritable() function: Determine whether a FILE stream supports writing.

Files:
lib/fwritable.h
lib/fwritable.c
m4/fwritable.m4

Depends-on:
stdbool

configure.ac:
gl_FUNC_FWRITABLE

Makefile.am:

Include:
"fwritable.h"

License:
LGPL

Maintainer:
Bruno Haible, Eric Blake

=============================== lib/fwritable.h ===============================
/* Retrieve information about a FILE stream.
   Copyright (C) 2007 Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License along
   with this program; if not, write to the Free Software Foundation,
   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */

#include <stdbool.h>
#include <stdio.h>

/* Return true if the stream STREAM supports writing, false if it supports
   only reading.
   STREAM must not be wide-character oriented.
   The result doesn't change until the stream is closed or re-opened.  */

#if HAVE___FWRITABLE /* glibc >= 2.2, Solaris >= 7 */

# include <stdio_ext.h>
# define fwritable(stream) (__fwritable (stream) != 0)

#else

# ifdef __cplusplus
extern "C" {
# endif

extern bool fwritable (FILE *stream);

# ifdef __cplusplus
}
# endif

#endif
=============================== lib/fwritable.c ===============================
/* Retrieve information about a FILE stream.
   Copyright (C) 2007 Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License along
   with this program; if not, write to the Free Software Foundation,
   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */

#include <config.h>

/* Specification.  */
#include "fwritable.h"

bool
fwritable (FILE *fp)
{
  /* Most systems provide FILE as a struct and the necessary bitmask in
     <stdio.h>, because they need it for implementing getc() and putc() as
     fast macros.  */
#if defined _IO_ferror_unlocked     /* GNU libc, BeOS */
  return (fp->_flags & _IO_NO_WRITES) == 0;
#elif defined __sferror             /* FreeBSD, NetBSD, OpenBSD, MacOS X, 
Cygwin */
  return (fp->_flags & (__SRW | __SWR)) != 0;
#elif defined _IOERR                /* AIX, HP-UX, IRIX, OSF/1, Solaris, mingw 
*/
  return (fp->_flag & (_IORW | _IOWRT)) != 0;
#else
 #error "Please port gnulib fwritable.c to your platform!"
#endif
}
=============================== m4/fwritable.m4 ===============================
# fwritable.m4 serial 1
dnl Copyright (C) 2007 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.

AC_DEFUN([gl_FUNC_FWRITABLE],
[
  AC_CHECK_FUNCS_ONCE([__fwritable])
  if test $ac_cv_func___fwritable = no; then
    AC_LIBOBJ([fwritable])
  fi
])