webmcp

annotate libraries/json/json.c @ 142:a686ed2ce967

find changesets by author, revision, files, or words in the commit message
Protect json.import(...) against Lua stack overflows (or integer overflows) due to too many nested levels
author jbe
date Wed Jul 30 02:01:24 2014 +0200 (2014-07-30)
parents ca27aae3f1a1
children 6f723e60acdc
rev   line source
jbe@121 1 #include <lua.h>
jbe@121 2 #include <lauxlib.h>
jbe@122 3 #include <stdlib.h>
jbe@121 4 #include <string.h>
jbe@121 5
jbe@142 6 #define JSON_MAXDEPTH 100
jbe@142 7
jbe@138 8 #define JSON_REGENT static char
jbe@138 9 #define JSON_REGREF void *
jbe@138 10
jbe@138 11 JSON_REGENT json_nullmark;
jbe@138 12 JSON_REGENT json_shadowtbl;
jbe@138 13 JSON_REGENT json_unknownmt;
jbe@138 14 JSON_REGENT json_objectmt;
jbe@138 15 JSON_REGENT json_arraymt;
jbe@138 16
jbe@138 17 #define json_regfetch(L, x) (lua_pushlightuserdata((L), &(x)), lua_rawget((L), LUA_REGISTRYINDEX))
jbe@138 18
jbe@138 19 #define json_regstore(L, x) (lua_pushlightuserdata(L, &(x)), lua_pushvalue(L, -2), lua_rawset(L, LUA_REGISTRYINDEX));
jbe@138 20
jbe@136 21 // marks a table as JSON object or JSON array:
jbe@136 22 // (returns its modified argument or a new table if argument is nil)
jbe@138 23 static int json_mark(lua_State *L, JSON_REGREF mt) {
jbe@136 24 // if argument is nil, then create new table:
jbe@136 25 if (lua_isnoneornil(L, 1)) {
jbe@136 26 lua_settop(L, 0);
jbe@136 27 lua_newtable(L);
jbe@136 28 // skip testing of existing shadow table:
jbe@136 29 goto json_object_create_shadow_table;
jbe@136 30 }
jbe@138 31 // check if shadow table already exists:
jbe@138 32 json_regfetch(L, json_shadowtbl);
jbe@136 33 lua_pushvalue(L, 1);
jbe@138 34 lua_rawget(L, -2);
jbe@136 35 if (lua_isnil(L, -1)) {
jbe@136 36 json_object_create_shadow_table:
jbe@136 37 // set shadow table:
jbe@136 38 lua_pushvalue(L, 1);
jbe@136 39 lua_newtable(L);
jbe@138 40 lua_rawset(L, -4);
jbe@136 41 }
jbe@138 42 // discard everything but table to return:
jbe@138 43 lua_settop(L, 1);
jbe@136 44 // set metatable:
jbe@138 45 json_regfetch(L, mt);
jbe@136 46 lua_setmetatable(L, 1);
jbe@138 47 // return table:
jbe@136 48 return 1;
jbe@136 49 }
jbe@136 50
jbe@136 51 // marks a table as JSON object:
jbe@136 52 // (returns its modified argument or a new table if argument is nil)
jbe@136 53 static int json_object(lua_State *L) {
jbe@138 54 return json_mark(L, &json_objectmt);
jbe@136 55 }
jbe@136 56
jbe@136 57 // marks a table as JSON array:
jbe@136 58 // (returns its modified argument or a new table if argument is nil)
jbe@136 59 static int json_array(lua_State *L) {
jbe@138 60 return json_mark(L, &json_arraymt);
jbe@136 61 }
jbe@136 62
jbe@124 63 #define JSON_STATE_VALUE 0
jbe@124 64 #define JSON_STATE_OBJECT_KEY 1
jbe@124 65 #define JSON_STATE_OBJECT_KEY_TERMINATOR 2
jbe@124 66 #define JSON_STATE_OBJECT_VALUE 3
jbe@124 67 #define JSON_STATE_OBJECT_SEPARATOR 4
jbe@124 68 #define JSON_STATE_ARRAY_VALUE 5
jbe@124 69 #define JSON_STATE_ARRAY_SEPARATOR 6
jbe@124 70 #define JSON_STATE_END 7
jbe@121 71
jbe@138 72 #define json_import_objectmt_idx 2
jbe@138 73 #define json_import_arraymt_idx 3
jbe@138 74 #define json_import_shadowtbl_idx 4
jbe@138 75 #define json_import_nullmark_idx 5
jbe@138 76
jbe@136 77 // decodes a JSON document:
jbe@121 78 static int json_import(lua_State *L) {
jbe@136 79 const char *str; // string to parse
jbe@136 80 size_t total; // total length of string to parse
jbe@136 81 size_t pos = 0; // current position in string to parse
jbe@136 82 size_t level = 0; // nested levels of objects/arrays currently being processed
jbe@136 83 int mode = JSON_STATE_VALUE; // state of parser
jbe@136 84 char c; // variable to store a single character to be processed
jbe@136 85 luaL_Buffer luabuf; // Lua buffer to decode (possibly escaped) strings
jbe@136 86 char *cbuf; // C buffer to decode (possibly escaped) strings
jbe@136 87 size_t writepos; // write position of decoded strings in C buffer
jbe@138 88 // limit stack to 1 element:
jbe@138 89 lua_settop(L, 1);
jbe@138 90 // push json_objectmt on stack position 2:
jbe@138 91 json_regfetch(L, json_objectmt);
jbe@138 92 // push json_arraymt on stack position 3:
jbe@138 93 json_regfetch(L, json_arraymt);
jbe@138 94 // push json_shadowtbl on stack position 4:
jbe@138 95 json_regfetch(L, json_shadowtbl);
jbe@138 96 // push json_nullmark on stack position 5:
jbe@138 97 json_regfetch(L, json_nullmark);
jbe@136 98 // require string as first argument:
jbe@136 99 str = luaL_checklstring(L, 1, &total);
jbe@136 100 // if string contains a NULL byte, this is a syntax error
jbe@136 101 if (strlen(str) != total) goto json_import_syntax_error;
jbe@136 102 // main loop of parser:
jbe@136 103 json_import_loop:
jbe@136 104 // skip whitespace and store next character in variable 'c':
jbe@121 105 while (c = str[pos], c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == '\f') pos++;
jbe@136 106 // switch statement to handle certain (single) characters:
jbe@121 107 switch (c) {
jbe@136 108 // handle end of JSON document:
jbe@121 109 case 0:
jbe@136 110 // if end of JSON document was expected, then return top element of stack as result:
jbe@124 111 if (mode == JSON_STATE_END) return 1;
jbe@136 112 // otherwise, the JSON document was malformed:
jbe@121 113 json_import_unexpected_eof:
jbe@121 114 lua_pushnil(L);
jbe@121 115 if (level == 0) lua_pushliteral(L, "Empty string");
jbe@121 116 else lua_pushliteral(L, "Unexpected end of JSON document");
jbe@121 117 return 2;
jbe@136 118 // new JSON object:
jbe@121 119 case '{':
jbe@136 120 // if a JSON object is not expected here, then return an error:
jbe@124 121 if (mode != JSON_STATE_VALUE && mode != JSON_STATE_OBJECT_VALUE && mode != JSON_STATE_ARRAY_VALUE)
jbe@121 122 goto json_import_syntax_error;
jbe@136 123 // create JSON object on stack:
jbe@136 124 lua_newtable(L);
jbe@136 125 // set metatable of JSON object:
jbe@138 126 lua_pushvalue(L, json_import_objectmt_idx);
jbe@125 127 lua_setmetatable(L, -2);
jbe@136 128 // create internal shadow table on stack:
jbe@136 129 lua_newtable(L);
jbe@138 130 // register internal shadow table (and cleanup stack afterwards):
jbe@123 131 lua_pushvalue(L, -2);
jbe@123 132 lua_pushvalue(L, -2);
jbe@138 133 lua_rawset(L, json_import_shadowtbl_idx);
jbe@136 134 // expect object key (or end of object) and continue with loop:
jbe@136 135 mode = JSON_STATE_OBJECT_KEY;
jbe@142 136 goto json_import_open;
jbe@136 137 // new JSON array:
jbe@121 138 case '[':
jbe@136 139 // if a JSON array is not expected here, then return an error:
jbe@124 140 if (mode != JSON_STATE_VALUE && mode != JSON_STATE_OBJECT_VALUE && mode != JSON_STATE_ARRAY_VALUE)
jbe@121 141 goto json_import_syntax_error;
jbe@136 142 // create JSON array on stack:
jbe@136 143 lua_newtable(L);
jbe@136 144 // set metatable of JSON array:
jbe@138 145 lua_pushvalue(L, json_import_arraymt_idx);
jbe@125 146 lua_setmetatable(L, -2);
jbe@136 147 // create internal shadow table on stack:
jbe@136 148 lua_newtable(L);
jbe@138 149 // register internal shadow table (and cleanup stack afterwards):
jbe@123 150 lua_pushvalue(L, -2);
jbe@123 151 lua_pushvalue(L, -2);
jbe@138 152 lua_rawset(L, json_import_shadowtbl_idx);
jbe@140 153 // add nil as key (needed to keep stack balance) and as magic to detect arrays:
jbe@140 154 lua_pushnil(L);
jbe@142 155 // expect array value (or end of array) and continue with loop:
jbe@142 156 mode = JSON_STATE_ARRAY_VALUE;
jbe@142 157 // continue with common code for opening JSON object and JSON array:
jbe@142 158 // commn code for opening JSON object or JSON array:
jbe@142 159 json_import_open:
jbe@142 160 // limit nested levels:
jbe@142 161 if (level >= JSON_MAXDEPTH) {
jbe@142 162 lua_pushnil(L);
jbe@142 163 lua_pushliteral(L, "Too many nested JSON levels");
jbe@142 164 return 2;
jbe@142 165 }
jbe@142 166 // additional buffer overflow protection:
jbe@142 167 if (!lua_checkstack(L, LUA_MINSTACK))
jbe@142 168 return luaL_error(L, "Caught stack overflow in JSON import function (too many nested levels and stack size too small)");
jbe@136 169 // increment level:
jbe@121 170 level++;
jbe@142 171 // consume input character:
jbe@142 172 pos++;
jbe@121 173 goto json_import_loop;
jbe@136 174 // end of JSON object:
jbe@121 175 case '}':
jbe@136 176 // if end of JSON object is not expected here, then return an error:
jbe@124 177 if (mode != JSON_STATE_OBJECT_KEY && mode != JSON_STATE_OBJECT_SEPARATOR)
jbe@121 178 goto json_import_syntax_error;
jbe@136 179 // jump to common code for end of JSON object and JSON array:
jbe@121 180 goto json_import_close;
jbe@136 181 // end of JSON array:
jbe@121 182 case ']':
jbe@136 183 // if end of JSON array is not expected here, then return an error:
jbe@124 184 if (mode != JSON_STATE_ARRAY_VALUE && mode != JSON_STATE_ARRAY_SEPARATOR)
jbe@121 185 goto json_import_syntax_error;
jbe@140 186 // pop nil key/magic:
jbe@140 187 lua_pop(L, 1);
jbe@136 188 // continue with common code for end of JSON object and JSON array:
jbe@136 189 // common code for end of JSON object or JSON array:
jbe@121 190 json_import_close:
jbe@136 191 // consume input character:
jbe@121 192 pos++;
jbe@136 193 // pop shadow table:
jbe@136 194 lua_pop(L, 1);
jbe@136 195 // check if nested:
jbe@121 196 if (--level) {
jbe@136 197 // if nested, then check if outer(!) structure is an array or object:
jbe@140 198 if (lua_isnil(L, -2)) {
jbe@136 199 // select array value processing:
jbe@124 200 mode = JSON_STATE_ARRAY_VALUE;
jbe@121 201 } else {
jbe@136 202 // select object value processing:
jbe@124 203 mode = JSON_STATE_OBJECT_VALUE;
jbe@121 204 }
jbe@136 205 // store value in outer structure:
jbe@121 206 goto json_import_process_value;
jbe@121 207 }
jbe@136 208 // if not nested, then expect end of JSON document and continue with loop:
jbe@136 209 mode = JSON_STATE_END;
jbe@121 210 goto json_import_loop;
jbe@136 211 // key terminator:
jbe@121 212 case ':':
jbe@136 213 // if key terminator is not expected here, then return an error:
jbe@124 214 if (mode != JSON_STATE_OBJECT_KEY_TERMINATOR)
jbe@121 215 goto json_import_syntax_error;
jbe@136 216 // consume input character:
jbe@121 217 pos++;
jbe@136 218 // set state of parser and continue with loop:
jbe@124 219 mode = JSON_STATE_OBJECT_VALUE;
jbe@121 220 goto json_import_loop;
jbe@136 221 // value terminator (NOTE: trailing comma at end of value or key-value list is tolerated by this parser)
jbe@121 222 case ',':
jbe@136 223 // change parser state accordingly:
jbe@124 224 if (mode == JSON_STATE_OBJECT_SEPARATOR) {
jbe@124 225 mode = JSON_STATE_OBJECT_KEY;
jbe@124 226 } else if (mode == JSON_STATE_ARRAY_SEPARATOR) {
jbe@124 227 mode = JSON_STATE_ARRAY_VALUE;
jbe@121 228 } else {
jbe@136 229 // if value terminator is not expected here, then return an error:
jbe@136 230 goto json_import_syntax_error;
jbe@121 231 }
jbe@136 232 // consume input character:
jbe@121 233 pos++;
jbe@136 234 // continue with loop:
jbe@121 235 goto json_import_loop;
jbe@136 236 // string literal:
jbe@121 237 case '"':
jbe@136 238 // prepare buffer to decode string (with maximum possible length) and set write position to zero:
jbe@121 239 cbuf = luaL_buffinitsize(L, &luabuf, total-pos);
jbe@121 240 writepos = 0;
jbe@136 241 // consume quote character:
jbe@121 242 pos++;
jbe@136 243 // read next character until encountering end quote:
jbe@121 244 while ((c = str[pos++]) != '"') {
jbe@121 245 if (c == 0) {
jbe@136 246 // handle unexpected end-of-string:
jbe@121 247 goto json_import_unexpected_eof;
jbe@121 248 } else if (c < 32 || c == 127) {
jbe@136 249 // do not allow ASCII control characters:
jbe@136 250 // NOTE: illegal UTF-8 sequences and extended control characters are not sanitized
jbe@136 251 // by this parser to allow different encodings than Unicode
jbe@121 252 lua_pushnil(L);
jbe@121 253 lua_pushliteral(L, "Unexpected control character in JSON string");
jbe@121 254 return 2;
jbe@121 255 } else if (c == '\\') {
jbe@136 256 // read next char after backslash escape:
jbe@121 257 c = str[pos++];
jbe@121 258 switch (c) {
jbe@136 259 // unexpected end-of-string:
jbe@121 260 case 0:
jbe@121 261 goto json_import_unexpected_eof;
jbe@136 262 // unescaping of quotation mark, slash, and backslash:
jbe@121 263 case '"':
jbe@121 264 case '/':
jbe@121 265 case '\\':
jbe@121 266 cbuf[writepos++] = c;
jbe@121 267 break;
jbe@136 268 // unescaping of backspace:
jbe@121 269 case 'b':
jbe@121 270 cbuf[writepos++] = '\b';
jbe@121 271 break;
jbe@136 272 // unescaping of form-feed:
jbe@121 273 case 'f':
jbe@121 274 cbuf[writepos++] = '\f';
jbe@121 275 break;
jbe@136 276 // unescaping of new-line:
jbe@121 277 case 'n':
jbe@121 278 cbuf[writepos++] = '\n';
jbe@121 279 break;
jbe@136 280 // unescaping of carriage-return:
jbe@121 281 case 'r':
jbe@121 282 cbuf[writepos++] = '\r';
jbe@121 283 break;
jbe@136 284 // unescaping of tabulator:
jbe@121 285 case 't':
jbe@121 286 cbuf[writepos++] = '\t';
jbe@121 287 break;
jbe@136 288 // unescaping of UTF-16 characters
jbe@121 289 case 'u':
jbe@121 290 lua_pushnil(L);
jbe@121 291 lua_pushliteral(L, "JSON unicode escape sequences are not implemented yet"); // TODO
jbe@121 292 return 2;
jbe@136 293 // unexpected escape sequence:
jbe@121 294 default:
jbe@121 295 lua_pushnil(L);
jbe@121 296 lua_pushliteral(L, "Unexpected string escape sequence in JSON document");
jbe@121 297 return 2;
jbe@121 298 }
jbe@121 299 } else {
jbe@136 300 // normal character:
jbe@121 301 cbuf[writepos++] = c;
jbe@121 302 }
jbe@121 303 }
jbe@136 304 // process buffer to Lua string:
jbe@121 305 luaL_pushresultsize(&luabuf, writepos);
jbe@136 306 // continue with processing of decoded string:
jbe@121 307 goto json_import_process_value;
jbe@121 308 }
jbe@136 309 // process values whose type is is not deducible from a single character:
jbe@136 310 if ((c >= '0' && c <= '9') || c == '-' || c == '+') {
jbe@136 311 // numbers:
jbe@122 312 char *endptr;
jbe@122 313 double numval;
jbe@122 314 numval = strtod(str+pos, &endptr);
jbe@122 315 if (endptr == str+pos) goto json_import_syntax_error;
jbe@122 316 pos += endptr - (str+pos);
jbe@122 317 lua_pushnumber(L, numval);
jbe@122 318 } else if (!strncmp(str+pos, "true", 4)) {
jbe@136 319 // consume 4 input characters for "true":
jbe@121 320 pos += 4;
jbe@136 321 // put Lua true value on stack:
jbe@136 322 lua_pushboolean(L, 1);
jbe@121 323 } else if (!strncmp(str+pos, "false", 5)) {
jbe@136 324 // consume 5 input characters for "false":
jbe@121 325 pos += 5;
jbe@136 326 // put Lua false value on stack:
jbe@136 327 lua_pushboolean(L, 0);
jbe@121 328 } else if (!strncmp(str+pos, "null", 4)) {
jbe@136 329 // consume 4 input characters for "null":
jbe@136 330 pos += 4;
jbe@136 331 // put special null-marker on stack:
jbe@138 332 lua_pushvalue(L, json_import_nullmark_idx);
jbe@121 333 } else {
jbe@136 334 // all other cases are a syntax error:
jbe@121 335 goto json_import_syntax_error;
jbe@121 336 }
jbe@136 337 // process a decoded value or key value pair (expected on top of Lua stack):
jbe@136 338 json_import_process_value:
jbe@121 339 switch (mode) {
jbe@136 340 // an object key has been read:
jbe@124 341 case JSON_STATE_OBJECT_KEY:
jbe@136 342 // if an object key is not a string, then this is a syntax error:
jbe@121 343 if (lua_type(L, -1) != LUA_TSTRING) goto json_import_syntax_error;
jbe@136 344 // expect key terminator and continue with loop:
jbe@124 345 mode = JSON_STATE_OBJECT_KEY_TERMINATOR;
jbe@121 346 goto json_import_loop;
jbe@136 347 // a key value pair has been read:
jbe@124 348 case JSON_STATE_OBJECT_VALUE:
jbe@136 349 // store key value pair in outer shadow table:
jbe@130 350 lua_rawset(L, -3);
jbe@136 351 // expect value terminator (or end of object) and continue with loop:
jbe@124 352 mode = JSON_STATE_OBJECT_SEPARATOR;
jbe@121 353 goto json_import_loop;
jbe@136 354 // an array value has been read:
jbe@124 355 case JSON_STATE_ARRAY_VALUE:
jbe@136 356 // store value in outer shadow table:
jbe@140 357 lua_rawseti(L, -3, lua_rawlen(L, -3) + 1);
jbe@136 358 // expect value terminator (or end of object) and continue with loop:
jbe@124 359 mode = JSON_STATE_ARRAY_SEPARATOR;
jbe@121 360 goto json_import_loop;
jbe@136 361 // a single value has been read:
jbe@124 362 case JSON_STATE_VALUE:
jbe@136 363 // leave value on top of stack, expect end of JSON document, and continue with loop:
jbe@124 364 mode = JSON_STATE_END;
jbe@121 365 goto json_import_loop;
jbe@121 366 }
jbe@136 367 // syntax error handling (only reachable by goto statement):
jbe@136 368 json_import_syntax_error:
jbe@121 369 lua_pushnil(L);
jbe@121 370 lua_pushliteral(L, "Syntax error in JSON document");
jbe@121 371 return 2;
jbe@121 372 }
jbe@121 373
jbe@138 374 #define json_path_shadowtbl_idx 1
jbe@138 375 #define json_path_nullmark_idx 2
jbe@138 376 #define json_path_idxshift 2
jbe@138 377
jbe@137 378 // gets a value or its type from a JSON document (first argument)
jbe@137 379 // optionally using a path (variable number of keys after first argument):
jbe@137 380 static int json_path(lua_State *L, int type_mode) {
jbe@138 381 int stacktop;
jbe@138 382 int idx = 2 + json_path_idxshift;
jbe@138 383 // insert json_shadowtbl on stack at position 1:
jbe@138 384 json_regfetch(L, json_shadowtbl);
jbe@138 385 lua_insert(L, 1);
jbe@138 386 // insert json_nullmark on stack at position 2:
jbe@138 387 json_regfetch(L, json_nullmark);
jbe@138 388 lua_insert(L, 2);
jbe@137 389 // store number of arguments:
jbe@138 390 stacktop = lua_gettop(L);
jbe@137 391 // follow path, starting with first argument as "current value":
jbe@138 392 lua_pushvalue(L, 1 + json_path_idxshift);
jbe@137 393 // process each "path key":
jbe@138 394 while (idx <= stacktop) {
jbe@137 395 // if "current value" is nil, then the path cannot be walked and nil is returned:
jbe@137 396 if (lua_isnil(L, -1)) return 1;
jbe@137 397 // try to get shadow table of "current value":
jbe@130 398 lua_pushvalue(L, -1);
jbe@138 399 lua_rawget(L, json_path_shadowtbl_idx);
jbe@126 400 if (lua_isnil(L, -1)) {
jbe@137 401 // if no shadow table is found,
jbe@137 402 // drop nil from stack:
jbe@126 403 lua_pop(L, 1);
jbe@130 404 if (lua_type(L, -1) == LUA_TTABLE) {
jbe@137 405 // if "current value" is a table,
jbe@137 406 // get "next value" using the "path key":
jbe@130 407 lua_pushvalue(L, idx++);
jbe@130 408 lua_gettable(L, -2);
jbe@130 409 } else {
jbe@137 410 // if "current value" is not a table,
jbe@137 411 // then the path cannot be walked and nil is returned:
jbe@130 412 lua_pushnil(L);
jbe@137 413 return 1;
jbe@130 414 }
jbe@130 415 } else {
jbe@137 416 // if a shadow table is found,
jbe@137 417 // set "current value" to its shadow table:
jbe@130 418 lua_replace(L, -2);
jbe@137 419 // get "next value" using the "path key":
jbe@130 420 lua_pushvalue(L, idx++);
jbe@130 421 lua_rawget(L, -2);
jbe@126 422 }
jbe@137 423 // the "next value" replaces the "current value":
jbe@130 424 lua_replace(L, -2);
jbe@126 425 }
jbe@137 426 if (!type_mode) {
jbe@137 427 // if a value (and not its type) was requested,
jbe@137 428 // check if value is the null-marker, and store nil on top of Lua stack in that case:
jbe@138 429 if (lua_rawequal(L, -1, json_path_nullmark_idx)) lua_pushnil(L);
jbe@137 430 } else {
jbe@137 431 // if the type was requested,
jbe@137 432 // check if value is the null-marker:
jbe@138 433 if (lua_rawequal(L, -1, json_path_nullmark_idx)) {
jbe@137 434 // if yes, store string "null" on top of Lua stack:
jbe@130 435 lua_pushliteral(L, "null");
jbe@137 436 } else {
jbe@137 437 // otherwise,
jbe@138 438 // check if metatable indicates "object" or "array":
jbe@138 439 if (lua_getmetatable(L, -1)) {
jbe@138 440 json_regfetch(L, json_objectmt);
jbe@138 441 if (lua_rawequal(L, -2, -1)) {
jbe@138 442 // return string "object":
jbe@138 443 lua_pushliteral(L, "object");
jbe@138 444 return 1;
jbe@138 445 }
jbe@138 446 json_regfetch(L, json_arraymt);
jbe@138 447 if (lua_rawequal(L, -3, -1)) {
jbe@138 448 // return string "array":
jbe@138 449 lua_pushliteral(L, "array");
jbe@138 450 return 1;
jbe@138 451 }
jbe@138 452 lua_pop(L, 3);
jbe@138 453 }
jbe@138 454 // otherwise, get the Lua type:
jbe@138 455 lua_pushstring(L, lua_typename(L, lua_type(L, -1)));
jbe@126 456 }
jbe@126 457 }
jbe@137 458 // return the top most value on the Lua stack:
jbe@137 459 return 1;
jbe@130 460 }
jbe@130 461
jbe@137 462 // gets a value from a JSON document (first argument)
jbe@137 463 // optionally using a path (variable number of keys after first argument):
jbe@130 464 static int json_get(lua_State *L) {
jbe@137 465 return json_path(L, 0);
jbe@130 466 }
jbe@130 467
jbe@137 468 // gets a value's type from a JSON document (first argument)
jbe@137 469 // optionally using a path (variable number of keys after first argument):
jbe@130 470 static int json_type(lua_State *L) {
jbe@137 471 return json_path(L, 1);
jbe@130 472 }
jbe@130 473
jbe@137 474 // checks if a value in a JSON document (first argument) is null:
jbe@130 475 static int json_isnull(lua_State *L) {
jbe@137 476 const char *jsontype;
jbe@138 477 lua_pushcfunction(L, json_type);
jbe@137 478 lua_insert(L, 1);
jbe@137 479 lua_call(L, lua_gettop(L) - 1, 1);
jbe@137 480 jsontype = lua_tostring(L, -1);
jbe@137 481 if (jsontype && !strcmp(jsontype, "null")) lua_pushboolean(L, 1);
jbe@137 482 else lua_pushboolean(L, 0);
jbe@137 483 return 1;
jbe@130 484 }
jbe@130 485
jbe@138 486 #define json_setnull_unknownmt_idx 3
jbe@138 487 #define json_setnull_objectmt_idx 4
jbe@138 488 #define json_setnull_arraymt_idx 5
jbe@138 489 #define json_setnull_shadowtbl_idx 6
jbe@138 490
jbe@131 491 static int json_setnull(lua_State *L) {
jbe@138 492 // truncate stack to two elements:
jbe@131 493 lua_settop(L, 2);
jbe@138 494 // push json_unknownmt to stack position 3:
jbe@138 495 json_regfetch(L, json_unknownmt);
jbe@138 496 // push json_objectmt to stack position 4:
jbe@138 497 json_regfetch(L, json_objectmt);
jbe@138 498 // push json_arraymt to stack position 5:
jbe@138 499 json_regfetch(L, json_arraymt);
jbe@138 500 // push json_shadowtbl to stack position 6:
jbe@138 501 json_regfetch(L, json_shadowtbl);
jbe@138 502 //
jbe@138 503 lua_getmetatable(L, 1);
jbe@138 504 if (
jbe@138 505 !lua_rawequal(L, -1, json_setnull_unknownmt_idx) &&
jbe@138 506 !lua_rawequal(L, -1, json_setnull_objectmt_idx) &&
jbe@138 507 !lua_rawequal(L, -1, json_setnull_arraymt_idx)
jbe@138 508 ) {
jbe@138 509 lua_pushvalue(L, json_setnull_unknownmt_idx);
jbe@138 510 lua_setmetatable(L, 1);
jbe@138 511 }
jbe@131 512 lua_pushvalue(L, 1);
jbe@138 513 lua_rawget(L, json_setnull_shadowtbl_idx);
jbe@131 514 if (lua_isnil(L, -1)) {
jbe@131 515 lua_newtable(L);
jbe@131 516 lua_pushvalue(L, 1);
jbe@131 517 lua_pushvalue(L, -2);
jbe@138 518 lua_rawset(L, json_setnull_shadowtbl_idx);
jbe@131 519 }
jbe@131 520 lua_pushvalue(L, 2);
jbe@138 521 json_regfetch(L, json_nullmark);
jbe@131 522 lua_rawset(L, -3);
jbe@131 523 return 0;
jbe@131 524 }
jbe@131 525
jbe@130 526 static int json_len(lua_State *L) {
jbe@130 527 lua_settop(L, 1);
jbe@138 528 json_regfetch(L, json_shadowtbl);
jbe@130 529 lua_pushvalue(L, 1);
jbe@138 530 lua_rawget(L, -2);
jbe@138 531 lua_pushinteger(L, lua_rawlen(L, lua_isnil(L, -1) ? 1 : -1));
jbe@123 532 return 1;
jbe@123 533 }
jbe@123 534
jbe@141 535 #define json_index_nullmark_idx 3
jbe@141 536 #define json_index_shadowtbl_idx 4
jbe@141 537
jbe@130 538 static int json_index(lua_State *L) {
jbe@130 539 lua_settop(L, 2);
jbe@141 540 json_regfetch(L, json_nullmark); // on stack position 3
jbe@139 541 json_regfetch(L, json_shadowtbl);
jbe@130 542 lua_pushvalue(L, 1);
jbe@141 543 lua_rawget(L, json_index_shadowtbl_idx);
jbe@139 544 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
jbe@130 545 lua_pushvalue(L, 2);
jbe@130 546 lua_rawget(L, -2);
jbe@141 547 if (lua_rawequal(L, -1, json_index_nullmark_idx)) lua_pushnil(L);
jbe@127 548 return 1;
jbe@127 549 }
jbe@127 550
jbe@130 551 static int json_newindex(lua_State *L) {
jbe@130 552 lua_settop(L, 3);
jbe@139 553 json_regfetch(L, json_shadowtbl);
jbe@123 554 lua_pushvalue(L, 1);
jbe@139 555 lua_rawget(L, -1);
jbe@130 556 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
jbe@130 557 lua_replace(L, 1);
jbe@139 558 lua_settop(L, 3);
jbe@130 559 lua_rawset(L, 1);
jbe@121 560 return 1;
jbe@121 561 }
jbe@121 562
jbe@139 563 #define json_pairs_iterfunc_nullmark_idx 3
jbe@139 564 #define json_pairs_iterfunc_shadowtbl_idx 4
jbe@139 565
jbe@135 566 static int json_pairs_iterfunc(lua_State *L) {
jbe@135 567 lua_settop(L, 2);
jbe@139 568 json_regfetch(L, json_nullmark); // on stack position 3
jbe@139 569 json_regfetch(L, json_shadowtbl);
jbe@135 570 lua_pushvalue(L, 1);
jbe@139 571 lua_rawget(L, json_pairs_iterfunc_shadowtbl_idx);
jbe@135 572 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
jbe@135 573 lua_pushvalue(L, 2);
jbe@135 574 if (!lua_next(L, -2)) return 0;
jbe@139 575 if (lua_rawequal(L, -1, json_pairs_iterfunc_nullmark_idx)) {
jbe@135 576 lua_pop(L, 1);
jbe@135 577 lua_pushnil(L);
jbe@135 578 }
jbe@135 579 return 2;
jbe@135 580 }
jbe@135 581
jbe@135 582 static int json_pairs(lua_State *L) {
jbe@139 583 lua_pushcfunction(L, json_pairs_iterfunc);
jbe@135 584 lua_pushvalue(L, 1);
jbe@135 585 lua_pushnil(L);
jbe@135 586 return 3;
jbe@135 587 }
jbe@135 588
jbe@139 589 #define json_ipairs_iterfunc_nullmark_idx 3
jbe@139 590 #define json_ipairs_iterfunc_shadowtbl_idx 4
jbe@139 591
jbe@134 592 static int json_ipairs_iterfunc(lua_State *L) {
jbe@134 593 int idx;
jbe@134 594 lua_settop(L, 2);
jbe@139 595 json_regfetch(L, json_nullmark); // on stack position 3
jbe@139 596 json_regfetch(L, json_shadowtbl);
jbe@134 597 idx = lua_tointeger(L, 2) + 1;
jbe@134 598 lua_pushvalue(L, 1);
jbe@139 599 lua_rawget(L, json_ipairs_iterfunc_shadowtbl_idx);
jbe@134 600 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
jbe@134 601 lua_rawgeti(L, -1, idx);
jbe@134 602 if (lua_isnil(L, -1)) return 0;
jbe@134 603 lua_pushinteger(L, idx);
jbe@139 604 if (lua_rawequal(L, -2, json_ipairs_iterfunc_nullmark_idx)) lua_pushnil(L);
jbe@134 605 else lua_pushvalue(L, -2);
jbe@134 606 return 2;
jbe@134 607 }
jbe@134 608
jbe@134 609 static int json_ipairs(lua_State *L) {
jbe@139 610 lua_pushcfunction(L, json_ipairs_iterfunc);
jbe@134 611 lua_pushvalue(L, 1);
jbe@134 612 lua_pushinteger(L, 0);
jbe@134 613 return 3;
jbe@134 614 }
jbe@134 615
jbe@121 616 static const struct luaL_Reg json_module_functions[] = {
jbe@133 617 {"object", json_object},
jbe@133 618 {"array", json_array},
jbe@121 619 {"import", json_import},
jbe@130 620 {"get", json_get},
jbe@127 621 {"type", json_type},
jbe@123 622 {"isnull", json_isnull},
jbe@131 623 {"setnull", json_setnull},
jbe@121 624 {NULL, NULL}
jbe@121 625 };
jbe@121 626
jbe@126 627 static const struct luaL_Reg json_metatable_functions[] = {
jbe@130 628 {"__len", json_len},
jbe@130 629 {"__index", json_index},
jbe@130 630 {"__newindex", json_newindex},
jbe@135 631 {"__pairs", json_pairs},
jbe@134 632 {"__ipairs", json_ipairs},
jbe@126 633 {NULL, NULL}
jbe@126 634 };
jbe@126 635
jbe@121 636 int luaopen_json(lua_State *L) {
jbe@126 637 lua_settop(L, 0);
jbe@138 638 lua_newtable(L); // library
jbe@138 639 lua_newtable(L);
jbe@138 640 luaL_setfuncs(L, json_metatable_functions, 0);
jbe@138 641 json_regstore(L, json_unknownmt);
jbe@138 642 lua_setfield(L, 1, "ambiguous_mt");
jbe@138 643 lua_newtable(L);
jbe@138 644 luaL_setfuncs(L, json_metatable_functions, 0);
jbe@138 645 json_regstore(L, json_objectmt);
jbe@138 646 lua_setfield(L, 1, "object_mt");
jbe@138 647 lua_newtable(L);
jbe@138 648 luaL_setfuncs(L, json_metatable_functions, 0);
jbe@138 649 json_regstore(L, json_arraymt);
jbe@138 650 lua_setfield(L, 1, "array_mt");
jbe@138 651 lua_newtable(L); // ephemeron table to store shadow tables for each JSON object/array to allow NULL values returned as nil
jbe@138 652 lua_newtable(L); // metatable for ephemeron table
jbe@121 653 lua_pushliteral(L, "__mode");
jbe@121 654 lua_pushliteral(L, "k");
jbe@138 655 lua_rawset(L, -3);
jbe@138 656 lua_setmetatable(L, -2);
jbe@138 657 json_regstore(L, json_shadowtbl);
jbe@138 658 lua_newtable(L);
jbe@138 659 json_regstore(L, json_nullmark);
jbe@138 660 lua_settop(L, 1);
jbe@138 661 luaL_setfuncs(L, json_module_functions, 0);
jbe@121 662 return 1;
jbe@121 663 }

Impressum / About Us