tree-wide: Migrate to pidref_safe_fork()

Let's migrate all remaining callers of safe_fork()
to pidref_safe_fork() and get rid of safe_fork().

src/core/automount.c

@@ -655,12 +655,13 @@ static int asynchronous_expire(int dev_autofs_fd, int ioctl_fd) {
          * child's PID, we are PID1/autoreaper after all, hence when it dies we'll automatically clean it up
          * anyway. */
 
-        r = safe_fork_full("(sd-expire)",
-                           /* stdio_fds= */ NULL,
-                           (int[]) { dev_autofs_fd, ioctl_fd },
-                           /* n_except_fds= */ 2,
-                           FORK_RESET_SIGNALS|FORK_CLOSE_ALL_FDS|FORK_REOPEN_LOG,
-                           /* ret= */ NULL);
+        r = pidref_safe_fork_full(
+                        "(sd-expire)",
+                        /* stdio_fds= */ NULL,
+                        (int[]) { dev_autofs_fd, ioctl_fd },
+                        /* n_except_fds= */ 2,
+                        FORK_RESET_SIGNALS|FORK_CLOSE_ALL_FDS|FORK_REOPEN_LOG,
+                        /* ret= */ NULL);
         if (r != 0)
                 return r;
 

src/core/exec-invoke.c

@@ -1416,7 +1416,7 @@ static int setup_pam(
 
         parent_pid = getpid_cached();
 
-        r = safe_fork("(sd-pam)", 0, NULL);
+        r = pidref_safe_fork("(sd-pam)", /* flags= */ 0, /* ret= */ NULL);
         if (r < 0)
                 goto fail;
         if (r == 0) {

src/core/manager.c

@@ -4133,7 +4133,7 @@ static int manager_run_generators(Manager *m) {
         if (is_dir("/tmp", /* follow= */ false) > 0 && !MANAGER_IS_TEST_RUN(m))
                 flags |= FORK_PRIVATE_TMP;
 
-        r = safe_fork("(sd-gens)", flags, NULL);
+        r = pidref_safe_fork("(sd-gens)", flags, /* ret= */ NULL);
         if (r == 0) {
                 r = manager_execute_generators(m, paths, /* remount_ro= */ true);
                 _exit(r >= 0 ? EXIT_SUCCESS : EXIT_FAILURE);

src/core/namespace.c

@@ -3502,7 +3502,6 @@ static int is_extension_overlay(const char *path, int fd) {
 static int unpeel_get_fd(const char *mount_path, int *ret_fd) {
         _cleanup_close_pair_ int pipe_fds[2] = EBADF_PAIR;
         _cleanup_close_ int fs_fd = -EBADF;
-        pid_t pid;
         int r;
 
         assert(mount_path);
@@ -3513,7 +3512,7 @@ static int unpeel_get_fd(const char *mount_path, int *ret_fd) {
                 return log_debug_errno(errno, "Failed to create socket pair: %m");
 
         /* Clone mount namespace here to unpeel without affecting live process */
-        r = safe_fork("(sd-ns-unpeel)", FORK_DEATHSIG_SIGTERM|FORK_LOG|FORK_WAIT|FORK_NEW_MOUNTNS|FORK_MOUNTNS_SLAVE, &pid);
+        r = pidref_safe_fork("(sd-ns-unpeel)", FORK_DEATHSIG_SIGTERM|FORK_LOG|FORK_WAIT|FORK_NEW_MOUNTNS|FORK_MOUNTNS_SLAVE, /* ret= */ NULL);
         if (r < 0)
                 return r;
         if (r == 0) {
@@ -3903,9 +3902,10 @@ int refresh_extensions_in_namespace(
          *    overlays to obtain FDs the underlying directories, over which we will reapply the overlays
          * 3. In the child again, receive the FDs and reapply the overlays
          */
-        r = safe_fork("(sd-ns-refresh-exts)",
-                      FORK_DEATHSIG_SIGTERM|FORK_WAIT|FORK_NEW_MOUNTNS|FORK_MOUNTNS_SLAVE,
-                      NULL);
+        r = pidref_safe_fork(
+                        "(sd-ns-refresh-exts)",
+                        FORK_DEATHSIG_SIGTERM|FORK_WAIT|FORK_NEW_MOUNTNS|FORK_MOUNTNS_SLAVE,
+                        /* ret= */ NULL);
         if (r < 0)
                 return r;
         if (r == 0) {

src/core/unit.c

@@ -5540,7 +5540,6 @@ int unit_set_exec_params(Unit *u, ExecParameters *p) {
 
 int unit_fork_helper_process_full(Unit *u, const char *name, bool into_cgroup, ForkFlags flags, PidRef *ret) {
         CGroupRuntime *crt = NULL;
-        pid_t pid;
         int r;
 
         assert(u);
@@ -5548,8 +5547,8 @@ int unit_fork_helper_process_full(Unit *u, const char *name, bool into_cgroup, F
         assert(ret);
 
         /* Forks off a helper process and makes sure it is a member of the unit's cgroup, if configured to
-         * do so. Returns == 0 in the child, and > 0 in the parent. The pid parameter is always filled in
-         * with the child's PID. */
+         * do so. Returns == 0 in the child, and > 0 in the parent. The pidref parameter is always filled in
+         * with the child's PID reference. */
 
         if (into_cgroup) {
                 r = unit_realize_cgroup(u);
@@ -5559,19 +5558,11 @@ int unit_fork_helper_process_full(Unit *u, const char *name, bool into_cgroup, F
                 crt = unit_get_cgroup_runtime(u);
         }
 
-        r = safe_fork(name, FORK_REOPEN_LOG|FORK_DEATHSIG_SIGTERM|flags, &pid);
+        _cleanup_(pidref_done) PidRef pidref = PIDREF_NULL;
+        r = pidref_safe_fork(name, FORK_REOPEN_LOG|FORK_DEATHSIG_SIGTERM|flags, &pidref);
         if (r < 0)
                 return r;
         if (r > 0) {
-                _cleanup_(pidref_done) PidRef pidref = PIDREF_NULL;
-                int q;
-
-                /* Parent */
-
-                q = pidref_set_pid(&pidref, pid);
-                if (q < 0)
-                        return q;
-
                 *ret = TAKE_PIDREF(pidref);
                 return r;
         }
@@ -5589,6 +5580,7 @@ int unit_fork_helper_process_full(Unit *u, const char *name, bool into_cgroup, F
                 }
         }
 
+        *ret = TAKE_PIDREF(pidref);
         return 0;
 }