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# sys_select_h.m4 serial 23 |
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dnl Copyright (C) 2006-2023 Free Software Foundation, Inc. |
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dnl This file is free software; the Free Software Foundation |
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dnl gives unlimited permission to copy and/or distribute it, |
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dnl with or without modifications, as long as this notice is preserved. |
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AC_DEFUN_ONCE([gl_SYS_SELECT_H], |
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[ |
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AC_REQUIRE([gl_SYS_SELECT_H_DEFAULTS]) |
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AC_REQUIRE([AC_C_RESTRICT]) |
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AC_CACHE_CHECK([whether <sys/select.h> is self-contained], |
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[gl_cv_header_sys_select_h_selfcontained], |
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[ |
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dnl Test against two bugs: |
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dnl 1. On many platforms, <sys/select.h> assumes prior inclusion of |
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dnl <sys/types.h>. |
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dnl 2. On OSF/1 4.0, <sys/select.h> provides only a forward declaration |
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dnl of 'struct timeval', and no definition of this type. |
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AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <sys/select.h>]], |
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[[struct timeval b;]])], |
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[gl_cv_header_sys_select_h_selfcontained=yes], |
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[gl_cv_header_sys_select_h_selfcontained=no]) |
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dnl Test against another bug: |
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dnl 3. On Solaris 10, <sys/select.h> provides an FD_ZERO implementation |
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dnl that relies on memset(), but without including <string.h>. |
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if test $gl_cv_header_sys_select_h_selfcontained = yes; then |
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AC_COMPILE_IFELSE( |
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[AC_LANG_PROGRAM([[#include <sys/select.h>]], |
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[[int memset; int bzero;]]) |
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], |
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[AC_LINK_IFELSE( |
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[AC_LANG_PROGRAM([[#include <sys/select.h>]], [[ |
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#undef memset |
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#define memset nonexistent_memset |
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extern |
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#ifdef __cplusplus |
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"C" |
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#endif |
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void *memset (void *, int, unsigned long); |
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#undef bzero |
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#define bzero nonexistent_bzero |
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extern |
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#ifdef __cplusplus |
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"C" |
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#endif |
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void bzero (void *, unsigned long); |
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fd_set fds; |
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FD_ZERO (&fds); |
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]]) |
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], |
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[], |
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[gl_cv_header_sys_select_h_selfcontained=no]) |
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]) |
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fi |
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]) |
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dnl <sys/select.h> is always overridden, because of GNULIB_POSIXCHECK. |
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gl_CHECK_NEXT_HEADERS([sys/select.h]) |
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if test $ac_cv_header_sys_select_h = yes; then |
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HAVE_SYS_SELECT_H=1 |
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else |
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HAVE_SYS_SELECT_H=0 |
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fi |
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AC_SUBST([HAVE_SYS_SELECT_H]) |
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gl_PREREQ_SYS_H_WINSOCK2 |
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dnl Check for declarations of anything we want to poison if the |
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dnl corresponding gnulib module is not in use. |
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gl_WARN_ON_USE_PREPARE([[ |
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#include <sys/types.h> |
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#if !(defined __GLIBC__ && !defined __UCLIBC__) && HAVE_SYS_TIME_H |
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# include <sys/time.h> |
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#endif |
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#include <sys/select.h> |
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]], [pselect select]) |
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]) |
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# gl_SYS_SELECT_MODULE_INDICATOR([modulename]) |
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# sets the shell variable that indicates the presence of the given module |
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# to a C preprocessor expression that will evaluate to 1. |
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# This macro invocation must not occur in macros that are AC_REQUIREd. |
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AC_DEFUN([gl_SYS_SELECT_MODULE_INDICATOR], |
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[ |
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dnl Ensure to expand the default settings once only. |
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gl_SYS_SELECT_H_REQUIRE_DEFAULTS |
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gl_MODULE_INDICATOR_SET_VARIABLE([$1]) |
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dnl Define it also as a C macro, for the benefit of the unit tests. |
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gl_MODULE_INDICATOR_FOR_TESTS([$1]) |
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]) |
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# Initializes the default values for AC_SUBSTed shell variables. |
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# This macro must not be AC_REQUIREd. It must only be invoked, and only |
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# outside of macros or in macros that are not AC_REQUIREd. |
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AC_DEFUN([gl_SYS_SELECT_H_REQUIRE_DEFAULTS], |
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[ |
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m4_defun(GL_MODULE_INDICATOR_PREFIX[_SYS_SELECT_H_MODULE_INDICATOR_DEFAULTS], [ |
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gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_PSELECT]) |
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gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SELECT]) |
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]) |
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m4_require(GL_MODULE_INDICATOR_PREFIX[_SYS_SELECT_H_MODULE_INDICATOR_DEFAULTS]) |
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AC_REQUIRE([gl_SYS_SELECT_H_DEFAULTS]) |
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]) |
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AC_DEFUN([gl_SYS_SELECT_H_DEFAULTS], |
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[ |
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dnl Assume proper GNU behavior unless another module says otherwise. |
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HAVE_PSELECT=1; AC_SUBST([HAVE_PSELECT]) |
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REPLACE_PSELECT=0; AC_SUBST([REPLACE_PSELECT]) |
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REPLACE_SELECT=0; AC_SUBST([REPLACE_SELECT]) |
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]) |
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