From: Alban Crequy <al...@endocode.com>
When a process starts systemd-nspawn with exec*() without fork(),
systemd-nspawn can be the parent process of children processes unknown
to systemd-nspawn. It can then receive the signal SIGCHLD for both the
container leader process and the previously started processes. So it
should distinguish them.
v2:
- correctly check if a child was in a waitable state.
---
src/nspawn/nspawn.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++------
1 file changed, 49 insertions(+), 6 deletions(-)
diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c
index 05d2c71..71a6239 100644
--- a/src/nspawn/nspawn.c
+++ b/src/nspawn/nspawn.c
@@ -23,6 +23,7 @@
#include <sched.h>
#include <unistd.h>
#include <sys/types.h>
+#include <sys/wait.h>
#include <sys/mount.h>
#include <stdlib.h>
#include <string.h>
@@ -3511,6 +3512,12 @@ static int change_uid_gid(char **_home) {
return 0;
}
+typedef struct SigChildData {
+ pid_t leader_pid;
+ siginfo_t leader_status;
+ bool terminated;
+} SigChildData;
+
/*
* Return values:
* < 0 : wait_for_terminate() failed to get the state of the
@@ -3528,13 +3535,17 @@ static int change_uid_gid(char **_home) {
* That is, success is indicated by a return value of zero, and an
* error is indicated by a non-zero value.
*/
-static int wait_for_container(pid_t pid, ContainerStatus *container) {
+static int wait_for_container(SigChildData *sigchld_ctx, pid_t pid,
ContainerStatus *container) {
siginfo_t status;
int r;
- r = wait_for_terminate(pid, &status);
- if (r < 0)
- return log_warning_errno(r, "Failed to wait for container:
%m");
+ if (sigchld_ctx->terminated) {
+ status = sigchld_ctx->leader_status;
+ } else {
+ r = wait_for_terminate(pid, &status);
+ if (r < 0)
+ return log_warning_errno(r, "Failed to wait for
container: %m");
+ }
switch (status.si_code) {
@@ -3594,6 +3605,35 @@ static int on_orderly_shutdown(sd_event_source *s, const
struct signalfd_siginfo
return 0;
}
+static int on_sigchld(sd_event_source *s, const struct signalfd_siginfo *si,
void *userdata) {
+ SigChildData *ctx = userdata;
+ pid_t leader_pid = ctx->leader_pid;
+
+ /* several terminated children could be merged in a single SIGCHLD, so
+ * don't rely on si->ssi_pid. */
+
+ while (1) {
+ int r;
+ siginfo_t status;
+
+ zero(status);
+ r = waitid(P_ALL, -1, &status, WEXITED | WNOHANG);
+ if (r < 0)
+ break;
+
+ if (status.si_pid <= 0)
+ break;
+
+ if (status.si_pid == leader_pid) {
+ ctx->leader_status = status;
+ ctx->terminated = true;
+ return sd_event_exit(sd_event_source_get_event(s), 0);
+ }
+ }
+
+ return 0;
+}
+
static int determine_names(void) {
int r;
@@ -3917,6 +3957,7 @@ int main(int argc, char *argv[]) {
.sa_handler = nop_handler,
.sa_flags = SA_NOCLDSTOP,
};
+ SigChildData sigchld_ctx = {0,};
r = barrier_create(&barrier);
if (r < 0) {
@@ -4386,7 +4427,9 @@ int main(int argc, char *argv[]) {
}
/* simply exit on sigchld */
- sd_event_add_signal(event, NULL, SIGCHLD,
NULL, NULL);
+ sigchld_ctx.leader_pid = pid;
+ sigchld_ctx.terminated = false;
+ sd_event_add_signal(event, NULL, SIGCHLD,
on_sigchld , &sigchld_ctx);
if (arg_expose_ports) {
r = watch_rtnl(event,
rtnl_socket_pair[0], &exposed, &rtnl);
@@ -4425,7 +4468,7 @@ int main(int argc, char *argv[]) {
/* Normally redundant, but better safe than sorry */
kill(pid, SIGKILL);
- r = wait_for_container(pid, &container_status);
+ r = wait_for_container(&sigchld_ctx, pid, &container_status);
pid = 0;
if (r < 0)
--
2.1.4
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