src/libnetdata/json/jsmn.c
#include <stdlib.h>
#include "jsmn.h"
/**
* Alloc token
*
* Allocates a fresh unused token from the token pull.
*
* @param parser the controller
* @param tokens the tokens I am working
* @param num_tokens the number total of tokens.
*
* @return it returns the next token to work.
*/
static jsmntok_t *jsmn_alloc_token(jsmn_parser *parser,
jsmntok_t *tokens, size_t num_tokens) {
jsmntok_t *tok;
if (parser->toknext >= num_tokens) {
return NULL;
}
tok = &tokens[parser->toknext++];
tok->start = tok->end = -1;
tok->size = 0;
#ifdef JSMN_PARENT_LINKS
tok->parent = -1;
#endif
return tok;
}
/**
* Fill Token
*
* Fills token type and boundaries.
*
* @param token the structure to set the values
* @param type is the token type
* @param start is the first position of the value
* @param end is the end of the value
*/
static void jsmn_fill_token(jsmntok_t *token, jsmntype_t type,
int start, int end) {
token->type = type;
token->start = start;
token->end = end;
token->size = 0;
}
/**
* Parse primitive
*
* Fills next available token with JSON primitive.
*
* @param parser is the control structure
* @param js is the json string
* @param type is the token type
*/
static jsmnerr_t jsmn_parse_primitive(jsmn_parser *parser, const char *js,
size_t len, jsmntok_t *tokens, size_t num_tokens) {
jsmntok_t *token;
int start;
start = parser->pos;
for (; parser->pos < len && js[parser->pos] != '\0'; parser->pos++) {
switch (js[parser->pos]) {
#ifndef JSMN_STRICT
/* In strict mode primitive must be followed by "," or "}" or "]" */
case ':':
#endif
case '\t' : case '\r' : case '\n' : case ' ' :
case ',' : case ']' : case '}' :
goto found;
}
if (js[parser->pos] < 32 || js[parser->pos] >= 127) {
parser->pos = start;
return JSMN_ERROR_INVAL;
}
}
#ifdef JSMN_STRICT
/* In strict mode primitive must be followed by a comma/object/array */
parser->pos = start;
return JSMN_ERROR_PART;
#endif
found:
if (tokens == NULL) {
parser->pos--;
return 0;
}
token = jsmn_alloc_token(parser, tokens, num_tokens);
if (token == NULL) {
parser->pos = start;
return JSMN_ERROR_NOMEM;
}
jsmn_fill_token(token, JSMN_PRIMITIVE, start, parser->pos);
#ifdef JSMN_PARENT_LINKS
token->parent = parser->toksuper;
#endif
parser->pos--;
return 0;
}
/**
* Parse string
*
* Fills next token with JSON string.
*
* @param parser is the control structure
* @param js is the json string
* @param len is the js length
* @param tokens is structure with the tokens mapped.
* @param num_tokens is the total number of tokens
*
* @return It returns 0 on success and another integer otherwise
*/
static jsmnerr_t jsmn_parse_string(jsmn_parser *parser, const char *js,
size_t len, jsmntok_t *tokens, size_t num_tokens) {
jsmntok_t *token;
int start = parser->pos;
parser->pos++;
/* Skip starting quote */
for (; parser->pos < len && js[parser->pos] != '\0'; parser->pos++) {
char c = js[parser->pos];
/* Quote: end of string */
if (c == '\"') {
if (tokens == NULL) {
return 0;
}
token = jsmn_alloc_token(parser, tokens, num_tokens);
if (token == NULL) {
parser->pos = start;
return JSMN_ERROR_NOMEM;
}
jsmn_fill_token(token, JSMN_STRING, start+1, parser->pos);
#ifdef JSMN_PARENT_LINKS
token->parent = parser->toksuper;
#endif
return 0;
}
/* Backslash: Quoted symbol expected */
if (c == '\\') {
parser->pos++;
switch (js[parser->pos]) {
/* Allowed escaped symbols */
case '\"': case '/' : case '\\' : case 'b' :
case 'f' : case 'r' : case 'n' : case 't' :
break;
/* Allows escaped symbol \uXXXX */
case 'u':
parser->pos++;
int i = 0;
for(; i < 4 && js[parser->pos] != '\0'; i++) {
/* If it isn't a hex character we have an error */
if(!((js[parser->pos] >= 48 && js[parser->pos] <= 57) || /* 0-9 */
(js[parser->pos] >= 65 && js[parser->pos] <= 70) || /* A-F */
(js[parser->pos] >= 97 && js[parser->pos] <= 102))) { /* a-f */
parser->pos = start;
return JSMN_ERROR_INVAL;
}
parser->pos++;
}
parser->pos--;
break;
/* Unexpected symbol */
default:
parser->pos = start;
return JSMN_ERROR_INVAL;
}
}
}
parser->pos = start;
return JSMN_ERROR_PART;
}
/**
* JSMN Parse
*
* Parse JSON string and fill tokens.
*
* @param parser the auxiliary vector used to parser
* @param js the string to parse
* @param len the string length
* @param tokens the place to map the tokens
* @param num_tokens the number of tokens present in the tokens structure.
*
* @return It returns the number of tokens present in the string on success or a negative number otherwise
*/
jsmnerr_t jsmn_parse(jsmn_parser *parser, const char *js, size_t len,
jsmntok_t *tokens, unsigned int num_tokens) {
jsmnerr_t r;
int i;
jsmntok_t *token;
int count = 0;
for (; parser->pos < len && js[parser->pos] != '\0'; parser->pos++) {
char c;
jsmntype_t type;
c = js[parser->pos];
switch (c) {
case '{': case '[':
count++;
if (tokens == NULL) {
break;
}
token = jsmn_alloc_token(parser, tokens, num_tokens);
if (token == NULL)
return JSMN_ERROR_NOMEM;
if (parser->toksuper != -1) {
tokens[parser->toksuper].size++;
#ifdef JSMN_PARENT_LINKS
token->parent = parser->toksuper;
#endif
}
token->type = (c == '{' ? JSMN_OBJECT : JSMN_ARRAY);
token->start = parser->pos;
parser->toksuper = parser->toknext - 1;
break;
case '}': case ']':
if (tokens == NULL)
break;
type = (c == '}' ? JSMN_OBJECT : JSMN_ARRAY);
#ifdef JSMN_PARENT_LINKS
if (parser->toknext < 1) {
return JSMN_ERROR_INVAL;
}
token = &tokens[parser->toknext - 1];
for (;;) {
if (token->start != -1 && token->end == -1) {
if (token->type != type) {
return JSMN_ERROR_INVAL;
}
token->end = parser->pos + 1;
parser->toksuper = token->parent;
break;
}
if (token->parent == -1) {
break;
}
token = &tokens[token->parent];
}
#else
for (i = parser->toknext - 1; i >= 0; i--) {
token = &tokens[i];
if (token->start != -1 && token->end == -1) {
if (token->type != type) {
return JSMN_ERROR_INVAL;
}
parser->toksuper = -1;
token->end = parser->pos + 1;
break;
}
}
/* Error if unmatched closing bracket */
if (i == -1) return JSMN_ERROR_INVAL;
for (; i >= 0; i--) {
token = &tokens[i];
if (token->start != -1 && token->end == -1) {
parser->toksuper = i;
break;
}
}
#endif
break;
case '\"':
r = jsmn_parse_string(parser, js, len, tokens, num_tokens);
if (r < 0) return r;
count++;
if (parser->toksuper != -1 && tokens != NULL)
tokens[parser->toksuper].size++;
break;
case '\t' : case '\r' : case '\n' : case ':' : case ',': case ' ':
break;
#ifdef JSMN_STRICT
/* In strict mode primitives are: numbers and booleans */
case '-': case '0': case '1' : case '2': case '3' : case '4':
case '5': case '6': case '7' : case '8': case '9':
case 't': case 'f': case 'n' :
#else
/* In non-strict mode every unquoted value is a primitive */
default:
#endif
r = jsmn_parse_primitive(parser, js, len, tokens, num_tokens);
if (r < 0) return r;
count++;
if (parser->toksuper != -1 && tokens != NULL)
tokens[parser->toksuper].size++;
break;
#ifdef JSMN_STRICT
/* Unexpected char in strict mode */
default:
return JSMN_ERROR_INVAL;
#endif
}
}
if (tokens) {
for (i = parser->toknext - 1; i >= 0; i--) {
/* Unmatched opened object or array */
if (tokens[i].start != -1 && tokens[i].end == -1) {
return JSMN_ERROR_PART;
}
}
}
return count;
}
/**
* JSMN Init
*
* Creates a new parser based over a given buffer with an array of tokens
* available.
*
* @param parser is the structure with values to reset
*/
void jsmn_init(jsmn_parser *parser) {
parser->pos = 0;
parser->toknext = 0;
parser->toksuper = -1;
}