| 1 | # sys_select_h.m4 serial 23
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| 2 | dnl Copyright (C) 2006-2021 Free Software Foundation, Inc.
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| 3 | dnl This file is free software; the Free Software Foundation
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| 4 | dnl gives unlimited permission to copy and/or distribute it,
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| 5 | dnl with or without modifications, as long as this notice is preserved.
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| 6 |
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| 7 | AC_DEFUN_ONCE([gl_SYS_SELECT_H],
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| 8 | [
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| 9 | AC_REQUIRE([gl_SYS_SELECT_H_DEFAULTS])
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| 10 | AC_REQUIRE([AC_C_RESTRICT])
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| 11 | AC_CACHE_CHECK([whether <sys/select.h> is self-contained],
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| 12 | [gl_cv_header_sys_select_h_selfcontained],
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| 13 | [
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| 14 | dnl Test against two bugs:
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| 15 | dnl 1. On many platforms, <sys/select.h> assumes prior inclusion of
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| 16 | dnl <sys/types.h>.
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| 17 | dnl 2. On OSF/1 4.0, <sys/select.h> provides only a forward declaration
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| 18 | dnl of 'struct timeval', and no definition of this type.
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| 19 | AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <sys/select.h>]],
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| 20 | [[struct timeval b;]])],
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| 21 | [gl_cv_header_sys_select_h_selfcontained=yes],
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| 22 | [gl_cv_header_sys_select_h_selfcontained=no])
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| 23 | dnl Test against another bug:
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| 24 | dnl 3. On Solaris 10, <sys/select.h> provides an FD_ZERO implementation
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| 25 | dnl that relies on memset(), but without including <string.h>.
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| 26 | if test $gl_cv_header_sys_select_h_selfcontained = yes; then
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| 27 | AC_COMPILE_IFELSE(
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| 28 | [AC_LANG_PROGRAM([[#include <sys/select.h>]],
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| 29 | [[int memset; int bzero;]])
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| 30 | ],
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| 31 | [AC_LINK_IFELSE(
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| 32 | [AC_LANG_PROGRAM([[#include <sys/select.h>]], [[
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| 33 | #undef memset
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| 34 | #define memset nonexistent_memset
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| 35 | extern
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| 36 | #ifdef __cplusplus
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| 37 | "C"
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| 38 | #endif
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| 39 | void *memset (void *, int, unsigned long);
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| 40 | #undef bzero
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| 41 | #define bzero nonexistent_bzero
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| 42 | extern
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| 43 | #ifdef __cplusplus
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| 44 | "C"
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| 45 | #endif
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| 46 | void bzero (void *, unsigned long);
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| 47 | fd_set fds;
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| 48 | FD_ZERO (&fds);
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| 49 | ]])
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| 50 | ],
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| 51 | [],
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| 52 | [gl_cv_header_sys_select_h_selfcontained=no])
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| 53 | ])
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| 54 | fi
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| 55 | ])
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| 56 | dnl <sys/select.h> is always overridden, because of GNULIB_POSIXCHECK.
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| 57 | gl_CHECK_NEXT_HEADERS([sys/select.h])
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| 58 | if test $ac_cv_header_sys_select_h = yes; then
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| 59 | HAVE_SYS_SELECT_H=1
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| 60 | else
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| 61 | HAVE_SYS_SELECT_H=0
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| 62 | fi
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| 63 | AC_SUBST([HAVE_SYS_SELECT_H])
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| 64 | gl_PREREQ_SYS_H_WINSOCK2
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| 65 |
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| 66 | dnl Check for declarations of anything we want to poison if the
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| 67 | dnl corresponding gnulib module is not in use.
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| 68 | gl_WARN_ON_USE_PREPARE([[
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| 69 | /* Some systems require prerequisite headers. */
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| 70 | #include <sys/types.h>
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| 71 | #if !(defined __GLIBC__ && !defined __UCLIBC__) && HAVE_SYS_TIME_H
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| 72 | # include <sys/time.h>
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| 73 | #endif
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| 74 | #include <sys/select.h>
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| 75 | ]], [pselect select])
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| 76 | ])
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| 77 |
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| 78 | # gl_SYS_SELECT_MODULE_INDICATOR([modulename])
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| 79 | # sets the shell variable that indicates the presence of the given module
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| 80 | # to a C preprocessor expression that will evaluate to 1.
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| 81 | # This macro invocation must not occur in macros that are AC_REQUIREd.
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| 82 | AC_DEFUN([gl_SYS_SELECT_MODULE_INDICATOR],
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| 83 | [
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| 84 | dnl Ensure to expand the default settings once only.
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| 85 | gl_SYS_SELECT_H_REQUIRE_DEFAULTS
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| 86 | gl_MODULE_INDICATOR_SET_VARIABLE([$1])
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| 87 | dnl Define it also as a C macro, for the benefit of the unit tests.
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| 88 | gl_MODULE_INDICATOR_FOR_TESTS([$1])
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| 89 | ])
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| 90 |
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| 91 | # Initializes the default values for AC_SUBSTed shell variables.
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| 92 | # This macro must not be AC_REQUIREd. It must only be invoked, and only
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| 93 | # outside of macros or in macros that are not AC_REQUIREd.
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| 94 | AC_DEFUN([gl_SYS_SELECT_H_REQUIRE_DEFAULTS],
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| 95 | [
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| 96 | m4_defun(GL_MODULE_INDICATOR_PREFIX[_SYS_SELECT_H_MODULE_INDICATOR_DEFAULTS], [
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| 97 | gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_PSELECT])
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| 98 | gl_MODULE_INDICATOR_INIT_VARIABLE([GNULIB_SELECT])
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| 99 | ])
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| 100 | m4_require(GL_MODULE_INDICATOR_PREFIX[_SYS_SELECT_H_MODULE_INDICATOR_DEFAULTS])
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| 101 | AC_REQUIRE([gl_SYS_SELECT_H_DEFAULTS])
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| 102 | ])
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| 103 |
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| 104 | AC_DEFUN([gl_SYS_SELECT_H_DEFAULTS],
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| 105 | [
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| 106 | dnl Assume proper GNU behavior unless another module says otherwise.
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| 107 | HAVE_PSELECT=1; AC_SUBST([HAVE_PSELECT])
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| 108 | REPLACE_PSELECT=0; AC_SUBST([REPLACE_PSELECT])
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| 109 | REPLACE_SELECT=0; AC_SUBST([REPLACE_SELECT])
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| 110 | ])
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