[PATCH 2/3] Add a new sethostname module

[Ben Walton]

Define sethostname on platforms that do not provide the declaration.
Provide a function for platforms that lack it.  The general handling
of the provided function is to simply return -1 and set errno to
ENOSYS.  A handler is provided for Minix.

Signed-off-by: Ben Walton <address@hidden>
---
 doc/glibc-functions/sethostname.texi |   11 +++++-
 lib/sethostname.c                    |   71 ++++++++++++++++++++++++++++++++++
 m4/sethostname.m4                    |   21 ++++++++++
 modules/sethostname                  |   32 +++++++++++++++
 4 files changed, 134 insertions(+), 1 deletions(-)
 create mode 100644 lib/sethostname.c
 create mode 100644 m4/sethostname.m4
 create mode 100644 modules/sethostname

diff --git a/doc/glibc-functions/sethostname.texi 
b/doc/glibc-functions/sethostname.texi
index 75cc8ca..7960eda 100644
--- a/doc/glibc-functions/sethostname.texi
+++ b/doc/glibc-functions/sethostname.texi
@@ -2,10 +2,15 @@
 @subsection @code{sethostname}
 @findex sethostname
 
-Gnulib module: ---
+Gnulib module: sethostname
 
 Portability problems fixed by Gnulib:
 @itemize
address@hidden
+On AIX 7.1, OSF/1 5.1 and Solaris 10 the declaration is missing.  On
+Minix 3.1.8, Cygwin, mingw, MSVC 9, Interix 3.5, BeOS the function is
+missing.  Provide a fallback for all platforms that returns -1 and
+sets ENOSYS.  Provide a specific implementation for Minix 3.1.8
 @end itemize
 
 Portability problems not fixed by Gnulib:
@@ -16,4 +21,8 @@ Minix 3.1.8, Cygwin, mingw, MSVC 9, Interix 3.5, BeOS.
 @item
 This function is not declared on some platforms:
 AIX 7.1, OSF/1 5.1, Solaris 10.
address@hidden
+On Solaris 10, the first argument is @code{char *} instead of
address@hidden char *} and the second parameter is @code{int} instead of
address@hidden
 @end itemize
diff --git a/lib/sethostname.c b/lib/sethostname.c
new file mode 100644
index 0000000..70d5955
--- /dev/null
+++ b/lib/sethostname.c
@@ -0,0 +1,71 @@
+/* sethostname emulation for glibc compliance.
+
+   Copyright (C) 2011 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
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/* Ben Walton <address@hidden> */
+
+#include <config.h>
+
+/* Unix API.  */
+
+/* Specification.  */
+#include <unistd.h>
+
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+#include <limits.h>
+
+/* Set up to LEN chars of NAME as system hostname.
+   Return 0 if ok, -1 if error.  */
+
+int
+sethostname (const char *name, size_t len)
+{
+  /* glibc seems to allow a zero length hostname: bail on names that
+     are too long or too short */
+  if (len < 0 || len > HOST_NAME_MAX)
+    {
+      errno = EINVAL;
+      return -1;
+    }
+
+  /* NAME does not need to be null terminated so leave room to terminate
+     regardless of input. */
+  char hostname[len + 1];
+  strncpy(hostname, name, len);
+  hostname[len] = '\0';
+
+#ifdef __minix /* Minix */
+  FILE *hostf;
+
+  /* leave errno alone in this case as it will provide a more useful error
+     indication than overriding with ENOSYS */
+  if ((hostf = fopen("/etc/hostname.file", "w")) == NULL)
+    return -1;
+  else
+    {
+      fprintf(hostf, "%s\n", hostname);
+      fclose(hostf);
+      return 0;
+    }
+#else
+  /* For platforms that we don't have a better option for, simply bail
+     out */
+  errno = ENOSYS;
+  return -1;
+#endif
+}
diff --git a/m4/sethostname.m4 b/m4/sethostname.m4
new file mode 100644
index 0000000..dbdbb39
--- /dev/null
+++ b/m4/sethostname.m4
@@ -0,0 +1,21 @@
+# sethostname.m4 serial 1
+dnl Copyright (C) 2011 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+# Ensure
+# - the sethostname() function,
+AC_DEFUN([gl_FUNC_SETHOSTNAME],
+[
+  AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
+
+  AC_REPLACE_FUNCS([sethostname])
+  AC_CHECK_DECLS([sethostname])
+  if test $ac_cv_func_sethostname = no; then
+    gl_PREREQ_HOST_NAME_MAX
+  fi
+  if test $ac_cv_have_decl_sethostname = no; then
+    HAVE_DECL_SETHOSTNAME=0
+  fi
+])
diff --git a/modules/sethostname b/modules/sethostname
new file mode 100644
index 0000000..a0f36a2
--- /dev/null
+++ b/modules/sethostname
@@ -0,0 +1,32 @@
+Description:
+sethostname() function: Set machine's hostname.
+
+Files:
+lib/sethostname.c
+m4/sethostname.m4
+
+Depends-on:
+unistd
+gethostname
+errno           [test $HAVE_SETHOSTNAME = 0]
+
+configure.ac:
+gl_FUNC_SETHOSTNAME
+if test $HAVE_SETHOSTNAME = 0; then
+  AC_LIBOBJ([sethostname])
+fi
+gl_UNISTD_MODULE_INDICATOR([sethostname])
+
+Makefile.am:
+
+Include:
+<unistd.h>
+
+Link:
+$(SETHOSTNAME_LIB)
+
+License:
+LGPLv2+
+
+Maintainer:
+Ben Walton
-- 
1.7.4.1