[CRIU] [PATCH v3 28/55] proc_parse: Implement collect_pid_status()

[Kirill Tkhai]

Implement helper, which allows to collect NSpids in
the whole pid hierarhy (i.e., when pid->level > 1).

Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
---
 criu/include/proc_parse.h |   11 +++++
 criu/proc_parse.c         |  100 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 111 insertions(+)

diff --git a/criu/include/proc_parse.h b/criu/include/proc_parse.h
index 13b710926..883360484 100644
--- a/criu/include/proc_parse.h
+++ b/criu/include/proc_parse.h
@@ -64,6 +64,14 @@ struct proc_pid_stat {
 	int			exit_code;
 };
 
+
+struct proc_pid_status {
+	uint32_t *nspid;
+	uint32_t *nspgid;
+	uint32_t *nssid;
+	size_t n_levels;
+};
+
 struct seccomp_info {
 	SeccompFilter filter;
 	int id;
@@ -105,4 +113,7 @@ extern int parse_threads(int pid, struct pid ***_t, int *_n);
 
 int parse_children(pid_t pid, pid_t **_c, int *_n);
 
+extern void free_pid_status(struct proc_pid_status *st);
+extern int collect_pid_status(pid_t tgid, pid_t tid, unsigned skip, struct proc_pid_status *st);
+
 #endif /* __CR_PROC_PARSE_H__ */
diff --git a/criu/proc_parse.c b/criu/proc_parse.c
index 84a8f9ea1..4201fd106 100644
--- a/criu/proc_parse.c
+++ b/criu/proc_parse.c
@@ -2579,3 +2579,103 @@ int parse_children(pid_t pid, pid_t **_c, int *_n)
 	return -1;
 }
 
+static int get_ns_pid(char *str, unsigned skip, uint32_t **pid, size_t *n_level)
+{
+	int nr, size;
+	pid_t val;
+
+	*pid = NULL;
+	nr = 0;
+	while (sscanf(str, "%d%n", &val, &size) == 1) {
+		str += size;
+		if (skip > 0) {
+			skip--;
+			continue;
+		}
+		nr++;
+		*pid = xrealloc(*pid, nr * sizeof(uint32_t));
+		if (!*pid) {
+			pr_err("Can't alloc memory\n");
+			return -1;
+		}
+		(*pid)[nr - 1] = val;
+	}
+
+	BUG_ON((*n_level && nr != *n_level) || nr < 1);
+	*n_level = nr;
+
+	return 0;
+}
+
+static void init_proc_pid_status(struct proc_pid_status *st)
+{
+	st->nspid = st->nspgid = st->nssid = NULL;
+	st->n_levels = 0;
+}
+
+int collect_pid_status(pid_t tgid, pid_t tid, unsigned skip, struct proc_pid_status *st)
+{
+	int nr_dump;
+	struct bfd f;
+	char *str;
+
+	if (tid == -1) {
+		f.fd = open_proc(tgid, "status");
+		nr_dump = 3;
+	} else {
+		f.fd = open_proc(tgid, "task/%d/status", tid);
+		nr_dump = 1; /* Threads don't need pgid and sid */
+	}
+	if (f.fd < 0)
+		return -1;
+	if (bfdopenr(&f))
+		return -1;
+	init_proc_pid_status(st);
+
+	while (nr_dump) {
+		str = breadline(&f);
+		if (str == NULL)
+			break;
+		if (IS_ERR(str))
+			goto out;
+
+		if (!strncmp(str, "NSpid:", 6)) {
+			if (get_ns_pid(str + 6, skip, &st->nspid, &st->n_levels) < 0) {
+				pr_err("Can't get NSpid\n");
+				goto out;
+			}
+			nr_dump--;
+		}
+
+		if (!strncmp(str, "NSpgid:", 7) && tid == -1) {
+			if (get_ns_pid(str + 7, skip, &st->nspgid, &st->n_levels) < 0) {
+				pr_err("Can't get NSpgid\n");
+				goto out;
+			}
+			nr_dump--;
+		}
+
+		if (!strncmp(str, "NSsid:", 6) && tid == -1) {
+			if (get_ns_pid(str + 6, skip, &st->nssid, &st->n_levels) < 0) {
+				pr_err("Can't get NSsid\n");
+				goto out;
+			}
+			nr_dump--;
+		}
+	}
+out:
+	bclose(&f);
+	if (nr_dump) {
+		pr_err("Can't get task's NS pids\n");
+		return -1;
+	}
+	return 0;
+}
+
+void free_pid_status(struct proc_pid_status *st)
+{
+	xfree(st->nspid);
+	xfree(st->nspgid);
+	xfree(st->nssid);
+	init_proc_pid_status(st);
+}