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/cutils.h" 16 #include "qemu/unicode.h" 17 #include "qapi/error.h" 18 #include "qemu-common.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 && ptr[1] != '%') { 212 parse_error(ctxt, token, "can't interpolate into string"); 213 goto out; 214 } 215 ptr++; 216 /* fall through */ 217 default: 218 cp = mod_utf8_codepoint(ptr, 6, &end); 219 if (cp < 0) { 220 parse_error(ctxt, token, "invalid UTF-8 sequence in string"); 221 goto out; 222 } 223 ptr = end; 224 len = mod_utf8_encode(utf8_buf, sizeof(utf8_buf), cp); 225 assert(len >= 0); 226 qstring_append(str, utf8_buf); 227 } 228 } 229 230 return str; 231 232 out: 233 qobject_unref(str); 234 return NULL; 235 } 236 237 /* Note: the token object returned by parser_context_peek_token or 238 * parser_context_pop_token is deleted as soon as parser_context_pop_token 239 * is called again. 240 */ 241 static JSONToken *parser_context_pop_token(JSONParserContext *ctxt) 242 { 243 g_free(ctxt->current); 244 ctxt->current = g_queue_pop_head(ctxt->buf); 245 return ctxt->current; 246 } 247 248 static JSONToken *parser_context_peek_token(JSONParserContext *ctxt) 249 { 250 return g_queue_peek_head(ctxt->buf); 251 } 252 253 /** 254 * Parsing rules 255 */ 256 static int parse_pair(JSONParserContext *ctxt, QDict *dict) 257 { 258 QObject *value; 259 QString *key = NULL; 260 JSONToken *peek, *token; 261 262 peek = parser_context_peek_token(ctxt); 263 if (peek == NULL) { 264 parse_error(ctxt, NULL, "premature EOI"); 265 goto out; 266 } 267 268 key = qobject_to(QString, parse_value(ctxt)); 269 if (!key) { 270 parse_error(ctxt, peek, "key is not a string in object"); 271 goto out; 272 } 273 274 token = parser_context_pop_token(ctxt); 275 if (token == NULL) { 276 parse_error(ctxt, NULL, "premature EOI"); 277 goto out; 278 } 279 280 if (token->type != JSON_COLON) { 281 parse_error(ctxt, token, "missing : in object pair"); 282 goto out; 283 } 284 285 value = parse_value(ctxt); 286 if (value == NULL) { 287 parse_error(ctxt, token, "Missing value in dict"); 288 goto out; 289 } 290 291 qdict_put_obj(dict, qstring_get_str(key), value); 292 293 qobject_unref(key); 294 295 return 0; 296 297 out: 298 qobject_unref(key); 299 300 return -1; 301 } 302 303 static QObject *parse_object(JSONParserContext *ctxt) 304 { 305 QDict *dict = NULL; 306 JSONToken *token, *peek; 307 308 token = parser_context_pop_token(ctxt); 309 assert(token && token->type == JSON_LCURLY); 310 311 dict = qdict_new(); 312 313 peek = parser_context_peek_token(ctxt); 314 if (peek == NULL) { 315 parse_error(ctxt, NULL, "premature EOI"); 316 goto out; 317 } 318 319 if (peek->type != JSON_RCURLY) { 320 if (parse_pair(ctxt, dict) == -1) { 321 goto out; 322 } 323 324 token = parser_context_pop_token(ctxt); 325 if (token == NULL) { 326 parse_error(ctxt, NULL, "premature EOI"); 327 goto out; 328 } 329 330 while (token->type != JSON_RCURLY) { 331 if (token->type != JSON_COMMA) { 332 parse_error(ctxt, token, "expected separator in dict"); 333 goto out; 334 } 335 336 if (parse_pair(ctxt, dict) == -1) { 337 goto out; 338 } 339 340 token = parser_context_pop_token(ctxt); 341 if (token == NULL) { 342 parse_error(ctxt, NULL, "premature EOI"); 343 goto out; 344 } 345 } 346 } else { 347 (void)parser_context_pop_token(ctxt); 348 } 349 350 return QOBJECT(dict); 351 352 out: 353 qobject_unref(dict); 354 return NULL; 355 } 356 357 static QObject *parse_array(JSONParserContext *ctxt) 358 { 359 QList *list = NULL; 360 JSONToken *token, *peek; 361 362 token = parser_context_pop_token(ctxt); 363 assert(token && token->type == JSON_LSQUARE); 364 365 list = qlist_new(); 366 367 peek = parser_context_peek_token(ctxt); 368 if (peek == NULL) { 369 parse_error(ctxt, NULL, "premature EOI"); 370 goto out; 371 } 372 373 if (peek->type != JSON_RSQUARE) { 374 QObject *obj; 375 376 obj = parse_value(ctxt); 377 if (obj == NULL) { 378 parse_error(ctxt, token, "expecting value"); 379 goto out; 380 } 381 382 qlist_append_obj(list, obj); 383 384 token = parser_context_pop_token(ctxt); 385 if (token == NULL) { 386 parse_error(ctxt, NULL, "premature EOI"); 387 goto out; 388 } 389 390 while (token->type != JSON_RSQUARE) { 391 if (token->type != JSON_COMMA) { 392 parse_error(ctxt, token, "expected separator in list"); 393 goto out; 394 } 395 396 obj = parse_value(ctxt); 397 if (obj == NULL) { 398 parse_error(ctxt, token, "expecting value"); 399 goto out; 400 } 401 402 qlist_append_obj(list, obj); 403 404 token = parser_context_pop_token(ctxt); 405 if (token == NULL) { 406 parse_error(ctxt, NULL, "premature EOI"); 407 goto out; 408 } 409 } 410 } else { 411 (void)parser_context_pop_token(ctxt); 412 } 413 414 return QOBJECT(list); 415 416 out: 417 qobject_unref(list); 418 return NULL; 419 } 420 421 static QObject *parse_keyword(JSONParserContext *ctxt) 422 { 423 JSONToken *token; 424 425 token = parser_context_pop_token(ctxt); 426 assert(token && token->type == JSON_KEYWORD); 427 428 if (!strcmp(token->str, "true")) { 429 return QOBJECT(qbool_from_bool(true)); 430 } else if (!strcmp(token->str, "false")) { 431 return QOBJECT(qbool_from_bool(false)); 432 } else if (!strcmp(token->str, "null")) { 433 return QOBJECT(qnull()); 434 } 435 parse_error(ctxt, token, "invalid keyword '%s'", token->str); 436 return NULL; 437 } 438 439 static QObject *parse_interpolation(JSONParserContext *ctxt) 440 { 441 JSONToken *token; 442 443 token = parser_context_pop_token(ctxt); 444 assert(token && token->type == JSON_INTERP); 445 446 if (!strcmp(token->str, "%p")) { 447 return va_arg(*ctxt->ap, QObject *); 448 } else if (!strcmp(token->str, "%i")) { 449 return QOBJECT(qbool_from_bool(va_arg(*ctxt->ap, int))); 450 } else if (!strcmp(token->str, "%d")) { 451 return QOBJECT(qnum_from_int(va_arg(*ctxt->ap, int))); 452 } else if (!strcmp(token->str, "%ld")) { 453 return QOBJECT(qnum_from_int(va_arg(*ctxt->ap, long))); 454 } else if (!strcmp(token->str, "%lld")) { 455 return QOBJECT(qnum_from_int(va_arg(*ctxt->ap, long long))); 456 } else if (!strcmp(token->str, "%" PRId64)) { 457 return QOBJECT(qnum_from_int(va_arg(*ctxt->ap, int64_t))); 458 } else if (!strcmp(token->str, "%u")) { 459 return QOBJECT(qnum_from_uint(va_arg(*ctxt->ap, unsigned int))); 460 } else if (!strcmp(token->str, "%lu")) { 461 return QOBJECT(qnum_from_uint(va_arg(*ctxt->ap, unsigned long))); 462 } else if (!strcmp(token->str, "%llu")) { 463 return QOBJECT(qnum_from_uint(va_arg(*ctxt->ap, unsigned long long))); 464 } else if (!strcmp(token->str, "%" PRIu64)) { 465 return QOBJECT(qnum_from_uint(va_arg(*ctxt->ap, uint64_t))); 466 } else if (!strcmp(token->str, "%s")) { 467 return QOBJECT(qstring_from_str(va_arg(*ctxt->ap, const char *))); 468 } else if (!strcmp(token->str, "%f")) { 469 return QOBJECT(qnum_from_double(va_arg(*ctxt->ap, double))); 470 } 471 parse_error(ctxt, token, "invalid interpolation '%s'", token->str); 472 return NULL; 473 } 474 475 static QObject *parse_literal(JSONParserContext *ctxt) 476 { 477 JSONToken *token; 478 479 token = parser_context_pop_token(ctxt); 480 assert(token); 481 482 switch (token->type) { 483 case JSON_STRING: 484 return QOBJECT(parse_string(ctxt, token)); 485 case JSON_INTEGER: { 486 /* 487 * Represent JSON_INTEGER as QNUM_I64 if possible, else as 488 * QNUM_U64, else as QNUM_DOUBLE. Note that qemu_strtoi64() 489 * and qemu_strtou64() fail with ERANGE when it's not 490 * possible. 491 * 492 * qnum_get_int() will then work for any signed 64-bit 493 * JSON_INTEGER, qnum_get_uint() for any unsigned 64-bit 494 * integer, and qnum_get_double() both for any JSON_INTEGER 495 * and any JSON_FLOAT (with precision loss for integers beyond 496 * 53 bits) 497 */ 498 int ret; 499 int64_t value; 500 uint64_t uvalue; 501 502 ret = qemu_strtoi64(token->str, NULL, 10, &value); 503 if (!ret) { 504 return QOBJECT(qnum_from_int(value)); 505 } 506 assert(ret == -ERANGE); 507 508 if (token->str[0] != '-') { 509 ret = qemu_strtou64(token->str, NULL, 10, &uvalue); 510 if (!ret) { 511 return QOBJECT(qnum_from_uint(uvalue)); 512 } 513 assert(ret == -ERANGE); 514 } 515 /* fall through to JSON_FLOAT */ 516 } 517 case JSON_FLOAT: 518 /* FIXME dependent on locale; a pervasive issue in QEMU */ 519 /* FIXME our lexer matches RFC 8259 in forbidding Inf or NaN, 520 * but those might be useful extensions beyond JSON */ 521 return QOBJECT(qnum_from_double(strtod(token->str, NULL))); 522 default: 523 abort(); 524 } 525 } 526 527 static QObject *parse_value(JSONParserContext *ctxt) 528 { 529 JSONToken *token; 530 531 token = parser_context_peek_token(ctxt); 532 if (token == NULL) { 533 parse_error(ctxt, NULL, "premature EOI"); 534 return NULL; 535 } 536 537 switch (token->type) { 538 case JSON_LCURLY: 539 return parse_object(ctxt); 540 case JSON_LSQUARE: 541 return parse_array(ctxt); 542 case JSON_INTERP: 543 return parse_interpolation(ctxt); 544 case JSON_INTEGER: 545 case JSON_FLOAT: 546 case JSON_STRING: 547 return parse_literal(ctxt); 548 case JSON_KEYWORD: 549 return parse_keyword(ctxt); 550 default: 551 parse_error(ctxt, token, "expecting value"); 552 return NULL; 553 } 554 } 555 556 JSONToken *json_token(JSONTokenType type, int x, int y, GString *tokstr) 557 { 558 JSONToken *token = g_malloc(sizeof(JSONToken) + tokstr->len + 1); 559 560 token->type = type; 561 memcpy(token->str, tokstr->str, tokstr->len); 562 token->str[tokstr->len] = 0; 563 token->x = x; 564 token->y = y; 565 return token; 566 } 567 568 QObject *json_parser_parse(GQueue *tokens, va_list *ap, Error **errp) 569 { 570 JSONParserContext ctxt = { .buf = tokens, .ap = ap }; 571 QObject *result; 572 573 result = parse_value(&ctxt); 574 assert(ctxt.err || g_queue_is_empty(ctxt.buf)); 575 576 error_propagate(errp, ctxt.err); 577 578 while (!g_queue_is_empty(ctxt.buf)) { 579 parser_context_pop_token(&ctxt); 580 } 581 g_free(ctxt.current); 582 583 return result; 584 } 585