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, 6 insertions, 9 deletions

diff --git a/src/core/mount.c b/src/core/mount.c
index 51a81a9488..4f245555f2 100644
--- a/src/core/mount.c
+++ b/src/core/mount.c
@@ -293,7 +293,7 @@ static int mount_add_requires_mounts_links(Mount *m) {
 }
 
 static char* mount_test_option(const char *haystack, const char *needle) {
-        struct mntent me;
+        struct mntent me = { .mnt_opts = (char*) haystack };
 
         assert(needle);
 
@@ -303,9 +303,6 @@ static char* mount_test_option(const char *haystack, const char *needle) {
         if (!haystack)
                 return NULL;
 
-        zero(me);
-        me.mnt_opts = (char*) haystack;
-
         return hasmntopt(&me, needle);
 }
 
@@ -1706,10 +1703,14 @@ static void mount_shutdown(Manager *m) {
 
 static int mount_enumerate(Manager *m) {
         int r;
-        struct epoll_event ev;
         assert(m);
 
         if (!m->proc_self_mountinfo) {
+                struct epoll_event ev = {
+                        .events = EPOLLPRI,
+                        .data.ptr = &m->mount_watch,
+                };
+
                 m->proc_self_mountinfo = fopen("/proc/self/mountinfo", "re");
                 if (!m->proc_self_mountinfo)
                         return -errno;
@@ -1717,10 +1718,6 @@ static int mount_enumerate(Manager *m) {
                 m->mount_watch.type = WATCH_MOUNT;
                 m->mount_watch.fd = fileno(m->proc_self_mountinfo);
 
-                zero(ev);
-                ev.events = EPOLLPRI;
-                ev.data.ptr = &m->mount_watch;
-
                 if (epoll_ctl(m->epoll_fd, EPOLL_CTL_ADD, m->mount_watch.fd, &ev) < 0)
                         return -errno;
         }