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process-util: slightly optimize querying of our own process metadata

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When we are checking our own data, we can optimize things a bit.
This commit is contained in:
Lennart Poettering 2017-07-17 23:35:25 +02:00
parent 7a1f1aaa78
commit 6f8cbcdb27
1 changed files with 27 additions and 3 deletions
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30
src/basic/process-util.c
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@ -388,7 +388,7 @@ int is_kernel_thread(pid_t pid) {
bool eof;
FILE *f;
if (pid == 0 || pid == 1) /* pid 1, and we ourselves certainly aren't a kernel thread */
if (pid == 0 || pid == 1 || pid == getpid_cached()) /* pid 1, and we ourselves certainly aren't a kernel thread */
return 0;
assert(pid > 1);
@ -471,6 +471,9 @@ static int get_process_id(pid_t pid, const char *field, uid_t *uid) {
assert(field);
assert(uid);
if (pid < 0)
return -EINVAL;
p = procfs_file_alloca(pid, "status");
f = fopen(p, "re");
if (!f) {
@ -498,10 +501,22 @@ static int get_process_id(pid_t pid, const char *field, uid_t *uid) {
}
int get_process_uid(pid_t pid, uid_t *uid) {
if (pid == 0 || pid == getpid_cached()) {
*uid = getuid();
return 0;
}
return get_process_id(pid, "Uid:", uid);
}
int get_process_gid(pid_t pid, gid_t *gid) {
if (pid == 0 || pid == getpid_cached()) {
*gid = getgid();
return 0;
}
assert_cc(sizeof(uid_t) == sizeof(gid_t));
return get_process_id(pid, "Gid:", gid);
}
@ -577,7 +592,7 @@ int get_process_ppid(pid_t pid, pid_t *_ppid) {
assert(pid >= 0);
assert(_ppid);
if (pid == 0) {
if (pid == 0 || pid == getpid_cached()) {
*_ppid = getppid();
return 0;
}
@ -775,6 +790,9 @@ bool pid_is_unwaited(pid_t pid) {
if (pid <= 1) /* If we or PID 1 would be dead and have been waited for, this code would not be running */
return true;
if (pid == getpid_cached())
return true;
if (kill(pid, 0) >= 0)
return true;
@ -792,6 +810,9 @@ bool pid_is_alive(pid_t pid) {
if (pid <= 1) /* If we or PID 1 would be a zombie, this code would not be running */
return true;
if (pid == getpid_cached())
return true;
r = get_process_state(pid);
if (r == -ESRCH || r == 'Z')
return false;
@ -803,7 +824,10 @@ int pid_from_same_root_fs(pid_t pid) {
const char *root;
if (pid < 0)
return 0;
return false;
if (pid == 0 || pid == getpid_cached())
return true;
root = procfs_file_alloca(pid, "root");