1 # gethostname.m4 serial 12
2 dnl Copyright (C) 2002, 2008-2011 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 it 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
43 dnl Also provide HOST_NAME_MAX when <limits.h> lacks it.
44 dnl - On most Unix systems, use MAXHOSTNAMELEN from <sys/param.h> instead.
45 dnl - On Solaris, Cygwin, BeOS, use MAXHOSTNAMELEN from <netdb.h> instead.
46 dnl - On mingw, use 256, because
47 dnl <http://msdn.microsoft.com/en-us/library/ms738527.aspx> says:
48 dnl "if a buffer of 256 bytes is passed in the name parameter and
49 dnl the namelen parameter is set to 256, the buffer size will always
51 dnl With this, there is no need to use sysconf (_SC_HOST_NAME_MAX), which
52 dnl is not a compile-time constant.
53 dnl We cannot override <limits.h> using the usual technique, because
54 dnl gl_CHECK_NEXT_HEADERS does not work for <limits.h>. Therefore retrieve
55 dnl the value of HOST_NAME_MAX at configure time.
56 AC_CHECK_HEADERS_ONCE([sys/param.h])
57 AC_CHECK_HEADERS_ONCE([sys/socket.h])
58 AC_CHECK_HEADERS_ONCE([netdb.h])
59 AC_CACHE_CHECK([for HOST_NAME_MAX], [gl_cv_decl_HOST_NAME_MAX], [
60 gl_cv_decl_HOST_NAME_MAX=
61 AC_EGREP_CPP([lucky], [
66 ], [gl_cv_decl_HOST_NAME_MAX=yes])
67 if test -z "$gl_cv_decl_HOST_NAME_MAX"; then
68 dnl It's not defined in <limits.h>. Substitute it.
69 if test "$gl_cv_w32_gethostname" = yes; then
71 gl_cv_decl_HOST_NAME_MAX=256
73 _AC_COMPUTE_INT([MAXHOSTNAMELEN], [gl_cv_decl_HOST_NAME_MAX], [
74 #include <sys/types.h>
76 # include <sys/param.h>
79 # include <sys/socket.h>
85 [dnl The system does not define MAXHOSTNAMELEN in any of the common
86 dnl headers. Use a safe fallback.
87 gl_cv_decl_HOST_NAME_MAX=256
92 if test "$gl_cv_decl_HOST_NAME_MAX" != yes; then
93 AC_DEFINE_UNQUOTED([HOST_NAME_MAX], [$gl_cv_decl_HOST_NAME_MAX],
94 [Define HOST_NAME_MAX when <limits.h> does not define it.])
98 # Prerequisites of lib/gethostname.c.
99 AC_DEFUN([gl_PREREQ_GETHOSTNAME], [
100 if test "$gl_cv_w32_gethostname" != "yes"; then
101 AC_CHECK_FUNCS([uname])