+/* 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 "freadahead.h"
+
+size_t
+freadahead (FILE *fp)
+{
+#if defined _IO_ferror_unlocked /* GNU libc, BeOS */
+ if (fp->_IO_write_ptr > fp->_IO_write_base)
+ return 0;
+ return fp->_IO_read_end - fp->_IO_read_ptr;
+#elif defined __sferror /* FreeBSD, NetBSD, OpenBSD, MacOS X, Cygwin */
+ if ((fp->_flags & __SWR) != 0 || fp->_r < 0)
+ return 0;
+ return fp->_r;
+#elif defined _IOERR /* AIX, HP-UX, IRIX, OSF/1, Solaris, mingw */
+# if defined __sun && defined _LP64 /* Solaris/{SPARC,AMD64} 64-bit */
+# define fp_ ((struct { unsigned char *_ptr; \
+ unsigned char *_base; \
+ unsigned char *_end; \
+ long _cnt; \
+ int _file; \
+ unsigned int _flag; \
+ } *) fp)
+ if ((fp_->_flag & _IOWRT) != 0)
+ return 0;
+ return fp_->_cnt;
+# else
+ if ((fp->_flag & _IOWRT) != 0)
+ return 0;
+ return fp->_cnt;
+# endif
+#elif defined __UCLIBC__ /* uClibc */
+# ifdef __STDIO_BUFFERS
+ if (fp->__modeflags & __FLAG_WRITING)
+ return 0;
+ return fp->__bufread - fp->__bufpos;
+# else
+ return 0;
+# endif
+#else
+ #error "Please port gnulib freadahead.c to your platform! Look at the definition of fflush, fread on your system, then report this to bug-gnulib."
+#endif
+}