From: Lennart Poettering <lennart@poettering.net>
Date: Wed, 8 Jan 2025 09:50:06 +0000 (+0100)
Subject: process-util: make pidref_safe_fork_full() work with FORK_WAIT
X-Git-Tag: v258-rc1~1634^2~1
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=47e45ea7389ea2e4ad074110ce7ac7f768f79eb0;p=thirdparty%2Fsystemd.git

process-util: make pidref_safe_fork_full() work with FORK_WAIT

(This is useful for the test case added in the next commit, where it's
kinda nice being able to use pidref_safe_fork_full() and acquiring a
pidref of the child in the child in one go. There's no other value in
this than a bit of synctactic sugar for that test. But otoh thre's no
good reason to prohibit FORK_WAIT use like this, hence either way, this
commit should be a good thing.)
---

diff --git a/src/basic/process-util.c b/src/basic/process-util.c
index f48285d3d52..1264bae3e61 100644
--- a/src/basic/process-util.c
+++ b/src/basic/process-util.c
@@ -1783,12 +1783,16 @@ int pidref_safe_fork_full(
         pid_t pid;
         int r, q;
 
-        assert(!FLAGS_SET(flags, FORK_WAIT));
-
         r = safe_fork_full(name, stdio_fds, except_fds, n_except_fds, flags, &pid);
-        if (r < 0)
+        if (r < 0 || !ret_pid)
                 return r;
 
+        if (r > 0 && FLAGS_SET(flags, FORK_WAIT)) {
+                /* If we are in the parent and successfully waited, then the process doesn't exist anymore */
+                *ret_pid = PIDREF_NULL;
+                return r;
+        }
+
         q = pidref_set_pid(ret_pid, pid);
         if (q < 0) /* Let's not fail for this, no matter what, the process exists after all, and that's key */
                 *ret_pid = PIDREF_MAKE_FROM_PID(pid);