Move freeze() into shared/

Library code should not call freeze(), this is something that should
only be done by "application code", so moving it into shared/ is appropriate.

The fallback to call _exit() is dropped: let's trust that the infinite loop
is infinite.

3 files changed, 27 insertions, 3 deletions

diff --git a/src/shared/exec-util.c b/src/shared/exec-util.c
index 68e896a8fa..42f6c4d75a 100644
--- a/src/shared/exec-util.c
+++ b/src/shared/exec-util.c
@@ -448,6 +448,29 @@ ExecCommandFlags exec_command_flags_from_string(const char *s) {
                 return 1 << idx;
 }
 
+_noreturn_ void freeze(void) {
+        log_close();
+
+        /* Make sure nobody waits for us on a socket anymore */
+        (void) close_all_fds(NULL, 0);
+
+        sync();
+
+        /* Let's not freeze right away, but keep reaping zombies. */
+        for (;;) {
+                int r;
+                siginfo_t si = {};
+
+                r = waitid(P_ALL, 0, &si, WEXITED);
+                if (r < 0 && errno != EINTR)
+                        break;
+        }
+
+        /* waitid() failed with an unexpected error, things are really borked. Freeze now! */
+        for (;;)
+                pause();
+}
+
 int fexecve_or_execve(int executable_fd, const char *executable, char *const argv[], char *const envp[]) {
 #if ENABLE_FEXECVE
         execveat(executable_fd, "", argv, envp, AT_EMPTY_PATH);
diff --git a/src/shared/exec-util.h b/src/shared/exec-util.h
index 21d28608f9..05f8e1af83 100644
--- a/src/shared/exec-util.h
+++ b/src/shared/exec-util.h
@@ -47,6 +47,8 @@ extern const gather_stdout_callback_t gather_environment[_STDOUT_CONSUME_MAX];
 const char* exec_command_flags_to_string(ExecCommandFlags i);
 ExecCommandFlags exec_command_flags_from_string(const char *s);
 
+_noreturn_ void freeze(void);
+
 int fexecve_or_execve(int executable_fd, const char *executable, char *const argv[], char *const envp[]);
 
 int fork_agent(const char *name, int except[], size_t n_except, pid_t *ret_pid, const char *path, ...) _sentinel_;
diff --git a/src/shared/mount-util.c b/src/shared/mount-util.c
index 594efea989..cf8ca8d9d3 100644
--- a/src/shared/mount-util.c
+++ b/src/shared/mount-util.c
@@ -11,6 +11,7 @@
 
 #include "alloc-util.h"
 #include "dissect-image.h"
+#include "exec-util.h"
 #include "extract-word.h"
 #include "fd-util.h"
 #include "fileio.h"
@@ -1010,11 +1011,9 @@ static int make_userns(uid_t uid_shift, uid_t uid_range) {
         r = safe_fork("(sd-mkuserns)", FORK_CLOSE_ALL_FDS|FORK_DEATHSIG|FORK_NEW_USERNS, &pid);
         if (r < 0)
                 return r;
-        if (r == 0) {
+        if (r == 0)
                 /* Child. We do nothing here, just freeze until somebody kills us. */
                 freeze();
-                _exit(EXIT_FAILURE);
-        }
 
         xsprintf(line, UID_FMT " " UID_FMT " " UID_FMT "\n", 0, uid_shift, uid_range);