annotate m4/poll.m4 @ 6679:41b90d084576

(gl_FUNC_POLL): If we deem poll(2) unacceptable, use our replacement poll.h in any case, to avoid a differing declaration from a system header. Seen on AIX.
author Paul Eggert <eggert@cs.ucla.edu>
date Sat, 04 Mar 2006 06:34:54 +0000
parents c0415917431f
children 427cd89c6d7b
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6679
41b90d084576 (gl_FUNC_POLL): If we deem poll(2) unacceptable, use
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1 # poll.m4 serial 5
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2 dnl Copyright (c) 2003, 2005, 2006 Free Software Foundation, Inc.
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3 dnl This file is free software; the Free Software Foundation
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4 dnl gives unlimited permission to copy and/or distribute it,
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5 dnl with or without modifications, as long as this notice is preserved.
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6
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7 AC_DEFUN([gl_FUNC_POLL],
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8 [
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9 AC_CHECK_HEADERS(poll.h)
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10 if test "$ac_cv_header_poll_h" = no; then
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11 POLL_H=poll.h
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12 else
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13 POLL_H=
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14 fi
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15 AC_SUBST([POLL_H])
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16
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17 AC_CHECK_FUNC(poll,
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18 [# Check whether poll() works on special files (like /dev/null) and
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19 # and ttys (like /dev/tty). On MacOS X 10.4.0, it doesn't.
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20 AC_TRY_RUN([
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21 #include <fcntl.h>
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22 #include <poll.h>
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23 int main()
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24 {
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25 struct pollfd ufd;
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26 /* Try /dev/null for reading. */
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27 ufd.fd = open ("/dev/null", O_RDONLY);
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28 if (ufd.fd < 0) /* If /dev/null does not exist, it's not MacOS X. */
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29 return 0;
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30 ufd.events = POLLIN;
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31 ufd.revents = 0;
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32 if (!(poll (&ufd, 1, 0) == 1 && ufd.revents == POLLIN))
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33 return 1;
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34 /* Try /dev/null for writing. */
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35 ufd.fd = open ("/dev/null", O_WRONLY);
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36 if (ufd.fd < 0) /* If /dev/null does not exist, it's not MacOS X. */
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37 return 0;
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38 ufd.events = POLLOUT;
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39 ufd.revents = 0;
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40 if (!(poll (&ufd, 1, 0) == 1 && ufd.revents == POLLOUT))
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41 return 1;
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42 /* Trying /dev/tty may be too environment dependent. */
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43 return 0;
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44 }],
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45 [gl_cv_func_poll=yes],
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46 [gl_cv_func_poll=no],
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47 [# When cross-compiling, assume that poll() works everywhere except on
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48 # MacOS X, regardless of its version.
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49 AC_EGREP_CPP([MacOSX], [
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50 #if defined(__APPLE__) && defined(__MACH__)
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51 This is MacOSX
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52 #endif
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53 ], [gl_cv_func_poll=no], [gl_cv_func_poll=yes])])])
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54 if test $gl_cv_func_poll = yes; then
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55 AC_DEFINE([HAVE_POLL], 1,
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56 [Define to 1 if you have the 'poll' function and it works.])
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57 fi
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58
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59 if test $gl_cv_func_poll = no; then
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60 POLL_H=poll.h # Avoid differing declaration from a system header.
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61 AC_LIBOBJ(poll)
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62 AC_DEFINE(poll, rpl_poll,
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63 [Define to poll if the replacement function should be used.])
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64 gl_PREREQ_POLL
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65 fi
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66 ])
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67
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68 # Prerequisites of lib/poll.c.
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69 AC_DEFUN([gl_PREREQ_POLL],
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70 [
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71 AC_REQUIRE([AC_HEADER_TIME])
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72 AC_CHECK_HEADERS_ONCE(sys/time.h)
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73 ])