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lua_cjson.c
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lua_cjson.c
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/* Lua CJSON - JSON support for Lua
*
* Copyright (c) 2010-2012 Mark Pulford <[email protected]>
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
/* Caveats:
* - JSON "null" values are represented as lightuserdata since Lua
* tables cannot contain "nil". Compare with cjson.null.
* - Invalid UTF-8 characters are not detected and will be passed
* untouched. If required, UTF-8 error checking should be done
* outside this library.
* - Javascript comments are not part of the JSON spec, and are not
* currently supported.
*
* Note: Decoding is slower than encoding. Lua spends significant
* time (30%) managing tables when parsing JSON since it is
* difficult to know object/array sizes ahead of time.
*/
#include <assert.h>
#include <string.h>
#include <math.h>
#include <limits.h>
#include <lua.h>
#include <lauxlib.h>
#include "strbuf.h"
#include "fpconv.h"
#ifndef CJSON_MODNAME
#define CJSON_MODNAME "cjson"
#endif
#ifndef CJSON_VERSION
#define CJSON_VERSION "2.1devel"
#endif
#ifdef _MSC_VER
#define CJSON_EXPORT __declspec(dllexport)
#else
#define CJSON_EXPORT extern
#endif
/* Workaround for Solaris platforms missing isinf() */
#if !defined(isinf) && (defined(USE_INTERNAL_ISINF) || defined(MISSING_ISINF))
#define isinf(x) (!isnan(x) && isnan((x) - (x)))
#endif
#define DEFAULT_SPARSE_CONVERT 0
#define DEFAULT_SPARSE_RATIO 2
#define DEFAULT_SPARSE_SAFE 10
#define DEFAULT_ENCODE_MAX_DEPTH 1000
#define DEFAULT_DECODE_MAX_DEPTH 1000
#define DEFAULT_ENCODE_INVALID_NUMBERS 0
#define DEFAULT_DECODE_INVALID_NUMBERS 1
#define DEFAULT_ENCODE_KEEP_BUFFER 1
#define DEFAULT_ENCODE_NUMBER_PRECISION 14
#define DEFAULT_ENCODE_EMPTY_TABLE_AS_ARRAY 0
#ifdef DISABLE_INVALID_NUMBERS
#undef DEFAULT_DECODE_INVALID_NUMBERS
#define DEFAULT_DECODE_INVALID_NUMBERS 0
#endif
typedef enum {
T_OBJ_BEGIN,
T_OBJ_END,
T_ARR_BEGIN,
T_ARR_END,
T_STRING,
T_NUMBER,
T_INTEGER,
T_BOOLEAN,
T_NULL,
T_COLON,
T_COMMA,
T_END,
T_WHITESPACE,
T_ERROR,
T_UNKNOWN
} json_token_type_t;
static const char *json_token_type_name[] = {
"T_OBJ_BEGIN",
"T_OBJ_END",
"T_ARR_BEGIN",
"T_ARR_END",
"T_STRING",
"T_NUMBER",
"T_INTEGER",
"T_BOOLEAN",
"T_NULL",
"T_COLON",
"T_COMMA",
"T_END",
"T_WHITESPACE",
"T_ERROR",
"T_UNKNOWN",
NULL
};
typedef struct {
json_token_type_t ch2token[256];
char escape2char[256]; /* Decoding */
/* encode_buf is only allocated and used when
* encode_keep_buffer is set */
strbuf_t encode_buf;
int encode_sparse_convert;
int encode_sparse_ratio;
int encode_sparse_safe;
int encode_max_depth;
int encode_invalid_numbers; /* 2 => Encode as "null" */
int encode_number_precision;
int encode_keep_buffer;
int encode_empty_table_as_array;
int decode_invalid_numbers;
int decode_max_depth;
} json_config_t;
typedef struct {
const char *data;
const char *ptr;
strbuf_t *tmp; /* Temporary storage for strings */
json_config_t *cfg;
int current_depth;
} json_parse_t;
typedef struct {
json_token_type_t type;
int index;
union {
const char *string;
double number;
lua_Integer integer;
int boolean;
} value;
int string_len;
} json_token_t;
static const char *char2escape[256] = {
"\\u0000", "\\u0001", "\\u0002", "\\u0003",
"\\u0004", "\\u0005", "\\u0006", "\\u0007",
"\\b", "\\t", "\\n", "\\u000b",
"\\f", "\\r", "\\u000e", "\\u000f",
"\\u0010", "\\u0011", "\\u0012", "\\u0013",
"\\u0014", "\\u0015", "\\u0016", "\\u0017",
"\\u0018", "\\u0019", "\\u001a", "\\u001b",
"\\u001c", "\\u001d", "\\u001e", "\\u001f",
NULL, NULL, "\\\"", NULL, NULL, NULL, NULL, NULL,
NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
NULL, NULL, NULL, NULL, "\\\\", NULL, NULL, NULL,
NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
NULL, NULL, NULL, NULL, NULL, NULL, NULL, "\\u007f",
NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
};
/* ===== CONFIGURATION ===== */
static json_config_t *json_fetch_config(lua_State *l)
{
json_config_t *cfg;
cfg = (json_config_t *)lua_touserdata(l, lua_upvalueindex(1));
if (!cfg)
luaL_error(l, "BUG: Unable to fetch CJSON configuration");
return cfg;
}
/* Ensure the correct number of arguments have been provided.
* Pad with nil to allow other functions to simply check arg[i]
* to find whether an argument was provided */
static json_config_t *json_arg_init(lua_State *l, int args)
{
luaL_argcheck(l, lua_gettop(l) <= args, args + 1,
"found too many arguments");
while (lua_gettop(l) < args)
lua_pushnil(l);
return json_fetch_config(l);
}
/* Process integer options for configuration functions */
static int json_integer_option(lua_State *l, int optindex, int *setting,
int min, int max)
{
char errmsg[64];
int value;
if (!lua_isnil(l, optindex)) {
value = luaL_checkinteger(l, optindex);
snprintf(errmsg, sizeof(errmsg), "expected integer between %d and %d", min, max);
luaL_argcheck(l, min <= value && value <= max, 1, errmsg);
*setting = value;
}
lua_pushinteger(l, *setting);
return 1;
}
/* Process enumerated arguments for a configuration function */
static int json_enum_option(lua_State *l, int optindex, int *setting,
const char **options, int bool_true)
{
static const char *bool_options[] = { "off", "on", NULL };
if (!options) {
options = bool_options;
bool_true = 1;
}
if (!lua_isnil(l, optindex)) {
if (bool_true && lua_isboolean(l, optindex))
*setting = lua_toboolean(l, optindex) * bool_true;
else
*setting = luaL_checkoption(l, optindex, NULL, options);
}
if (bool_true && (*setting == 0 || *setting == bool_true))
lua_pushboolean(l, *setting);
else
lua_pushstring(l, options[*setting]);
return 1;
}
/* Configures handling of extremely sparse arrays:
* convert: Convert extremely sparse arrays into objects? Otherwise error.
* ratio: 0: always allow sparse; 1: never allow sparse; >1: use ratio
* safe: Always use an array when the max index <= safe */
static int json_cfg_encode_sparse_array(lua_State *l)
{
json_config_t *cfg = json_arg_init(l, 3);
json_enum_option(l, 1, &cfg->encode_sparse_convert, NULL, 1);
json_integer_option(l, 2, &cfg->encode_sparse_ratio, 0, INT_MAX);
json_integer_option(l, 3, &cfg->encode_sparse_safe, 0, INT_MAX);
return 3;
}
/* Configures the maximum number of nested arrays/objects allowed when
* encoding */
static int json_cfg_encode_max_depth(lua_State *l)
{
json_config_t *cfg = json_arg_init(l, 1);
return json_integer_option(l, 1, &cfg->encode_max_depth, 1, INT_MAX);
}
/* Configures the maximum number of nested arrays/objects allowed when
* encoding */
static int json_cfg_decode_max_depth(lua_State *l)
{
json_config_t *cfg = json_arg_init(l, 1);
return json_integer_option(l, 1, &cfg->decode_max_depth, 1, INT_MAX);
}
/* Configures number precision when converting doubles to text */
static int json_cfg_encode_number_precision(lua_State *l)
{
json_config_t *cfg = json_arg_init(l, 1);
return json_integer_option(l, 1, &cfg->encode_number_precision, 1, 14);
}
/* Configures JSON encoding buffer persistence */
static int json_cfg_encode_keep_buffer(lua_State *l)
{
json_config_t *cfg = json_arg_init(l, 1);
int old_value;
old_value = cfg->encode_keep_buffer;
json_enum_option(l, 1, &cfg->encode_keep_buffer, NULL, 1);
/* Init / free the buffer if the setting has changed */
if (old_value ^ cfg->encode_keep_buffer) {
if (cfg->encode_keep_buffer)
strbuf_init(&cfg->encode_buf, 0);
else
strbuf_free(&cfg->encode_buf);
}
return 1;
}
#if defined(DISABLE_INVALID_NUMBERS) && !defined(USE_INTERNAL_FPCONV)
void json_verify_invalid_number_setting(lua_State *l, int *setting)
{
if (*setting == 1) {
*setting = 0;
luaL_error(l, "Infinity, NaN, and/or hexadecimal numbers are not supported.");
}
}
#else
#define json_verify_invalid_number_setting(l, s) do { } while(0)
#endif
static int json_cfg_encode_invalid_numbers(lua_State *l)
{
static const char *options[] = { "off", "on", "null", NULL };
json_config_t *cfg = json_arg_init(l, 1);
json_enum_option(l, 1, &cfg->encode_invalid_numbers, options, 1);
json_verify_invalid_number_setting(l, &cfg->encode_invalid_numbers);
return 1;
}
static int json_cfg_decode_invalid_numbers(lua_State *l)
{
json_config_t *cfg = json_arg_init(l, 1);
json_enum_option(l, 1, &cfg->decode_invalid_numbers, NULL, 1);
json_verify_invalid_number_setting(l, &cfg->encode_invalid_numbers);
return 1;
}
static int json_cfg_encode_empty_tables_as_array(lua_State *l)
{
json_config_t *cfg = json_arg_init(l, 1);
return json_enum_option(l, 1, &cfg->encode_empty_table_as_array, NULL, 1);
}
static int json_destroy_config(lua_State *l)
{
json_config_t *cfg;
cfg = (json_config_t *)lua_touserdata(l, 1);
if (cfg)
strbuf_free(&cfg->encode_buf);
cfg = NULL;
return 0;
}
static void json_create_config(lua_State *l)
{
json_config_t *cfg;
int i;
cfg = (json_config_t *)lua_newuserdata(l, sizeof(*cfg));
/* Create GC method to clean up strbuf */
lua_newtable(l);
lua_pushcfunction(l, json_destroy_config);
lua_setfield(l, -2, "__gc");
lua_setmetatable(l, -2);
cfg->encode_sparse_convert = DEFAULT_SPARSE_CONVERT;
cfg->encode_sparse_ratio = DEFAULT_SPARSE_RATIO;
cfg->encode_sparse_safe = DEFAULT_SPARSE_SAFE;
cfg->encode_max_depth = DEFAULT_ENCODE_MAX_DEPTH;
cfg->decode_max_depth = DEFAULT_DECODE_MAX_DEPTH;
cfg->encode_invalid_numbers = DEFAULT_ENCODE_INVALID_NUMBERS;
cfg->decode_invalid_numbers = DEFAULT_DECODE_INVALID_NUMBERS;
cfg->encode_keep_buffer = DEFAULT_ENCODE_KEEP_BUFFER;
cfg->encode_number_precision = DEFAULT_ENCODE_NUMBER_PRECISION;
cfg->encode_empty_table_as_array = DEFAULT_ENCODE_EMPTY_TABLE_AS_ARRAY;
#if DEFAULT_ENCODE_KEEP_BUFFER > 0
strbuf_init(&cfg->encode_buf, 0);
#endif
/* Decoding init */
/* Tag all characters as an error */
for (i = 0; i < 256; i++)
cfg->ch2token[i] = T_ERROR;
/* Set tokens that require no further processing */
cfg->ch2token['{'] = T_OBJ_BEGIN;
cfg->ch2token['}'] = T_OBJ_END;
cfg->ch2token['['] = T_ARR_BEGIN;
cfg->ch2token[']'] = T_ARR_END;
cfg->ch2token[','] = T_COMMA;
cfg->ch2token[':'] = T_COLON;
cfg->ch2token['\0'] = T_END;
cfg->ch2token[' '] = T_WHITESPACE;
cfg->ch2token['\t'] = T_WHITESPACE;
cfg->ch2token['\n'] = T_WHITESPACE;
cfg->ch2token['\r'] = T_WHITESPACE;
/* Update characters that require further processing */
cfg->ch2token['f'] = T_UNKNOWN; /* false? */
cfg->ch2token['i'] = T_UNKNOWN; /* inf, ininity? */
cfg->ch2token['I'] = T_UNKNOWN;
cfg->ch2token['n'] = T_UNKNOWN; /* null, nan? */
cfg->ch2token['N'] = T_UNKNOWN;
cfg->ch2token['t'] = T_UNKNOWN; /* true? */
cfg->ch2token['"'] = T_UNKNOWN; /* string? */
cfg->ch2token['+'] = T_UNKNOWN; /* number? */
cfg->ch2token['-'] = T_UNKNOWN;
for (i = 0; i < 10; i++)
cfg->ch2token['0' + i] = T_UNKNOWN;
/* Lookup table for parsing escape characters */
for (i = 0; i < 256; i++)
cfg->escape2char[i] = 0; /* String error */
cfg->escape2char['"'] = '"';
cfg->escape2char['\\'] = '\\';
cfg->escape2char['/'] = '/';
cfg->escape2char['b'] = '\b';
cfg->escape2char['t'] = '\t';
cfg->escape2char['n'] = '\n';
cfg->escape2char['f'] = '\f';
cfg->escape2char['r'] = '\r';
cfg->escape2char['u'] = 'u'; /* Unicode parsing required */
}
/* ===== ENCODING ===== */
static void json_encode_exception(lua_State *l, json_config_t *cfg, strbuf_t *json, int lindex,
const char *reason)
{
if (!cfg->encode_keep_buffer)
strbuf_free(json);
luaL_error(l, "Cannot serialise %s: %s",
lua_typename(l, lua_type(l, lindex)), reason);
}
/* json_append_string args:
* - lua_State
* - JSON strbuf
* - String (Lua stack index)
*
* Returns nothing. Doesn't remove string from Lua stack */
static void json_append_string(lua_State *l, strbuf_t *json, int lindex)
{
const char *escstr;
const char *str;
size_t len;
size_t i;
str = lua_tolstring(l, lindex, &len);
/* Worst case is len * 6 (all unicode escapes).
* This buffer is reused constantly for small strings
* If there are any excess pages, they won't be hit anyway.
* This gains ~5% speedup. */
strbuf_ensure_empty_length(json, len * 6 + 2);
strbuf_append_char_unsafe(json, '\"');
for (i = 0; i < len; i++) {
escstr = char2escape[(unsigned char)str[i]];
if (escstr)
strbuf_append_string(json, escstr);
else
strbuf_append_char_unsafe(json, str[i]);
}
strbuf_append_char_unsafe(json, '\"');
}
/* Find the size of the array on the top of the Lua stack
* -1 object (not a pure array)
* >=0 elements in array
*/
static int lua_array_length(lua_State *l, json_config_t *cfg, strbuf_t *json)
{
double k;
int max;
int items;
max = 0;
items = 0;
lua_pushnil(l);
/* table, startkey */
while (lua_next(l, -2) != 0) {
/* table, key, value */
if (lua_type(l, -2) == LUA_TNUMBER &&
(k = lua_tonumber(l, -2))) {
/* Integer >= 1 ? */
if (floor(k) == k && k >= 1) {
if (k > max)
max = k;
items++;
lua_pop(l, 1);
continue;
}
}
/* Must not be an array (non integer key) */
lua_pop(l, 2);
return -1;
}
/* Encode excessively sparse arrays as objects (if enabled) */
if (cfg->encode_sparse_ratio > 0 &&
max > items * cfg->encode_sparse_ratio &&
max > cfg->encode_sparse_safe) {
if (!cfg->encode_sparse_convert)
json_encode_exception(l, cfg, json, -1, "excessively sparse array");
return -1;
}
return max;
}
static void json_check_encode_depth(lua_State *l, json_config_t *cfg,
int current_depth, strbuf_t *json)
{
/* Ensure there are enough slots free to traverse a table (key,
* value) and push a string for a potential error message.
*
* Unlike "decode", the key and value are still on the stack when
* lua_checkstack() is called. Hence an extra slot for luaL_error()
* below is required just in case the next check to lua_checkstack()
* fails.
*
* While this won't cause a crash due to the EXTRA_STACK reserve
* slots, it would still be an improper use of the API. */
if (current_depth <= cfg->encode_max_depth && lua_checkstack(l, 3))
return;
if (!cfg->encode_keep_buffer)
strbuf_free(json);
luaL_error(l, "Cannot serialise, excessive nesting (%d)",
current_depth);
}
static void json_append_data(lua_State *l, json_config_t *cfg,
int current_depth, strbuf_t *json);
/* json_append_array args:
* - lua_State
* - JSON strbuf
* - Size of passwd Lua array (top of stack) */
static void json_append_array(lua_State *l, json_config_t *cfg, int current_depth,
strbuf_t *json, int array_length)
{
int comma, i;
strbuf_append_char(json, '[');
comma = 0;
for (i = 1; i <= array_length; i++) {
if (comma)
strbuf_append_char(json, ',');
else
comma = 1;
lua_rawgeti(l, -1, i);
json_append_data(l, cfg, current_depth, json);
lua_pop(l, 1);
}
strbuf_append_char(json, ']');
}
static void json_append_number(lua_State *l, json_config_t *cfg,
strbuf_t *json, int lindex)
{
int len;
#if LUA_VERSION_NUM >= 503
if (lua_isinteger(l, lindex)) {
lua_Integer num = lua_tointeger(l, lindex);
strbuf_ensure_empty_length(json, FPCONV_G_FMT_BUFSIZE); /* max length of int64 is 19 */
len = sprintf(strbuf_empty_ptr(json), LUA_INTEGER_FMT, num);
strbuf_extend_length(json, len);
return;
}
#endif
double num = lua_tonumber(l, lindex);
if (cfg->encode_invalid_numbers == 0) {
/* Prevent encoding invalid numbers */
if (isinf(num) || isnan(num))
json_encode_exception(l, cfg, json, lindex,
"must not be NaN or Infinity");
} else if (cfg->encode_invalid_numbers == 1) {
/* Encode NaN/Infinity separately to ensure Javascript compatible
* values are used. */
if (isnan(num)) {
strbuf_append_mem(json, "NaN", 3);
return;
}
if (isinf(num)) {
if (num < 0)
strbuf_append_mem(json, "-Infinity", 9);
else
strbuf_append_mem(json, "Infinity", 8);
return;
}
} else {
/* Encode invalid numbers as "null" */
if (isinf(num) || isnan(num)) {
strbuf_append_mem(json, "null", 4);
return;
}
}
strbuf_ensure_empty_length(json, FPCONV_G_FMT_BUFSIZE);
len = fpconv_g_fmt(strbuf_empty_ptr(json), num, cfg->encode_number_precision);
strbuf_extend_length(json, len);
}
static void json_append_object(lua_State *l, json_config_t *cfg,
int current_depth, strbuf_t *json)
{
int comma, keytype;
/* Object */
strbuf_append_char(json, '{');
lua_pushnil(l);
/* table, startkey */
comma = 0;
while (lua_next(l, -2) != 0) {
if (comma)
strbuf_append_char(json, ',');
else
comma = 1;
/* table, key, value */
keytype = lua_type(l, -2);
if (keytype == LUA_TNUMBER) {
strbuf_append_char(json, '"');
json_append_number(l, cfg, json, -2);
strbuf_append_mem(json, "\":", 2);
} else if (keytype == LUA_TSTRING) {
json_append_string(l, json, -2);
strbuf_append_char(json, ':');
} else {
json_encode_exception(l, cfg, json, -2,
"table key must be a number or string");
/* never returns */
}
/* table, key, value */
json_append_data(l, cfg, current_depth, json);
lua_pop(l, 1);
/* table, key */
}
strbuf_append_char(json, '}');
}
/* Serialise Lua data into JSON string. */
static void json_append_data(lua_State *l, json_config_t *cfg,
int current_depth, strbuf_t *json)
{
int len;
switch (lua_type(l, -1)) {
case LUA_TSTRING:
json_append_string(l, json, -1);
break;
case LUA_TNUMBER:
json_append_number(l, cfg, json, -1);
break;
case LUA_TBOOLEAN:
if (lua_toboolean(l, -1))
strbuf_append_mem(json, "true", 4);
else
strbuf_append_mem(json, "false", 5);
break;
case LUA_TTABLE:
current_depth++;
json_check_encode_depth(l, cfg, current_depth, json);
if (luaL_getmetafield(l, -1, "__len") != LUA_TNIL) {
lua_pushvalue(l, -2);
lua_call(l, 1, 1);
if (!lua_isinteger(l, -1)) {
luaL_error(l, "__len should return integer");
}
len = lua_tointeger(l, -1);
lua_pop(l, 1);
json_append_array(l, cfg, current_depth, json, len);
} else {
len = lua_array_length(l, cfg, json);
if (len > 0 || (cfg->encode_empty_table_as_array && len == 0))
json_append_array(l, cfg, current_depth, json, len);
else
json_append_object(l, cfg, current_depth, json);
}
break;
case LUA_TNIL:
strbuf_append_mem(json, "null", 4);
break;
case LUA_TLIGHTUSERDATA:
if (lua_touserdata(l, -1) == NULL) {
strbuf_append_mem(json, "null", 4);
break;
}
default:
/* Remaining types (LUA_TFUNCTION, LUA_TUSERDATA, LUA_TTHREAD,
* and LUA_TLIGHTUSERDATA) cannot be serialised */
json_encode_exception(l, cfg, json, -1, "type not supported");
/* never returns */
}
}
static int json_encode(lua_State *l)
{
json_config_t *cfg = json_fetch_config(l);
strbuf_t local_encode_buf;
strbuf_t *encode_buf;
char *json;
int len;
luaL_argcheck(l, lua_gettop(l) == 1, 1, "expected 1 argument");
if (!cfg->encode_keep_buffer) {
/* Use private buffer */
encode_buf = &local_encode_buf;
strbuf_init(encode_buf, 0);
} else {
/* Reuse existing buffer */
encode_buf = &cfg->encode_buf;
strbuf_reset(encode_buf);
}
json_append_data(l, cfg, 0, encode_buf);
json = strbuf_string(encode_buf, &len);
lua_pushlstring(l, json, len);
if (!cfg->encode_keep_buffer)
strbuf_free(encode_buf);
return 1;
}
/* ===== DECODING ===== */
static void json_process_value(lua_State *l, json_parse_t *json,
json_token_t *token);
static int hexdigit2int(char hex)
{
if ('0' <= hex && hex <= '9')
return hex - '0';
/* Force lowercase */
hex |= 0x20;
if ('a' <= hex && hex <= 'f')
return 10 + hex - 'a';
return -1;
}
static int decode_hex4(const char *hex)
{
int digit[4];
int i;
/* Convert ASCII hex digit to numeric digit
* Note: this returns an error for invalid hex digits, including
* NULL */
for (i = 0; i < 4; i++) {
digit[i] = hexdigit2int(hex[i]);
if (digit[i] < 0) {
return -1;
}
}
return (digit[0] << 12) +
(digit[1] << 8) +
(digit[2] << 4) +
digit[3];
}
/* Converts a Unicode codepoint to UTF-8.
* Returns UTF-8 string length, and up to 4 bytes in *utf8 */
static int codepoint_to_utf8(char *utf8, int codepoint)
{
/* 0xxxxxxx */
if (codepoint <= 0x7F) {
utf8[0] = codepoint;
return 1;
}
/* 110xxxxx 10xxxxxx */
if (codepoint <= 0x7FF) {
utf8[0] = (codepoint >> 6) | 0xC0;
utf8[1] = (codepoint & 0x3F) | 0x80;
return 2;
}
/* 1110xxxx 10xxxxxx 10xxxxxx */
if (codepoint <= 0xFFFF) {
utf8[0] = (codepoint >> 12) | 0xE0;
utf8[1] = ((codepoint >> 6) & 0x3F) | 0x80;
utf8[2] = (codepoint & 0x3F) | 0x80;
return 3;
}
/* 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx */
if (codepoint <= 0x1FFFFF) {
utf8[0] = (codepoint >> 18) | 0xF0;
utf8[1] = ((codepoint >> 12) & 0x3F) | 0x80;
utf8[2] = ((codepoint >> 6) & 0x3F) | 0x80;
utf8[3] = (codepoint & 0x3F) | 0x80;
return 4;
}
return 0;
}
/* Called when index pointing to beginning of UTF-16 code escape: \uXXXX
* \u is guaranteed to exist, but the remaining hex characters may be
* missing.
* Translate to UTF-8 and append to temporary token string.
* Must advance index to the next character to be processed.
* Returns: 0 success
* -1 error
*/
static int json_append_unicode_escape(json_parse_t *json)
{
char utf8[4]; /* Surrogate pairs require 4 UTF-8 bytes */
int codepoint;
int surrogate_low;
int len;
int escape_len = 6;
/* Fetch UTF-16 code unit */
codepoint = decode_hex4(json->ptr + 2);
if (codepoint < 0)
return -1;
/* UTF-16 surrogate pairs take the following 2 byte form:
* 11011 x yyyyyyyyyy
* When x = 0: y is the high 10 bits of the codepoint
* x = 1: y is the low 10 bits of the codepoint
*
* Check for a surrogate pair (high or low) */
if ((codepoint & 0xF800) == 0xD800) {
/* Error if the 1st surrogate is not high */
if (codepoint & 0x400)
return -1;
/* Ensure the next code is a unicode escape */
if (*(json->ptr + escape_len) != '\\' ||
*(json->ptr + escape_len + 1) != 'u') {
return -1;
}
/* Fetch the next codepoint */
surrogate_low = decode_hex4(json->ptr + 2 + escape_len);
if (surrogate_low < 0)
return -1;
/* Error if the 2nd code is not a low surrogate */
if ((surrogate_low & 0xFC00) != 0xDC00)
return -1;
/* Calculate Unicode codepoint */
codepoint = (codepoint & 0x3FF) << 10;
surrogate_low &= 0x3FF;
codepoint = (codepoint | surrogate_low) + 0x10000;
escape_len = 12;
}
/* Convert codepoint to UTF-8 */
len = codepoint_to_utf8(utf8, codepoint);
if (!len)
return -1;
/* Append bytes and advance parse index */
strbuf_append_mem_unsafe(json->tmp, utf8, len);
json->ptr += escape_len;
return 0;
}
static void json_set_token_error(json_token_t *token, json_parse_t *json,
const char *errtype)
{
token->type = T_ERROR;
token->index = json->ptr - json->data;
token->value.string = errtype;
}
static void json_next_string_token(json_parse_t *json, json_token_t *token)
{
char *escape2char = json->cfg->escape2char;
char ch;
/* Caller must ensure a string is next */
assert(*json->ptr == '"');
/* Skip " */
json->ptr++;
/* json->tmp is the temporary strbuf used to accumulate the
* decoded string value.
* json->tmp is sized to handle JSON containing only a string value.
*/
strbuf_reset(json->tmp);
while ((ch = *json->ptr) != '"') {
if (!ch) {
/* Premature end of the string */
json_set_token_error(token, json, "unexpected end of string");
return;
}
/* Handle escapes */
if (ch == '\\') {
/* Fetch escape character */
ch = *(json->ptr + 1);
/* Translate escape code and append to tmp string */
ch = escape2char[(unsigned char)ch];
if (ch == 'u') {
if (json_append_unicode_escape(json) == 0)
continue;
json_set_token_error(token, json,
"invalid unicode escape code");
return;
}
if (!ch) {
json_set_token_error(token, json, "invalid escape code");
return;
}
/* Skip '\' */
json->ptr++;
}
/* Append normal character or translated single character
* Unicode escapes are handled above */
strbuf_append_char_unsafe(json->tmp, ch);
json->ptr++;
}
json->ptr++; /* Eat final quote (") */
strbuf_ensure_null(json->tmp);
token->type = T_STRING;
token->value.string = strbuf_string(json->tmp, &token->string_len);
}
/* JSON numbers should take the following form:
* -?(0|[1-9]|[1-9][0-9]+)(.[0-9]+)?([eE][-+]?[0-9]+)?
*
* json_next_number_token() uses strtod() which allows other forms:
* - numbers starting with '+'
* - NaN, -NaN, infinity, -infinity
* - hexadecimal numbers
* - numbers with leading zeros
*
* json_is_invalid_number() detects "numbers" which may pass strtod()'s
* error checking, but should not be allowed with strict JSON.
*