+
+bool pid_valid(pid_t pid) {
+ if (pid <= 0)
+ return false;
+
+ if (kill(pid, 0) >= 0)
+ return true;
+
+ return errno != ESRCH;
+}
+
+int getpeercred(int fd, struct ucred *ucred) {
+ socklen_t n = sizeof(struct ucred);
+ struct ucred u;
+ int r;
+
+ assert(fd >= 0);
+ assert(ucred);
+
+ r = getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &u, &n);
+ if (r < 0)
+ return -errno;
+
+ if (n != sizeof(struct ucred))
+ return -EIO;
+
+ /* Check if the data is actually useful and not suppressed due
+ * to namespacing issues */
+ if (u.pid <= 0)
+ return -ENODATA;
+
+ *ucred = u;
+ return 0;
+}
+
+int getpeersec(int fd, char **ret) {
+ socklen_t n = 64;
+ char *s;
+ int r;
+
+ assert(fd >= 0);
+ assert(ret);
+
+ s = new0(char, n);
+ if (!s)
+ return -ENOMEM;
+
+ r = getsockopt(fd, SOL_SOCKET, SO_PEERSEC, s, &n);
+ if (r < 0) {
+ free(s);
+
+ if (errno != ERANGE)
+ return -errno;
+
+ s = new0(char, n);
+ if (!s)
+ return -ENOMEM;
+
+ r = getsockopt(fd, SOL_SOCKET, SO_PEERSEC, s, &n);
+ if (r < 0) {
+ free(s);
+ return -errno;
+ }
+ }
+
+ if (isempty(s)) {
+ free(s);
+ return -ENOTSUP;
+ }
+
+ *ret = s;
+ return 0;
+}