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 if (qdict_haskey(dict, qstring_get_str(key))) { 292 parse_error(ctxt, token, "duplicate key"); 293 goto out; 294 } 295 296 qdict_put_obj(dict, qstring_get_str(key), value); 297 298 qobject_unref(key); 299 300 return 0; 301 302 out: 303 qobject_unref(key); 304 305 return -1; 306 } 307 308 static QObject *parse_object(JSONParserContext *ctxt) 309 { 310 QDict *dict = NULL; 311 JSONToken *token, *peek; 312 313 token = parser_context_pop_token(ctxt); 314 assert(token && token->type == JSON_LCURLY); 315 316 dict = qdict_new(); 317 318 peek = parser_context_peek_token(ctxt); 319 if (peek == NULL) { 320 parse_error(ctxt, NULL, "premature EOI"); 321 goto out; 322 } 323 324 if (peek->type != JSON_RCURLY) { 325 if (parse_pair(ctxt, dict) == -1) { 326 goto out; 327 } 328 329 token = parser_context_pop_token(ctxt); 330 if (token == NULL) { 331 parse_error(ctxt, NULL, "premature EOI"); 332 goto out; 333 } 334 335 while (token->type != JSON_RCURLY) { 336 if (token->type != JSON_COMMA) { 337 parse_error(ctxt, token, "expected separator in dict"); 338 goto out; 339 } 340 341 if (parse_pair(ctxt, dict) == -1) { 342 goto out; 343 } 344 345 token = parser_context_pop_token(ctxt); 346 if (token == NULL) { 347 parse_error(ctxt, NULL, "premature EOI"); 348 goto out; 349 } 350 } 351 } else { 352 (void)parser_context_pop_token(ctxt); 353 } 354 355 return QOBJECT(dict); 356 357 out: 358 qobject_unref(dict); 359 return NULL; 360 } 361 362 static QObject *parse_array(JSONParserContext *ctxt) 363 { 364 QList *list = NULL; 365 JSONToken *token, *peek; 366 367 token = parser_context_pop_token(ctxt); 368 assert(token && token->type == JSON_LSQUARE); 369 370 list = qlist_new(); 371 372 peek = parser_context_peek_token(ctxt); 373 if (peek == NULL) { 374 parse_error(ctxt, NULL, "premature EOI"); 375 goto out; 376 } 377 378 if (peek->type != JSON_RSQUARE) { 379 QObject *obj; 380 381 obj = parse_value(ctxt); 382 if (obj == NULL) { 383 parse_error(ctxt, token, "expecting value"); 384 goto out; 385 } 386 387 qlist_append_obj(list, obj); 388 389 token = parser_context_pop_token(ctxt); 390 if (token == NULL) { 391 parse_error(ctxt, NULL, "premature EOI"); 392 goto out; 393 } 394 395 while (token->type != JSON_RSQUARE) { 396 if (token->type != JSON_COMMA) { 397 parse_error(ctxt, token, "expected separator in list"); 398 goto out; 399 } 400 401 obj = parse_value(ctxt); 402 if (obj == NULL) { 403 parse_error(ctxt, token, "expecting value"); 404 goto out; 405 } 406 407 qlist_append_obj(list, obj); 408 409 token = parser_context_pop_token(ctxt); 410 if (token == NULL) { 411 parse_error(ctxt, NULL, "premature EOI"); 412 goto out; 413 } 414 } 415 } else { 416 (void)parser_context_pop_token(ctxt); 417 } 418 419 return QOBJECT(list); 420 421 out: 422 qobject_unref(list); 423 return NULL; 424 } 425 426 static QObject *parse_keyword(JSONParserContext *ctxt) 427 { 428 JSONToken *token; 429 430 token = parser_context_pop_token(ctxt); 431 assert(token && token->type == JSON_KEYWORD); 432 433 if (!strcmp(token->str, "true")) { 434 return QOBJECT(qbool_from_bool(true)); 435 } else if (!strcmp(token->str, "false")) { 436 return QOBJECT(qbool_from_bool(false)); 437 } else if (!strcmp(token->str, "null")) { 438 return QOBJECT(qnull()); 439 } 440 parse_error(ctxt, token, "invalid keyword '%s'", token->str); 441 return NULL; 442 } 443 444 static QObject *parse_interpolation(JSONParserContext *ctxt) 445 { 446 JSONToken *token; 447 448 token = parser_context_pop_token(ctxt); 449 assert(token && token->type == JSON_INTERP); 450 451 if (!strcmp(token->str, "%p")) { 452 return va_arg(*ctxt->ap, QObject *); 453 } else if (!strcmp(token->str, "%i")) { 454 return QOBJECT(qbool_from_bool(va_arg(*ctxt->ap, int))); 455 } else if (!strcmp(token->str, "%d")) { 456 return QOBJECT(qnum_from_int(va_arg(*ctxt->ap, int))); 457 } else if (!strcmp(token->str, "%ld")) { 458 return QOBJECT(qnum_from_int(va_arg(*ctxt->ap, long))); 459 } else if (!strcmp(token->str, "%lld")) { 460 return QOBJECT(qnum_from_int(va_arg(*ctxt->ap, long long))); 461 } else if (!strcmp(token->str, "%" PRId64)) { 462 return QOBJECT(qnum_from_int(va_arg(*ctxt->ap, int64_t))); 463 } else if (!strcmp(token->str, "%u")) { 464 return QOBJECT(qnum_from_uint(va_arg(*ctxt->ap, unsigned int))); 465 } else if (!strcmp(token->str, "%lu")) { 466 return QOBJECT(qnum_from_uint(va_arg(*ctxt->ap, unsigned long))); 467 } else if (!strcmp(token->str, "%llu")) { 468 return QOBJECT(qnum_from_uint(va_arg(*ctxt->ap, unsigned long long))); 469 } else if (!strcmp(token->str, "%" PRIu64)) { 470 return QOBJECT(qnum_from_uint(va_arg(*ctxt->ap, uint64_t))); 471 } else if (!strcmp(token->str, "%s")) { 472 return QOBJECT(qstring_from_str(va_arg(*ctxt->ap, const char *))); 473 } else if (!strcmp(token->str, "%f")) { 474 return QOBJECT(qnum_from_double(va_arg(*ctxt->ap, double))); 475 } 476 parse_error(ctxt, token, "invalid interpolation '%s'", token->str); 477 return NULL; 478 } 479 480 static QObject *parse_literal(JSONParserContext *ctxt) 481 { 482 JSONToken *token; 483 484 token = parser_context_pop_token(ctxt); 485 assert(token); 486 487 switch (token->type) { 488 case JSON_STRING: 489 return QOBJECT(parse_string(ctxt, token)); 490 case JSON_INTEGER: { 491 /* 492 * Represent JSON_INTEGER as QNUM_I64 if possible, else as 493 * QNUM_U64, else as QNUM_DOUBLE. Note that qemu_strtoi64() 494 * and qemu_strtou64() fail with ERANGE when it's not 495 * possible. 496 * 497 * qnum_get_int() will then work for any signed 64-bit 498 * JSON_INTEGER, qnum_get_uint() for any unsigned 64-bit 499 * integer, and qnum_get_double() both for any JSON_INTEGER 500 * and any JSON_FLOAT (with precision loss for integers beyond 501 * 53 bits) 502 */ 503 int ret; 504 int64_t value; 505 uint64_t uvalue; 506 507 ret = qemu_strtoi64(token->str, NULL, 10, &value); 508 if (!ret) { 509 return QOBJECT(qnum_from_int(value)); 510 } 511 assert(ret == -ERANGE); 512 513 if (token->str[0] != '-') { 514 ret = qemu_strtou64(token->str, NULL, 10, &uvalue); 515 if (!ret) { 516 return QOBJECT(qnum_from_uint(uvalue)); 517 } 518 assert(ret == -ERANGE); 519 } 520 /* fall through to JSON_FLOAT */ 521 } 522 case JSON_FLOAT: 523 /* FIXME dependent on locale; a pervasive issue in QEMU */ 524 /* FIXME our lexer matches RFC 8259 in forbidding Inf or NaN, 525 * but those might be useful extensions beyond JSON */ 526 return QOBJECT(qnum_from_double(strtod(token->str, NULL))); 527 default: 528 abort(); 529 } 530 } 531 532 static QObject *parse_value(JSONParserContext *ctxt) 533 { 534 JSONToken *token; 535 536 token = parser_context_peek_token(ctxt); 537 if (token == NULL) { 538 parse_error(ctxt, NULL, "premature EOI"); 539 return NULL; 540 } 541 542 switch (token->type) { 543 case JSON_LCURLY: 544 return parse_object(ctxt); 545 case JSON_LSQUARE: 546 return parse_array(ctxt); 547 case JSON_INTERP: 548 return parse_interpolation(ctxt); 549 case JSON_INTEGER: 550 case JSON_FLOAT: 551 case JSON_STRING: 552 return parse_literal(ctxt); 553 case JSON_KEYWORD: 554 return parse_keyword(ctxt); 555 default: 556 parse_error(ctxt, token, "expecting value"); 557 return NULL; 558 } 559 } 560 561 JSONToken *json_token(JSONTokenType type, int x, int y, GString *tokstr) 562 { 563 JSONToken *token = g_malloc(sizeof(JSONToken) + tokstr->len + 1); 564 565 token->type = type; 566 memcpy(token->str, tokstr->str, tokstr->len); 567 token->str[tokstr->len] = 0; 568 token->x = x; 569 token->y = y; 570 return token; 571 } 572 573 QObject *json_parser_parse(GQueue *tokens, va_list *ap, Error **errp) 574 { 575 JSONParserContext ctxt = { .buf = tokens, .ap = ap }; 576 QObject *result; 577 578 result = parse_value(&ctxt); 579 assert(ctxt.err || g_queue_is_empty(ctxt.buf)); 580 581 error_propagate(errp, ctxt.err); 582 583 while (!g_queue_is_empty(ctxt.buf)) { 584 parser_context_pop_token(&ctxt); 585 } 586 g_free(ctxt.current); 587 588 return result; 589 } 590