gethostname on Windows

[Simon Josefsson]

The current gethostname module will return an empty string on mingw:

  strcpy (name, "");            /* Hardcode your system name if you want.  */

This is sub-optimal since Windows has a gethostname function in
-lws2_32.

The following patch should make gethostname return proper values.
Tested on x86 debian lenny and mingw cross-compile.  Any objections to
installing it?  Suggestions on improvements welcome.

/Simon

>From 75863be5aa98f25cc29fd491235fe7a8b7356a96 Mon Sep 17 00:00:00 2001
From: Simon Josefsson <address@hidden>
Date: Tue, 31 Mar 2009 19:32:13 +0200
Subject: [PATCH] gethostname: Make it return correct values under Windows.

---
 ChangeLog                 |    8 ++++++++
 lib/gethostname.c         |   30 ++++++++++++++++++++++++++++--
 m4/gethostname.m4         |   35 +++++++++++++++++++++++++++++++----
 modules/gethostname       |    7 ++++++-
 modules/gethostname-tests |    1 +
 5 files changed, 74 insertions(+), 7 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 3bf424d..a862e03 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,13 @@
 2009-03-31  Simon Josefsson  <address@hidden>
 
+       * lib/gethostname.c: Add Windows wrapper.
+       * m4/gethostname.m4: Look for gethostname in -lws2_32.
+       * modules/gethostname: Depend on sys_socket & errno, for also
+       added lib/w32sock.h.  Add GETHOSTNAME_LIB link directive.
+       * modules/gethostname-tests: Link to @address@hidden
+
+2009-03-31  Simon Josefsson  <address@hidden>
+
        * modules/u64-tests: New file.
        * tests/test-u64.c: New file.
 
diff --git a/lib/gethostname.c b/lib/gethostname.c
index acff351..782c402 100644
--- a/lib/gethostname.c
+++ b/lib/gethostname.c
@@ -1,6 +1,6 @@
 /* gethostname emulation for SysV and POSIX.1.
 
-   Copyright (C) 1992, 2003, 2006, 2008 Free Software Foundation, Inc.
+   Copyright (C) 1992, 2003, 2006, 2008, 2009 Free Software Foundation, Inc.
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -15,10 +15,13 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
-/* David MacKenzie <address@hidden> */
+/* David MacKenzie <address@hidden>
+   Windows port by Simon Josefsson <address@hidden> */
 
 #include <config.h>
 
+#if !((defined _WIN32 || defined __WIN32__) && !defined __CYGWIN__)
+
 /* Specification.  */
 #include <unistd.h>
 
@@ -54,3 +57,26 @@ gethostname (char *name, size_t len)
 #endif
   return 0;
 }
+
+#else
+
+#define WIN32_LEAN_AND_MEAN
+/* Get winsock2.h. */
+#include <unistd.h>
+
+/* Get set_winsock_errno. */
+#include "w32sock.h"
+
+#undef gethostname
+
+int
+rpl_gethostname (char *name, size_t namelen)
+{
+  int r = gethostname (name, (int) namelen);
+  if (r < 0)
+    set_winsock_errno ();
+
+  return r;
+}
+
+#endif
diff --git a/m4/gethostname.m4 b/m4/gethostname.m4
index 6b6fca9..620e023 100644
--- a/m4/gethostname.m4
+++ b/m4/gethostname.m4
@@ -1,4 +1,4 @@
-# gethostname.m4 serial 5
+# gethostname.m4 serial 6
 dnl Copyright (C) 2002, 2008, 2009 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -8,8 +8,33 @@ AC_DEFUN([gl_FUNC_GETHOSTNAME],
 [
   AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
   gl_PREREQ_SYS_H_WINSOCK2
-  AC_REPLACE_FUNCS([gethostname])
-  if test $ac_cv_func_gethostname = no; then
+
+  dnl Where is gethostname() defined?
+  dnl - On native Windows, it is in ws2_32.dll.
+  dnl - Otherwise is is in libc.
+  GETHOSTNAME_LIB=
+  AC_CHECK_FUNCS([gethostname], , [
+    AC_CACHE_CHECK([for gethostname in winsock2.h and -lws2_32],
+      [gl_cv_w32_gethostname],
+      [gl_cv_w32_gethostname=no
+       gl_save_LIBS="$LIBS"
+       LIBS="$LIBS -lws2_32"
+       AC_TRY_LINK([
+#ifdef HAVE_WINSOCK2_H
+#include <winsock2.h>
+#endif
+#include <stddef.h>
+], [gethostname(NULL, 0);], [gl_cv_w32_gethostname=yes])
+       LIBS="$gl_save_LIBS"
+      ])
+    if test "$gl_cv_w32_gethostname" = "yes"; then
+      GETHOSTNAME_LIB="-lws2_32"
+    fi
+  ])
+  AC_SUBST([GETHOSTNAME_LIB])
+
+  if test "$ac_cv_func_gethostname" = no; then
+    AC_LIBOBJ([gethostname])
     HAVE_GETHOSTNAME=0
     gl_PREREQ_GETHOSTNAME
   fi
@@ -17,5 +42,7 @@ AC_DEFUN([gl_FUNC_GETHOSTNAME],
 
 # Prerequisites of lib/gethostname.c.
 AC_DEFUN([gl_PREREQ_GETHOSTNAME], [
-  AC_CHECK_FUNCS([uname])
+  if test "$gl_cv_w32_gethostname" != "yes"; then
+    AC_CHECK_FUNCS([uname])
+  fi
 ])
diff --git a/modules/gethostname b/modules/gethostname
index 796dc6f..e21afe6 100644
--- a/modules/gethostname
+++ b/modules/gethostname
@@ -4,10 +4,12 @@ gethostname() function: Return machine's hostname.
 Files:
 lib/gethostname.c
 m4/gethostname.m4
-m4/sys_socket_h.m4
+lib/w32sock.h
 
 Depends-on:
 unistd
+sys_socket
+errno
 
 configure.ac:
 gl_FUNC_GETHOSTNAME
@@ -18,6 +20,9 @@ Makefile.am:
 Include:
 <unistd.h>
 
+Link:
+$(GETHOSTNAME_LIB)
+
 License:
 LGPLv2+
 
diff --git a/modules/gethostname-tests b/modules/gethostname-tests
index 236ca58..ea17aba 100644
--- a/modules/gethostname-tests
+++ b/modules/gethostname-tests
@@ -8,3 +8,4 @@ configure.ac:
 Makefile.am:
 TESTS += test-gethostname
 check_PROGRAMS += test-gethostname
+test_gethostname_LDADD = $(LDADD) @GETHOSTNAME_LIB@
-- 
1.5.6.5