dbus-daemon: add --syslog, --nosyslog, --syslog-only

Like --fork and --nofork, these override what the configuration says.

Use --syslog-only to force the systemd services to log to the Journal
(via syslog, which means we see the severity metadata) instead of
testing sd_booted() in the configuration implementation.

Signed-off-by: Simon McVittie <smcv@debian.org>

6 files changed, 76 insertions, 21 deletions

diff --git a/bus/bus.c b/bus/bus.c
index a134dc6c..8856dab3 100644
--- a/bus/bus.c
+++ b/bus/bus.c
@@ -47,10 +47,6 @@
 #include <signal.h>
 #endif
 
-#ifdef HAVE_SYSTEMD
-#include <systemd/sd-daemon.h>
-#endif
-
 struct BusContext
 {
   int refcount;
@@ -285,6 +281,7 @@ process_config_first_time_only (BusContext       *context,
   DBusList **auth_mechanisms_list;
   int len;
   dbus_bool_t retval;
+  DBusLogFlags log_flags = DBUS_LOG_FLAGS_STDERR;
 
   _DBUS_ASSERT_ERROR_IS_CLEAR (error);
 
@@ -292,26 +289,28 @@ process_config_first_time_only (BusContext       *context,
   auth_mechanisms = NULL;
   pidfile = NULL;
 
-  context->syslog = bus_config_parser_get_syslog (parser);
+  if (flags & BUS_CONTEXT_FLAG_SYSLOG_ALWAYS)
+    {
+      context->syslog = TRUE;
+      log_flags |= DBUS_LOG_FLAGS_SYSTEM_LOG;
 
-  if (context->syslog)
+      if (flags & BUS_CONTEXT_FLAG_SYSLOG_ONLY)
+        log_flags &= ~DBUS_LOG_FLAGS_STDERR;
+    }
+  else if (flags & BUS_CONTEXT_FLAG_SYSLOG_NEVER)
     {
-#ifdef HAVE_SYSTEMD
-      /* If running under systemd, we don't want to log to both stderr and
-       * syslog, because our stderr is probably connected to journald too,
-       * so we'd duplicate all our messages. */
-      if (sd_booted () > 0)
-        _dbus_init_system_log ("dbus-daemon", DBUS_LOG_FLAGS_SYSTEM_LOG);
-      else
-#endif
-        _dbus_init_system_log ("dbus-daemon",
-            DBUS_LOG_FLAGS_SYSTEM_LOG | DBUS_LOG_FLAGS_STDERR);
+      context->syslog = FALSE;
     }
   else
     {
-      _dbus_init_system_log ("dbus-daemon", DBUS_LOG_FLAGS_STDERR);
+      context->syslog = bus_config_parser_get_syslog (parser);
+
+      if (context->syslog)
+        log_flags |= DBUS_LOG_FLAGS_SYSTEM_LOG;
     }
 
+  _dbus_init_system_log ("dbus-daemon", log_flags);
+
   if (flags & BUS_CONTEXT_FLAG_SYSTEMD_ACTIVATION)
     context->systemd_activation = TRUE;
   else
diff --git a/bus/bus.h b/bus/bus.h
index 3fab59ff..b7869b20 100644
--- a/bus/bus.h
+++ b/bus/bus.h
@@ -72,7 +72,10 @@ typedef enum
   BUS_CONTEXT_FLAG_FORK_ALWAYS = (1 << 1),
   BUS_CONTEXT_FLAG_FORK_NEVER = (1 << 2),
   BUS_CONTEXT_FLAG_WRITE_PID_FILE = (1 << 3),
-  BUS_CONTEXT_FLAG_SYSTEMD_ACTIVATION = (1 << 4)
+  BUS_CONTEXT_FLAG_SYSTEMD_ACTIVATION = (1 << 4),
+  BUS_CONTEXT_FLAG_SYSLOG_ALWAYS = (1 << 5),
+  BUS_CONTEXT_FLAG_SYSLOG_NEVER = (1 << 6),
+  BUS_CONTEXT_FLAG_SYSLOG_ONLY = (1 << 7)
 } BusContextFlags;
 
 BusContext*       bus_context_new                                (const DBusString *config_file,
diff --git a/bus/dbus.service.in b/bus/dbus.service.in
index 3bc4726a..ca0b7e96 100644
--- a/bus/dbus.service.in
+++ b/bus/dbus.service.in
@@ -4,6 +4,6 @@ Documentation=man:dbus-daemon(1)
 Requires=dbus.socket
 
 [Service]
-ExecStart=@EXPANDED_BINDIR@/dbus-daemon --system --address=systemd: --nofork --nopidfile --systemd-activation
+ExecStart=@EXPANDED_BINDIR@/dbus-daemon --system --address=systemd: --nofork --nopidfile --systemd-activation --syslog-only
 ExecReload=@EXPANDED_BINDIR@/dbus-send --print-reply --system --type=method_call --dest=org.freedesktop.DBus / org.freedesktop.DBus.ReloadConfig
 OOMScoreAdjust=-900
diff --git a/bus/main.c b/bus/main.c
index 0331dafa..1d36c512 100644
--- a/bus/main.c
+++ b/bus/main.c
@@ -146,6 +146,9 @@ usage (void)
       " [--introspect]"
       " [--address=ADDRESS]"
       " [--nopidfile]"
+      " [--nosyslog]"
+      " [--syslog]"
+      " [--syslog-only]"
       " [--nofork]"
 #ifdef DBUS_UNIX
       " [--fork]"
@@ -441,6 +444,21 @@ main (int argc, char **argv)
         {
           introspect ();
         }
+      else if (strcmp (arg, "--nosyslog") == 0)
+        {
+          flags &= ~BUS_CONTEXT_FLAG_SYSLOG_ALWAYS;
+          flags |= BUS_CONTEXT_FLAG_SYSLOG_NEVER;
+        }
+      else if (strcmp (arg, "--syslog") == 0)
+        {
+          flags &= ~BUS_CONTEXT_FLAG_SYSLOG_NEVER;
+          flags |= BUS_CONTEXT_FLAG_SYSLOG_ALWAYS;
+        }
+      else if (strcmp (arg, "--syslog-only") == 0)
+        {
+          flags &= ~BUS_CONTEXT_FLAG_SYSLOG_NEVER;
+          flags |= (BUS_CONTEXT_FLAG_SYSLOG_ALWAYS|BUS_CONTEXT_FLAG_SYSLOG_ONLY);
+        }
       else if (strcmp (arg, "--nofork") == 0)
         {
           flags &= ~BUS_CONTEXT_FLAG_FORK_ALWAYS;
diff --git a/bus/systemd-user/dbus.service.in b/bus/systemd-user/dbus.service.in
index 4355d728..7ceffbee 100644
--- a/bus/systemd-user/dbus.service.in
+++ b/bus/systemd-user/dbus.service.in
@@ -4,5 +4,5 @@ Documentation=man:dbus-daemon(1)
 Requires=dbus.socket
 
 [Service]
-ExecStart=@EXPANDED_BINDIR@/dbus-daemon --session --address=systemd: --nofork --nopidfile --systemd-activation
+ExecStart=@EXPANDED_BINDIR@/dbus-daemon --session --address=systemd: --nofork --nopidfile --systemd-activation --syslog-only
 ExecReload=@EXPANDED_BINDIR@/dbus-send --print-reply --session --type=method_call --dest=org.freedesktop.DBus / org.freedesktop.DBus.ReloadConfig
diff --git a/doc/dbus-daemon.1.xml.in b/doc/dbus-daemon.1.xml.in
index df67a907..f2170377 100644
--- a/doc/dbus-daemon.1.xml.in
+++ b/doc/dbus-daemon.1.xml.in
@@ -29,6 +29,9 @@
     <arg choice='opt'><arg choice='plain'>--print-address </arg><arg choice='opt'><replaceable>=DESCRIPTOR</replaceable></arg></arg>
     <arg choice='opt'><arg choice='plain'>--print-pid </arg><arg choice='opt'><replaceable>=DESCRIPTOR</replaceable></arg></arg>
     <arg choice='opt'>--fork </arg>
+    <arg choice='opt'>--nosyslog </arg>
+    <arg choice='opt'>--syslog </arg>
+    <arg choice='opt'>--syslog-only </arg>
     <sbr/>
 </cmdsynopsis>
 </refsynopsisdiv>
@@ -164,6 +167,36 @@ files.</para>
 
   </listitem>
   </varlistentry>
+
+  <varlistentry>
+    <term><option>--syslog</option></term>
+    <listitem>
+      <para>Force the message bus to use the system log for messages,
+        in addition to writing to standard error, even if the configuration
+        file does not specify that it should. On Unix, this uses
+        the syslog; on Windows, this uses OutputDebugString().</para>
+    </listitem>
+  </varlistentry>
+
+  <varlistentry>
+    <term><option>--syslog-only</option></term>
+    <listitem>
+      <para>Force the message bus to use the system log for messages,
+        and <emphasis>not</emphasis> duplicate them to standard error.
+        On Unix, this uses the syslog; on Windows, this uses
+        OutputDebugString().</para>
+    </listitem>
+  </varlistentry>
+
+  <varlistentry>
+    <term><option>--nosyslog</option></term>
+    <listitem>
+      <para>Force the message bus to use only standard error for messages,
+        even if the configuration file specifies that it should use
+        the system log.</para>
+    </listitem>
+  </varlistentry>
+
 </variablelist>
 </refsect1>
 
@@ -325,7 +358,9 @@ This may be useful to avoid affecting the behavior of child processes.</para>
 
 </itemizedlist>
 
-<para>If present, the bus daemon will log to syslog.</para>
+<para>If present, the bus daemon will log to syslog. The
+  --syslog, --syslog-only and --nosyslog command-line options take precedence
+  over this setting.</para>
 
 <itemizedlist remap='TP'>