107 lines
3.4 KiB
Text
107 lines
3.4 KiB
Text
# gethostname.m4 serial 15
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dnl Copyright (C) 2002, 2008-2023 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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# Ensure
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# - the gethostname() function,
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# - the HOST_NAME_MAX macro in <limits.h>.
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AC_DEFUN([gl_FUNC_GETHOSTNAME],
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[
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AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
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gl_PREREQ_SYS_H_WINSOCK2
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dnl Where is gethostname() defined?
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dnl - On native Windows, it is in ws2_32.dll.
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dnl - Otherwise it is in libc.
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GETHOSTNAME_LIB=
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AC_CHECK_FUNCS([gethostname], , [
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AC_CACHE_CHECK([for gethostname in winsock2.h and -lws2_32],
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[gl_cv_w32_gethostname],
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[gl_cv_w32_gethostname=no
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gl_save_LIBS="$LIBS"
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LIBS="$LIBS -lws2_32"
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AC_LINK_IFELSE([AC_LANG_PROGRAM([[
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#ifdef HAVE_WINSOCK2_H
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#include <winsock2.h>
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#endif
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#include <stddef.h>
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]], [[gethostname(NULL, 0);]])], [gl_cv_w32_gethostname=yes])
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LIBS="$gl_save_LIBS"
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])
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if test "$gl_cv_w32_gethostname" = "yes"; then
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GETHOSTNAME_LIB="-lws2_32"
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fi
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])
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AC_SUBST([GETHOSTNAME_LIB])
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if test "$ac_cv_func_gethostname" = no; then
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HAVE_GETHOSTNAME=0
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fi
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gl_PREREQ_HOST_NAME_MAX
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])
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# Provide HOST_NAME_MAX when <limits.h> lacks it.
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AC_DEFUN([gl_PREREQ_HOST_NAME_MAX], [
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dnl - On most Unix systems, use MAXHOSTNAMELEN from <sys/param.h> instead.
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dnl - On Solaris, Cygwin, BeOS, use MAXHOSTNAMELEN from <netdb.h> instead.
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dnl - On mingw, use 256, because
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dnl <https://docs.microsoft.com/en-us/windows/desktop/api/winsock/nf-winsock-gethostname> says:
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dnl "if a buffer of 256 bytes is passed in the name parameter and
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dnl the namelen parameter is set to 256, the buffer size will always
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dnl be adequate."
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dnl With this, there is no need to use sysconf (_SC_HOST_NAME_MAX), which
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dnl is not a compile-time constant.
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dnl We cannot override <limits.h> using the usual technique, because
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dnl gl_CHECK_NEXT_HEADERS does not work for <limits.h>. Therefore retrieve
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dnl the value of HOST_NAME_MAX at configure time.
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AC_CHECK_HEADERS_ONCE([sys/param.h])
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AC_CHECK_HEADERS_ONCE([sys/socket.h])
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AC_CHECK_HEADERS_ONCE([netdb.h])
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AC_CACHE_CHECK([for HOST_NAME_MAX], [gl_cv_decl_HOST_NAME_MAX], [
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gl_cv_decl_HOST_NAME_MAX=
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AC_EGREP_CPP([lucky], [
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#include <limits.h>
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#ifdef HOST_NAME_MAX
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lucky
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#endif
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], [gl_cv_decl_HOST_NAME_MAX=yes])
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if test -z "$gl_cv_decl_HOST_NAME_MAX"; then
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dnl It's not defined in <limits.h>. Substitute it.
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if test "$gl_cv_w32_gethostname" = yes; then
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dnl mingw.
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gl_cv_decl_HOST_NAME_MAX=256
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else
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AC_COMPUTE_INT([gl_cv_decl_HOST_NAME_MAX], [MAXHOSTNAMELEN], [
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#include <sys/types.h>
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#if HAVE_SYS_PARAM_H
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# include <sys/param.h>
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#endif
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#if HAVE_SYS_SOCKET_H
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# include <sys/socket.h>
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#endif
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#if HAVE_NETDB_H
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# include <netdb.h>
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#endif
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],
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[dnl The system does not define MAXHOSTNAMELEN in any of the common
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dnl headers. Use a safe fallback.
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gl_cv_decl_HOST_NAME_MAX=256
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])
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fi
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fi
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])
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if test "$gl_cv_decl_HOST_NAME_MAX" != yes; then
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AC_DEFINE_UNQUOTED([HOST_NAME_MAX], [$gl_cv_decl_HOST_NAME_MAX],
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[Define HOST_NAME_MAX when <limits.h> does not define it.])
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fi
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])
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# Prerequisites of lib/gethostname.c.
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AC_DEFUN([gl_PREREQ_GETHOSTNAME], [
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if test "$gl_cv_w32_gethostname" != "yes"; then
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AC_CHECK_FUNCS([uname])
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fi
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])
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