Add epoll check to autoconf and Makefile
[lttng-tools.git] / config / epoll.m4
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
47 AC_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
62 int fd, rc;
63 struct epoll_event ev;
64 fd = epoll_create(128);
65 rc = 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 $2])
73 ])dnl
74
75 AC_DEFUN([AX_HAVE_EPOLL_PWAIT], [dnl
76 ax_have_epoll_cppflags="${CPPFLAGS}"
77 AC_CHECK_HEADER([linux/version.h],
78 [CPPFLAGS="${CPPFLAGS} -DHAVE_LINUX_VERSION_H"])
79 AC_MSG_CHECKING([for Linux epoll(7) interface with signals extension])
80 AC_CACHE_VAL([ax_cv_have_epoll_pwait], [dnl
81 AC_LINK_IFELSE([dnl
82 AC_LANG_PROGRAM([dnl
83 #ifdef HAVE_LINUX_VERSION_H
84 # include <linux/version.h>
85 # if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,19)
86 # error linux kernel version is too old to have epoll_pwait
87 # endif
88 #endif
89 #include <sys/epoll.h>
90 #include <signal.h>
91 ], [dnl
92 int fd, rc;
93 struct epoll_event ev;
94 fd = epoll_create(128);
95 rc = epoll_wait(fd, &ev, 1, 0);
96 rc = epoll_pwait(fd, &ev, 1, 0, (sigset_t const *)(0));])],
97 [ax_cv_have_epoll_pwait=yes],
98 [ax_cv_have_epoll_pwait=no])])
99 CPPFLAGS="${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
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