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.

1 files changed, 9 insertions, 13 deletions

diff --git a/src/core/unit.c b/src/core/unit.c
index dbb1882965..63e42b2330 100644
--- a/src/core/unit.c
+++ b/src/core/unit.c
@@ -1520,17 +1520,16 @@ void unit_notify(Unit *u, UnitActiveState os, UnitActiveState ns, bool reload_su
 }
 
 int unit_watch_fd(Unit *u, int fd, uint32_t events, Watch *w) {
-        struct epoll_event ev;
+        struct epoll_event ev = {
+                .data.ptr = w,
+                .events = events,
+        };
 
         assert(u);
         assert(fd >= 0);
         assert(w);
         assert(w->type == WATCH_INVALID || (w->type == WATCH_FD && w->fd == fd && w->data.unit == u));
 
-        zero(ev);
-        ev.data.ptr = w;
-        ev.events = events;
-
         if (epoll_ctl(u->manager->epoll_fd,
                       w->type == WATCH_INVALID ? EPOLL_CTL_ADD : EPOLL_CTL_MOD,
                       fd,
@@ -1578,7 +1577,7 @@ void unit_unwatch_pid(Unit *u, pid_t pid) {
 }
 
 int unit_watch_timer(Unit *u, clockid_t clock_id, bool relative, usec_t usec, Watch *w) {
-        struct itimerspec its;
+        struct itimerspec its = {};
         int flags, fd;
         bool ours;
 
@@ -1603,8 +1602,6 @@ int unit_watch_timer(Unit *u, clockid_t clock_id, bool relative, usec_t usec, Wa
         } else
                 assert_not_reached("Invalid watch type");
 
-        zero(its);
-
         if (usec <= 0) {
                 /* Set absolute time in the past, but not 0, since we
                  * don't want to disarm the timer */
@@ -1622,11 +1619,10 @@ int unit_watch_timer(Unit *u, clockid_t clock_id, bool relative, usec_t usec, Wa
                 goto fail;
 
         if (w->type == WATCH_INVALID) {
-                struct epoll_event ev;
-
-                zero(ev);
-                ev.data.ptr = w;
-                ev.events = EPOLLIN;
+                struct epoll_event ev = {
+                        .data.ptr = w,
+                        .events = EPOLLIN,
+                };
 
                 if (epoll_ctl(u->manager->epoll_fd, EPOLL_CTL_ADD, fd, &ev) < 0)
                         goto fail;