From 5ca99dfabda20927a0d47e5f19339d1b48f82f7a Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= Date: Wed, 5 Jan 2022 15:04:06 +0100 Subject: man: add example of sd_event_add_child() The thing with blocking SIGCHLD is rather annoying. I think we could/should make this automatic. --- man/event-quick-child.c | 42 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) create mode 100644 man/event-quick-child.c (limited to 'man/event-quick-child.c') diff --git a/man/event-quick-child.c b/man/event-quick-child.c new file mode 100644 index 0000000000..16cc6cf3a4 --- /dev/null +++ b/man/event-quick-child.c @@ -0,0 +1,42 @@ +/* SPDX-License-Identifier: CC0-1.0 */ + +#include +#include +#include +#include + +int main(int argc, char **argv) { + pid_t pid = fork(); + assert(pid >= 0); + + /* SIGCHLD signal must be blocked for sd_event_add_child to work */ + sigset_t ss; + sigemptyset(&ss); + sigaddset(&ss, SIGCHLD); + sigprocmask(SIG_BLOCK, &ss, NULL); + + if (pid == 0) /* child */ + sleep(1); + + else { /* parent */ + sd_event *e = NULL; + int r; + + /* Create the default event loop */ + sd_event_default(&e); + assert(e); + + /* We create a floating child event source (attached to 'e'). + * The default handler will be called with 666 as userdata, which + * will become the exit value of the loop. */ + r = sd_event_add_child(e, NULL, pid, WEXITED, NULL, (void*) 666); + assert(r >= 0); + + r = sd_event_loop(e); + assert(r == 666); + + sd_event_unref(e); + } + + return 0; +} -- cgit v1.2.1