forked from chromium/chromium
-
Notifications
You must be signed in to change notification settings - Fork 0
/
json_parser.cc
754 lines (638 loc) · 19 KB
/
json_parser.cc
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
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/json/json_parser.h"
#include <cmath>
#include <utility>
#include <vector>
#include "base/logging.h"
#include "base/macros.h"
#include "base/numerics/safe_conversions.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/string_piece.h"
#include "base/strings/string_util.h"
#include "base/strings/stringprintf.h"
#include "base/strings/utf_string_conversion_utils.h"
#include "base/strings/utf_string_conversions.h"
#include "base/third_party/icu/icu_utf.h"
#include "base/values.h"
namespace base {
namespace internal {
namespace {
const int32_t kExtendedASCIIStart = 0x80;
// Simple class that checks for maximum recursion/"stack overflow."
class StackMarker {
public:
StackMarker(int max_depth, int* depth)
: max_depth_(max_depth), depth_(depth) {
++(*depth_);
DCHECK_LE(*depth_, max_depth_);
}
~StackMarker() {
--(*depth_);
}
bool IsTooDeep() const { return *depth_ >= max_depth_; }
private:
const int max_depth_;
int* const depth_;
DISALLOW_COPY_AND_ASSIGN(StackMarker);
};
constexpr uint32_t kUnicodeReplacementPoint = 0xFFFD;
} // namespace
// This is U+FFFD.
const char kUnicodeReplacementString[] = "\xEF\xBF\xBD";
JSONParser::JSONParser(int options, int max_depth)
: options_(options),
max_depth_(max_depth),
index_(0),
stack_depth_(0),
line_number_(0),
index_last_line_(0),
error_code_(JSONReader::JSON_NO_ERROR),
error_line_(0),
error_column_(0) {
CHECK_LE(max_depth, JSONReader::kStackMaxDepth);
}
JSONParser::~JSONParser() = default;
Optional<Value> JSONParser::Parse(StringPiece input) {
input_ = input;
index_ = 0;
line_number_ = 1;
index_last_line_ = 0;
error_code_ = JSONReader::JSON_NO_ERROR;
error_line_ = 0;
error_column_ = 0;
// ICU and ReadUnicodeCharacter() use int32_t for lengths, so ensure
// that the index_ will not overflow when parsing.
if (!base::IsValueInRangeForNumericType<int32_t>(input.length())) {
ReportError(JSONReader::JSON_TOO_LARGE, 0);
return nullopt;
}
// When the input JSON string starts with a UTF-8 Byte-Order-Mark,
// advance the start position to avoid the ParseNextToken function mis-
// treating a Unicode BOM as an invalid character and returning NULL.
ConsumeIfMatch("\xEF\xBB\xBF");
// Parse the first and any nested tokens.
Optional<Value> root(ParseNextToken());
if (!root)
return nullopt;
// Make sure the input stream is at an end.
if (GetNextToken() != T_END_OF_INPUT) {
ReportError(JSONReader::JSON_UNEXPECTED_DATA_AFTER_ROOT, 1);
return nullopt;
}
return root;
}
JSONReader::JsonParseError JSONParser::error_code() const {
return error_code_;
}
std::string JSONParser::GetErrorMessage() const {
return FormatErrorMessage(error_line_, error_column_,
JSONReader::ErrorCodeToString(error_code_));
}
int JSONParser::error_line() const {
return error_line_;
}
int JSONParser::error_column() const {
return error_column_;
}
// StringBuilder ///////////////////////////////////////////////////////////////
JSONParser::StringBuilder::StringBuilder() : StringBuilder(nullptr) {}
JSONParser::StringBuilder::StringBuilder(const char* pos)
: pos_(pos), length_(0) {}
JSONParser::StringBuilder::~StringBuilder() = default;
JSONParser::StringBuilder& JSONParser::StringBuilder::operator=(
StringBuilder&& other) = default;
void JSONParser::StringBuilder::Append(uint32_t point) {
DCHECK(IsValidCharacter(point));
if (point < kExtendedASCIIStart && !string_) {
DCHECK_EQ(static_cast<char>(point), pos_[length_]);
++length_;
} else {
Convert();
if (UNLIKELY(point == kUnicodeReplacementPoint)) {
string_->append(kUnicodeReplacementString);
} else {
WriteUnicodeCharacter(point, &*string_);
}
}
}
void JSONParser::StringBuilder::Convert() {
if (string_)
return;
string_.emplace(pos_, length_);
}
std::string JSONParser::StringBuilder::DestructiveAsString() {
if (string_)
return std::move(*string_);
return std::string(pos_, length_);
}
// JSONParser private //////////////////////////////////////////////////////////
Optional<StringPiece> JSONParser::PeekChars(int count) {
if (static_cast<size_t>(index_) + count > input_.length())
return nullopt;
// Using StringPiece::substr() is significantly slower (according to
// base_perftests) than constructing a substring manually.
return StringPiece(input_.data() + index_, count);
}
Optional<char> JSONParser::PeekChar() {
Optional<StringPiece> chars = PeekChars(1);
if (chars)
return (*chars)[0];
return nullopt;
}
Optional<StringPiece> JSONParser::ConsumeChars(int count) {
Optional<StringPiece> chars = PeekChars(count);
if (chars)
index_ += count;
return chars;
}
Optional<char> JSONParser::ConsumeChar() {
Optional<StringPiece> chars = ConsumeChars(1);
if (chars)
return (*chars)[0];
return nullopt;
}
const char* JSONParser::pos() {
CHECK_LE(static_cast<size_t>(index_), input_.length());
return input_.data() + index_;
}
JSONParser::Token JSONParser::GetNextToken() {
EatWhitespaceAndComments();
Optional<char> c = PeekChar();
if (!c)
return T_END_OF_INPUT;
switch (*c) {
case '{':
return T_OBJECT_BEGIN;
case '}':
return T_OBJECT_END;
case '[':
return T_ARRAY_BEGIN;
case ']':
return T_ARRAY_END;
case '"':
return T_STRING;
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
case '-':
return T_NUMBER;
case 't':
return T_BOOL_TRUE;
case 'f':
return T_BOOL_FALSE;
case 'n':
return T_NULL;
case ',':
return T_LIST_SEPARATOR;
case ':':
return T_OBJECT_PAIR_SEPARATOR;
default:
return T_INVALID_TOKEN;
}
}
void JSONParser::EatWhitespaceAndComments() {
while (Optional<char> c = PeekChar()) {
switch (*c) {
case '\r':
case '\n':
index_last_line_ = index_;
// Don't increment line_number_ twice for "\r\n".
if (!(c == '\n' && index_ > 0 && input_[index_ - 1] == '\r')) {
++line_number_;
}
FALLTHROUGH;
case ' ':
case '\t':
ConsumeChar();
break;
case '/':
if (!EatComment())
return;
break;
default:
return;
}
}
}
bool JSONParser::EatComment() {
Optional<StringPiece> comment_start = ConsumeChars(2);
if (!comment_start)
return false;
if (comment_start == "//") {
// Single line comment, read to newline.
while (Optional<char> c = PeekChar()) {
if (c == '\n' || c == '\r')
return true;
ConsumeChar();
}
} else if (comment_start == "/*") {
char previous_char = '\0';
// Block comment, read until end marker.
while (Optional<char> c = PeekChar()) {
if (previous_char == '*' && c == '/') {
// EatWhitespaceAndComments will inspect pos(), which will still be on
// the last / of the comment, so advance once more (which may also be
// end of input).
ConsumeChar();
return true;
}
previous_char = *ConsumeChar();
}
// If the comment is unterminated, GetNextToken will report T_END_OF_INPUT.
}
return false;
}
Optional<Value> JSONParser::ParseNextToken() {
return ParseToken(GetNextToken());
}
Optional<Value> JSONParser::ParseToken(Token token) {
switch (token) {
case T_OBJECT_BEGIN:
return ConsumeDictionary();
case T_ARRAY_BEGIN:
return ConsumeList();
case T_STRING:
return ConsumeString();
case T_NUMBER:
return ConsumeNumber();
case T_BOOL_TRUE:
case T_BOOL_FALSE:
case T_NULL:
return ConsumeLiteral();
default:
ReportError(JSONReader::JSON_UNEXPECTED_TOKEN, 1);
return nullopt;
}
}
Optional<Value> JSONParser::ConsumeDictionary() {
if (ConsumeChar() != '{') {
ReportError(JSONReader::JSON_UNEXPECTED_TOKEN, 1);
return nullopt;
}
StackMarker depth_check(max_depth_, &stack_depth_);
if (depth_check.IsTooDeep()) {
ReportError(JSONReader::JSON_TOO_MUCH_NESTING, 0);
return nullopt;
}
std::vector<Value::DictStorage::value_type> dict_storage;
Token token = GetNextToken();
while (token != T_OBJECT_END) {
if (token != T_STRING) {
ReportError(JSONReader::JSON_UNQUOTED_DICTIONARY_KEY, 1);
return nullopt;
}
// First consume the key.
StringBuilder key;
if (!ConsumeStringRaw(&key)) {
return nullopt;
}
// Read the separator.
token = GetNextToken();
if (token != T_OBJECT_PAIR_SEPARATOR) {
ReportError(JSONReader::JSON_SYNTAX_ERROR, 1);
return nullopt;
}
// The next token is the value. Ownership transfers to |dict|.
ConsumeChar();
Optional<Value> value = ParseNextToken();
if (!value) {
// ReportError from deeper level.
return nullopt;
}
dict_storage.emplace_back(key.DestructiveAsString(),
std::make_unique<Value>(std::move(*value)));
token = GetNextToken();
if (token == T_LIST_SEPARATOR) {
ConsumeChar();
token = GetNextToken();
if (token == T_OBJECT_END && !(options_ & JSON_ALLOW_TRAILING_COMMAS)) {
ReportError(JSONReader::JSON_TRAILING_COMMA, 1);
return nullopt;
}
} else if (token != T_OBJECT_END) {
ReportError(JSONReader::JSON_SYNTAX_ERROR, 0);
return nullopt;
}
}
ConsumeChar(); // Closing '}'.
return Value(Value::DictStorage(std::move(dict_storage), KEEP_LAST_OF_DUPES));
}
Optional<Value> JSONParser::ConsumeList() {
if (ConsumeChar() != '[') {
ReportError(JSONReader::JSON_UNEXPECTED_TOKEN, 1);
return nullopt;
}
StackMarker depth_check(max_depth_, &stack_depth_);
if (depth_check.IsTooDeep()) {
ReportError(JSONReader::JSON_TOO_MUCH_NESTING, 0);
return nullopt;
}
Value::ListStorage list_storage;
Token token = GetNextToken();
while (token != T_ARRAY_END) {
Optional<Value> item = ParseToken(token);
if (!item) {
// ReportError from deeper level.
return nullopt;
}
list_storage.push_back(std::move(*item));
token = GetNextToken();
if (token == T_LIST_SEPARATOR) {
ConsumeChar();
token = GetNextToken();
if (token == T_ARRAY_END && !(options_ & JSON_ALLOW_TRAILING_COMMAS)) {
ReportError(JSONReader::JSON_TRAILING_COMMA, 1);
return nullopt;
}
} else if (token != T_ARRAY_END) {
ReportError(JSONReader::JSON_SYNTAX_ERROR, 1);
return nullopt;
}
}
ConsumeChar(); // Closing ']'.
return Value(std::move(list_storage));
}
Optional<Value> JSONParser::ConsumeString() {
StringBuilder string;
if (!ConsumeStringRaw(&string))
return nullopt;
return Value(string.DestructiveAsString());
}
bool JSONParser::ConsumeStringRaw(StringBuilder* out) {
if (ConsumeChar() != '"') {
ReportError(JSONReader::JSON_UNEXPECTED_TOKEN, 1);
return false;
}
// StringBuilder will internally build a StringPiece unless a UTF-16
// conversion occurs, at which point it will perform a copy into a
// std::string.
StringBuilder string(pos());
while (PeekChar()) {
uint32_t next_char = 0;
if (!ReadUnicodeCharacter(input_.data(),
static_cast<int32_t>(input_.length()),
&index_,
&next_char) ||
!IsValidCharacter(next_char)) {
if ((options_ & JSON_REPLACE_INVALID_CHARACTERS) == 0) {
ReportError(JSONReader::JSON_UNSUPPORTED_ENCODING, 1);
return false;
}
ConsumeChar();
string.Append(kUnicodeReplacementPoint);
continue;
}
if (next_char == '"') {
ConsumeChar();
*out = std::move(string);
return true;
}
if (next_char != '\\') {
// If this character is not an escape sequence...
ConsumeChar();
string.Append(next_char);
} else {
// And if it is an escape sequence, the input string will be adjusted
// (either by combining the two characters of an encoded escape sequence,
// or with a UTF conversion), so using StringPiece isn't possible -- force
// a conversion.
string.Convert();
// Read past the escape '\' and ensure there's a character following.
Optional<StringPiece> escape_sequence = ConsumeChars(2);
if (!escape_sequence) {
ReportError(JSONReader::JSON_INVALID_ESCAPE, 0);
return false;
}
switch ((*escape_sequence)[1]) {
// Allowed esape sequences:
case 'x': { // UTF-8 sequence.
// UTF-8 \x escape sequences are not allowed in the spec, but they
// are supported here for backwards-compatiblity with the old parser.
escape_sequence = ConsumeChars(2);
if (!escape_sequence) {
ReportError(JSONReader::JSON_INVALID_ESCAPE, -2);
return false;
}
int hex_digit = 0;
if (!HexStringToInt(*escape_sequence, &hex_digit) ||
!IsValidCharacter(hex_digit)) {
ReportError(JSONReader::JSON_INVALID_ESCAPE, -2);
return false;
}
string.Append(hex_digit);
break;
}
case 'u': { // UTF-16 sequence.
// UTF units are of the form \uXXXX.
uint32_t code_point;
if (!DecodeUTF16(&code_point)) {
ReportError(JSONReader::JSON_INVALID_ESCAPE, 0);
return false;
}
string.Append(code_point);
break;
}
case '"':
string.Append('"');
break;
case '\\':
string.Append('\\');
break;
case '/':
string.Append('/');
break;
case 'b':
string.Append('\b');
break;
case 'f':
string.Append('\f');
break;
case 'n':
string.Append('\n');
break;
case 'r':
string.Append('\r');
break;
case 't':
string.Append('\t');
break;
case 'v': // Not listed as valid escape sequence in the RFC.
string.Append('\v');
break;
// All other escape squences are illegal.
default:
ReportError(JSONReader::JSON_INVALID_ESCAPE, 0);
return false;
}
}
}
ReportError(JSONReader::JSON_SYNTAX_ERROR, 0);
return false;
}
// Entry is at the first X in \uXXXX.
bool JSONParser::DecodeUTF16(uint32_t* out_code_point) {
Optional<StringPiece> escape_sequence = ConsumeChars(4);
if (!escape_sequence)
return false;
// Consume the UTF-16 code unit, which may be a high surrogate.
int code_unit16_high = 0;
if (!HexStringToInt(*escape_sequence, &code_unit16_high))
return false;
// If this is a high surrogate, consume the next code unit to get the
// low surrogate.
if (CBU16_IS_SURROGATE(code_unit16_high)) {
// Make sure this is the high surrogate. If not, it's an encoding
// error.
if (!CBU16_IS_SURROGATE_LEAD(code_unit16_high))
return false;
// Make sure that the token has more characters to consume the
// lower surrogate.
if (!ConsumeIfMatch("\\u"))
return false;
escape_sequence = ConsumeChars(4);
if (!escape_sequence)
return false;
int code_unit16_low = 0;
if (!HexStringToInt(*escape_sequence, &code_unit16_low))
return false;
if (!CBU16_IS_TRAIL(code_unit16_low))
return false;
uint32_t code_point =
CBU16_GET_SUPPLEMENTARY(code_unit16_high, code_unit16_low);
if (!IsValidCharacter(code_point))
return false;
*out_code_point = code_point;
} else {
// Not a surrogate.
DCHECK(CBU16_IS_SINGLE(code_unit16_high));
if (!IsValidCharacter(code_unit16_high)) {
if ((options_ & JSON_REPLACE_INVALID_CHARACTERS) == 0) {
return false;
}
*out_code_point = kUnicodeReplacementPoint;
return true;
}
*out_code_point = code_unit16_high;
}
return true;
}
Optional<Value> JSONParser::ConsumeNumber() {
const char* num_start = pos();
const int start_index = index_;
int end_index = start_index;
if (PeekChar() == '-')
ConsumeChar();
if (!ReadInt(false)) {
ReportError(JSONReader::JSON_SYNTAX_ERROR, 1);
return nullopt;
}
end_index = index_;
// The optional fraction part.
if (PeekChar() == '.') {
ConsumeChar();
if (!ReadInt(true)) {
ReportError(JSONReader::JSON_SYNTAX_ERROR, 1);
return nullopt;
}
end_index = index_;
}
// Optional exponent part.
Optional<char> c = PeekChar();
if (c == 'e' || c == 'E') {
ConsumeChar();
if (PeekChar() == '-' || PeekChar() == '+') {
ConsumeChar();
}
if (!ReadInt(true)) {
ReportError(JSONReader::JSON_SYNTAX_ERROR, 1);
return nullopt;
}
end_index = index_;
}
// ReadInt is greedy because numbers have no easily detectable sentinel,
// so save off where the parser should be on exit (see Consume invariant at
// the top of the header), then make sure the next token is one which is
// valid.
int exit_index = index_;
switch (GetNextToken()) {
case T_OBJECT_END:
case T_ARRAY_END:
case T_LIST_SEPARATOR:
case T_END_OF_INPUT:
break;
default:
ReportError(JSONReader::JSON_SYNTAX_ERROR, 1);
return nullopt;
}
index_ = exit_index;
StringPiece num_string(num_start, end_index - start_index);
int num_int;
if (StringToInt(num_string, &num_int))
return Value(num_int);
double num_double;
if (StringToDouble(num_string.as_string(), &num_double) &&
std::isfinite(num_double)) {
return Value(num_double);
}
return nullopt;
}
bool JSONParser::ReadInt(bool allow_leading_zeros) {
size_t len = 0;
char first = 0;
while (Optional<char> c = PeekChar()) {
if (!IsAsciiDigit(c))
break;
if (len == 0)
first = *c;
++len;
ConsumeChar();
}
if (len == 0)
return false;
if (!allow_leading_zeros && len > 1 && first == '0')
return false;
return true;
}
Optional<Value> JSONParser::ConsumeLiteral() {
if (ConsumeIfMatch("true"))
return Value(true);
if (ConsumeIfMatch("false"))
return Value(false);
if (ConsumeIfMatch("null"))
return Value(Value::Type::NONE);
ReportError(JSONReader::JSON_SYNTAX_ERROR, 1);
return nullopt;
}
bool JSONParser::ConsumeIfMatch(StringPiece match) {
if (match == PeekChars(match.size())) {
ConsumeChars(match.size());
return true;
}
return false;
}
void JSONParser::ReportError(JSONReader::JsonParseError code,
int column_adjust) {
error_code_ = code;
error_line_ = line_number_;
error_column_ = index_ - index_last_line_ + column_adjust;
}
// static
std::string JSONParser::FormatErrorMessage(int line, int column,
const std::string& description) {
if (line || column) {
return StringPrintf("Line: %i, column: %i, %s",
line, column, description.c_str());
}
return description;
}
} // namespace internal
} // namespace base