core: Save tasks' namespaces IDs in the ids image

The recent kernels allow to get namespaces IDs by reading proc-ns links.
Use this to generate IDs for tasks' namespaces (I do generate them, since
IDs provided by kernel look ugly :( ).
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

cr-dump.c

@@ -913,6 +913,10 @@ static int dump_task_ids(struct pstree_item *item, const struct cr_fdset *cr_fds
 	if (ret)
 		goto err_free;
 
+	ret = dump_task_ns_ids(item);
+	if (ret)
+		goto err_free;
+
 	ret = pb_write_one(fd_ids, item->ids, PB_IDS);
 	if (ret < 0)
 		goto err_free;

include/namespaces.h

@@ -18,4 +18,7 @@ int switch_ns(int pid, struct ns_desc *nd, int *rst);
 int restore_ns(int rst, struct ns_desc *nd);
 extern struct ns_desc pid_ns_desc;
 
+struct pstree_item;
+int dump_task_ns_ids(struct pstree_item *);
+
 #endif /* __CR_NS_H__ */

namespaces.c

@@ -61,6 +61,104 @@ int restore_ns(int rst, struct ns_desc *nd)
 	return ret;
 }
 
+struct ns_id {
+	unsigned int kid;
+	unsigned int id;
+	struct ns_desc *nd;
+	struct ns_id *next;
+};
+
+static struct ns_id *ns_ids;
+static unsigned int ns_next_id = 1;
+
+static unsigned int generate_ns_id(unsigned int kid, struct ns_desc *nd)
+{
+	struct ns_id *nsid;
+
+	for (nsid = ns_ids; nsid != NULL; nsid = nsid->next)
+		if (nsid->kid == kid && nsid->nd == nd)
+			return nsid->id;
+
+	nsid = xmalloc(sizeof(*nsid));
+	if (!nsid)
+		return 0;
+
+	nsid->id = ns_next_id++;
+	nsid->kid = kid;
+	nsid->nd = nd;
+	nsid->next = ns_ids;
+	ns_ids = nsid;
+
+	pr_info("Collected %u.%s namespace\n", nsid->id, nd->str);
+
+	return nsid->id;
+}
+
+static unsigned int get_ns_id(int pid, struct ns_desc *nd)
+{
+	int proc_dir, ret;
+	unsigned int kid;
+	char ns_path[10], ns_id[32], *end;
+
+	proc_dir = open_pid_proc(pid);
+	if (proc_dir < 0)
+		return 0;
+
+	sprintf(ns_path, "ns/%s", nd->str);
+	ret = readlinkat(proc_dir, ns_path, ns_id, sizeof(ns_id));
+	if (ret < 0) {
+		pr_perror("Can't readlink ns link");
+		return 0;
+	}
+
+	/* XXX: Does it make sence to validate kernel links to <name>:[<id>]? */
+	kid = strtoul(ns_id + strlen(nd->str) + 2, &end, 10);
+	return generate_ns_id(kid, nd);
+}
+
+int dump_task_ns_ids(struct pstree_item *item)
+{
+	int pid = item->pid.real;
+	TaskKobjIdsEntry *ids = item->ids;
+
+	ids->has_pid_ns_id = true;
+	ids->pid_ns_id = get_ns_id(pid, &pid_ns_desc);
+	if (!ids->pid_ns_id) {
+		pr_err("Can't make pidns id\n");
+		return -1;
+	}
+
+	ids->has_net_ns_id = true;
+	ids->net_ns_id = get_ns_id(pid, &net_ns_desc);
+	if (!ids->net_ns_id) {
+		pr_err("Can't make netns id\n");
+		return -1;
+	}
+
+	ids->has_ipc_ns_id = true;
+	ids->ipc_ns_id = get_ns_id(pid, &ipc_ns_desc);
+	if (!ids->ipc_ns_id) {
+		pr_err("Can't make ipcns id\n");
+		return -1;
+	}
+
+	ids->has_uts_ns_id = true;
+	ids->uts_ns_id = get_ns_id(pid, &uts_ns_desc);
+	if (!ids->uts_ns_id) {
+		pr_err("Can't make utsns id\n");
+		return -1;
+	}
+
+	ids->has_mnt_ns_id = true;
+	ids->mnt_ns_id = get_ns_id(pid, &mnt_ns_desc);
+	if (!ids->mnt_ns_id) {
+		pr_err("Can't make mntns id\n");
+		return -1;
+	}
+
+	return 0;
+}
+
 static int do_dump_namespaces(struct pid *ns_pid, unsigned int ns_flags)
 {
 	struct cr_fdset *fdset;

protobuf/core.proto

@@ -70,6 +70,12 @@ message task_kobj_ids_entry {
 	required uint32			files_id	= 2;
 	required uint32			fs_id		= 3;
 	required uint32			sighand_id	= 4;
+
+	optional uint32			pid_ns_id	= 5;
+	optional uint32			net_ns_id	= 6;
+	optional uint32			ipc_ns_id	= 7;
+	optional uint32			uts_ns_id	= 8;
+	optional uint32			mnt_ns_id	= 9;
 }
 
 message thread_info_x86 {