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* lib/stdio_.h [REPLACE_FFLUSH]: Declare rpl_fflush. * modules/stdio (Makefile.am): Support fflush. * m4/stdio_h.m4 (gl_STDIO_H_DEFAULTS): Likewise. * modules/fflush: New file. * lib/fflush.c: Likewise. * m4/fflush.m4: Likewise. * modules/fflush-tests: New test. * tests/test-fflush.c: Likewise. * MODULES.html.sh (Input/output <stdio.h>): Document new module.
author Eric Blake <ebb9@byu.net>
date Tue, 10 Apr 2007 03:09:07 +0000
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children 996bed2dc377
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8657
05f21166eb81 * lib/stdio_.h [REPLACE_FFLUSH]: Declare rpl_fflush.
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1 #serial 1
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2
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3 # Copyright (C) 2007 Free Software Foundation, Inc.
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4 # This file is free software; the Free Software Foundation
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5 # gives unlimited permission to copy and/or distribute it,
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6 # with or without modifications, as long as this notice is preserved.
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7
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8 dnl From Eric Blake
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9
05f21166eb81 * lib/stdio_.h [REPLACE_FFLUSH]: Declare rpl_fflush.
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10 dnl Find out how to obey POSIX semantics of fflush(stdin) discarding
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11 dnl unread input, rather than C99 undefined semantics. fpurge is not
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12 dnl standardized, but has the desired properties.
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13
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14 AC_DEFUN([gl_FUNC_FFLUSH],
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15 [
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16 AC_CACHE_CHECK([whether fflush works on input streams],
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17 [gl_cv_func_fflush_stdin],
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18 [echo hello world > conftest.txt
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19 AC_RUN_IFELSE([AC_LANG_PROGRAM(
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20 [[
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21 #include <stdio.h>
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22 #include <unistd.h>
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23 ]], [[FILE *f = fopen ("conftest.txt", "r");
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24 char buffer[10];
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25 int fd = fileno (f);
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26 if (!f || 0 > fd || fread (buffer, 1, 5, f) != 5)
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27 return 2;
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28 /* For deterministic results, ensure f read a bigger buffer. */
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29 if (lseek (fd, 0, SEEK_CUR) == 5)
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30 return 3;
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31 /* POSIX requires fflush-fseek to set file offset of fd. */
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32 if (fflush (f) != 0 || fseek (f, 0, SEEK_CUR) != 0)
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33 return 4;
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34 return !(lseek (fd, 0, SEEK_CUR) == 5);
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35 ]])], [gl_cv_func_fflush_stdin=yes], [gl_cv_func_fflush_stdin=no],
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36 [dnl Pessimistically assume fflush is broken. This is wrong for
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37 dnl at least glibc and cygwin; but lib/fflush.c takes this into account.
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38 gl_cv_func_fflush_stdin=no])
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39 rm conftest.txt
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40 ])
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41 if test $gl_cv_func_fflush_stdin = no; then
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42 gl_REPLACE_FFLUSH
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43 fi
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44 ])
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45
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46 AC_DEFUN([gl_REPLACE_FFLUSH],
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47 [
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48 AC_CHECK_HEADERS_ONCE([stdio_ext.h])
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49 AC_CHECK_FUNCS_ONCE([fpurge __fpurge])
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50 dnl Linux documents int fpurge(), but only declares void __fpurge().
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51 AC_CHECK_DECLS([fpurge], [], [], [[
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52 #include <stdio.h>
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53 #if HAVE_STDIO_EXT_H
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54 # include <stdio_ext.h>
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55 #endif
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56 ]])
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57 AC_LIBOBJ([fflush])
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58 AC_REQUIRE([gl_STDIO_H_DEFAULTS])
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59 REPLACE_FFLUSH=1
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60 ])