aboutsummaryrefslogtreecommitdiff
path: root/qobject/json-parser.c
blob: 717cb8fde7e9dcd5aecb16a38a36cdd88c4cc541 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
/*
 * JSON Parser 
 *
 * Copyright IBM, Corp. 2009
 *
 * Authors:
 *  Anthony Liguori   <aliguori@us.ibm.com>
 *
 * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
 * See the COPYING.LIB file in the top-level directory.
 *
 */

#include <stdarg.h>

#include "qemu-common.h"
#include "qapi/qmp/qstring.h"
#include "qapi/qmp/qint.h"
#include "qapi/qmp/qdict.h"
#include "qapi/qmp/qlist.h"
#include "qapi/qmp/qfloat.h"
#include "qapi/qmp/qbool.h"
#include "qapi/qmp/json-parser.h"
#include "qapi/qmp/json-lexer.h"
#include "qapi/qmp/qerror.h"

typedef struct JSONParserContext
{
    Error *err;
    struct {
        QObject **buf;
        size_t pos;
        size_t count;
    } tokens;
} JSONParserContext;

#define BUG_ON(cond) assert(!(cond))

/**
 * TODO
 *
 * 0) make errors meaningful again
 * 1) add geometry information to tokens
 * 3) should we return a parsed size?
 * 4) deal with premature EOI
 */

static QObject *parse_value(JSONParserContext *ctxt, va_list *ap);

/**
 * Token manipulators
 *
 * tokens are dictionaries that contain a type, a string value, and geometry information
 * about a token identified by the lexer.  These are routines that make working with
 * these objects a bit easier.
 */
static const char *token_get_value(QObject *obj)
{
    return qdict_get_str(qobject_to_qdict(obj), "token");
}

static JSONTokenType token_get_type(QObject *obj)
{
    return qdict_get_int(qobject_to_qdict(obj), "type");
}

static int token_is_operator(QObject *obj, char op)
{
    const char *val;

    if (token_get_type(obj) != JSON_OPERATOR) {
        return 0;
    }

    val = token_get_value(obj);

    return (val[0] == op) && (val[1] == 0);
}

static int token_is_keyword(QObject *obj, const char *value)
{
    if (token_get_type(obj) != JSON_KEYWORD) {
        return 0;
    }

    return strcmp(token_get_value(obj), value) == 0;
}

static int token_is_escape(QObject *obj, const char *value)
{
    if (token_get_type(obj) != JSON_ESCAPE) {
        return 0;
    }

    return (strcmp(token_get_value(obj), value) == 0);
}

/**
 * Error handler
 */
static void GCC_FMT_ATTR(3, 4) parse_error(JSONParserContext *ctxt,
                                           QObject *token, const char *msg, ...)
{
    va_list ap;
    char message[1024];
    va_start(ap, msg);
    vsnprintf(message, sizeof(message), msg, ap);
    va_end(ap);
    if (ctxt->err) {
        error_free(ctxt->err);
        ctxt->err = NULL;
    }
    error_setg(&ctxt->err, "JSON parse error, %s", message);
}

/**
 * String helpers
 *
 * These helpers are used to unescape strings.
 */
static void wchar_to_utf8(uint16_t wchar, char *buffer, size_t buffer_length)
{
    if (wchar <= 0x007F) {
        BUG_ON(buffer_length < 2);

        buffer[0] = wchar & 0x7F;
        buffer[1] = 0;
    } else if (wchar <= 0x07FF) {
        BUG_ON(buffer_length < 3);

        buffer[0] = 0xC0 | ((wchar >> 6) & 0x1F);
        buffer[1] = 0x80 | (wchar & 0x3F);
        buffer[2] = 0;
    } else {
        BUG_ON(buffer_length < 4);

        buffer[0] = 0xE0 | ((wchar >> 12) & 0x0F);
        buffer[1] = 0x80 | ((wchar >> 6) & 0x3F);
        buffer[2] = 0x80 | (wchar & 0x3F);
        buffer[3] = 0;
    }
}

static int hex2decimal(char ch)
{
    if (ch >= '0' && ch <= '9') {
        return (ch - '0');
    } else if (ch >= 'a' && ch <= 'f') {
        return 10 + (ch - 'a');
    } else if (ch >= 'A' && ch <= 'F') {
        return 10 + (ch - 'A');
    }

    return -1;
}

/**
 * parse_string(): Parse a json string and return a QObject
 *
 *  string
 *      ""
 *      " chars "
 *  chars
 *      char
 *      char chars
 *  char
 *      any-Unicode-character-
 *          except-"-or-\-or-
 *          control-character
 *      \"
 *      \\
 *      \/
 *      \b
 *      \f
 *      \n
 *      \r
 *      \t
 *      \u four-hex-digits 
 */
static QString *qstring_from_escaped_str(JSONParserContext *ctxt, QObject *token)
{
    const char *ptr = token_get_value(token);
    QString *str;
    int double_quote = 1;

    if (*ptr == '"') {
        double_quote = 1;
    } else {
        double_quote = 0;
    }
    ptr++;

    str = qstring_new();
    while (*ptr && 
           ((double_quote && *ptr != '"') || (!double_quote && *ptr != '\''))) {
        if (*ptr == '\\') {
            ptr++;

            switch (*ptr) {
            case '"':
                qstring_append(str, "\"");
                ptr++;
                break;
            case '\'':
                qstring_append(str, "'");
                ptr++;
                break;
            case '\\':
                qstring_append(str, "\\");
                ptr++;
                break;
            case '/':
                qstring_append(str, "/");
                ptr++;
                break;
            case 'b':
                qstring_append(str, "\b");
                ptr++;
                break;
            case 'f':
                qstring_append(str, "\f");
                ptr++;
                break;
            case 'n':
                qstring_append(str, "\n");
                ptr++;
                break;
            case 'r':
                qstring_append(str, "\r");
                ptr++;
                break;
            case 't':
                qstring_append(str, "\t");
                ptr++;
                break;
            case 'u': {
                uint16_t unicode_char = 0;
                char utf8_char[4];
                int i = 0;

                ptr++;

                for (i = 0; i < 4; i++) {
                    if (qemu_isxdigit(*ptr)) {
                        unicode_char |= hex2decimal(*ptr) << ((3 - i) * 4);
                    } else {
                        parse_error(ctxt, token,
                                    "invalid hex escape sequence in string");
                        goto out;
                    }
                    ptr++;
                }

                wchar_to_utf8(unicode_char, utf8_char, sizeof(utf8_char));
                qstring_append(str, utf8_char);
            }   break;
            default:
                parse_error(ctxt, token, "invalid escape sequence in string");
                goto out;
            }
        } else {
            char dummy[2];

            dummy[0] = *ptr++;
            dummy[1] = 0;

            qstring_append(str, dummy);
        }
    }

    return str;

out:
    QDECREF(str);
    return NULL;
}

static QObject *parser_context_pop_token(JSONParserContext *ctxt)
{
    QObject *token;
    g_assert(ctxt->tokens.pos < ctxt->tokens.count);
    token = ctxt->tokens.buf[ctxt->tokens.pos];
    ctxt->tokens.pos++;
    return token;
}

/* Note: parser_context_{peek|pop}_token do not increment the
 * token object's refcount. In both cases the references will continue
 * to be tracked and cleaned up in parser_context_free(), so do not
 * attempt to free the token object.
 */
static QObject *parser_context_peek_token(JSONParserContext *ctxt)
{
    QObject *token;
    g_assert(ctxt->tokens.pos < ctxt->tokens.count);
    token = ctxt->tokens.buf[ctxt->tokens.pos];
    return token;
}

static JSONParserContext parser_context_save(JSONParserContext *ctxt)
{
    JSONParserContext saved_ctxt = {0};
    saved_ctxt.tokens.pos = ctxt->tokens.pos;
    saved_ctxt.tokens.count = ctxt->tokens.count;
    saved_ctxt.tokens.buf = ctxt->tokens.buf;
    return saved_ctxt;
}

static void parser_context_restore(JSONParserContext *ctxt,
                                   JSONParserContext saved_ctxt)
{
    ctxt->tokens.pos = saved_ctxt.tokens.pos;
    ctxt->tokens.count = saved_ctxt.tokens.count;
    ctxt->tokens.buf = saved_ctxt.tokens.buf;
}

static void tokens_append_from_iter(QObject *obj, void *opaque)
{
    JSONParserContext *ctxt = opaque;
    g_assert(ctxt->tokens.pos < ctxt->tokens.count);
    ctxt->tokens.buf[ctxt->tokens.pos++] = obj;
    qobject_incref(obj);
}

static JSONParserContext *parser_context_new(QList *tokens)
{
    JSONParserContext *ctxt;
    size_t count;

    if (!tokens) {
        return NULL;
    }

    count = qlist_size(tokens);
    if (count == 0) {
        return NULL;
    }

    ctxt = g_malloc0(sizeof(JSONParserContext));
    ctxt->tokens.pos = 0;
    ctxt->tokens.count = count;
    ctxt->tokens.buf = g_malloc(count * sizeof(QObject *));
    qlist_iter(tokens, tokens_append_from_iter, ctxt);
    ctxt->tokens.pos = 0;

    return ctxt;
}

/* to support error propagation, ctxt->err must be freed separately */
static void parser_context_free(JSONParserContext *ctxt)
{
    int i;
    if (ctxt) {
        for (i = 0; i < ctxt->tokens.count; i++) {
            qobject_decref(ctxt->tokens.buf[i]);
        }
        g_free(ctxt->tokens.buf);
        g_free(ctxt);
    }
}

/**
 * Parsing rules
 */
static int parse_pair(JSONParserContext *ctxt, QDict *dict, va_list *ap)
{
    QObject *key = NULL, *token = NULL, *value, *peek;
    JSONParserContext saved_ctxt = parser_context_save(ctxt);

    peek = parser_context_peek_token(ctxt);
    if (peek == NULL) {
        parse_error(ctxt, NULL, "premature EOI");
        goto out;
    }

    key = parse_value(ctxt, ap);
    if (!key || qobject_type(key) != QTYPE_QSTRING) {
        parse_error(ctxt, peek, "key is not a string in object");
        goto out;
    }

    token = parser_context_pop_token(ctxt);
    if (token == NULL) {
        parse_error(ctxt, NULL, "premature EOI");
        goto out;
    }

    if (!token_is_operator(token, ':')) {
        parse_error(ctxt, token, "missing : in object pair");
        goto out;
    }

    value = parse_value(ctxt, ap);
    if (value == NULL) {
        parse_error(ctxt, token, "Missing value in dict");
        goto out;
    }

    qdict_put_obj(dict, qstring_get_str(qobject_to_qstring(key)), value);

    qobject_decref(key);

    return 0;

out:
    parser_context_restore(ctxt, saved_ctxt);
    qobject_decref(key);

    return -1;
}

static QObject *parse_object(JSONParserContext *ctxt, va_list *ap)
{
    QDict *dict = NULL;
    QObject *token, *peek;
    JSONParserContext saved_ctxt = parser_context_save(ctxt);

    token = parser_context_pop_token(ctxt);
    if (token == NULL) {
        goto out;
    }

    if (!token_is_operator(token, '{')) {
        goto out;
    }

    dict = qdict_new();

    peek = parser_context_peek_token(ctxt);
    if (peek == NULL) {
        parse_error(ctxt, NULL, "premature EOI");
        goto out;
    }

    if (!token_is_operator(peek, '}')) {
        if (parse_pair(ctxt, dict, ap) == -1) {
            goto out;
        }

        token = parser_context_pop_token(ctxt);
        if (token == NULL) {
            parse_error(ctxt, NULL, "premature EOI");
            goto out;
        }

        while (!token_is_operator(token, '}')) {
            if (!token_is_operator(token, ',')) {
                parse_error(ctxt, token, "expected separator in dict");
                goto out;
            }

            if (parse_pair(ctxt, dict, ap) == -1) {
                goto out;
            }

            token = parser_context_pop_token(ctxt);
            if (token == NULL) {
                parse_error(ctxt, NULL, "premature EOI");
                goto out;
            }
        }
    } else {
        (void)parser_context_pop_token(ctxt);
    }

    return QOBJECT(dict);

out:
    parser_context_restore(ctxt, saved_ctxt);
    QDECREF(dict);
    return NULL;
}

static QObject *parse_array(JSONParserContext *ctxt, va_list *ap)
{
    QList *list = NULL;
    QObject *token, *peek;
    JSONParserContext saved_ctxt = parser_context_save(ctxt);

    token = parser_context_pop_token(ctxt);
    if (token == NULL) {
        goto out;
    }

    if (!token_is_operator(token, '[')) {
        goto out;
    }

    list = qlist_new();

    peek = parser_context_peek_token(ctxt);
    if (peek == NULL) {
        parse_error(ctxt, NULL, "premature EOI");
        goto out;
    }

    if (!token_is_operator(peek, ']')) {
        QObject *obj;

        obj = parse_value(ctxt, ap);
        if (obj == NULL) {
            parse_error(ctxt, token, "expecting value");
            goto out;
        }

        qlist_append_obj(list, obj);

        token = parser_context_pop_token(ctxt);
        if (token == NULL) {
            parse_error(ctxt, NULL, "premature EOI");
            goto out;
        }

        while (!token_is_operator(token, ']')) {
            if (!token_is_operator(token, ',')) {
                parse_error(ctxt, token, "expected separator in list");
                goto out;
            }

            obj = parse_value(ctxt, ap);
            if (obj == NULL) {
                parse_error(ctxt, token, "expecting value");
                goto out;
            }

            qlist_append_obj(list, obj);

            token = parser_context_pop_token(ctxt);
            if (token == NULL) {
                parse_error(ctxt, NULL, "premature EOI");
                goto out;
            }
        }
    } else {
        (void)parser_context_pop_token(ctxt);
    }

    return QOBJECT(list);

out:
    parser_context_restore(ctxt, saved_ctxt);
    QDECREF(list);
    return NULL;
}

static QObject *parse_keyword(JSONParserContext *ctxt)
{
    QObject *token, *ret;
    JSONParserContext saved_ctxt = parser_context_save(ctxt);

    token = parser_context_pop_token(ctxt);
    if (token == NULL) {
        goto out;
    }

    if (token_get_type(token) != JSON_KEYWORD) {
        goto out;
    }

    if (token_is_keyword(token, "true")) {
        ret = QOBJECT(qbool_from_int(true));
    } else if (token_is_keyword(token, "false")) {
        ret = QOBJECT(qbool_from_int(false));
    } else if (token_is_keyword(token, "null")) {
        ret = qnull();
    } else {
        parse_error(ctxt, token, "invalid keyword `%s'", token_get_value(token));
        goto out;
    }

    return ret;

out: 
    parser_context_restore(ctxt, saved_ctxt);

    return NULL;
}

static QObject *parse_escape(JSONParserContext *ctxt, va_list *ap)
{
    QObject *token = NULL, *obj;
    JSONParserContext saved_ctxt = parser_context_save(ctxt);

    if (ap == NULL) {
        goto out;
    }

    token = parser_context_pop_token(ctxt);
    if (token == NULL) {
        goto out;
    }

    if (token_is_escape(token, "%p")) {
        obj = va_arg(*ap, QObject *);
    } else if (token_is_escape(token, "%i")) {
        obj = QOBJECT(qbool_from_int(va_arg(*ap, int)));
    } else if (token_is_escape(token, "%d")) {
        obj = QOBJECT(qint_from_int(va_arg(*ap, int)));
    } else if (token_is_escape(token, "%ld")) {
        obj = QOBJECT(qint_from_int(va_arg(*ap, long)));
    } else if (token_is_escape(token, "%lld") ||
               token_is_escape(token, "%I64d")) {
        obj = QOBJECT(qint_from_int(va_arg(*ap, long long)));
    } else if (token_is_escape(token, "%s")) {
        obj = QOBJECT(qstring_from_str(va_arg(*ap, const char *)));
    } else if (token_is_escape(token, "%f")) {
        obj = QOBJECT(qfloat_from_double(va_arg(*ap, double)));
    } else {
        goto out;
    }

    return obj;

out:
    parser_context_restore(ctxt, saved_ctxt);

    return NULL;
}

static QObject *parse_literal(JSONParserContext *ctxt)
{
    QObject *token, *obj;
    JSONParserContext saved_ctxt = parser_context_save(ctxt);

    token = parser_context_pop_token(ctxt);
    if (token == NULL) {
        goto out;
    }

    switch (token_get_type(token)) {
    case JSON_STRING:
        obj = QOBJECT(qstring_from_escaped_str(ctxt, token));
        break;
    case JSON_INTEGER: {
        /* A possibility exists that this is a whole-valued float where the
         * fractional part was left out due to being 0 (.0). It's not a big
         * deal to treat these as ints in the parser, so long as users of the
         * resulting QObject know to expect a QInt in place of a QFloat in
         * cases like these.
         *
         * However, in some cases these values will overflow/underflow a
         * QInt/int64 container, thus we should assume these are to be handled
         * as QFloats/doubles rather than silently changing their values.
         *
         * strtoll() indicates these instances by setting errno to ERANGE
         */
        int64_t value;

        errno = 0; /* strtoll doesn't set errno on success */
        value = strtoll(token_get_value(token), NULL, 10);
        if (errno != ERANGE) {
            obj = QOBJECT(qint_from_int(value));
            break;
        }
        /* fall through to JSON_FLOAT */
    }
    case JSON_FLOAT:
        /* FIXME dependent on locale */
        obj = QOBJECT(qfloat_from_double(strtod(token_get_value(token), NULL)));
        break;
    default:
        goto out;
    }

    return obj;

out:
    parser_context_restore(ctxt, saved_ctxt);

    return NULL;
}

static QObject *parse_value(JSONParserContext *ctxt, va_list *ap)
{
    QObject *obj;

    obj = parse_object(ctxt, ap);
    if (obj == NULL) {
        obj = parse_array(ctxt, ap);
    }
    if (obj == NULL) {
        obj = parse_escape(ctxt, ap);
    }
    if (obj == NULL) {
        obj = parse_keyword(ctxt);
    } 
    if (obj == NULL) {
        obj = parse_literal(ctxt);
    }

    return obj;
}

QObject *json_parser_parse(QList *tokens, va_list *ap)
{
    return json_parser_parse_err(tokens, ap, NULL);
}

QObject *json_parser_parse_err(QList *tokens, va_list *ap, Error **errp)
{
    JSONParserContext *ctxt = parser_context_new(tokens);
    QObject *result;

    if (!ctxt) {
        return NULL;
    }

    result = parse_value(ctxt, ap);

    error_propagate(errp, ctxt->err);

    parser_context_free(ctxt);

    return result;
}