infect: add SIGTSTP support

Add SIGTSTP signal dump and restore. Add a corresponding field
in the image, save it only if a task is in the stopped state.

Restore task state by sending desired stop signal if it is present
in the image. Fallback to SIGSTOP if it's absent.

Signed-off-by: Yuriy Vasiliev <yuriy.vasiliev@openvz.org>

6 files changed, 40 insertions, 4 deletions

diff --git a/criu/cr-dump.c b/criu/cr-dump.c
index 60e90baed..e60da88ed 100644
--- a/criu/cr-dump.c
+++ b/criu/cr-dump.c
@@ -781,6 +781,11 @@ static int dump_task_core_all(struct parasite_ctl *ctl, struct pstree_item *item
 	core->thread_core->creds->lsm_profile = dmpi(item)->thread_lsms[0]->profile;
 	core->thread_core->creds->lsm_sockcreate = dmpi(item)->thread_lsms[0]->sockcreate;
 
+	if (core->tc->task_state == TASK_STOPPED) {
+		core->tc->has_stop_signo = true;
+		core->tc->stop_signo = item->pid->stop_signo;
+	}
+
 	ret = parasite_dump_thread_leader_seized(ctl, pid, core);
 	if (ret)
 		goto err;
diff --git a/criu/cr-restore.c b/criu/cr-restore.c
index 398faf048..279246c19 100644
--- a/criu/cr-restore.c
+++ b/criu/cr-restore.c
@@ -1350,6 +1350,9 @@ static inline int fork_with_pid(struct pstree_item *item)
 		item->pid->state = ca.core->tc->task_state;
 		rsti(item)->cg_set = ca.core->tc->cg_set;
 
+		if (ca.core->tc->has_stop_signo)
+			item->pid->stop_signo = ca.core->tc->stop_signo;
+
 		if (item->pid->state != TASK_DEAD && !task_alive(item)) {
 			pr_err("Unknown task state %d\n", item->pid->state);
 			return -1;
@@ -2104,8 +2107,14 @@ static void finalize_restore(void)
 
 		xfree(ctl);
 
-		if ((item->pid->state == TASK_STOPPED) || (opts.final_state == TASK_STOPPED))
+		if (opts.final_state == TASK_STOPPED)
 			kill(item->pid->real, SIGSTOP);
+		else if (item->pid->state == TASK_STOPPED) {
+			if (item->pid->stop_signo > 0)
+				kill(item->pid->real, item->pid->stop_signo);
+			else
+				kill(item->pid->real, SIGSTOP);
+		}
 	}
 }
 
diff --git a/criu/include/pid.h b/criu/include/pid.h
index 49cb2d322..b2b7a361a 100644
--- a/criu/include/pid.h
+++ b/criu/include/pid.h
@@ -31,6 +31,10 @@ struct pid {
 	pid_t real;
 
 	int state; /* TASK_XXX constants */
+	/* If an item is in stopped state it has a signal number
+	 * that caused task to stop.
+	 */
+	int stop_signo;
 
 	/*
 	 * The @virt pid is one which used in the image itself and keeps
diff --git a/criu/proc_parse.c b/criu/proc_parse.c
index 6b41a81db..946b0fc40 100644
--- a/criu/proc_parse.c
+++ b/criu/proc_parse.c
@@ -1027,12 +1027,13 @@ int parse_pid_status(pid_t pid, struct seize_task_status *ss, void *data)
 
 	cr->s.sigpnd = 0;
 	cr->s.shdpnd = 0;
+	cr->s.sigblk = 0;
 	cr->s.seccomp_mode = SECCOMP_MODE_DISABLED;
 
 	if (bfdopenr(&f))
 		return -1;
 
-	while (done < 13) {
+	while (done < 14) {
 		str = breadline(&f);
 		if (str == NULL)
 			break;
@@ -1146,10 +1147,20 @@ int parse_pid_status(pid_t pid, struct seize_task_status *ss, void *data)
 			done++;
 			continue;
 		}
+		if (!strncmp(str, "SigBlk:", 7)) {
+			unsigned long long sigblk = 0;
+
+			if (sscanf(str + 7, "%llx", &sigblk) != 1)
+				goto err_parse;
+			cr->s.sigblk |= sigblk;
+
+			done++;
+			continue;
+		}
 	}
 
 	/* seccomp and nspids are optional */
-	expected_done = (parsed_seccomp ? 11 : 10);
+	expected_done = (parsed_seccomp ? 12 : 11);
 	if (kdat.has_nspid)
 		expected_done++;
 	if (done == expected_done)
diff --git a/criu/pstree.c b/criu/pstree.c
index f4d77b3a4..72c4a3502 100644
--- a/criu/pstree.c
+++ b/criu/pstree.c
@@ -222,6 +222,7 @@ struct pstree_item *__alloc_pstree_item(bool rst)
 	item->pid->ns[0].virt = -1;
 	item->pid->real = -1;
 	item->pid->state = TASK_UNDEF;
+	item->pid->stop_signo = -1;
 	item->born_sid = -1;
 	item->pid->item = item;
 	futex_init(&item->task_st);
diff --git a/criu/seize.c b/criu/seize.c
index 58564ca74..1333d6db9 100644
--- a/criu/seize.c
+++ b/criu/seize.c
@@ -615,6 +615,9 @@ static int collect_children(struct pstree_item *item)
 		else
 			processes_to_wait--;
 
+		if (ret == TASK_STOPPED)
+			c->pid->stop_signo = compel_parse_stop_signo(pid);
+
 		c->pid->real = pid;
 		c->parent = item;
 		c->pid->state = ret;
@@ -646,7 +649,7 @@ static void unseize_task_and_threads(const struct pstree_item *item, int st)
 	 * the item->state is the state task was in when we seized one.
 	 */
 
-	compel_resume_task(item->pid->real, item->pid->state, st);
+	compel_resume_task_sig(item->pid->real, item->pid->state, st, item->pid->stop_signo);
 
 	if (st == TASK_DEAD)
 		return;
@@ -950,6 +953,9 @@ int collect_pstree(void)
 	else
 		processes_to_wait--;
 
+	if (ret == TASK_STOPPED)
+		root_item->pid->stop_signo = compel_parse_stop_signo(pid);
+
 	pr_info("Seized task %d, state %d\n", pid, ret);
 	root_item->pid->state = ret;