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# sys_select_h.m4 serial 23
dnl Copyright (C) 2006-2024 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.
AC_DEFUN_ONCE([gl_SYS_SELECT_H],
[
AC_REQUIRE([gl_SYS_SELECT_H_DEFAULTS])
AC_REQUIRE([AC_C_RESTRICT])
AC_CACHE_CHECK([whether <sys/select.h> is self-contained],
[gl_cv_header_sys_select_h_selfcontained],
[
dnl Test against two bugs:
dnl 1. On many platforms, <sys/select.h> assumes prior inclusion of
dnl <sys/types.h>.
dnl 2. On OSF/1 4.0, <sys/select.h> provides only a forward declaration
dnl of 'struct timeval', and no definition of this type.
AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <sys/select.h>]],
[[struct timeval b;]])],
[gl_cv_header_sys_select_h_selfcontained=yes],
[gl_cv_header_sys_select_h_selfcontained=no])
dnl Test against another bug:
dnl 3. On Solaris 10, <sys/select.h> provides an FD_ZERO implementation
dnl that relies on memset(), but without including <string.h>.
if test $gl_cv_header_sys_select_h_selfcontained = yes; then
AC_COMPILE_IFELSE(
[AC_LANG_PROGRAM([[#include <sys/select.h>]],
[[int memset; int bzero;]])
],
[AC_LINK_IFELSE(
[AC_LANG_PROGRAM([[#include <sys/select.h>]], [[
#undef memset
#define memset nonexistent_memset
extern
#ifdef __cplusplus
"C"
#endif
void *memset (void *, int, unsigned long);
#undef bzero
#define bzero nonexistent_bzero
extern
#ifdef __cplusplus
"C"
#endif
void bzero (void *, unsigned long);
fd_set fds;
FD_ZERO (&fds);
]])
],
[],
[gl_cv_header_sys_select_h_selfcontained=no])
])
fi
])
dnl <sys/select.h> is always overridden, because of GNULIB_POSIXCHECK.
gl_CHECK_NEXT_HEADERS([sys/select.h])
if test $ac_cv_header_sys_select_h = yes; then
HAVE_SYS_SELECT_H=1
else
HAVE_SYS_SELECT_H=0
fi
AC_SUBST([HAVE_SYS_SELECT_H])
gl_PREREQ_SYS_H_WINSOCK2
dnl Check for declarations of anything we want to poison if the
dnl corresponding gnulib module is not in use.
gl_WARN_ON_USE_PREPARE([[
/* Some systems require prerequisite headers. */
#include <sys/types.h>
#if !(defined __GLIBC__ && !defined __UCLIBC__) && HAVE_SYS_TIME_H
# include <sys/time.h>
#endif
#include <sys/select.h>
]], [pselect select])
])
# gl_SYS_SELECT_MODULE_INDICATOR([modulename])
# sets the shell variable that indicates the presence of the given module
# to a C preprocessor expression that will evaluate to 1.
# This macro invocation must not occur in macros that are AC_REQUIREd.
AC_DEFUN([gl_SYS_SELECT_MODULE_INDICATOR],
[
dnl Ensure to expand the default settings once only.
gl_SYS_SELECT_H_REQUIRE_DEFAULTS
gl_MODULE_INDICATOR_SET_VARIABLE([$1])
dnl Define it also as a C macro, for the benefit of the unit tests.
gl_MODULE_INDICATOR_FOR_TESTS([$1])
])
# Initializes the default values for AC_SUBSTed shell variables.
# This macro must not be AC_REQUIREd. It must only be invoked, and only
# outside of macros or in macros that are not AC_REQUIREd.
AC_DEFUN([gl_SYS_SELECT_H_REQUIRE_DEFAULTS],
[
m4_defun(GL_MODULE_INDICATOR_PREFIX[_SYS_SELECT_H_MODULE_INDICATOR_DEFAULTS], [
gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_PSELECT])
gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SELECT])
])
m4_require(GL_MODULE_INDICATOR_PREFIX[_SYS_SELECT_H_MODULE_INDICATOR_DEFAULTS])
AC_REQUIRE([gl_SYS_SELECT_H_DEFAULTS])
])
AC_DEFUN([gl_SYS_SELECT_H_DEFAULTS],
[
dnl Assume proper GNU behavior unless another module says otherwise.
HAVE_PSELECT=1; AC_SUBST([HAVE_PSELECT])
REPLACE_PSELECT=0; AC_SUBST([REPLACE_PSELECT])
REPLACE_SELECT=0; AC_SUBST([REPLACE_SELECT])
])
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