Merge pull request #9068 from poettering/nspawn-pty-deadlock

nspawn logging deadlock fix

src/basic/log.c

@@ -1330,3 +1330,20 @@ int log_emergency_level(void) {
 
         return getpid_cached() == 1 ? LOG_EMERG : LOG_ERR;
 }
+
+int log_dup_console(void) {
+        int copy;
+
+        /* Duplicate the fd we use for fd logging if it's < 3 and use the copy from now on. This call is useful
+         * whenever we want to continue logging through the original fd, but want to rearrange stderr. */
+
+        if (console_fd >= 3)
+                return 0;
+
+        copy = fcntl(console_fd, F_DUPFD_CLOEXEC, 3);
+        if (copy < 0)
+                return -errno;
+
+        console_fd = copy;
+        return 0;
+}

src/basic/log.h

@@ -284,6 +284,8 @@ void log_set_open_when_needed(bool b);
  * stderr, the console or kmsg */
 void log_set_prohibit_ipc(bool b);
 
+int log_dup_console(void);
+
 int log_syntax_internal(
                 const char *unit,
                 int level,