Cleaner version of waitid hack on macOS

diff --git a/src/lib/server/exec.c b/src/lib/server/exec.c
index a75009614927f7705fd7dd1fb7af4d73d85ef5e3..23884d57ae399e28b6a50fc14dfcaa827a587520 100644 (file)
--- a/src/lib/server/exec.c
+++ b/src/lib/server/exec.c
@@ -306,6 +306,35 @@ static NEVER_RETURNS void exec_child(request_t *request, char **argv, char **env
        exit(2);
 }
 
+#ifdef __APPLE__
+static inline CC_HINT(always_inline)
+void exec_child_pid_visible(request_t *request, pid_t pid)
+{
+       siginfo_t       info;
+
+       fr_assert(pid > 0);
+
+       /*
+        *      Apparently in macOS >= 10.11 there's a race between 
+        *      the kernel handing back the PID to userland and it 
+        *      becoming visible to waitid.
+        *
+        *      Better to hang indefinitely spewing log messages
+        *      than to create obscure resource leaks.
+        */
+       while (true) {
+               if ((waitid(P_PID, pid, &info, WNOHANG | WNOWAIT) < 0)) {
+                       if (errno != ECHILD) {
+                               RWDEBUG("PID %u not visible to parent - %s", (unsigned int) pid, fr_syserror(errno));
+                               break;
+                       }
+                       RWDEBUG("PID %u not visible to parent, retrying...", (unsigned int) pid);
+                       usleep(10000);
+               }
+       }
+}
+#endif
+
 /** Execute a program without waiting for the program to finish.
  *
  * @param[in] request          the request
@@ -380,23 +409,11 @@ int fr_exec_fork_nowait(request_t *request, FR_DLIST_HEAD(fr_value_box_list) *ar
        }
 
        pid = fork();
-#ifdef __APPLE__
-       for (unsigned int i = 0; i < 10; i++) {
-               siginfo_t       info;
-
-               if ((waitid(P_PID, pid, &info, WNOHANG | WNOWAIT) < 0)) {
-                       REDEBUG("WAITID ERRORED %s", fr_syserror(errno));
-                       usleep(10000);
-               }
-       }
-#endif
-
        /*
         *      The child never returns from calling exec_child();
         */
        if (pid == 0) {
                int unused[2] = { -1, -1 };
-
                exec_child(request, argv, env, false, unused, unused, unused);
        }
 
@@ -405,6 +422,10 @@ int fr_exec_fork_nowait(request_t *request, FR_DLIST_HEAD(fr_value_box_list) *ar
                return -1;
        }
 
+#ifdef __APPLE__
+       exec_child_pid_visible(request, pid);
+#endif
+
        /*
         *      Ensure that we can clean up any child processes.  We
         *      don't want them left over as zombies.
@@ -561,6 +582,10 @@ int fr_exec_fork_wait(pid_t *pid_p, int *stdin_fd, int *stdout_fd, int *stderr_f
                return -1;
        }
 
+#ifdef __APPLE__
+       exec_child_pid_visible(request, pid);
+#endif
+
        /*
         *      Tell the caller the childs PID, and the FD to read
         *      from.