m4/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