1 # gethostname.m4 serial 10
2 dnl Copyright (C) 2002, 2008-2010 Free Software Foundation, Inc.
3 dnl This file is free software; the Free Software Foundation
4 dnl gives unlimited permission to copy and/or distribute it,
5 dnl with or without modifications, as long as this notice is preserved.
8 # - the gethostname() function,
9 # - the HOST_NAME_MAX macro in <limits.h>.
10 AC_DEFUN([gl_FUNC_GETHOSTNAME],
12 AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
13 gl_PREREQ_SYS_H_WINSOCK2
15 dnl Where is gethostname() defined?
16 dnl - On native Windows, it is in ws2_32.dll.
17 dnl - Otherwise is is in libc.
19 AC_CHECK_FUNCS([gethostname], , [
20 AC_CACHE_CHECK([for gethostname in winsock2.h and -lws2_32],
21 [gl_cv_w32_gethostname],
22 [gl_cv_w32_gethostname=no
25 AC_LINK_IFELSE([AC_LANG_PROGRAM([[
26 #ifdef HAVE_WINSOCK2_H
30 ]], [[gethostname(NULL, 0);]])], [gl_cv_w32_gethostname=yes])
33 if test "$gl_cv_w32_gethostname" = "yes"; then
34 GETHOSTNAME_LIB="-lws2_32"
37 AC_SUBST([GETHOSTNAME_LIB])
39 if test "$ac_cv_func_gethostname" = no; then
40 AC_LIBOBJ([gethostname])
45 dnl Also provide HOST_NAME_MAX when <limits.h> lacks it.
46 dnl - On most Unix systems, use MAXHOSTNAMELEN from <sys/param.h> instead.
47 dnl - On Solaris, Cygwin, BeOS, use MAXHOSTNAMELEN from <netdb.h> instead.
48 dnl - On mingw, use 256, because
49 dnl <http://msdn.microsoft.com/en-us/library/ms738527.aspx> says:
50 dnl "if a buffer of 256 bytes is passed in the name parameter and
51 dnl the namelen parameter is set to 256, the buffer size will always
53 dnl With this, there is no need to use sysconf (_SC_HOST_NAME_MAX), which
54 dnl is not a compile-time constant.
55 dnl We cannot override <limits.h> using the usual technique, because
56 dnl gl_CHECK_NEXT_HEADERS does not work for <limits.h>. Therefore retrieve
57 dnl the value of HOST_NAME_MAX at configure time.
58 AC_CHECK_HEADERS_ONCE([sys/param.h])
59 AC_CHECK_HEADERS_ONCE([sys/socket.h])
60 AC_CHECK_HEADERS_ONCE([netdb.h])
61 AC_CACHE_CHECK([for HOST_NAME_MAX], [gl_cv_decl_HOST_NAME_MAX], [
62 gl_cv_decl_HOST_NAME_MAX=
63 AC_EGREP_CPP([lucky], [
68 ], [gl_cv_decl_HOST_NAME_MAX=yes])
69 if test -z "$gl_cv_decl_HOST_NAME_MAX"; then
70 dnl It's not defined in <limits.h>. Substitute it.
71 if test "$gl_cv_w32_gethostname" = yes; then
73 gl_cv_decl_HOST_NAME_MAX=256
75 _AC_COMPUTE_INT([MAXHOSTNAMELEN], [gl_cv_decl_HOST_NAME_MAX], [
76 #include <sys/types.h>
78 # include <sys/param.h>
81 # include <sys/socket.h>
87 [dnl The system does not define MAXHOSTNAMELEN in any of the common
88 dnl headers. Use a safe fallback.
89 gl_cv_decl_HOST_NAME_MAX=256
94 if test "$gl_cv_decl_HOST_NAME_MAX" != yes; then
95 AC_DEFINE_UNQUOTED([HOST_NAME_MAX], [$gl_cv_decl_HOST_NAME_MAX],
96 [Define HOST_NAME_MAX when <limits.h> does not define it.])
100 # Prerequisites of lib/gethostname.c.
101 AC_DEFUN([gl_PREREQ_GETHOSTNAME], [
102 if test "$gl_cv_w32_gethostname" != "yes"; then
103 AC_CHECK_FUNCS([uname])