hostname: on all distros make the name configured in /etc/hostname take precedence over distro-specific configuration

In order to unify configuration across distributions we pick the
simple-most option by default (Debian's /etc/hostname) and then fall
back to distro-specific hacks if that doesn't exist.

.gitignore

@@ -1,3 +1,4 @@
+test-hostname
 systemd-modules-load
 systemd-auto-console-getty
 systemd-shutdownd

Makefile.am

@@ -81,6 +81,7 @@ noinst_PROGRAMS = \
 	test-job-type \
 	test-ns \
 	test-loopback \
+	test-hostname \
 	test-daemon \
 	test-cgroup \
 	test-env-replace
@@ -473,6 +474,13 @@ test_loopback_SOURCES = \
 test_loopback_LDADD = \
 	libsystemd-basic.la
 
+test_hostname_SOURCES = \
+	src/test-hostname.c \
+	src/hostname-setup.c
+
+test_hostname_LDADD = \
+	libsystemd-basic.la
+
 test_daemon_SOURCES = \
 	src/test-daemon.c \
 	src/sd-daemon.c

fixme

@@ -63,8 +63,6 @@
 
 * X-Interactive is kaputt
 
-* universal fallback for hostname
-
 * bash completion a la gdbus
 
 External:

src/hostname-setup.c

@@ -34,8 +34,6 @@
 #define FILENAME "/etc/sysconfig/network"
 #elif defined(TARGET_SUSE) || defined(TARGET_SLACKWARE)
 #define FILENAME "/etc/HOSTNAME"
-#elif defined(TARGET_DEBIAN)
-#define FILENAME "/etc/hostname"
 #elif defined(TARGET_ARCH)
 #define FILENAME "/etc/rc.conf"
 #elif defined(TARGET_GENTOO)
@@ -59,7 +57,7 @@ static char* strip_bad_chars(char *s) {
         return s;
 }
 
-static int read_hostname(char **hn) {
+static int read_distro_hostname(char **hn) {
 
 #if defined(TARGET_FEDORA) || defined(TARGET_ARCH) || defined(TARGET_GENTOO)
         int r;
@@ -111,7 +109,7 @@ finish:
         fclose(f);
         return r;
 
-#elif defined(TARGET_SUSE) || defined(TARGET_DEBIAN) || defined(TARGET_SLACKWARE)
+#elif defined(TARGET_SUSE) || defined(TARGET_SLACKWARE)
         int r;
         char *s, *k;
 
@@ -134,12 +132,44 @@ finish:
         }
 
         *hn = k;
+        return 0;
 
 #else
-#warning "Don't know how to read the hostname"
-
         return -ENOENT;
 #endif
+}
+
+static int read_hostname(char **hn) {
+        int r;
+        char *s, *k;
+
+        assert(hn);
+
+        /* First, try to load the generic hostname configuration file,
+         * that we support on all distributions */
+
+        if ((r = read_one_line_file("/etc/hostname", &s)) < 0) {
+
+                if (r == -ENOENT)
+                        return read_distro_hostname(hn);
+
+                return r;
+        }
+
+        k = strdup(strstrip(s));
+        free(s);
+
+        if (!k)
+                return -ENOMEM;
+
+        strip_bad_chars(k);
+
+        if (k[0] == 0) {
+                free(k);
+                return -ENOENT;
+        }
+
+        *hn = k;
 
         return 0;
 }

src/test-hostname.c

@@ -0,0 +1,37 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2010 Lennart Poettering
+
+  systemd 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 2 of the License, or
+  (at your option) any later version.
+
+  systemd 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 systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <errno.h>
+#include <string.h>
+#include <stdio.h>
+#include <fcntl.h>
+
+#include "hostname-setup.h"
+#include "util.h"
+
+int main(int argc, char* argv[]) {
+        int r;
+
+        if ((r = hostname_setup()) < 0)
+                fprintf(stderr, "hostname: %s\n", strerror(-r));
+
+        return 0;
+}