json: fix parsing json problems when json config is invalid.

Add parsing json as invalid cases:
1.json content that not enclosed in {}, it should be parsed as invalid, e.g.

"abc":"not encloesed in {}"

2.json content that 'subsystems' not associate with array, it will report error and return failure, e.g.

{"subsystems":"123"}

3.handle other invalid json formats, report and return failure, e.g. duplicate keys.

Added `spdk_json_find` API return errcode: EPROTOTYPE - json not enclosed in {}.

json config with content:
1."not enclosed in {}"
2."'subsystems' not be an array"
3."duplicate key in json"
and some other invaild cases will be regarded as invalid json config, and will fail to start app.

Fixes #2599

Signed-off-by: tongkunkun <tongkunkun_yewu@cmss.chinamobile.com>
Change-Id: I02574c9acd7671e336d4c589ebbff8ed21eb3681
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/13754
Community-CI: Mellanox Build Bot
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: GangCao <gang.cao@intel.com>
Reviewed-by: Aleksey Marchuk <alexeymar@nvidia.com>
Reviewed-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>

CHANGELOG.md

@@ -2,6 +2,17 @@
 
 ## v22.09: (Upcoming Release)
 
+### json
+
+Added `spdk_json_find` API return errcode: EPROTOTYPE - json not enclosed in {}.
+`spdk_json_find` now returns -EPROTOTYPE instead of -ENOENT if the object parameter
+does not point to a JSON object (i.e. is not enclosed with {}).
+
+### init
+
+`spdk_subsystem_init_from_json_config` now fails if the JSON configuration file is not
+an object with an array named "subsystems".
+
 ### bdev
 
 New RPCs `bdev_xnvme_create` and `bdev_xnvme_delete` were added to support the xNVMe bdev.

include/spdk/json.h

@@ -266,6 +266,7 @@ int spdk_json_write_named_object_begin(struct spdk_json_write_ctx *w, const char
  * -EINVAL - json object is invalid
  * -ENOENT - key not found
  * -EDOM - key exists but value type mismatch.
+ * -EPROTOTYPE - json not enclosed in {}.
  */
 int spdk_json_find(struct spdk_json_val *object, const char *key_name, struct spdk_json_val **key,
 		   struct spdk_json_val **val, enum spdk_json_val_type type);

lib/init/json_config.c

@@ -566,14 +566,26 @@ spdk_subsystem_init_from_json_config(const char *json_config_file, const char *r
 
 	/* Capture subsystems array */
 	rc = spdk_json_find_array(ctx->values, "subsystems", NULL, &ctx->subsystems);
-	if (rc) {
-		SPDK_WARNLOG("No 'subsystems' key JSON configuration file.\n");
-	} else {
+	switch (rc) {
+	case 0:
 		/* Get first subsystem */
 		ctx->subsystems_it = spdk_json_array_first(ctx->subsystems);
 		if (ctx->subsystems_it == NULL) {
 			SPDK_NOTICELOG("'subsystems' configuration is empty\n");
 		}
+		break;
+	case -EPROTOTYPE:
+		SPDK_ERRLOG("Invalid JSON configuration: not enclosed in {}.\n");
+		goto fail;
+	case -ENOENT:
+		SPDK_WARNLOG("No 'subsystems' key JSON configuration file.\n");
+		break;
+	case -EDOM:
+		SPDK_ERRLOG("Invalid JSON configuration: 'subsystems' should be an array.\n");
+		goto fail;
+	default:
+		SPDK_ERRLOG("Failed to parse JSON configuration.\n");
+		goto fail;
 	}
 
 	/* If rpc_addr is not an Unix socket use default address as prefix. */

lib/json/json_util.c

@@ -530,11 +530,17 @@ spdk_json_find(struct spdk_json_val *object, const char *key_name, struct spdk_j
 {
 	struct spdk_json_val *_key = NULL;
 	struct spdk_json_val *_val = NULL;
-	struct spdk_json_val *it;
+	struct spdk_json_val *it_first, *it;
 
 	assert(object != NULL);
 
-	for (it = json_first(object, SPDK_JSON_VAL_ARRAY_BEGIN | SPDK_JSON_VAL_OBJECT_BEGIN);
+	it_first = json_first(object, SPDK_JSON_VAL_OBJECT_BEGIN);
+	if (!it_first) {
+		SPDK_JSON_DEBUG("Not enclosed in {}\n");
+		return -EPROTOTYPE;
+	}
+
+	for (it = it_first;
 	     it != NULL;
 	     it = spdk_json_next(it)) {
 		if (it->type != SPDK_JSON_VAL_NAME) {
@@ -553,7 +559,7 @@ spdk_json_find(struct spdk_json_val *object, const char *key_name, struct spdk_j
 		_key = it;
 		_val = json_value(_key);
 
-		if (type != SPDK_JSON_VAL_INVALID && (_val->type & type) == 0) {
+		if (type != SPDK_JSON_VAL_ANY && (_val->type & type) == 0) {
 			SPDK_JSON_DEBUG("key '%s' type is %#x but expected one of %#x\n", key_name, _val->type, type);
 			return -EDOM;
 		}

test/bdev/blockdev.sh

@@ -7,6 +7,9 @@ source $testdir/nbd_common.sh
 
 rpc_py=rpc_cmd
 conf_file="$testdir/bdev.json"
+nonenclosed_conf_file="$testdir/nonenclosed.json"
+nonarray_conf_file="$testdir/nonarray.json"
+
 # Make sure the configuration is clean
 : > "$conf_file"
 
@@ -566,6 +569,12 @@ trap "cleanup" SIGINT SIGTERM EXIT
 run_test "bdev_verify" $testdir/bdevperf/bdevperf --json "$conf_file" -q 128 -o 4096 -w verify -t 5 -C -m 0x3 "$env_ctx"
 run_test "bdev_write_zeroes" $testdir/bdevperf/bdevperf --json "$conf_file" -q 128 -o 4096 -w write_zeroes -t 1 "$env_ctx"
 
+# test json config not enclosed with {}
+run_test "bdev_json_nonenclosed" $testdir/bdevperf/bdevperf --json "$nonenclosed_conf_file" -q 128 -o 4096 -w write_zeroes -t 1 "$env_ctx" || true
+
+# test json config "subsystems" not with array
+run_test "bdev_json_nonarray" $testdir/bdevperf/bdevperf --json "$nonarray_conf_file" -q 128 -o 4096 -w write_zeroes -t 1 "$env_ctx" || true
+
 if [[ $test_type == bdev ]]; then
 	run_test "bdev_qos" qos_test_suite "$env_ctx"
 	run_test "bdev_qd_sampling" qd_sampling_test_suite "$env_ctx"

test/bdev/nonarray.json

@@ -0,0 +1 @@
+{"subsystems": "test non array"}

test/bdev/nonenclosed.json

@@ -0,0 +1 @@
+"subsystems" : "test nonenclosed json"