1# sys_select_h.m4 serial 23 2dnl Copyright (C) 2006-2022 Free Software Foundation, Inc. 3dnl This file is free software; the Free Software Foundation 4dnl gives unlimited permission to copy and/or distribute it, 5dnl with or without modifications, as long as this notice is preserved. 6 7AC_DEFUN_ONCE([gl_SYS_SELECT_H], 8[ 9 AC_REQUIRE([gl_SYS_SELECT_H_DEFAULTS]) 10 AC_REQUIRE([AC_C_RESTRICT]) 11 AC_CACHE_CHECK([whether <sys/select.h> is self-contained], 12 [gl_cv_header_sys_select_h_selfcontained], 13 [ 14 dnl Test against two bugs: 15 dnl 1. On many platforms, <sys/select.h> assumes prior inclusion of 16 dnl <sys/types.h>. 17 dnl 2. On OSF/1 4.0, <sys/select.h> provides only a forward declaration 18 dnl of 'struct timeval', and no definition of this type. 19 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <sys/select.h>]], 20 [[struct timeval b;]])], 21 [gl_cv_header_sys_select_h_selfcontained=yes], 22 [gl_cv_header_sys_select_h_selfcontained=no]) 23 dnl Test against another bug: 24 dnl 3. On Solaris 10, <sys/select.h> provides an FD_ZERO implementation 25 dnl that relies on memset(), but without including <string.h>. 26 if test $gl_cv_header_sys_select_h_selfcontained = yes; then 27 AC_COMPILE_IFELSE( 28 [AC_LANG_PROGRAM([[#include <sys/select.h>]], 29 [[int memset; int bzero;]]) 30 ], 31 [AC_LINK_IFELSE( 32 [AC_LANG_PROGRAM([[#include <sys/select.h>]], [[ 33 #undef memset 34 #define memset nonexistent_memset 35 extern 36 #ifdef __cplusplus 37 "C" 38 #endif 39 void *memset (void *, int, unsigned long); 40 #undef bzero 41 #define bzero nonexistent_bzero 42 extern 43 #ifdef __cplusplus 44 "C" 45 #endif 46 void bzero (void *, unsigned long); 47 fd_set fds; 48 FD_ZERO (&fds); 49 ]]) 50 ], 51 [], 52 [gl_cv_header_sys_select_h_selfcontained=no]) 53 ]) 54 fi 55 ]) 56 dnl <sys/select.h> is always overridden, because of GNULIB_POSIXCHECK. 57 gl_CHECK_NEXT_HEADERS([sys/select.h]) 58 if test $ac_cv_header_sys_select_h = yes; then 59 HAVE_SYS_SELECT_H=1 60 else 61 HAVE_SYS_SELECT_H=0 62 fi 63 AC_SUBST([HAVE_SYS_SELECT_H]) 64 gl_PREREQ_SYS_H_WINSOCK2 65 66 dnl Check for declarations of anything we want to poison if the 67 dnl corresponding gnulib module is not in use. 68 gl_WARN_ON_USE_PREPARE([[ 69/* Some systems require prerequisite headers. */ 70#include <sys/types.h> 71#if !(defined __GLIBC__ && !defined __UCLIBC__) && HAVE_SYS_TIME_H 72# include <sys/time.h> 73#endif 74#include <sys/select.h> 75 ]], [pselect select]) 76]) 77 78# gl_SYS_SELECT_MODULE_INDICATOR([modulename]) 79# sets the shell variable that indicates the presence of the given module 80# to a C preprocessor expression that will evaluate to 1. 81# This macro invocation must not occur in macros that are AC_REQUIREd. 82AC_DEFUN([gl_SYS_SELECT_MODULE_INDICATOR], 83[ 84 dnl Ensure to expand the default settings once only. 85 gl_SYS_SELECT_H_REQUIRE_DEFAULTS 86 gl_MODULE_INDICATOR_SET_VARIABLE([$1]) 87 dnl Define it also as a C macro, for the benefit of the unit tests. 88 gl_MODULE_INDICATOR_FOR_TESTS([$1]) 89]) 90 91# Initializes the default values for AC_SUBSTed shell variables. 92# This macro must not be AC_REQUIREd. It must only be invoked, and only 93# outside of macros or in macros that are not AC_REQUIREd. 94AC_DEFUN([gl_SYS_SELECT_H_REQUIRE_DEFAULTS], 95[ 96 m4_defun(GL_MODULE_INDICATOR_PREFIX[_SYS_SELECT_H_MODULE_INDICATOR_DEFAULTS], [ 97 gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_PSELECT]) 98 gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SELECT]) 99 ]) 100 m4_require(GL_MODULE_INDICATOR_PREFIX[_SYS_SELECT_H_MODULE_INDICATOR_DEFAULTS]) 101 AC_REQUIRE([gl_SYS_SELECT_H_DEFAULTS]) 102]) 103 104AC_DEFUN([gl_SYS_SELECT_H_DEFAULTS], 105[ 106 dnl Assume proper GNU behavior unless another module says otherwise. 107 HAVE_PSELECT=1; AC_SUBST([HAVE_PSELECT]) 108 REPLACE_PSELECT=0; AC_SUBST([REPLACE_PSELECT]) 109 REPLACE_SELECT=0; AC_SUBST([REPLACE_SELECT]) 110]) 111