1 /* 2 * JSON Parser 3 * 4 * Copyright IBM, Corp. 2009 5 * 6 * Authors: 7 * Anthony Liguori <aliguori@us.ibm.com> 8 * 9 * This work is licensed under the terms of the GNU LGPL, version 2.1 or later. 10 * See the COPYING.LIB file in the top-level directory. 11 * 12 */ 13 14 #include "qemu/osdep.h" 15 #include "qemu/ctype.h" 16 #include "qemu/cutils.h" 17 #include "qemu/unicode.h" 18 #include "qapi/error.h" 19 #include "qapi/qmp/qbool.h" 20 #include "qapi/qmp/qdict.h" 21 #include "qapi/qmp/qlist.h" 22 #include "qapi/qmp/qnull.h" 23 #include "qapi/qmp/qnum.h" 24 #include "qapi/qmp/qstring.h" 25 #include "json-parser-int.h" 26 27 struct JSONToken { 28 JSONTokenType type; 29 int x; 30 int y; 31 char str[]; 32 }; 33 34 typedef struct JSONParserContext 35 { 36 Error *err; 37 JSONToken *current; 38 GQueue *buf; 39 va_list *ap; 40 } JSONParserContext; 41 42 #define BUG_ON(cond) assert(!(cond)) 43 44 /** 45 * TODO 46 * 47 * 0) make errors meaningful again 48 * 1) add geometry information to tokens 49 * 3) should we return a parsed size? 50 * 4) deal with premature EOI 51 */ 52 53 static QObject *parse_value(JSONParserContext *ctxt); 54 55 /** 56 * Error handler 57 */ 58 static void GCC_FMT_ATTR(3, 4) parse_error(JSONParserContext *ctxt, 59 JSONToken *token, const char *msg, ...) 60 { 61 va_list ap; 62 char message[1024]; 63 64 if (ctxt->err) { 65 return; 66 } 67 va_start(ap, msg); 68 vsnprintf(message, sizeof(message), msg, ap); 69 va_end(ap); 70 error_setg(&ctxt->err, "JSON parse error, %s", message); 71 } 72 73 static int cvt4hex(const char *s) 74 { 75 int cp, i; 76 77 cp = 0; 78 for (i = 0; i < 4; i++) { 79 if (!qemu_isxdigit(s[i])) { 80 return -1; 81 } 82 cp <<= 4; 83 if (s[i] >= '0' && s[i] <= '9') { 84 cp |= s[i] - '0'; 85 } else if (s[i] >= 'a' && s[i] <= 'f') { 86 cp |= 10 + s[i] - 'a'; 87 } else if (s[i] >= 'A' && s[i] <= 'F') { 88 cp |= 10 + s[i] - 'A'; 89 } else { 90 return -1; 91 } 92 } 93 return cp; 94 } 95 96 /** 97 * parse_string(): Parse a JSON string 98 * 99 * From RFC 8259 "The JavaScript Object Notation (JSON) Data 100 * Interchange Format": 101 * 102 * char = unescaped / 103 * escape ( 104 * %x22 / ; " quotation mark U+0022 105 * %x5C / ; \ reverse solidus U+005C 106 * %x2F / ; / solidus U+002F 107 * %x62 / ; b backspace U+0008 108 * %x66 / ; f form feed U+000C 109 * %x6E / ; n line feed U+000A 110 * %x72 / ; r carriage return U+000D 111 * %x74 / ; t tab U+0009 112 * %x75 4HEXDIG ) ; uXXXX U+XXXX 113 * escape = %x5C ; \ 114 * quotation-mark = %x22 ; " 115 * unescaped = %x20-21 / %x23-5B / %x5D-10FFFF 116 * 117 * Extensions over RFC 8259: 118 * - Extra escape sequence in strings: 119 * 0x27 (apostrophe) is recognized after escape, too 120 * - Single-quoted strings: 121 * Like double-quoted strings, except they're delimited by %x27 122 * (apostrophe) instead of %x22 (quotation mark), and can't contain 123 * unescaped apostrophe, but can contain unescaped quotation mark. 124 * 125 * Note: 126 * - Encoding is modified UTF-8. 127 * - Invalid Unicode characters are rejected. 128 * - Control characters \x00..\x1F are rejected by the lexer. 129 */ 130 static QString *parse_string(JSONParserContext *ctxt, JSONToken *token) 131 { 132 const char *ptr = token->str; 133 QString *str; 134 char quote; 135 const char *beg; 136 int cp, trailing; 137 char *end; 138 ssize_t len; 139 char utf8_buf[5]; 140 141 assert(*ptr == '"' || *ptr == '\''); 142 quote = *ptr++; 143 str = qstring_new(); 144 145 while (*ptr != quote) { 146 assert(*ptr); 147 switch (*ptr) { 148 case '\\': 149 beg = ptr++; 150 switch (*ptr++) { 151 case '"': 152 qstring_append_chr(str, '"'); 153 break; 154 case '\'': 155 qstring_append_chr(str, '\''); 156 break; 157 case '\\': 158 qstring_append_chr(str, '\\'); 159 break; 160 case '/': 161 qstring_append_chr(str, '/'); 162 break; 163 case 'b': 164 qstring_append_chr(str, '\b'); 165 break; 166 case 'f': 167 qstring_append_chr(str, '\f'); 168 break; 169 case 'n': 170 qstring_append_chr(str, '\n'); 171 break; 172 case 'r': 173 qstring_append_chr(str, '\r'); 174 break; 175 case 't': 176 qstring_append_chr(str, '\t'); 177 break; 178 case 'u': 179 cp = cvt4hex(ptr); 180 ptr += 4; 181 182 /* handle surrogate pairs */ 183 if (cp >= 0xD800 && cp <= 0xDBFF 184 && ptr[0] == '\\' && ptr[1] == 'u') { 185 /* leading surrogate followed by \u */ 186 cp = 0x10000 + ((cp & 0x3FF) << 10); 187 trailing = cvt4hex(ptr + 2); 188 if (trailing >= 0xDC00 && trailing <= 0xDFFF) { 189 /* followed by trailing surrogate */ 190 cp |= trailing & 0x3FF; 191 ptr += 6; 192 } else { 193 cp = -1; /* invalid */ 194 } 195 } 196 197 if (mod_utf8_encode(utf8_buf, sizeof(utf8_buf), cp) < 0) { 198 parse_error(ctxt, token, 199 "%.*s is not a valid Unicode character", 200 (int)(ptr - beg), beg); 201 goto out; 202 } 203 qstring_append(str, utf8_buf); 204 break; 205 default: 206 parse_error(ctxt, token, "invalid escape sequence in string"); 207 goto out; 208 } 209 break; 210 case '%': 211 if (ctxt->ap) { 212 if (ptr[1] != '%') { 213 parse_error(ctxt, token, "can't interpolate into string"); 214 goto out; 215 } 216 ptr++; 217 } 218 /* fall through */ 219 default: 220 cp = mod_utf8_codepoint(ptr, 6, &end); 221 if (cp < 0) { 222 parse_error(ctxt, token, "invalid UTF-8 sequence in string"); 223 goto out; 224 } 225 ptr = end; 226 len = mod_utf8_encode(utf8_buf, sizeof(utf8_buf), cp); 227 assert(len >= 0); 228 qstring_append(str, utf8_buf); 229 } 230 } 231 232 return str; 233 234 out: 235 qobject_unref(str); 236 return NULL; 237 } 238 239 /* Note: the token object returned by parser_context_peek_token or 240 * parser_context_pop_token is deleted as soon as parser_context_pop_token 241 * is called again. 242 */ 243 static JSONToken *parser_context_pop_token(JSONParserContext *ctxt) 244 { 245 g_free(ctxt->current); 246 ctxt->current = g_queue_pop_head(ctxt->buf); 247 return ctxt->current; 248 } 249 250 static JSONToken *parser_context_peek_token(JSONParserContext *ctxt) 251 { 252 return g_queue_peek_head(ctxt->buf); 253 } 254 255 /** 256 * Parsing rules 257 */ 258 static int parse_pair(JSONParserContext *ctxt, QDict *dict) 259 { 260 QObject *value; 261 QString *key = NULL; 262 JSONToken *peek, *token; 263 264 peek = parser_context_peek_token(ctxt); 265 if (peek == NULL) { 266 parse_error(ctxt, NULL, "premature EOI"); 267 goto out; 268 } 269 270 key = qobject_to(QString, parse_value(ctxt)); 271 if (!key) { 272 parse_error(ctxt, peek, "key is not a string in object"); 273 goto out; 274 } 275 276 token = parser_context_pop_token(ctxt); 277 if (token == NULL) { 278 parse_error(ctxt, NULL, "premature EOI"); 279 goto out; 280 } 281 282 if (token->type != JSON_COLON) { 283 parse_error(ctxt, token, "missing : in object pair"); 284 goto out; 285 } 286 287 value = parse_value(ctxt); 288 if (value == NULL) { 289 parse_error(ctxt, token, "Missing value in dict"); 290 goto out; 291 } 292 293 if (qdict_haskey(dict, qstring_get_str(key))) { 294 parse_error(ctxt, token, "duplicate key"); 295 goto out; 296 } 297 298 qdict_put_obj(dict, qstring_get_str(key), value); 299 300 qobject_unref(key); 301 302 return 0; 303 304 out: 305 qobject_unref(key); 306 307 return -1; 308 } 309 310 static QObject *parse_object(JSONParserContext *ctxt) 311 { 312 QDict *dict = NULL; 313 JSONToken *token, *peek; 314 315 token = parser_context_pop_token(ctxt); 316 assert(token && token->type == JSON_LCURLY); 317 318 dict = qdict_new(); 319 320 peek = parser_context_peek_token(ctxt); 321 if (peek == NULL) { 322 parse_error(ctxt, NULL, "premature EOI"); 323 goto out; 324 } 325 326 if (peek->type != JSON_RCURLY) { 327 if (parse_pair(ctxt, dict) == -1) { 328 goto out; 329 } 330 331 token = parser_context_pop_token(ctxt); 332 if (token == NULL) { 333 parse_error(ctxt, NULL, "premature EOI"); 334 goto out; 335 } 336 337 while (token->type != JSON_RCURLY) { 338 if (token->type != JSON_COMMA) { 339 parse_error(ctxt, token, "expected separator in dict"); 340 goto out; 341 } 342 343 if (parse_pair(ctxt, dict) == -1) { 344 goto out; 345 } 346 347 token = parser_context_pop_token(ctxt); 348 if (token == NULL) { 349 parse_error(ctxt, NULL, "premature EOI"); 350 goto out; 351 } 352 } 353 } else { 354 (void)parser_context_pop_token(ctxt); 355 } 356 357 return QOBJECT(dict); 358 359 out: 360 qobject_unref(dict); 361 return NULL; 362 } 363 364 static QObject *parse_array(JSONParserContext *ctxt) 365 { 366 QList *list = NULL; 367 JSONToken *token, *peek; 368 369 token = parser_context_pop_token(ctxt); 370 assert(token && token->type == JSON_LSQUARE); 371 372 list = qlist_new(); 373 374 peek = parser_context_peek_token(ctxt); 375 if (peek == NULL) { 376 parse_error(ctxt, NULL, "premature EOI"); 377 goto out; 378 } 379 380 if (peek->type != JSON_RSQUARE) { 381 QObject *obj; 382 383 obj = parse_value(ctxt); 384 if (obj == NULL) { 385 parse_error(ctxt, token, "expecting value"); 386 goto out; 387 } 388 389 qlist_append_obj(list, obj); 390 391 token = parser_context_pop_token(ctxt); 392 if (token == NULL) { 393 parse_error(ctxt, NULL, "premature EOI"); 394 goto out; 395 } 396 397 while (token->type != JSON_RSQUARE) { 398 if (token->type != JSON_COMMA) { 399 parse_error(ctxt, token, "expected separator in list"); 400 goto out; 401 } 402 403 obj = parse_value(ctxt); 404 if (obj == NULL) { 405 parse_error(ctxt, token, "expecting value"); 406 goto out; 407 } 408 409 qlist_append_obj(list, obj); 410 411 token = parser_context_pop_token(ctxt); 412 if (token == NULL) { 413 parse_error(ctxt, NULL, "premature EOI"); 414 goto out; 415 } 416 } 417 } else { 418 (void)parser_context_pop_token(ctxt); 419 } 420 421 return QOBJECT(list); 422 423 out: 424 qobject_unref(list); 425 return NULL; 426 } 427 428 static QObject *parse_keyword(JSONParserContext *ctxt) 429 { 430 JSONToken *token; 431 432 token = parser_context_pop_token(ctxt); 433 assert(token && token->type == JSON_KEYWORD); 434 435 if (!strcmp(token->str, "true")) { 436 return QOBJECT(qbool_from_bool(true)); 437 } else if (!strcmp(token->str, "false")) { 438 return QOBJECT(qbool_from_bool(false)); 439 } else if (!strcmp(token->str, "null")) { 440 return QOBJECT(qnull()); 441 } 442 parse_error(ctxt, token, "invalid keyword '%s'", token->str); 443 return NULL; 444 } 445 446 static QObject *parse_interpolation(JSONParserContext *ctxt) 447 { 448 JSONToken *token; 449 450 token = parser_context_pop_token(ctxt); 451 assert(token && token->type == JSON_INTERP); 452 453 if (!strcmp(token->str, "%p")) { 454 return va_arg(*ctxt->ap, QObject *); 455 } else if (!strcmp(token->str, "%i")) { 456 return QOBJECT(qbool_from_bool(va_arg(*ctxt->ap, int))); 457 } else if (!strcmp(token->str, "%d")) { 458 return QOBJECT(qnum_from_int(va_arg(*ctxt->ap, int))); 459 } else if (!strcmp(token->str, "%ld")) { 460 return QOBJECT(qnum_from_int(va_arg(*ctxt->ap, long))); 461 } else if (!strcmp(token->str, "%lld")) { 462 return QOBJECT(qnum_from_int(va_arg(*ctxt->ap, long long))); 463 } else if (!strcmp(token->str, "%" PRId64)) { 464 return QOBJECT(qnum_from_int(va_arg(*ctxt->ap, int64_t))); 465 } else if (!strcmp(token->str, "%u")) { 466 return QOBJECT(qnum_from_uint(va_arg(*ctxt->ap, unsigned int))); 467 } else if (!strcmp(token->str, "%lu")) { 468 return QOBJECT(qnum_from_uint(va_arg(*ctxt->ap, unsigned long))); 469 } else if (!strcmp(token->str, "%llu")) { 470 return QOBJECT(qnum_from_uint(va_arg(*ctxt->ap, unsigned long long))); 471 } else if (!strcmp(token->str, "%" PRIu64)) { 472 return QOBJECT(qnum_from_uint(va_arg(*ctxt->ap, uint64_t))); 473 } else if (!strcmp(token->str, "%s")) { 474 return QOBJECT(qstring_from_str(va_arg(*ctxt->ap, const char *))); 475 } else if (!strcmp(token->str, "%f")) { 476 return QOBJECT(qnum_from_double(va_arg(*ctxt->ap, double))); 477 } 478 parse_error(ctxt, token, "invalid interpolation '%s'", token->str); 479 return NULL; 480 } 481 482 static QObject *parse_literal(JSONParserContext *ctxt) 483 { 484 JSONToken *token; 485 486 token = parser_context_pop_token(ctxt); 487 assert(token); 488 489 switch (token->type) { 490 case JSON_STRING: 491 return QOBJECT(parse_string(ctxt, token)); 492 case JSON_INTEGER: { 493 /* 494 * Represent JSON_INTEGER as QNUM_I64 if possible, else as 495 * QNUM_U64, else as QNUM_DOUBLE. Note that qemu_strtoi64() 496 * and qemu_strtou64() fail with ERANGE when it's not 497 * possible. 498 * 499 * qnum_get_int() will then work for any signed 64-bit 500 * JSON_INTEGER, qnum_get_uint() for any unsigned 64-bit 501 * integer, and qnum_get_double() both for any JSON_INTEGER 502 * and any JSON_FLOAT (with precision loss for integers beyond 503 * 53 bits) 504 */ 505 int ret; 506 int64_t value; 507 uint64_t uvalue; 508 509 ret = qemu_strtoi64(token->str, NULL, 10, &value); 510 if (!ret) { 511 return QOBJECT(qnum_from_int(value)); 512 } 513 assert(ret == -ERANGE); 514 515 if (token->str[0] != '-') { 516 ret = qemu_strtou64(token->str, NULL, 10, &uvalue); 517 if (!ret) { 518 return QOBJECT(qnum_from_uint(uvalue)); 519 } 520 assert(ret == -ERANGE); 521 } 522 } 523 /* fall through to JSON_FLOAT */ 524 case JSON_FLOAT: 525 /* FIXME dependent on locale; a pervasive issue in QEMU */ 526 /* FIXME our lexer matches RFC 8259 in forbidding Inf or NaN, 527 * but those might be useful extensions beyond JSON */ 528 return QOBJECT(qnum_from_double(strtod(token->str, NULL))); 529 default: 530 abort(); 531 } 532 } 533 534 static QObject *parse_value(JSONParserContext *ctxt) 535 { 536 JSONToken *token; 537 538 token = parser_context_peek_token(ctxt); 539 if (token == NULL) { 540 parse_error(ctxt, NULL, "premature EOI"); 541 return NULL; 542 } 543 544 switch (token->type) { 545 case JSON_LCURLY: 546 return parse_object(ctxt); 547 case JSON_LSQUARE: 548 return parse_array(ctxt); 549 case JSON_INTERP: 550 return parse_interpolation(ctxt); 551 case JSON_INTEGER: 552 case JSON_FLOAT: 553 case JSON_STRING: 554 return parse_literal(ctxt); 555 case JSON_KEYWORD: 556 return parse_keyword(ctxt); 557 default: 558 parse_error(ctxt, token, "expecting value"); 559 return NULL; 560 } 561 } 562 563 JSONToken *json_token(JSONTokenType type, int x, int y, GString *tokstr) 564 { 565 JSONToken *token = g_malloc(sizeof(JSONToken) + tokstr->len + 1); 566 567 token->type = type; 568 memcpy(token->str, tokstr->str, tokstr->len); 569 token->str[tokstr->len] = 0; 570 token->x = x; 571 token->y = y; 572 return token; 573 } 574 575 QObject *json_parser_parse(GQueue *tokens, va_list *ap, Error **errp) 576 { 577 JSONParserContext ctxt = { .buf = tokens, .ap = ap }; 578 QObject *result; 579 580 result = parse_value(&ctxt); 581 assert(ctxt.err || g_queue_is_empty(ctxt.buf)); 582 583 error_propagate(errp, ctxt.err); 584 585 while (!g_queue_is_empty(ctxt.buf)) { 586 parser_context_pop_token(&ctxt); 587 } 588 g_free(ctxt.current); 589 590 return result; 591 } 592