dbus: more efficient implementation of properties

The way the various properties[] arrays are initialized is inefficient:
 - only the .data members change at runtime, yet the whole arrays of
   properties with all the fields are constructed on the stack one by
   one by the code.
 - there's duplication, eg. the properties of "org.freedesktop.systemd1.Unit"
   are repeated in several unit types.

Fix it by moving the information about properties into static const
sections. Instead of storing the .data directly in the property, store
a constant offset from a run-time base.
The small arrays of struct BusBoundProperties bind together the constant
information with the right runtime information (the base pointer).

On my system the code shrinks by 60 KB, data increases by 10 KB.

1 files changed, 63 insertions, 52 deletions

diff --git a/src/timedate/timedated.c b/src/timedate/timedated.c
index 16f54b59d..97306e9a3 100644
--- a/src/timedate/timedated.c
+++ b/src/timedate/timedated.c
@@ -74,17 +74,23 @@
 
 const char timedate_interface[] _introspect_("timedate1") = INTERFACE;
 
-static char *zone = NULL;
-static bool local_rtc = false;
-static int use_ntp = -1;
+typedef struct TZ {
+        char *zone;
+        bool local_rtc;
+        int use_ntp;
+} TZ;
 
-static usec_t remain_until = 0;
+static TZ tz = {
+        .use_ntp = -1,
+};
+
+static usec_t remain_until;
 
 static void free_data(void) {
-        free(zone);
-        zone = NULL;
+        free(tz.zone);
+        tz.zone = NULL;
 
-        local_rtc = false;
+        tz.local_rtc = false;
 }
 
 static bool valid_timezone(const char *name) {
@@ -140,10 +146,10 @@ static void verify_timezone(void) {
         size_t l, q;
         int j, k;
 
-        if (!zone)
+        if (!tz.zone)
                 return;
 
-        p = strappend("/usr/share/zoneinfo/", zone);
+        p = strappend("/usr/share/zoneinfo/", tz.zone);
         if (!p) {
                 log_error("Out of memory");
                 return;
@@ -156,8 +162,8 @@ static void verify_timezone(void) {
 
         if (j < 0 || k < 0 || l != q || memcmp(a, b, l)) {
                 log_warning("/etc/localtime and /etc/timezone out of sync.");
-                free(zone);
-                zone = NULL;
+                free(tz.zone);
+                tz.zone = NULL;
         }
 
         free(a);
@@ -169,14 +175,14 @@ static int read_data(void) {
 
         free_data();
 
-        r = read_one_line_file("/etc/timezone", &zone);
+        r = read_one_line_file("/etc/timezone", &tz.zone);
         if (r < 0) {
                 if (r != -ENOENT)
                         log_warning("Failed to read /etc/timezone: %s", strerror(-r));
 
 #ifdef TARGET_FEDORA
                 r = parse_env_file("/etc/sysconfig/clock", NEWLINE,
-                                   "ZONE", &zone,
+                                   "ZONE", &tz.zone,
                                    NULL);
 
                 if (r < 0 && r != -ENOENT)
@@ -184,14 +190,14 @@ static int read_data(void) {
 #endif
         }
 
-        if (isempty(zone)) {
-                free(zone);
-                zone = NULL;
+        if (isempty(tz.zone)) {
+                free(tz.zone);
+                tz.zone = NULL;
         }
 
         verify_timezone();
 
-        local_rtc = hwclock_is_localtime() > 0;
+        tz.local_rtc = hwclock_is_localtime() > 0;
 
         return 0;
 }
@@ -200,7 +206,7 @@ static int write_data_timezone(void) {
         int r = 0;
         char *p;
 
-        if (!zone) {
+        if (!tz.zone) {
                 if (unlink("/etc/timezone") < 0 && errno != ENOENT)
                         r = -errno;
 
@@ -210,7 +216,7 @@ static int write_data_timezone(void) {
                 return r;
         }
 
-        p = strappend("/usr/share/zoneinfo/", zone);
+        p = strappend("/usr/share/zoneinfo/", tz.zone);
         if (!p) {
                 log_error("Out of memory");
                 return -ENOMEM;
@@ -222,7 +228,7 @@ static int write_data_timezone(void) {
         if (r < 0)
                 return r;
 
-        r = write_one_line_file_atomic("/etc/timezone", zone);
+        r = write_one_line_file_atomic("/etc/timezone", tz.zone);
         if (r < 0)
                 return r;
 
@@ -238,7 +244,7 @@ static int write_data_local_rtc(void) {
                 if (r != -ENOENT)
                         return r;
 
-                if (!local_rtc)
+                if (!tz.local_rtc)
                         return 0;
 
                 w = strdup(NULL_ADJTIME_LOCAL);
@@ -270,13 +276,13 @@ static int write_data_local_rtc(void) {
                 a = p - s;
                 b = strlen(e);
 
-                w = new(char, a + (local_rtc ? 5 : 3) + b + 1);
+                w = new(char, a + (tz.local_rtc ? 5 : 3) + b + 1);
                 if (!w) {
                         free(s);
                         return -ENOMEM;
                 }
 
-                *(char*) mempcpy(stpcpy(mempcpy(w, s, a), local_rtc ? "LOCAL" : "UTC"), e, b) = 0;
+                *(char*) mempcpy(stpcpy(mempcpy(w, s, a), tz.local_rtc ? "LOCAL" : "UTC"), e, b) = 0;
 
                 if (streq(w, NULL_ADJTIME_UTC)) {
                         free(w);
@@ -341,7 +347,7 @@ static int read_ntp(DBusConnection *bus) {
                 goto finish;
         }
 
-        use_ntp =
+        tz.use_ntp =
                 streq(s, "enabled") ||
                 streq(s, "enabled-runtime");
         r = 0;
@@ -370,7 +376,7 @@ static int start_ntp(DBusConnection *bus, DBusError *error) {
                         "org.freedesktop.systemd1",
                         "/org/freedesktop/systemd1",
                         "org.freedesktop.systemd1.Manager",
-                        use_ntp ? "StartUnit" : "StopUnit");
+                        tz.use_ntp ? "StartUnit" : "StopUnit");
         if (!m) {
                 log_error("Could not allocate message.");
                 r = -ENOMEM;
@@ -419,7 +425,7 @@ static int enable_ntp(DBusConnection *bus, DBusError *error) {
                         "org.freedesktop.systemd1",
                         "/org/freedesktop/systemd1",
                         "org.freedesktop.systemd1.Manager",
-                        use_ntp ? "EnableUnitFiles" : "DisableUnitFiles");
+                        tz.use_ntp ? "EnableUnitFiles" : "DisableUnitFiles");
 
         if (!m) {
                 log_error("Could not allocate message.");
@@ -441,7 +447,7 @@ static int enable_ntp(DBusConnection *bus, DBusError *error) {
                 goto finish;
         }
 
-        if (use_ntp) {
+        if (tz.use_ntp) {
                 /* send force bool */
                 if (!dbus_message_iter_append_basic(&iter, DBUS_TYPE_BOOLEAN, &t)) {
                         log_error("Failed to append force boolean.");
@@ -495,7 +501,7 @@ static int property_append_ntp(DBusMessageIter *i, const char *property, void *d
         assert(i);
         assert(property);
 
-        db = use_ntp > 0;
+        db = tz.use_ntp > 0;
 
         if (!dbus_message_iter_append_basic(i, DBUS_TYPE_BOOLEAN, &db))
                 return -ENOMEM;
@@ -503,18 +509,23 @@ static int property_append_ntp(DBusMessageIter *i, const char *property, void *d
         return 0;
 }
 
+static const BusProperty bus_timedate_properties[] = {
+        { "Timezone", bus_property_append_string, "s", offsetof(TZ, zone),     true },
+        { "LocalRTC", bus_property_append_bool,   "b", offsetof(TZ, local_rtc) },
+        { "NTP",      property_append_ntp,        "b", offsetof(TZ, use_ntp)   },
+        { NULL, }
+};
+
+static const BusBoundProperties bps[] = {
+        { "org.freedesktop.timedate1", bus_timedate_properties, &tz },
+        { NULL, }
+};
+
 static DBusHandlerResult timedate_message_handler(
                 DBusConnection *connection,
                 DBusMessage *message,
                 void *userdata) {
 
-        const BusProperty properties[] = {
-                { "org.freedesktop.timedate1", "Timezone", bus_property_append_string, "s", zone       },
-                { "org.freedesktop.timedate1", "LocalRTC", bus_property_append_bool,   "b", &local_rtc },
-                { "org.freedesktop.timedate1", "NTP",      property_append_ntp,        "b", NULL       },
-                { NULL, NULL, NULL, NULL, NULL }
-        };
-
         DBusMessage *reply = NULL, *changed = NULL;
         DBusError error;
         int r;
@@ -539,7 +550,7 @@ static DBusHandlerResult timedate_message_handler(
                 if (!valid_timezone(z))
                         return bus_send_error_reply(connection, message, NULL, -EINVAL);
 
-                if (!streq_ptr(z, zone)) {
+                if (!streq_ptr(z, tz.zone)) {
                         char *t;
 
                         r = verify_polkit(connection, message, "org.freedesktop.timedate1.set-timezone", interactive, &error);
@@ -550,8 +561,8 @@ static DBusHandlerResult timedate_message_handler(
                         if (!t)
                                 goto oom;
 
-                        free(zone);
-                        zone = t;
+                        free(tz.zone);
+                        tz.zone = t;
 
                         /* 1. Write new configuration file */
                         r = write_data_timezone();
@@ -560,7 +571,7 @@ static DBusHandlerResult timedate_message_handler(
                                 return bus_send_error_reply(connection, message, NULL, r);
                         }
 
-                        if (local_rtc) {
+                        if (tz.local_rtc) {
                                 struct timespec ts;
                                 struct tm *tm;
 
@@ -573,7 +584,7 @@ static DBusHandlerResult timedate_message_handler(
                                 hwclock_set_time(tm);
                         }
 
-                        log_info("Changed timezone to '%s'.", zone);
+                        log_info("Changed timezone to '%s'.", tz.zone);
 
                         changed = bus_properties_changed_new(
                                         "/org/freedesktop/timedate1",
@@ -597,14 +608,14 @@ static DBusHandlerResult timedate_message_handler(
                                     DBUS_TYPE_INVALID))
                         return bus_send_error_reply(connection, message, &error, -EINVAL);
 
-                if (lrtc != local_rtc) {
+                if (lrtc != tz.local_rtc) {
                         struct timespec ts;
 
                         r = verify_polkit(connection, message, "org.freedesktop.timedate1.set-local-rtc", interactive, &error);
                         if (r < 0)
                                 return bus_send_error_reply(connection, message, &error, r);
 
-                        local_rtc = lrtc;
+                        tz.local_rtc = lrtc;
 
                         /* 1. Write new configuration file */
                         r = write_data_local_rtc();
@@ -614,7 +625,7 @@ static DBusHandlerResult timedate_message_handler(
                         }
 
                         /* 2. Teach kernel new timezone */
-                        if (local_rtc)
+                        if (tz.local_rtc)
                                 hwclock_apply_localtime_delta(NULL);
                         else
                                 hwclock_reset_localtime_delta();
@@ -628,7 +639,7 @@ static DBusHandlerResult timedate_message_handler(
                                 /* Sync system clock from RTC; first,
                                  * initialize the timezone fields of
                                  * struct tm. */
-                                if (local_rtc)
+                                if (tz.local_rtc)
                                         tm = *localtime(&ts.tv_sec);
                                 else
                                         tm = *gmtime(&ts.tv_sec);
@@ -640,7 +651,7 @@ static DBusHandlerResult timedate_message_handler(
 
                                         /* And set the system clock
                                          * with this */
-                                        if (local_rtc)
+                                        if (tz.local_rtc)
                                                 ts.tv_sec = mktime(&tm);
                                         else
                                                 ts.tv_sec = timegm(&tm);
@@ -652,7 +663,7 @@ static DBusHandlerResult timedate_message_handler(
                                 struct tm *tm;
 
                                 /* Sync RTC from system clock */
-                                if (local_rtc)
+                                if (tz.local_rtc)
                                         tm = localtime(&ts.tv_sec);
                                 else
                                         tm = gmtime(&ts.tv_sec);
@@ -660,7 +671,7 @@ static DBusHandlerResult timedate_message_handler(
                                 hwclock_set_time(tm);
                         }
 
-                        log_info("RTC configured to %s time.", local_rtc ? "local" : "UTC");
+                        log_info("RTC configured to %s time.", tz.local_rtc ? "local" : "UTC");
 
                         changed = bus_properties_changed_new(
                                         "/org/freedesktop/timedate1",
@@ -707,7 +718,7 @@ static DBusHandlerResult timedate_message_handler(
                         }
 
                         /* Sync down to RTC */
-                        if (local_rtc)
+                        if (tz.local_rtc)
                                 tm = localtime(&ts.tv_sec);
                         else
                                 tm = gmtime(&ts.tv_sec);
@@ -728,13 +739,13 @@ static DBusHandlerResult timedate_message_handler(
                                     DBUS_TYPE_INVALID))
                         return bus_send_error_reply(connection, message, &error, -EINVAL);
 
-                if (ntp != !!use_ntp) {
+                if (ntp != !!tz.use_ntp) {
 
                         r = verify_polkit(connection, message, "org.freedesktop.timedate1.set-ntp", interactive, &error);
                         if (r < 0)
                                 return bus_send_error_reply(connection, message, &error, r);
 
-                        use_ntp = !!ntp;
+                        tz.use_ntp = !!ntp;
 
                         r = enable_ntp(connection, &error);
                         if (r < 0)
@@ -744,7 +755,7 @@ static DBusHandlerResult timedate_message_handler(
                         if (r < 0)
                                 return bus_send_error_reply(connection, message, &error, r);
 
-                        log_info("Set NTP to %s", use_ntp ? "enabled" : "disabled");
+                        log_info("Set NTP to %s", tz.use_ntp ? "enabled" : "disabled");
 
                         changed = bus_properties_changed_new(
                                         "/org/freedesktop/timedate1",
@@ -755,7 +766,7 @@ static DBusHandlerResult timedate_message_handler(
                 }
 
         } else
-                return bus_default_message_handler(connection, message, INTROSPECTION, INTERFACES_LIST, properties);
+                return bus_default_message_handler(connection, message, INTROSPECTION, INTERFACES_LIST, bps);
 
         if (!(reply = dbus_message_new_method_return(message)))
                 goto oom;