lib: json: Parse nested objects and arrays
Parse arrays and nested objects.
Array parsing is limited to items of the same type, and requires an array
with fixed number of elements. Elements can be of any type supported by
the parser, including arrays and objects.
The return value of json_obj_parse() won't be that helpful: the nth bit
will only be set if the object has been fully decoded.
Jira: ZEP-1607
Change-Id: I472e402ae3f36a1bd1505decc0313f74cbfa2e07
Signed-off-by: Leandro Pereira <leandro.pereira@intel.com>
diff --git a/lib/json/json.c b/lib/json/json.c
index 5e9591f..c71e5e9 100644
--- a/lib/json/json.c
+++ b/lib/json/json.c
@@ -263,6 +263,8 @@
return NULL;
case '}':
case '{':
+ case '[':
+ case ']':
case ',':
case ':':
emit(lexer, (enum json_tokens)chr);
@@ -321,7 +323,23 @@
return 0;
}
-static int obj_next(struct json_obj *json, struct json_obj_key_value *kv)
+static int element_token(enum json_tokens token)
+{
+ switch (token) {
+ case JSON_TOK_OBJECT_START:
+ case JSON_TOK_LIST_START:
+ case JSON_TOK_STRING:
+ case JSON_TOK_NUMBER:
+ case JSON_TOK_TRUE:
+ case JSON_TOK_FALSE:
+ return 0;
+ default:
+ return -EINVAL;
+ }
+}
+
+static int obj_next(struct json_obj *json,
+ struct json_obj_key_value *kv)
{
struct token token;
@@ -369,16 +387,26 @@
return -EINVAL;
}
- switch (kv->value.type) {
- case JSON_TOK_STRING:
- case JSON_TOK_NUMBER:
- case JSON_TOK_TRUE:
- case JSON_TOK_FALSE:
- case JSON_TOK_NULL:
- return 0;
- default:
+ return element_token(kv->value.type);
+}
+
+static int arr_next(struct json_obj *json, struct token *value)
+{
+ if (!lexer_next(&json->lexer, value)) {
return -EINVAL;
}
+
+ if (value->type == JSON_TOK_LIST_END) {
+ return 0;
+ }
+
+ if (value->type == JSON_TOK_COMMA) {
+ if (!lexer_next(&json->lexer, value)) {
+ return -EINVAL;
+ }
+ }
+
+ return element_token(value->type);
}
static int decode_num(const struct token *token, int32_t *num)
@@ -418,34 +446,131 @@
return type1 == type2;
}
-int json_obj_parse(char *payload, size_t len,
- const struct json_obj_descr *descr, size_t descr_len,
- void *val)
+static int obj_parse(struct json_obj *obj,
+ const struct json_obj_descr *descr, size_t descr_len,
+ void *val);
+static int arr_parse(struct json_obj *obj,
+ const struct json_obj_descr *elem_descr,
+ size_t max_elements, void *field, void *val);
+
+static int decode_value(struct json_obj *obj,
+ const struct json_obj_descr *descr,
+ struct token *value, void *field, void *val)
{
- struct json_obj obj;
+
+ if (!equivalent_types(value->type, descr->type)) {
+ return -EINVAL;
+ }
+
+ switch (descr->type) {
+ case JSON_TOK_OBJECT_START:
+ return obj_parse(obj, descr->sub_descr,
+ descr->sub_descr_len,
+ field);
+ case JSON_TOK_LIST_START:
+ return arr_parse(obj, descr->element_descr,
+ descr->n_elements, field, val);
+ case JSON_TOK_FALSE:
+ case JSON_TOK_TRUE: {
+ bool *value = field;
+
+ *value = descr->type == JSON_TOK_TRUE;
+
+ return 0;
+ }
+ case JSON_TOK_NUMBER: {
+ int32_t *num = field;
+
+ return decode_num(value, num);
+ }
+ case JSON_TOK_STRING: {
+ char **str = field;
+
+ *value->end = '\0';
+ *str = value->start;
+
+ return 0;
+ }
+ default:
+ return -EINVAL;
+ }
+}
+
+static ptrdiff_t get_elem_size(const struct json_obj_descr *descr)
+{
+ switch (descr->type) {
+ case JSON_TOK_NUMBER:
+ return sizeof(int32_t);
+ case JSON_TOK_STRING:
+ return sizeof(char *);
+ case JSON_TOK_TRUE:
+ case JSON_TOK_FALSE:
+ return sizeof(bool);
+ case JSON_TOK_LIST_START:
+ return descr->n_elements * get_elem_size(descr->element_descr);
+ case JSON_TOK_OBJECT_START: {
+ ptrdiff_t total = 0;
+ size_t i;
+
+ for (i = 0; i < descr->sub_descr_len; i++) {
+ total += get_elem_size(&descr->sub_descr[i]);
+ }
+
+ return total;
+ }
+ default:
+ return -EINVAL;
+ }
+}
+
+static int arr_parse(struct json_obj *obj,
+ const struct json_obj_descr *elem_descr,
+ size_t max_elements, void *field, void *val)
+{
+ ptrdiff_t elem_size = get_elem_size(elem_descr);
+ void *last_elem = (char *)field + elem_size * max_elements;
+ size_t *elements = (size_t *)((char *)val + elem_descr->offset);
+ struct token value;
+
+ assert(elem_size > 0);
+
+ *elements = 0;
+
+ while (!arr_next(obj, &value)) {
+ if (value.type == JSON_TOK_LIST_END) {
+ return 0;
+ }
+
+ if (decode_value(obj, elem_descr, &value, field, val) < 0) {
+ return -EINVAL;
+ }
+
+ (*elements)++;
+
+ field = (char *)field + elem_size;
+ if (field == last_elem) {
+ return -ENOSPC;
+ }
+ }
+
+ return -EINVAL;
+}
+
+static int obj_parse(struct json_obj *obj, const struct json_obj_descr *descr,
+ size_t descr_len, void *val)
+{
struct json_obj_key_value kv;
int32_t decoded_fields = 0;
size_t i;
int ret;
- assert(descr_len < (sizeof(decoded_fields) * CHAR_BIT - 1));
-
- ret = obj_init(&obj, payload, len);
- if (ret < 0) {
- return ret;
- }
-
- while (!obj_next(&obj, &kv)) {
+ while (!obj_next(obj, &kv)) {
if (kv.value.type == JSON_TOK_OBJECT_END) {
- if (decoded_fields == (1 << descr_len) - 1) {
- return decoded_fields;
- }
-
- return -EINVAL;
+ return decoded_fields;
}
for (i = 0; i < descr_len; i++) {
- void *field = (char *)val + descr[i].offset;
+ void *decode_field = (char *)val + descr[i].offset;
/* Field has been decoded already, skip */
if (decoded_fields & (1 << i)) {
@@ -458,53 +583,42 @@
}
if (memcmp(kv.key, descr[i].field_name,
- descr[i].field_name_len)) {
+ descr[i].field_name_len)) {
continue;
}
- /* Is the value of the expected type? */
- if (!equivalent_types(kv.value.type, descr[i].type)) {
- return -EINVAL;
- }
-
/* Store the decoded value */
- switch (descr[i].type) {
- case JSON_TOK_FALSE:
- case JSON_TOK_TRUE: {
- bool *value = field;
-
- *value = descr[i].type == JSON_TOK_TRUE;
-
- break;
- }
- case JSON_TOK_NUMBER: {
- int32_t *num = field;
-
- if (decode_num(&kv.value, num) < 0) {
- return -EINVAL;
- }
-
- break;
- }
- case JSON_TOK_STRING: {
- char **str = field;
-
- *kv.value.end = '\0';
- *str = kv.value.start;
-
- break;
- }
- default:
- return -EINVAL;
+ ret = decode_value(obj, &descr[i], &kv.value,
+ decode_field, val);
+ if (ret < 0) {
+ return ret;
}
decoded_fields |= 1<<i;
+ break;
}
}
return -EINVAL;
}
+int json_obj_parse(char *payload, size_t len,
+ const struct json_obj_descr *descr, size_t descr_len,
+ void *val)
+{
+ struct json_obj obj;
+ int ret;
+
+ assert(descr_len < (sizeof(ret) * CHAR_BIT - 1));
+
+ ret = obj_init(&obj, payload, len);
+ if (ret < 0) {
+ return ret;
+ }
+
+ return obj_parse(&obj, descr, descr_len, val);
+}
+
static const char escapable[] = "\"\\/\b\f\n\r\t";
static int json_escape_internal(char *str, size_t *len, size_t buf_size)
