reaper: remove child from list *before* calling the user provided callback

The user provided callback may call reaper_del(), in which case we
will crash when we also try to remove the child from the list.

Remove it from the list before the callback means reaper_del() (if
called by the callback) will just loop through the entire list without
finding the pid and thus do nothing.
This commit is contained in:
Daniel Eklöf 2021-01-12 09:30:27 +01:00
parent e563c863d1
commit 324a1f80a8
No known key found for this signature in database
GPG key ID: 5BBD4992C116573F

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@ -138,23 +138,27 @@ fdm_reap(struct fdm *fdm, int fd, int events, void *data)
}
tll_foreach(reaper->children, it) {
struct child *child = &it->item;
pid_t pid = child->pid;
struct child *_child = &it->item;
if (pid != (pid_t)info.ssi_pid)
if (_child->pid != (pid_t)info.ssi_pid)
continue;
/* Make sure we remove it *before* the callback, since it too
* may remove it */
struct child child = it->item;
tll_remove(reaper->children, it);
bool reap_ourselves = true;
if (child->cb != NULL)
reap_ourselves = !child->cb(reaper, pid, child->cb_data);
if (child.cb != NULL)
reap_ourselves = !child.cb(reaper, child.pid, child.cb_data);
if (reap_ourselves) {
int result;
int res = waitpid(pid, &result, WNOHANG);
int res = waitpid(child.pid, &result, WNOHANG);
if (res <= 0) {
if (res < 0)
LOG_ERRNO("waitpid failed for pid=%d", pid);
LOG_ERRNO("waitpid failed for pid=%d", child.pid);
continue;
}
@ -165,8 +169,6 @@ fdm_reap(struct fdm *fdm, int fd, int events, void *data)
else
LOG_DBG("pid=%d: died of unknown resason", pid);
}
tll_remove(reaper->children, it);
}
if (hup)