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Use initalization instead of explicit zeroing

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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
2013-04-05 19:50:57 -04:00
parent 8c62ecf1a9
commit b92bea5d2a
49 changed files with 392 additions and 554 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/core/execute.c
+9 -13
View File
@@ -205,7 +205,10 @@ static int open_null_as(int flags, int nfd) {
static int connect_logger_as(const ExecContext *context, ExecOutput output, const char *ident, const char *unit_id, int nfd) {
int fd, r;
union sockaddr_union sa;
union sockaddr_union sa = {
.un.sun_family = AF_UNIX,
.un.sun_path = "/run/systemd/journal/stdout",
};
assert(context);
assert(output < _EXEC_OUTPUT_MAX);
@@ -216,10 +219,6 @@ static int connect_logger_as(const ExecContext *context, ExecOutput output, cons
if (fd < 0)
return -errno;
zero(sa);
sa.un.sun_family = AF_UNIX;
strncpy(sa.un.sun_path, "/run/systemd/journal/stdout", sizeof(sa.un.sun_path));
r = connect(fd, &sa.sa, offsetof(struct sockaddr_un, sun_path) + strlen(sa.un.sun_path));
if (r < 0) {
close_nointr_nofail(fd);
@@ -938,7 +937,7 @@ static int apply_seccomp(uint32_t *syscall_filter) {
int i;
unsigned n;
struct sock_filter *f;
struct sock_fprog prog;
struct sock_fprog prog = {};
assert(syscall_filter);
@@ -970,7 +969,6 @@ static int apply_seccomp(uint32_t *syscall_filter) {
memcpy(f + (ELEMENTSOF(header) + 2*n), footer, sizeof(footer));
/* Third: install the filter */
zero(prog);
prog.len = ELEMENTSOF(header) + ELEMENTSOF(footer) + 2*n;
prog.filter = f;
if (prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog) < 0)
@@ -1210,10 +1208,9 @@ int exec_spawn(ExecCommand *command,
}
if (context->cpu_sched_set) {
struct sched_param param;
zero(param);
param.sched_priority = context->cpu_sched_priority;
struct sched_param param = {
.sched_priority = context->cpu_sched_priority,
};
r = sched_setscheduler(0,
context->cpu_sched_policy |
@@ -1701,7 +1698,7 @@ int exec_context_load_environment(const ExecContext *c, char ***l) {
int k;
bool ignore = false;
char **p;
glob_t pglob;
glob_t pglob = {};
int count, n;
fn = *i;
@@ -1721,7 +1718,6 @@ int exec_context_load_environment(const ExecContext *c, char ***l) {
}
/* Filename supports globbing, take all matching files */
zero(pglob);
errno = 0;
if (glob(fn, 0, NULL, &pglob) != 0) {
globfree(&pglob);