1# ===========================================================================
2#       http://www.gnu.org/software/autoconf-archive/ax_have_epoll.html
3# ===========================================================================
4#
5# SYNOPSIS
6#
7#   AX_HAVE_EPOLL([ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND])
8#   AX_HAVE_EPOLL_PWAIT([ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND])
9#
10# DESCRIPTION
11#
12#   This macro determines whether the system supports the epoll I/O event
13#   interface. A neat usage example would be:
14#
15#     AX_HAVE_EPOLL(
16#       [AX_CONFIG_FEATURE_ENABLE(epoll)],
17#       [AX_CONFIG_FEATURE_DISABLE(epoll)])
18#     AX_CONFIG_FEATURE(
19#       [epoll], [This platform supports epoll(7)],
20#       [HAVE_EPOLL], [This platform supports epoll(7).])
21#
22#   The epoll interface was added to the Linux kernel in version 2.5.45, and
23#   the macro verifies that a kernel newer than this is installed. This
24#   check is somewhat unreliable if <linux/version.h> doesn't match the
25#   running kernel, but it is necessary regardless, because glibc comes with
26#   stubs for the epoll_create(), epoll_wait(), etc. that allow programs to
27#   compile and link even if the kernel is too old; the problem would then
28#   be detected only at runtime.
29#
30#   Linux kernel version 2.6.19 adds the epoll_pwait() call in addition to
31#   epoll_wait(). The availability of that function can be tested with the
32#   second macro. Generally speaking, it is safe to assume that
33#   AX_HAVE_EPOLL would succeed if AX_HAVE_EPOLL_PWAIT has, but not the
34#   other way round.
35#
36# LICENSE
37#
38#   Copyright (c) 2008 Peter Simons <simons@cryp.to>
39#
40#   Copying and distribution of this file, with or without modification, are
41#   permitted in any medium without royalty provided the copyright notice
42#   and this notice are preserved. This file is offered as-is, without any
43#   warranty.
44
45#serial 10
46
47AC_DEFUN([AX_HAVE_EPOLL], [dnl
48  ax_have_epoll_cppflags="${CPPFLAGS}"
49  AC_CHECK_HEADER([linux/version.h], [CPPFLAGS="${CPPFLAGS} -DHAVE_LINUX_VERSION_H"])
50  AC_MSG_CHECKING([for Linux epoll(7) interface])
51  AC_CACHE_VAL([ax_cv_have_epoll], [dnl
52    AC_LINK_IFELSE([dnl
53      AC_LANG_PROGRAM([dnl
54#include <sys/epoll.h>
55#ifdef HAVE_LINUX_VERSION_H
56#  include <linux/version.h>
57#  if LINUX_VERSION_CODE < KERNEL_VERSION(2,5,45)
58#    error linux kernel version is too old to have epoll
59#  endif
60#endif
61], [dnl
62int fd, rc;
63struct epoll_event ev;
64fd = epoll_create(128);
65rc = epoll_wait(fd, &ev, 1, 0);])],
66      [ax_cv_have_epoll=yes],
67      [ax_cv_have_epoll=no])])
68  CPPFLAGS="${ax_have_epoll_cppflags}"
69  AS_IF([test "${ax_cv_have_epoll}" = "yes"],
70    [AC_MSG_RESULT([yes])
71$1],[AC_MSG_RESULT([no])
72$2])
73])dnl
74
75AC_DEFUN([AX_HAVE_EPOLL_PWAIT], [dnl
76  ax_have_epoll_cppflags="${CPPFLAGS}"
77  AC_CHECK_HEADER([linux/version.h],
78    [CPPFLAGS="${CPPFLAGS} -DHAVE_LINUX_VERSION_H"])
79  AC_MSG_CHECKING([for Linux epoll(7) interface with signals extension])
80  AC_CACHE_VAL([ax_cv_have_epoll_pwait], [dnl
81    AC_LINK_IFELSE([dnl
82      AC_LANG_PROGRAM([dnl
83#ifdef HAVE_LINUX_VERSION_H
84#  include <linux/version.h>
85#  if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,19)
86#    error linux kernel version is too old to have epoll_pwait
87#  endif
88#endif
89#include <sys/epoll.h>
90#include <signal.h>
91], [dnl
92int fd, rc;
93struct epoll_event ev;
94fd = epoll_create(128);
95rc = epoll_wait(fd, &ev, 1, 0);
96rc = epoll_pwait(fd, &ev, 1, 0, (sigset_t const *)(0));])],
97      [ax_cv_have_epoll_pwait=yes],
98      [ax_cv_have_epoll_pwait=no])])
99  CPPFLAGS="${ax_have_epoll_cppflags}"
100  AS_IF([test "${ax_cv_have_epoll_pwait}" = "yes"],
101    [AC_MSG_RESULT([yes])
102$1],[AC_MSG_RESULT([no])
103$2])
104])dnl
105