LXR qemu/json-parser.c

   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 <stdarg.h>
  15
  16#include "qemu-common.h"
  17#include "qstring.h"
  18#include "qint.h"
  19#include "qdict.h"
  20#include "qlist.h"
  21#include "qfloat.h"
  22#include "qbool.h"
  23#include "json-parser.h"
  24#include "json-lexer.h"
  25#include "qerror.h"
  26
  27typedef struct JSONParserContext
  28{
  29    Error *err;
  30} JSONParserContext;
  31
  32#define BUG_ON(cond) assert(!(cond))
  33
  34/**
  35 * TODO
  36 *
  37 * 0) make errors meaningful again
  38 * 1) add geometry information to tokens
  39 * 3) should we return a parsed size?
  40 * 4) deal with premature EOI
  41 */
  42
  43static QObject *parse_value(JSONParserContext *ctxt, QList **tokens, va_list *ap);
  44
  45/**
  46 * Token manipulators
  47 *
  48 * tokens are dictionaries that contain a type, a string value, and geometry information
  49 * about a token identified by the lexer.  These are routines that make working with
  50 * these objects a bit easier.
  51 */
  52static const char *token_get_value(QObject *obj)
  53{
  54    return qdict_get_str(qobject_to_qdict(obj), "token");
  55}
  56
  57static JSONTokenType token_get_type(QObject *obj)
  58{
  59    return qdict_get_int(qobject_to_qdict(obj), "type");
  60}
  61
  62static int token_is_operator(QObject *obj, char op)
  63{
  64    const char *val;
  65
  66    if (token_get_type(obj) != JSON_OPERATOR) {
  67        return 0;
  68    }
  69
  70    val = token_get_value(obj);
  71
  72    return (val[0] == op) && (val[1] == 0);
  73}
  74
  75static int token_is_keyword(QObject *obj, const char *value)
  76{
  77    if (token_get_type(obj) != JSON_KEYWORD) {
  78        return 0;
  79    }
  80
  81    return strcmp(token_get_value(obj), value) == 0;
  82}
  83
  84static int token_is_escape(QObject *obj, const char *value)
  85{
  86    if (token_get_type(obj) != JSON_ESCAPE) {
  87        return 0;
  88    }
  89
  90    return (strcmp(token_get_value(obj), value) == 0);
  91}
  92
  93/**
  94 * Error handler
  95 */
  96static void GCC_FMT_ATTR(3, 4) parse_error(JSONParserContext *ctxt,
  97                                           QObject *token, const char *msg, ...)
  98{
  99    va_list ap;
 100    char message[1024];
 101    va_start(ap, msg);
 102    vsnprintf(message, sizeof(message), msg, ap);
 103    va_end(ap);
 104    if (ctxt->err) {
 105        error_free(ctxt->err);
 106        ctxt->err = NULL;
 107    }
 108    error_set(&ctxt->err, QERR_JSON_PARSE_ERROR, message);
 109}
 110
 111/**
 112 * String helpers
 113 *
 114 * These helpers are used to unescape strings.
 115 */
 116static void wchar_to_utf8(uint16_t wchar, char *buffer, size_t buffer_length)
 117{
 118    if (wchar <= 0x007F) {
 119        BUG_ON(buffer_length < 2);
 120
 121        buffer[0] = wchar & 0x7F;
 122        buffer[1] = 0;
 123    } else if (wchar <= 0x07FF) {
 124        BUG_ON(buffer_length < 3);
 125
 126        buffer[0] = 0xC0 | ((wchar >> 6) & 0x1F);
 127        buffer[1] = 0x80 | (wchar & 0x3F);
 128        buffer[2] = 0;
 129    } else {
 130        BUG_ON(buffer_length < 4);
 131
 132        buffer[0] = 0xE0 | ((wchar >> 12) & 0x0F);
 133        buffer[1] = 0x80 | ((wchar >> 6) & 0x3F);
 134        buffer[2] = 0x80 | (wchar & 0x3F);
 135        buffer[3] = 0;
 136    }
 137}
 138
 139static int hex2decimal(char ch)
 140{
 141    if (ch >= '0' && ch <= '9') {
 142        return (ch - '0');
 143    } else if (ch >= 'a' && ch <= 'f') {
 144        return 10 + (ch - 'a');
 145    } else if (ch >= 'A' && ch <= 'F') {
 146        return 10 + (ch - 'A');
 147    }
 148
 149    return -1;
 150}
 151
 152/**
 153 * parse_string(): Parse a json string and return a QObject
 154 *
 155 *  string
 156 *      ""
 157 *      " chars "
 158 *  chars
 159 *      char
 160 *      char chars
 161 *  char
 162 *      any-Unicode-character-
 163 *          except-"-or-\-or-
 164 *          control-character
 165 *      \"
 166 *      \\
 167 *      \/
 168 *      \b
 169 *      \f
 170 *      \n
 171 *      \r
 172 *      \t
 173 *      \u four-hex-digits 
 174 */
 175static QString *qstring_from_escaped_str(JSONParserContext *ctxt, QObject *token)
 176{
 177    const char *ptr = token_get_value(token);
 178    QString *str;
 179    int double_quote = 1;
 180
 181    if (*ptr == '"') {
 182        double_quote = 1;
 183    } else {
 184        double_quote = 0;
 185    }
 186    ptr++;
 187
 188    str = qstring_new();
 189    while (*ptr && 
 190           ((double_quote && *ptr != '"') || (!double_quote && *ptr != '\''))) {
 191        if (*ptr == '\\') {
 192            ptr++;
 193
 194            switch (*ptr) {
 195            case '"':
 196                qstring_append(str, "\"");
 197                ptr++;
 198                break;
 199            case '\'':
 200                qstring_append(str, "'");
 201                ptr++;
 202                break;
 203            case '\\':
 204                qstring_append(str, "\\");
 205                ptr++;
 206                break;
 207            case '/':
 208                qstring_append(str, "/");
 209                ptr++;
 210                break;
 211            case 'b':
 212                qstring_append(str, "\b");
 213                ptr++;
 214                break;
 215            case 'f':
 216                qstring_append(str, "\f");
 217                ptr++;
 218                break;
 219            case 'n':
 220                qstring_append(str, "\n");
 221                ptr++;
 222                break;
 223            case 'r':
 224                qstring_append(str, "\r");
 225                ptr++;
 226                break;
 227            case 't':
 228                qstring_append(str, "\t");
 229                ptr++;
 230                break;
 231            case 'u': {
 232                uint16_t unicode_char = 0;
 233                char utf8_char[4];
 234                int i = 0;
 235
 236                ptr++;
 237
 238                for (i = 0; i < 4; i++) {
 239                    if (qemu_isxdigit(*ptr)) {
 240                        unicode_char |= hex2decimal(*ptr) << ((3 - i) * 4);
 241                    } else {
 242                        parse_error(ctxt, token,
 243                                    "invalid hex escape sequence in string");
 244                        goto out;
 245                    }
 246                    ptr++;
 247                }
 248
 249                wchar_to_utf8(unicode_char, utf8_char, sizeof(utf8_char));
 250                qstring_append(str, utf8_char);
 251            }   break;
 252            default:
 253                parse_error(ctxt, token, "invalid escape sequence in string");
 254                goto out;
 255            }
 256        } else {
 257            char dummy[2];
 258
 259            dummy[0] = *ptr++;
 260            dummy[1] = 0;
 261
 262            qstring_append(str, dummy);
 263        }
 264    }
 265
 266    return str;
 267
 268out:
 269    QDECREF(str);
 270    return NULL;
 271}
 272
 273/**
 274 * Parsing rules
 275 */
 276static int parse_pair(JSONParserContext *ctxt, QDict *dict, QList **tokens, va_list *ap)
 277{
 278    QObject *key = NULL, *token = NULL, *value, *peek;
 279    QList *working = qlist_copy(*tokens);
 280
 281    peek = qlist_peek(working);
 282    if (peek == NULL) {
 283        parse_error(ctxt, NULL, "premature EOI");
 284        goto out;
 285    }
 286
 287    key = parse_value(ctxt, &working, ap);
 288    if (!key || qobject_type(key) != QTYPE_QSTRING) {
 289        parse_error(ctxt, peek, "key is not a string in object");
 290        goto out;
 291    }
 292
 293    token = qlist_pop(working);
 294    if (token == NULL) {
 295        parse_error(ctxt, NULL, "premature EOI");
 296        goto out;
 297    }
 298
 299    if (!token_is_operator(token, ':')) {
 300        parse_error(ctxt, token, "missing : in object pair");
 301        goto out;
 302    }
 303
 304    value = parse_value(ctxt, &working, ap);
 305    if (value == NULL) {
 306        parse_error(ctxt, token, "Missing value in dict");
 307        goto out;
 308    }
 309
 310    qdict_put_obj(dict, qstring_get_str(qobject_to_qstring(key)), value);
 311
 312    qobject_decref(token);
 313    qobject_decref(key);
 314    QDECREF(*tokens);
 315    *tokens = working;
 316
 317    return 0;
 318
 319out:
 320    qobject_decref(token);
 321    qobject_decref(key);
 322    QDECREF(working);
 323
 324    return -1;
 325}
 326
 327static QObject *parse_object(JSONParserContext *ctxt, QList **tokens, va_list *ap)
 328{
 329    QDict *dict = NULL;
 330    QObject *token, *peek;
 331    QList *working = qlist_copy(*tokens);
 332
 333    token = qlist_pop(working);
 334    if (token == NULL) {
 335        goto out;
 336    }
 337
 338    if (!token_is_operator(token, '{')) {
 339        goto out;
 340    }
 341    qobject_decref(token);
 342    token = NULL;
 343
 344    dict = qdict_new();
 345
 346    peek = qlist_peek(working);
 347    if (peek == NULL) {
 348        parse_error(ctxt, NULL, "premature EOI");
 349        goto out;
 350    }
 351
 352    if (!token_is_operator(peek, '}')) {
 353        if (parse_pair(ctxt, dict, &working, ap) == -1) {
 354            goto out;
 355        }
 356
 357        token = qlist_pop(working);
 358        if (token == NULL) {
 359            parse_error(ctxt, NULL, "premature EOI");
 360            goto out;
 361        }
 362
 363        while (!token_is_operator(token, '}')) {
 364            if (!token_is_operator(token, ',')) {
 365                parse_error(ctxt, token, "expected separator in dict");
 366                goto out;
 367            }
 368            qobject_decref(token);
 369            token = NULL;
 370
 371            if (parse_pair(ctxt, dict, &working, ap) == -1) {
 372                goto out;
 373            }
 374
 375            token = qlist_pop(working);
 376            if (token == NULL) {
 377                parse_error(ctxt, NULL, "premature EOI");
 378                goto out;
 379            }
 380        }
 381        qobject_decref(token);
 382        token = NULL;
 383    } else {
 384        token = qlist_pop(working);
 385        qobject_decref(token);
 386        token = NULL;
 387    }
 388
 389    QDECREF(*tokens);
 390    *tokens = working;
 391
 392    return QOBJECT(dict);
 393
 394out:
 395    qobject_decref(token);
 396    QDECREF(working);
 397    QDECREF(dict);
 398    return NULL;
 399}
 400
 401static QObject *parse_array(JSONParserContext *ctxt, QList **tokens, va_list *ap)
 402{
 403    QList *list = NULL;
 404    QObject *token, *peek;
 405    QList *working = qlist_copy(*tokens);
 406
 407    token = qlist_pop(working);
 408    if (token == NULL) {
 409        goto out;
 410    }
 411
 412    if (!token_is_operator(token, '[')) {
 413        goto out;
 414    }
 415    qobject_decref(token);
 416    token = NULL;
 417
 418    list = qlist_new();
 419
 420    peek = qlist_peek(working);
 421    if (peek == NULL) {
 422        parse_error(ctxt, NULL, "premature EOI");
 423        goto out;
 424    }
 425
 426    if (!token_is_operator(peek, ']')) {
 427        QObject *obj;
 428
 429        obj = parse_value(ctxt, &working, ap);
 430        if (obj == NULL) {
 431            parse_error(ctxt, token, "expecting value");
 432            goto out;
 433        }
 434
 435        qlist_append_obj(list, obj);
 436
 437        token = qlist_pop(working);
 438        if (token == NULL) {
 439            parse_error(ctxt, NULL, "premature EOI");
 440            goto out;
 441        }
 442
 443        while (!token_is_operator(token, ']')) {
 444            if (!token_is_operator(token, ',')) {
 445                parse_error(ctxt, token, "expected separator in list");
 446                goto out;
 447            }
 448
 449            qobject_decref(token);
 450            token = NULL;
 451
 452            obj = parse_value(ctxt, &working, ap);
 453            if (obj == NULL) {
 454                parse_error(ctxt, token, "expecting value");
 455                goto out;
 456            }
 457
 458            qlist_append_obj(list, obj);
 459
 460            token = qlist_pop(working);
 461            if (token == NULL) {
 462                parse_error(ctxt, NULL, "premature EOI");
 463                goto out;
 464            }
 465        }
 466
 467        qobject_decref(token);
 468        token = NULL;
 469    } else {
 470        token = qlist_pop(working);
 471        qobject_decref(token);
 472        token = NULL;
 473    }
 474
 475    QDECREF(*tokens);
 476    *tokens = working;
 477
 478    return QOBJECT(list);
 479
 480out:
 481    qobject_decref(token);
 482    QDECREF(working);
 483    QDECREF(list);
 484    return NULL;
 485}
 486
 487static QObject *parse_keyword(JSONParserContext *ctxt, QList **tokens)
 488{
 489    QObject *token, *ret;
 490    QList *working = qlist_copy(*tokens);
 491
 492    token = qlist_pop(working);
 493    if (token == NULL) {
 494        goto out;
 495    }
 496
 497    if (token_get_type(token) != JSON_KEYWORD) {
 498        goto out;
 499    }
 500
 501    if (token_is_keyword(token, "true")) {
 502        ret = QOBJECT(qbool_from_int(true));
 503    } else if (token_is_keyword(token, "false")) {
 504        ret = QOBJECT(qbool_from_int(false));
 505    } else {
 506        parse_error(ctxt, token, "invalid keyword `%s'", token_get_value(token));
 507        goto out;
 508    }
 509
 510    qobject_decref(token);
 511    QDECREF(*tokens);
 512    *tokens = working;
 513
 514    return ret;
 515
 516out: 
 517    qobject_decref(token);
 518    QDECREF(working);
 519
 520    return NULL;
 521}
 522
 523static QObject *parse_escape(JSONParserContext *ctxt, QList **tokens, va_list *ap)
 524{
 525    QObject *token = NULL, *obj;
 526    QList *working = qlist_copy(*tokens);
 527
 528    if (ap == NULL) {
 529        goto out;
 530    }
 531
 532    token = qlist_pop(working);
 533    if (token == NULL) {
 534        goto out;
 535    }
 536
 537    if (token_is_escape(token, "%p")) {
 538        obj = va_arg(*ap, QObject *);
 539    } else if (token_is_escape(token, "%i")) {
 540        obj = QOBJECT(qbool_from_int(va_arg(*ap, int)));
 541    } else if (token_is_escape(token, "%d")) {
 542        obj = QOBJECT(qint_from_int(va_arg(*ap, int)));
 543    } else if (token_is_escape(token, "%ld")) {
 544        obj = QOBJECT(qint_from_int(va_arg(*ap, long)));
 545    } else if (token_is_escape(token, "%lld") ||
 546               token_is_escape(token, "%I64d")) {
 547        obj = QOBJECT(qint_from_int(va_arg(*ap, long long)));
 548    } else if (token_is_escape(token, "%s")) {
 549        obj = QOBJECT(qstring_from_str(va_arg(*ap, const char *)));
 550    } else if (token_is_escape(token, "%f")) {
 551        obj = QOBJECT(qfloat_from_double(va_arg(*ap, double)));
 552    } else {
 553        goto out;
 554    }
 555
 556    qobject_decref(token);
 557    QDECREF(*tokens);
 558    *tokens = working;
 559
 560    return obj;
 561
 562out:
 563    qobject_decref(token);
 564    QDECREF(working);
 565
 566    return NULL;
 567}
 568
 569static QObject *parse_literal(JSONParserContext *ctxt, QList **tokens)
 570{
 571    QObject *token, *obj;
 572    QList *working = qlist_copy(*tokens);
 573
 574    token = qlist_pop(working);
 575    if (token == NULL) {
 576        goto out;
 577    }
 578
 579    switch (token_get_type(token)) {
 580    case JSON_STRING:
 581        obj = QOBJECT(qstring_from_escaped_str(ctxt, token));
 582        break;
 583    case JSON_INTEGER:
 584        obj = QOBJECT(qint_from_int(strtoll(token_get_value(token), NULL, 10)));
 585        break;
 586    case JSON_FLOAT:
 587        /* FIXME dependent on locale */
 588        obj = QOBJECT(qfloat_from_double(strtod(token_get_value(token), NULL)));
 589        break;
 590    default:
 591        goto out;
 592    }
 593
 594    qobject_decref(token);
 595    QDECREF(*tokens);
 596    *tokens = working;
 597
 598    return obj;
 599
 600out:
 601    qobject_decref(token);
 602    QDECREF(working);
 603
 604    return NULL;
 605}
 606
 607static QObject *parse_value(JSONParserContext *ctxt, QList **tokens, va_list *ap)
 608{
 609    QObject *obj;
 610
 611    obj = parse_object(ctxt, tokens, ap);
 612    if (obj == NULL) {
 613        obj = parse_array(ctxt, tokens, ap);
 614    }
 615    if (obj == NULL) {
 616        obj = parse_escape(ctxt, tokens, ap);
 617    }
 618    if (obj == NULL) {
 619        obj = parse_keyword(ctxt, tokens);
 620    } 
 621    if (obj == NULL) {
 622        obj = parse_literal(ctxt, tokens);
 623    }
 624
 625    return obj;
 626}
 627
 628QObject *json_parser_parse(QList *tokens, va_list *ap)
 629{
 630    return json_parser_parse_err(tokens, ap, NULL);
 631}
 632
 633QObject *json_parser_parse_err(QList *tokens, va_list *ap, Error **errp)
 634{
 635    JSONParserContext ctxt = {};
 636    QList *working;
 637    QObject *result;
 638
 639    if (!tokens) {
 640        return NULL;
 641    }
 642    working = qlist_copy(tokens);
 643    result = parse_value(&ctxt, &working, ap);
 644
 645    QDECREF(working);
 646
 647    error_propagate(errp, ctxt.err);
 648
 649    return result;
 650}
 651