json: introduce JSON module
This is a minimal wrapper around jsmn.h to make things a bit easier for iterating through a JSON object. To use, first parse the JSON and create a contents object using json_contents_new(). This object can then be used to initialize a json_iter object using json_iter_init(). The json_iter object can then be parsed with json_iter_parse by passing in JSON_MANDATORY/JSON_OPTIONAL arguments. Currently only JSON_STRING and JSON_OBJECT types are supported. Any JSON_MANDATORY values that are not found will result in an error. If a JSON_OPTIONAL string is not found, the pointer will be NULL. If a JSON_OPTIONAL object is not found, this iterator will be initialized but 'start' will be -1. This can be checked with a convenience macro json_object_not_found();
This commit is contained in:
James Prestwood
Denis Kenzior
parent
f17fd791cf
commit
abfd749335
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@ -249,6 +249,7 @@ src_iwd_SOURCES = src/main.c linux/nl80211.h src/iwd.h src/missing.h \
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src/sysfs.h src/sysfs.c \
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src/offchannel.h src/offchannel.c \
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src/dpp-util.h src/dpp-util.c \
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src/json.h src/json.c \
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$(eap_sources) \
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$(builtin_sources)
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@ -564,7 +565,8 @@ EXTRA_DIST = src/genbuiltin src/iwd.service.in src/net.connman.iwd.service \
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AM_CFLAGS = $(ell_cflags) -fvisibility=hidden \
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-DUNITDIR=\""$(top_srcdir)/unit/"\" \
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-DCERTDIR=\""$(top_builddir)/unit/"\"
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-DCERTDIR=\""$(top_builddir)/unit/"\" \
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-DJSMN_PARENT_LINKS -DJSMN_STRICT
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if MAINTAINER_MODE
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AM_CFLAGS += -DHAVE_PKCS8_SUPPORT
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@ -0,0 +1,270 @@
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/*
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*
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* Wireless daemon for Linux
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*
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* Copyright (C) 2021 Intel Corporation. All rights reserved.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*
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*/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif
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#include <errno.h>
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#include <ell/ell.h>
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#include "src/json.h"
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#include "shared/jsmn.h"
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/* Max number of tokens supported. Increase if larger objects are expected */
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#define JSON_DEFAULT_TOKENS 30
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#define TOK_LEN(token) (token)->end - (token)->start
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#define TOK_PTR(json, token) (void *)((json) + (token)->start)
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#define TOK_TO_STR(json, token) \
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({ \
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char *_tmp = l_malloc(TOK_LEN((token)) + 1); \
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memcpy(_tmp, TOK_PTR((json), (token)), TOK_LEN((token))); \
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_tmp[TOK_LEN((token))] = '\0'; \
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_tmp; \
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})
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#define ITER_END(iter) \
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(((iter)->contents->tokens + (iter)->start) + (iter)->count)
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struct json_contents {
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const char *json;
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size_t json_len;
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jsmntok_t *tokens;
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int tokens_len;
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jsmn_parser *p;
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};
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static jsmntok_t *next_key_in_parent(struct json_iter *iter, jsmntok_t *current)
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{
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int parent = current->parent;
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/* iterate the list and stop on the first token with the same parent */
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while (++current < ITER_END(iter)) {
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if (current->parent == parent)
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return current;
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}
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return NULL;
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}
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/*
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* 'object' is expected to be a value, so object - 1 is its key. Find
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* the next key who's parent matches the parent of object - 1. The
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* token preceeding this next key will mark the end of 'object'.
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*/
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static int find_object_tokens(struct json_iter *iter, jsmntok_t *object)
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{
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jsmntok_t *next = next_key_in_parent(iter, object - 1);
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/* End of token list */
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if (!next)
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next = ITER_END(iter);
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return ((next - object) % sizeof(jsmntok_t)) - 1;
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}
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static void iter_recurse(struct json_iter *iter, jsmntok_t *object,
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struct json_iter *child)
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{
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struct json_contents *c = iter->contents;
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child->contents = c;
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child->start = (object - c->tokens) % sizeof(jsmntok_t);
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child->count = find_object_tokens(iter, object);
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}
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struct json_contents *json_contents_new(const char *json, size_t json_len)
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{
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struct json_contents *c = l_new(struct json_contents, 1);
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c->json = json;
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c->json_len = json_len;
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c->p = l_new(jsmn_parser, 1);
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c->tokens = l_new(jsmntok_t, JSON_DEFAULT_TOKENS);
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jsmn_init(c->p);
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c->tokens_len = jsmn_parse(c->p, c->json, c->json_len,
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c->tokens, JSON_DEFAULT_TOKENS);
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if (c->tokens_len < 0) {
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json_contents_free(c);
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return NULL;
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}
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return c;
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}
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void json_iter_init(struct json_iter *iter, struct json_contents *c)
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{
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iter->contents = c;
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iter->start = 0;
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iter->count = c->tokens_len;
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}
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void json_contents_free(struct json_contents *c)
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{
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l_free(c->p);
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l_free(c->tokens);
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l_free(c);
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}
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struct json_arg {
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enum json_type type;
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void *value;
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jsmntok_t *v;
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};
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static void push_arg(struct l_queue *q, enum json_type type,
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void *value, jsmntok_t *v)
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{
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struct json_arg *arg = l_new(struct json_arg, 1);
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arg->type = type;
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arg->value = value;
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arg->v = v;
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l_queue_push_head(q, arg);
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}
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static void assign_arg(void *data, void *user_data)
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{
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struct json_iter *iter = user_data;
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struct json_arg *arg = data;
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struct json_contents *c = iter->contents;
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char **sval;
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struct json_iter *oval;
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switch (arg->type) {
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case JSON_STRING:
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sval = arg->value;
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*sval = arg->v ? TOK_TO_STR(c->json, arg->v) : NULL;
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break;
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case JSON_OBJECT:
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oval = arg->value;
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if (!arg->v)
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oval->start = -1;
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else
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iter_recurse(iter, arg->v, oval);
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break;
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default:
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/* Types are verified earlier, this should never happen */
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return;
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}
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l_free(arg);
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}
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bool json_iter_parse(struct json_iter *iter, enum json_type type, ...)
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{
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struct json_contents *c = iter->contents;
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va_list va;
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int i;
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int num = c->tokens->size;
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jsmntok_t *next;
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struct l_queue *args;
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if (iter->start == -1)
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return false;
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args = l_queue_new();
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va_start(va, type);
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while (true) {
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enum json_flag flag;
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char *key;
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void *value;
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jsmntok_t *v = NULL;
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void *ptr;
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size_t len;
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/* Check the type is supported before wasting any cycles */
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switch (type) {
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case JSON_UNDEFINED:
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goto done;
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case JSON_STRING:
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case JSON_OBJECT:
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break;
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default:
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goto error;
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}
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key = va_arg(va, char *);
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value = va_arg(va, void *);
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flag = va_arg(va, enum json_flag);
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/* First key */
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next = c->tokens + iter->start + 1;
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/* Iterate over this objects keys */
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for (i = 0; i < num; i++) {
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ptr = TOK_PTR(c->json, next);
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len = TOK_LEN(next);
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if (next + 1 > ITER_END(iter))
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goto error;
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if (strlen(key) == len && !memcmp(ptr, key, len)) {
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/* Key found but the wrong value type */
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if ((next + 1)->type != (jsmntype_t)type)
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goto error;
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v = next + 1;
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break;
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}
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next = next_key_in_parent(iter, next);
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if (!next)
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break;
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}
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if (flag == JSON_FLAG_MANDATORY && !v)
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goto error;
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/*
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* Still push even if an optional value doesn't exist (!v) so
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* the caller can check if it was found or not.
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*/
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if (value)
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push_arg(args, type, value, v);
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type = va_arg(va, enum json_type);
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}
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done:
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va_end(va);
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l_queue_foreach(args, assign_arg, iter);
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l_queue_destroy(args, NULL);
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return true;
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error:
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l_queue_destroy(args, l_free);
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return false;
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}
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@ -0,0 +1,83 @@
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/*
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*
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* Wireless daemon for Linux
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*
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* Copyright (C) 2021 Intel Corporation. All rights reserved.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*
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*/
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struct json_iter;
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/*
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* Identical to JSMN types
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*/
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enum json_type {
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JSON_UNDEFINED = 0,
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JSON_OBJECT = 1,
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JSON_ARRAY = 2,
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JSON_STRING = 3,
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JSON_PRIMITIVE = 4
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};
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enum json_flag {
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JSON_FLAG_MANDATORY = 1,
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JSON_FLAG_OPTIONAL = 2,
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};
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struct json_iter {
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struct json_contents *contents;
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int start;
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int count;
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};
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#define JSON_MANDATORY(key, type, out) \
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(type), (key), (out), JSON_FLAG_MANDATORY
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#define JSON_OPTIONAL(key, type, out) \
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(type), (key), (out), JSON_FLAG_OPTIONAL
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#define json_iter_is_valid(iter) ((iter)->start != -1)
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struct json_contents *json_contents_new(const char *json, size_t json_len);
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void json_contents_free(struct json_contents *c);
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void json_iter_init(struct json_iter *iter, struct json_contents *c);
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/*
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* Parse an arbitrary number of key/value pairs from a JSON iterator. Initially
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* a new JSON contents object should be created with json_contents_new() and,
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* when done, freed with json_contents_free.
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*
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* Iterators can be initialized with the json_contents object. Nested object
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* iterators are also parsed with this function.
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*
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* Arguments should be specified using JSON_MANDATORY or JSON_OPTIONAL:
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*
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* r = json_iter_parse(iter, JSON_MANDATORY("mykey", JSON_STRING, &strvalue),
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* JSON_OPTIONAL("optkey", JSON_STRING, &optvalue),
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* JSON_UNDEFINED);
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*
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* String values should be of type char ** and must be freed
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* Object values should be of type struct json_iter *
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*
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* No other types are supported at this time, and json_iter_parse will fail if
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* other types are encountered.
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*
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* JSON_OPTIONAL string values will point to NULL if not found
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* JSON_OPTIONAL objects can be checked with json_object_not_found.
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*/
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bool json_iter_parse(struct json_iter *iter, enum json_type type, ...);
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