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/job.c b/src/core/job.c
index d5b7987a00..af5855b71d 100644
--- a/src/core/job.c
+++ b/src/core/job.c
@@ -858,10 +858,12 @@ finish:
 }
 
 int job_start_timer(Job *j) {
-        struct itimerspec its;
-        struct epoll_event ev;
+        struct itimerspec its = {};
+        struct epoll_event ev = {
+                .data.ptr = &j->timer_watch,
+                .events = EPOLLIN,
+        };
         int fd, r;
-        assert(j);
 
         if (j->unit->job_timeout <= 0 ||
             j->timer_watch.type == WATCH_JOB_TIMER)
@@ -874,7 +876,6 @@ int job_start_timer(Job *j) {
                 goto fail;
         }
 
-        zero(its);
         timespec_store(&its.it_value, j->unit->job_timeout);
 
         if (timerfd_settime(fd, 0, &its, NULL) < 0) {
@@ -882,10 +883,6 @@ int job_start_timer(Job *j) {
                 goto fail;
         }
 
-        zero(ev);
-        ev.data.ptr = &j->timer_watch;
-        ev.events = EPOLLIN;
-
         if (epoll_ctl(j->manager->epoll_fd, EPOLL_CTL_ADD, fd, &ev) < 0) {
                 r = -errno;
                 goto fail;
@@ -1064,15 +1061,14 @@ int job_deserialize(Job *j, FILE *f, FDSet *fds) {
 }
 
 int job_coldplug(Job *j) {
-        struct epoll_event ev;
+        struct epoll_event ev = {
+                .data.ptr = &j->timer_watch,
+                .events = EPOLLIN,
+        };
 
         if (j->timer_watch.type != WATCH_JOB_TIMER)
                 return 0;
 
-        zero(ev);
-        ev.data.ptr = &j->timer_watch;
-        ev.events = EPOLLIN;
-
         if (epoll_ctl(j->manager->epoll_fd, EPOLL_CTL_ADD, j->timer_watch.fd, &ev) < 0)
                 return -errno;