1#serial 10
2
3# Copyright (C) 2000, 2001, 2004, 2005, 2006 Free Software Foundation, Inc.
4# This file is free software; the Free Software Foundation
5# gives unlimited permission to copy and/or distribute it,
6# with or without modifications, as long as this notice is preserved.
7
8dnl From Jim Meyering
9dnl Using code from emacs, based on suggestions from Paul Eggert
10dnl and Ulrich Drepper.
11
12dnl Find out how to determine the number of pending output bytes on a stream.
13dnl glibc (2.1.93 and newer) and Solaris provide __fpending.  On other systems,
14dnl we have to grub around in the FILE struct.
15
16AC_DEFUN([gl_FUNC_FPENDING],
17[
18  AC_CHECK_HEADERS_ONCE(stdio_ext.h)
19  AC_REPLACE_FUNCS([__fpending])
20  fp_headers='
21#     include <stdio.h>
22#     if HAVE_STDIO_EXT_H
23#      include <stdio_ext.h>
24#     endif
25'
26  AC_CHECK_DECLS([__fpending], , , $fp_headers)
27  if test $ac_cv_func___fpending = no; then
28    AC_CACHE_CHECK(
29	      [how to determine the number of pending output bytes on a stream],
30		   ac_cv_sys_pending_output_n_bytes,
31      [
32	for ac_expr in						\
33								\
34	    '# glibc2'						\
35	    'fp->_IO_write_ptr - fp->_IO_write_base'		\
36								\
37	    '# traditional Unix'				\
38	    'fp->_ptr - fp->_base'				\
39								\
40	    '# BSD'						\
41	    'fp->_p - fp->_bf._base'				\
42								\
43	    '# SCO, Unixware'					\
44	    '(fp->__ptr ? fp->__ptr - fp->__base : 0)'		\
45								\
46	    '# old glibc?'					\
47	    'fp->__bufp - fp->__buffer'				\
48								\
49	    '# old glibc iostream?'				\
50	    'fp->_pptr - fp->_pbase'				\
51								\
52	    '# VMS'						\
53	    '(*fp)->_ptr - (*fp)->_base'			\
54								\
55	    '# e.g., DGUX R4.11; the info is not available'	\
56	    1							\
57	    ; do
58
59	  # Skip each embedded comment.
60	  case "$ac_expr" in '#'*) continue;; esac
61
62	  AC_TRY_COMPILE(
63	    [#include <stdio.h>
64	    ],
65	    [FILE *fp = stdin; (void) ($ac_expr);],
66	    fp_done=yes
67	  )
68	  test "$fp_done" = yes && break
69	done
70
71	ac_cv_sys_pending_output_n_bytes=$ac_expr
72      ]
73    )
74    AC_DEFINE_UNQUOTED(PENDING_OUTPUT_N_BYTES,
75      $ac_cv_sys_pending_output_n_bytes,
76      [the number of pending output bytes on stream `fp'])
77  fi
78])
79