Use initalization instead of explicit zeroing
Before, we would initialize many fields twice: first
by filling the structure with zeros, and then a second
time with the real values. We can let the compiler do
the job for us, avoiding one copy.
A downside of this patch is that text gets slightly
bigger. This is because all zero() calls are effectively
inlined:
$ size build/.libs/systemd
text data bss dec hex filename
before 897737 107300 2560 1007597 f5fed build/.libs/systemd
after 897873 107300 2560 1007733 f6075 build/.libs/systemd
… actually less than 1‰.
A few asserts that the parameter is not null had to be removed. I
don't think this changes much, because first, it is quite unlikely
for the assert to fail, and second, an immediate SEGV is almost as
good as an assert.
This commit is contained in:
Zbigniew Jędrzejewski-Szmek
+30
-41
@@ -1193,14 +1193,11 @@ static int enable_wait_for_jobs(DBusConnection *bus) {
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static int wait_for_jobs(DBusConnection *bus, Set *s) {
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int r = 0;
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WaitData d;
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WaitData d = { .set = s };
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assert(bus);
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assert(s);
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zero(d);
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d.set = s;
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if (!dbus_connection_add_filter(bus, wait_filter, &d, NULL))
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return log_oom();
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@@ -3021,9 +3018,8 @@ static int print_property(const char *name, DBusMessageIter *iter) {
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dbus_message_iter_recurse(iter, &sub);
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while (dbus_message_iter_get_arg_type(&sub) == DBUS_TYPE_STRUCT) {
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ExecStatusInfo info;
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ExecStatusInfo info = {};
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zero(info);
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if (exec_status_info_deserialize(&sub, &info) >= 0) {
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char timestamp1[FORMAT_TIMESTAMP_MAX], timestamp2[FORMAT_TIMESTAMP_MAX];
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char _cleanup_free_ *t;
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@@ -3070,14 +3066,12 @@ static int show_one(const char *verb, DBusConnection *bus, const char *path, boo
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const char *interface = "";
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int r;
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DBusMessageIter iter, sub, sub2, sub3;
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UnitStatusInfo info;
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UnitStatusInfo info = {};
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ExecStatusInfo *p;
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assert(path);
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assert(new_line);
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zero(info);
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r = bus_method_call_with_reply(
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bus,
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"org.freedesktop.systemd1",
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@@ -3654,7 +3648,7 @@ static int enable_sysv_units(char **args) {
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#if defined(HAVE_SYSV_COMPAT) && defined(HAVE_CHKCONFIG)
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const char *verb = args[0];
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unsigned f = 1, t = 1;
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LookupPaths paths;
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LookupPaths paths = {};
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if (arg_scope != UNIT_FILE_SYSTEM)
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return 0;
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@@ -3667,7 +3661,6 @@ static int enable_sysv_units(char **args) {
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/* Processes all SysV units, and reshuffles the array so that
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* afterwards only the native units remain */
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zero(paths);
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r = lookup_paths_init(&paths, SYSTEMD_SYSTEM, false, NULL, NULL, NULL);
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if (r < 0)
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return r;
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@@ -4716,7 +4709,7 @@ static int parse_time_spec(const char *t, usec_t *_u) {
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} else {
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char *e = NULL;
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long hour, minute;
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struct tm tm;
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struct tm tm = {};
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time_t s;
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usec_t n;
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@@ -4732,7 +4725,6 @@ static int parse_time_spec(const char *t, usec_t *_u) {
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n = now(CLOCK_REALTIME);
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s = (time_t) (n / USEC_PER_SEC);
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zero(tm);
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assert_se(localtime_r(&s, &tm));
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tm.tm_hour = (int) hour;
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@@ -5134,7 +5126,7 @@ finish:
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}
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static int talk_initctl(void) {
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struct init_request request = {0};
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struct init_request request = {};
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int r;
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int _cleanup_close_ fd = -1;
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char rl;
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@@ -5339,41 +5331,38 @@ static int systemctl_main(DBusConnection *bus, int argc, char *argv[], DBusError
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static int send_shutdownd(usec_t t, char mode, bool dry_run, bool warn, const char *message) {
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int _cleanup_close_ fd;
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struct msghdr msghdr;
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struct iovec iovec[2];
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union sockaddr_union sockaddr;
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struct sd_shutdown_command c;
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struct sd_shutdown_command c = {
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.usec = t,
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.mode = mode,
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.dry_run = dry_run,
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.warn_wall = warn,
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};
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union sockaddr_union sockaddr = {
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.un.sun_family = AF_UNIX,
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.un.sun_path = "/run/systemd/shutdownd",
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};
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struct iovec iovec[2] = {
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{.iov_base = (char*) &c,
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.iov_len = offsetof(struct sd_shutdown_command, wall_message),
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}
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};
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struct msghdr msghdr = {
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.msg_name = &sockaddr,
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.msg_namelen = offsetof(struct sockaddr_un, sun_path)
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+ sizeof("/run/systemd/shutdownd") - 1,
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.msg_iov = iovec,
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.msg_iovlen = 1,
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};
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fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0);
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if (fd < 0)
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return -errno;
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zero(c);
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c.usec = t;
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c.mode = mode;
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c.dry_run = dry_run;
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c.warn_wall = warn;
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zero(sockaddr);
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sockaddr.sa.sa_family = AF_UNIX;
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strncpy(sockaddr.un.sun_path, "/run/systemd/shutdownd", sizeof(sockaddr.un.sun_path));
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zero(msghdr);
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msghdr.msg_name = &sockaddr;
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msghdr.msg_namelen = offsetof(struct sockaddr_un, sun_path) + sizeof("/run/systemd/shutdownd") - 1;
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zero(iovec);
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iovec[0].iov_base = (char*) &c;
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iovec[0].iov_len = offsetof(struct sd_shutdown_command, wall_message);
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if (isempty(message))
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msghdr.msg_iovlen = 1;
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else {
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if (!isempty(message)) {
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iovec[1].iov_base = (char*) message;
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iovec[1].iov_len = strlen(message);
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msghdr.msg_iovlen = 2;
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msghdr.msg_iovlen++;
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}
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msghdr.msg_iov = iovec;
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if (sendmsg(fd, &msghdr, MSG_NOSIGNAL) < 0)
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return -errno;
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