log: Add support for the systemd journal

The journal is a component of systemd, that captures Syslog messages,
Kernel log messages, initial RAM disk and early boot messages as well
as messages written to STDOUT/STDERR of all services, indexes them and
makes this available to the user.

It can be used in parallel, or in place of a traditional syslog daemon,
such as rsyslog or syslog-ng.

The journal offers a couple of improvements over traditional logging
facilities (e.g. advanced filtering capabilities).

This patch adds support for logging directly to the journal using its
native API.

configure.ac

@@ -1160,6 +1160,22 @@ AC_SUBST(HAVE_SYSTEMD)
 AM_CONDITIONAL([HAVE_SYSTEMD], [test "x$HAVE_SYSTEMD" = x1])
 AS_IF([test "x$HAVE_SYSTEMD" = "x1"], AC_DEFINE([HAVE_SYSTEMD], 1, [Have SYSTEMD?]))
 
+#### journal support (optional) ####
+
+AC_ARG_ENABLE([systemd-journal],
+    AS_HELP_STRING([--disable-systemd-journal],[Disable optional systemd journal support]))
+
+AS_IF([test "x$enable_systemd_journal" != "xno"],
+    [PKG_CHECK_MODULES(JOURNAL, [ libsystemd-journal ], HAVE_SYSTEMD_JOURNAL=1, HAVE_SYSTEMD_JOURNAL=0)],
+    HAVE_SYSTEMD_JOURNAL=0)
+
+AS_IF([test "x$enable_systemd_journal" = "xyes" && test "x$HAVE_SYSTEMD_JOURNAL" = "x0"],
+    [AC_MSG_ERROR([*** Needed systemd journal support not found])])
+
+AC_SUBST(HAVE_SYSTEMD_JOURNAL)
+AM_CONDITIONAL([HAVE_SYSTEMD_JOURNAL], [test "x$HAVE_SYSTEMD_JOURNAL" = x1])
+AS_IF([test "x$HAVE_SYSTEMD_JOURNAL" = "x1"], AC_DEFINE([HAVE_JOURNAL], 1, [Have JOURNAL?]))
+
 #### Build and Install man pages ####
 
 AC_ARG_ENABLE([manpages],
@@ -1405,6 +1421,7 @@ AS_IF([test "x$HAVE_XEN" = "x1"], ENABLE_XEN=yes, ENABLE_XEN=no)
 AS_IF([test "x$HAVE_DBUS" = "x1"], ENABLE_DBUS=yes, ENABLE_DBUS=no)
 AS_IF([test "x$HAVE_UDEV" = "x1"], ENABLE_UDEV=yes, ENABLE_UDEV=no)
 AS_IF([test "x$HAVE_SYSTEMD" = "x1"], ENABLE_SYSTEMD=yes, ENABLE_SYSTEMD=no)
+AS_IF([test "x$HAVE_SYSTEMD_JOURNAL" = "x1"], ENABLE_SYSTEMD_JOURNAL=yes, ENABLE_SYSTEMD_JOURNAL=no)
 AS_IF([test "x$HAVE_BLUEZ_4" = "x1"], ENABLE_BLUEZ_4=yes, ENABLE_BLUEZ_4=no)
 AS_IF([test "x$HAVE_BLUEZ_5" = "x1"], ENABLE_BLUEZ_5=yes, ENABLE_BLUEZ_5=no)
 AS_IF([test "x$HAVE_HAL_COMPAT" = "x1"], ENABLE_HAL_COMPAT=yes, ENABLE_HAL_COMPAT=no)
@@ -1463,6 +1480,7 @@ echo "
     Enable udev:                   ${ENABLE_UDEV}
       Enable HAL->udev compat:     ${ENABLE_HAL_COMPAT}
     Enable systemd login:          ${ENABLE_SYSTEMD}
+    Enable systemd journal:        ${ENABLE_SYSTEMD_JOURNAL}
     Enable TCP Wrappers:           ${ENABLE_TCPWRAP}
     Enable libsamplerate:          ${ENABLE_LIBSAMPLERATE}
     Enable IPv6:                   ${ENABLE_IPV6}

man/pulse-daemon.conf.5.xml.in

@@ -297,11 +297,12 @@ USA.
 
     <option>
       <p><opt>log-target=</opt> The default log target. Use either
-      <opt>stderr</opt>, <opt>syslog</opt>, <opt>auto</opt>,
-      <opt>file:PATH</opt> or <opt>newfile:PATH</opt>. <opt>auto</opt> is
-      equivalent to <opt>sylog</opt> in case <opt>daemonize</opt> is enabled,
-      otherwise to <opt>stderr</opt>. If set to <opt>file:PATH</opt>, logging
-      is directed to the file indicated by PATH. <opt>newfile:PATH</opt> is
+      <opt>stderr</opt>, <opt>syslog</opt>, <opt>journal</opt> (optional),
+      <opt>auto</opt>, <opt>file:PATH</opt> or <opt>newfile:PATH</opt>. On traditional
+      systems <opt>auto</opt> is equivalent to <opt>syslog</opt>. On systemd-enabled
+      systems, auto is equivalent to <opt>journal</opt>, in case <opt>daemonize</opt>
+      is enabled, and to <opt>stderr</opt> otherwise. If set to <opt>file:PATH</opt>,
+      logging is directed to the file indicated by PATH. <opt>newfile:PATH</opt> is
       otherwise the same as <opt>file:PATH</opt>, but existing files are never
       overwritten. If the specified file already exists, a suffix is added to
       the file name to avoid overwriting. Defaults to <opt>auto</opt>. The

man/pulseaudio.1.xml.in

@@ -217,12 +217,13 @@ USA.
     </option>
 
     <option>
-      <p><opt>--log-target</opt><arg>={auto,syslog,stderr,file:PATH,newfile:PATH}</arg></p>
+      <p><opt>--log-target</opt><arg>={auto,syslog,journal,stderr,file:PATH,newfile:PATH}</arg></p>
 
       <optdesc><p>Specify the log target. If set to <arg>auto</arg>
       (which is the default), then logging is directed to syslog when
       <opt>--daemonize</opt> is passed, otherwise to
-      STDERR. If set to <arg>file:PATH</arg>, logging is directed to
+      STDERR. If set to <arg>journal</arg> logging is directed to the systemd
+      journal. If set to <arg>file:PATH</arg>, logging is directed to
       the file indicated by PATH. <arg>newfile:PATH</arg> is otherwise
       the same as file:PATH, but existing files are never overwritten.
       If the specified file already exists, a suffix is added to the

src/Makefile.am

@@ -687,6 +687,11 @@ libpulsecommon_@PA_MAJORMINOR@_la_CFLAGS += $(X11_CFLAGS)
 libpulsecommon_@PA_MAJORMINOR@_la_LDFLAGS += $(X11_LIBS)
 endif
 
+if HAVE_SYSTEMD_JOURNAL
+libpulsecommon_@PA_MAJORMINOR@_la_CFLAGS += $(JOURNAL_FLAGS)
+libpulsecommon_@PA_MAJORMINOR@_la_LDFLAGS += $(JOURNAL_LIBS)
+endif
+
 # proplist-util.h uses these header files, but not the library itself!
 libpulsecommon_@PA_MAJORMINOR@_la_CFLAGS += $(GLIB20_CFLAGS) $(GTK30_CFLAGS)
 

src/daemon/cmdline.c

@@ -323,7 +323,11 @@ int pa_cmdline_parse(pa_daemon_conf *conf, int argc, char *const argv [], int *d
 
             case ARG_LOG_TARGET:
                 if (pa_daemon_conf_set_log_target(conf, optarg) < 0) {
+#ifdef HAVE_JOURNAL
+                    pa_log(_("Invalid log target: use either 'syslog', 'journal','stderr' or 'auto' or a valid file name 'file:<path>', 'newfile:<path>'."));
+#else
                     pa_log(_("Invalid log target: use either 'syslog', 'stderr' or 'auto' or a valid file name 'file:<path>', 'newfile:<path>'."));
+#endif
                     goto fail;
                 }
                 break;

src/daemon/main.c

@@ -817,7 +817,11 @@ int main(int argc, char *argv[]) {
 #endif
 
         if (!conf->log_target) {
+#ifdef HAVE_JOURNAL
+            pa_log_target target = { .type = PA_LOG_JOURNAL, .file = NULL };
+#else
             pa_log_target target = { .type = PA_LOG_SYSLOG, .file = NULL };
+#endif
             pa_log_set_target(&target);
         }
 

src/pulsecore/log.c

@@ -40,6 +40,10 @@
 #include <syslog.h>
 #endif
 
+#ifdef HAVE_JOURNAL
+#include <systemd/sd-journal.h>
+#endif
+
 #include <pulse/gccmacro.h>
 #include <pulse/rtclock.h>
 #include <pulse/utf8.h>
@@ -90,6 +94,18 @@ static const int level_to_syslog[] = {
 };
 #endif
 
+/* These are actually equivalent to the syslog ones
+ * but we don't want to depend on syslog.h */
+#ifdef HAVE_JOURNAL
+static const int level_to_journal[] = {
+    [PA_LOG_ERROR]  = 3,
+    [PA_LOG_WARN]   = 4,
+    [PA_LOG_NOTICE] = 5,
+    [PA_LOG_INFO]   = 6,
+    [PA_LOG_DEBUG]  = 7
+};
+#endif
+
 static const char level_to_char[] = {
     [PA_LOG_ERROR] = 'E',
     [PA_LOG_WARN] = 'W',
@@ -129,6 +145,9 @@ int pa_log_set_target(pa_log_target *t) {
     switch (t->type) {
         case PA_LOG_STDERR:
         case PA_LOG_SYSLOG:
+#ifdef HAVE_JOURNAL
+        case PA_LOG_JOURNAL:
+#endif
         case PA_LOG_NULL:
             break;
         case PA_LOG_FILE:
@@ -318,6 +337,20 @@ static void init_defaults(void) {
     } PA_ONCE_END;
 }
 
+#ifdef HAVE_SYSLOG_H
+static void log_syslog(pa_log_level_t level, char *t, char *timestamp, char *location, char *bt) {
+    char *local_t;
+
+    openlog(ident, LOG_PID, LOG_USER);
+
+    if ((local_t = pa_utf8_to_locale(t)))
+        t = local_t;
+
+    syslog(level_to_syslog[level], "%s%s%s%s", timestamp, location, t, pa_strempty(bt));
+    pa_xfree(local_t);
+}
+#endif
+
 void pa_log_levelv_meta(
         pa_log_level_t level,
         const char*file,
@@ -450,19 +483,35 @@ void pa_log_levelv_meta(
             }
 
 #ifdef HAVE_SYSLOG_H
-            case PA_LOG_SYSLOG: {
-                char *local_t;
-
-                openlog(ident, LOG_PID, LOG_USER);
-
-                if ((local_t = pa_utf8_to_locale(t)))
-                    t = local_t;
-
-                syslog(level_to_syslog[level], "%s%s%s%s", timestamp, location, t, pa_strempty(bt));
-                pa_xfree(local_t);
-
+            case PA_LOG_SYSLOG:
+                log_syslog(level, t, timestamp, location, bt);
+                break;
+#endif
+
+#ifdef HAVE_JOURNAL
+            case PA_LOG_JOURNAL:
+                if (sd_journal_send("MESSAGE=%s", t,
+                                "PRIORITY=%i", level_to_journal[level],
+                                "CODE_FILE=%s", file,
+                                "CODE_FUNC=%s", func,
+                                "CODE_LINE=%d", line,
+                                NULL) < 0) {
+#ifdef HAVE_SYSLOG_H
+                    pa_log_target new_target = { .type = PA_LOG_SYSLOG, .file = NULL };
+
+                    syslog(level_to_syslog[PA_LOG_ERROR], "%s%s%s", timestamp, __FILE__,
+                           "Error writing logs to the journal. Redirect log messages to syslog.");
+                    log_syslog(level, t, timestamp, location, bt);
+#else
+                    pa_log_target new_target = { .type = PA_LOG_STDERR, .file = NULL };
+
+                    saved_errno = errno;
+                    fprintf(stderr, "%s\n", "Error writing logs to the journal. Redirect log messages to console.");
+                    fprintf(stderr, "%s %s\n", metadata, t);
+#endif
+                    pa_log_set_target(&new_target);
+                }
                 break;
-            }
 #endif
 
             case PA_LOG_FILE:
@@ -570,6 +619,10 @@ pa_log_target *pa_log_parse_target(const char *string) {
         t = pa_log_target_new(PA_LOG_STDERR, NULL);
     else if (pa_streq(string, "syslog"))
         t = pa_log_target_new(PA_LOG_SYSLOG, NULL);
+#ifdef HAVE_JOURNAL
+    else if (pa_streq(string, "journal"))
+        t = pa_log_target_new(PA_LOG_JOURNAL, NULL);
+#endif
     else if (pa_streq(string, "null"))
         t = pa_log_target_new(PA_LOG_NULL, NULL);
     else if (pa_startswith(string, "file:"))
@@ -594,6 +647,11 @@ char *pa_log_target_to_string(const pa_log_target *t) {
         case PA_LOG_SYSLOG:
             string = pa_xstrdup("syslog");
             break;
+#ifdef HAVE_JOURNAL
+        case PA_LOG_JOURNAL:
+            string = pa_xstrdup("journal");
+            break;
+#endif
         case PA_LOG_NULL:
             string = pa_xstrdup("null");
             break;

src/pulsecore/log.h

@@ -35,6 +35,9 @@
 typedef enum pa_log_target_type {
     PA_LOG_STDERR,      /* default */
     PA_LOG_SYSLOG,
+#ifdef HAVE_JOURNAL
+    PA_LOG_JOURNAL,     /* systemd journal */
+#endif
     PA_LOG_NULL,        /* to /dev/null */
     PA_LOG_FILE,        /* to a user specified file */
     PA_LOG_NEWFILE,     /* with an automatic suffix to avoid overwriting anything */