[PATCH 2/4] 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 specific handler is provided for Minix.

Signed-off-by: Ben Walton <address@hidden>
---
 ChangeLog                            |    8 +++
 doc/glibc-functions/sethostname.texi |   16 ++++--
 lib/sethostname.c                    |   87 ++++++++++++++++++++++++++++++++++
 m4/sethostname.m4                    |   25 ++++++++++
 modules/sethostname                  |   31 ++++++++++++
 5 files changed, 162 insertions(+), 5 deletions(-)
 create mode 100644 lib/sethostname.c
 create mode 100644 m4/sethostname.m4
 create mode 100644 modules/sethostname

diff --git a/ChangeLog b/ChangeLog
index eee02b6..c6cf901 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,13 @@
 2011-12-01  Ben Walton  <address@hidden>
 
+       * lib/sethostname.c (sethostname): New file.  Provide sethostname
+       for systems that lack it
+       * m4/sethostname.m4 (gl_FUNC_SETHOSTNAME): New file.  Detection of
+       sethostname declaration and function.
+       * modules/sethostname: New file.  Define the sethostname module.
+
+2011-12-01  Ben Walton  <address@hidden>
+
        * m4/gethostname.m4 (gl_PREREQ_HOST_NAME_MAX): Make this a separate
        macro so it can be used by the pending sethostname module.
 
diff --git a/doc/glibc-functions/sethostname.texi 
b/doc/glibc-functions/sethostname.texi
index 75cc8ca..ec7b11a 100644
--- a/doc/glibc-functions/sethostname.texi
+++ b/doc/glibc-functions/sethostname.texi
@@ -2,18 +2,24 @@
 @subsection @code{sethostname}
 @findex sethostname
 
-Gnulib module: ---
+Gnulib module: sethostname
 
 Portability problems fixed by Gnulib:
 @itemize
address@hidden itemize
-
-Portability problems not fixed by Gnulib:
address@hidden
 @item
 This function is missing on some platforms:
 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
address@hidden
+On some platforms the Gnulib replacement always fails with ENOSYS.
address@hidden itemize
+
+Portability problems not fixed by Gnulib:
address@hidden
 @end itemize
diff --git a/lib/sethostname.c b/lib/sethostname.c
new file mode 100644
index 0000000..e1b7d74
--- /dev/null
+++ b/lib/sethostname.c
@@ -0,0 +1,87 @@
+/* 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, set errno and return -1 on error. */
+
+int
+sethostname (const char *name, size_t len)
+{
+  /* Ensure the string isn't too long.  glibc does allow setting an
+     empty hostname so no point in enforcing a lower bound. */
+  if (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[HOST_NAME_MAX + 1];
+  memcpy ((void *) hostname, (const void *) name, len);
+  hostname[len] = '\0';
+
+#ifdef __minix /* Minix */
+  {
+    FILE *hostf;
+    int r = 0;
+
+    /* glibc returns EFAULT, EINVAL, and EPERM on error.  None of
+       these are appropriate for us to set, even if they may match the
+       situation, during failed open/write/close operations, so we
+       leave errno alone and rely on what the system sets up. */
+    hostf = fopen ("/etc/hostname.file", "w");
+    if (hostf == NULL)
+      r = -1;
+    else
+      {
+        fprintf (hostf, "%s\n", hostname);
+        if (ferror (hostf))
+          {
+            clearerr (hostf);
+            r = -1;
+          }
+
+        /* use return value of fclose for function return value as it
+           matches our needs.  fclose will also set errno on
+           failure */
+        r = fclose (hostf);
+      }
+
+    return r;
+  }
+#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..be5b036
--- /dev/null
+++ b/m4/sethostname.m4
@@ -0,0 +1,25 @@
+# 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])
+
+  gl_PREREQ_HOST_NAME_MAX
+
+  AC_REPLACE_FUNCS([sethostname])
+  AC_CHECK_FUNCS([sethostname])
+  if test $ac_cv_func_sethostname = no; then
+    HAVE_SETHOSTNAME=0
+  fi
+
+  AC_CHECK_DECLS([sethostname])
+  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..8008756
--- /dev/null
+++ b/modules/sethostname
@@ -0,0 +1,31 @@
+Description:
+sethostname() function: Set machine's hostname.
+
+Files:
+lib/sethostname.c
+m4/sethostname.m4
+m4/gethostname.m4
+
+Depends-on:
+unistd
+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:
+
+License:
+LGPLv2+
+
+Maintainer:
+Ben Walton
-- 
1.7.4.1