# ===========================================================================

#      https://www.gnu.org/software/autoconf-archive/ax_have_epoll.html

# ===========================================================================

#

# SYNOPSIS

#

#   AX_HAVE_EPOLL([ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND])

#   AX_HAVE_EPOLL_PWAIT([ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND])

#

# DESCRIPTION

#

#   This macro determines whether the system supports the epoll I/O event

#   interface. A neat usage example would be:

#

#     AX_HAVE_EPOLL(

#       [AX_CONFIG_FEATURE_ENABLE(epoll)],

#       [AX_CONFIG_FEATURE_DISABLE(epoll)])

#     AX_CONFIG_FEATURE(

#       [epoll], [This platform supports epoll(7)],

#       [HAVE_EPOLL], [This platform supports epoll(7).])

#

#   The epoll interface was added to the Linux kernel in version 2.5.45, and

#   the macro verifies that a kernel newer than this is installed. This

#   check is somewhat unreliable if <linux/version.h> doesn't match the

#   running kernel, but it is necessary regardless, because glibc comes with

#   stubs for the epoll_create(), epoll_wait(), etc. that allow programs to

#   compile and link even if the kernel is too old; the problem would then

#   be detected only at runtime.

#

#   Linux kernel version 2.6.19 adds the epoll_pwait() call in addition to

#   epoll_wait(). The availability of that function can be tested with the

#   second macro. Generally speaking, it is safe to assume that

#   AX_HAVE_EPOLL would succeed if AX_HAVE_EPOLL_PWAIT has, but not the

#   other way round.

#

# LICENSE

#

#   Copyright (c) 2008 Peter Simons <simons@cryp.to>

#

#   Copying and distribution of this file, with or without modification, are

#   permitted in any medium without royalty provided the copyright notice

#   and this notice are preserved. This file is offered as-is, without any

#   warranty.

#serial 11

AC_DEFUN([AX_HAVE_EPOLL], [dnl

  ax_have_epoll_cppflags="${CPPFLAGS}"

  AC_CHECK_HEADER([linux/version.h], [CPPFLAGS="${CPPFLAGS} -DHAVE_LINUX_VERSION_H"])

  AC_MSG_CHECKING([for Linux epoll(7) interface])

  AC_CACHE_VAL([ax_cv_have_epoll], [dnl

    AC_LINK_IFELSE([dnl

      AC_LANG_PROGRAM([dnl

#include <sys/epoll.h>

#ifdef HAVE_LINUX_VERSION_H

#  include <linux/version.h>

#  if LINUX_VERSION_CODE < KERNEL_VERSION(2,5,45)

#    error linux kernel version is too old to have epoll

#  endif

#endif

], [dnl

int fd, rc;

struct epoll_event ev;

fd = epoll_create(128);

rc = epoll_wait(fd, &ev, 1, 0);])],

      [ax_cv_have_epoll=yes],

      [ax_cv_have_epoll=no])])

  CPPFLAGS="${ax_have_epoll_cppflags}"

  AS_IF([test "${ax_cv_have_epoll}" = "yes"],

    [AC_MSG_RESULT([yes])

$1],[AC_MSG_RESULT([no])

$2])

])dnl

AC_DEFUN([AX_HAVE_EPOLL_PWAIT], [dnl

  ax_have_epoll_cppflags="${CPPFLAGS}"

  AC_CHECK_HEADER([linux/version.h],

    [CPPFLAGS="${CPPFLAGS} -DHAVE_LINUX_VERSION_H"])

  AC_MSG_CHECKING([for Linux epoll(7) interface with signals extension])

  AC_CACHE_VAL([ax_cv_have_epoll_pwait], [dnl

    AC_LINK_IFELSE([dnl

      AC_LANG_PROGRAM([dnl

#ifdef HAVE_LINUX_VERSION_H

#  include <linux/version.h>

#  if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,19)

#    error linux kernel version is too old to have epoll_pwait

#  endif

#endif

#include <sys/epoll.h>

#include <signal.h>

], [dnl

int fd, rc;

struct epoll_event ev;

fd = epoll_create(128);

rc = epoll_wait(fd, &ev, 1, 0);

rc = epoll_pwait(fd, &ev, 1, 0, (sigset_t const *)(0));])],

      [ax_cv_have_epoll_pwait=yes],

      [ax_cv_have_epoll_pwait=no])])

  CPPFLAGS="${ax_have_epoll_cppflags}"

  AS_IF([test "${ax_cv_have_epoll_pwait}" = "yes"],

    [AC_MSG_RESULT([yes])

$1],[AC_MSG_RESULT([no])

$2])

])dnl