+
+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;
+}
+
+int writev_safe(int fd, const struct iovec *w, int j) {
+ for (int i = 0; i < j; i++) {
+ size_t written = 0;
+
+ while (written < w[i].iov_len) {
+ ssize_t r;
+
+ r = write(fd, (char*) w[i].iov_base + written, w[i].iov_len - written);
+ if (r < 0 && errno != -EINTR)
+ return -errno;
+
+ written += r;
+ }
+ }
+
+ return 0;
+}
+
+int mkostemp_safe(char *pattern, int flags) {
+ unsigned long tries = TMP_MAX;
+ char *s;
+ int r;
+
+ assert(pattern);
+
+ /* This is much like like mkostemp() but avoids using any
+ * static variables, thus is async signal safe */
+
+ s = endswith(pattern, "XXXXXX");
+ if (!s)
+ return -EINVAL;
+
+ while (tries--) {
+ unsigned i;
+ int fd;
+
+ r = dev_urandom(s, 6);
+ if (r < 0)
+ return r;
+
+ for (i = 0; i < 6; i++)
+ s[i] = ALPHANUMERICAL[(unsigned) s[i] % (sizeof(ALPHANUMERICAL)-1)];
+
+ fd = open(pattern, flags|O_EXCL|O_CREAT, S_IRUSR|S_IWUSR);
+ if (fd >= 0)
+ return fd;
+ if (!IN_SET(errno, EEXIST, EINTR))
+ return -errno;
+ }
+
+ return -EEXIST;
+}
+
+int open_tmpfile(const char *path, int flags) {
+ int fd;
+ char *p;
+
+#ifdef O_TMPFILE
+ fd = open(path, flags|O_TMPFILE, S_IRUSR|S_IWUSR);
+ if (fd >= 0)
+ return fd;
+#endif
+ p = strappenda(path, "/systemd-tmp-XXXXXX");
+
+ fd = mkostemp_safe(p, O_RDWR|O_CLOEXEC);
+ if (fd < 0)
+ return fd;
+
+ unlink(p);
+ return fd;
+}