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authorZbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>2013-03-24 19:59:00 -0400
committerZbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>2013-04-05 19:50:57 -0400
commitb92bea5d2a9481de69bb627a7b442a9f58fca43d (patch)
treed43f5e340014d5c3ce723eabb60cd74e3dd20a18 /src/shutdownd
parent8c62ecf1a99ab4a3f69cb81be38715c504ef5723 (diff)
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.
Diffstat (limited to 'src/shutdownd')
-rw-r--r--src/shutdownd/shutdownd.c41
1 files changed, 18 insertions, 23 deletions
diff --git a/src/shutdownd/shutdownd.c b/src/shutdownd/shutdownd.c
index ee2a328b4e..4c9c149a2d 100644
--- a/src/shutdownd/shutdownd.c
+++ b/src/shutdownd/shutdownd.c
@@ -46,30 +46,29 @@ union shutdown_buffer {
};
static int read_packet(int fd, union shutdown_buffer *_b) {
- struct msghdr msghdr;
- struct iovec iovec;
struct ucred *ucred;
+ ssize_t n;
+
+ union shutdown_buffer b; /* We maintain our own copy here, in
+ * order not to corrupt the last message */
+ struct iovec iovec = {
+ iovec.iov_base = &b,
+ iovec.iov_len = sizeof(b) - 1,
+ };
union {
struct cmsghdr cmsghdr;
uint8_t buf[CMSG_SPACE(sizeof(struct ucred))];
- } control;
- ssize_t n;
- union shutdown_buffer b; /* We maintain our own copy here, in order not to corrupt the last message */
+ } control = {};
+ struct msghdr msghdr = {
+ .msg_iov = &iovec,
+ msghdr.msg_iovlen = 1,
+ msghdr.msg_control = &control,
+ msghdr.msg_controllen = sizeof(control),
+ };
assert(fd >= 0);
assert(_b);
- zero(iovec);
- iovec.iov_base = &b;
- iovec.iov_len = sizeof(b) - 1;
-
- zero(control);
- zero(msghdr);
- msghdr.msg_iov = &iovec;
- msghdr.msg_iovlen = 1;
- msghdr.msg_control = &control;
- msghdr.msg_controllen = sizeof(control);
-
n = recvmsg(fd, &msghdr, MSG_DONTWAIT);
if (n <= 0) {
if (n == 0) {
@@ -270,8 +269,8 @@ int main(int argc, char *argv[]) {
};
int r = EXIT_FAILURE, n_fds;
- union shutdown_buffer b;
- struct pollfd pollfd[_FD_MAX];
+ union shutdown_buffer b = {};
+ struct pollfd pollfd[_FD_MAX] = {};
bool exec_shutdown = false, unlink_nologin = false;
unsigned i;
@@ -302,9 +301,6 @@ int main(int argc, char *argv[]) {
return EXIT_FAILURE;
}
- zero(b);
- zero(pollfd);
-
pollfd[FD_SOCKET].fd = SD_LISTEN_FDS_START;
pollfd[FD_SOCKET].events = POLLIN;
@@ -402,13 +398,12 @@ int main(int argc, char *argv[]) {
}
if (pollfd[FD_WALL_TIMER].revents) {
- struct itimerspec its;
+ struct itimerspec its = {};
warn_wall(n, &b.command);
flush_fd(pollfd[FD_WALL_TIMER].fd);
/* Restart timer */
- zero(its);
timespec_store(&its.it_value, when_wall(n, b.command.usec));
if (timerfd_settime(pollfd[FD_WALL_TIMER].fd, TFD_TIMER_ABSTIME, &its, NULL) < 0) {
log_error("timerfd_settime(): %m");