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
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
|
/*-------------------------------------------------------------------------
*
* jsonapi.c
* JSON parser and lexer interfaces
*
* Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* src/common/jsonapi.c
*
*-------------------------------------------------------------------------
*/
#ifndef FRONTEND
#include "postgres.h"
#else
#include "postgres_fe.h"
#endif
#include "common/jsonapi.h"
#include "mb/pg_wchar.h"
#include "port/pg_lfind.h"
#ifndef FRONTEND
#include "miscadmin.h"
#endif
/*
* The context of the parser is maintained by the recursive descent
* mechanism, but is passed explicitly to the error reporting routine
* for better diagnostics.
*/
typedef enum /* contexts of JSON parser */
{
JSON_PARSE_VALUE, /* expecting a value */
JSON_PARSE_STRING, /* expecting a string (for a field name) */
JSON_PARSE_ARRAY_START, /* saw '[', expecting value or ']' */
JSON_PARSE_ARRAY_NEXT, /* saw array element, expecting ',' or ']' */
JSON_PARSE_OBJECT_START, /* saw '{', expecting label or '}' */
JSON_PARSE_OBJECT_LABEL, /* saw object label, expecting ':' */
JSON_PARSE_OBJECT_NEXT, /* saw object value, expecting ',' or '}' */
JSON_PARSE_OBJECT_COMMA, /* saw object ',', expecting next label */
JSON_PARSE_END /* saw the end of a document, expect nothing */
} JsonParseContext;
static inline JsonParseErrorType json_lex_string(JsonLexContext *lex);
static inline JsonParseErrorType json_lex_number(JsonLexContext *lex, char *s,
bool *num_err, int *total_len);
static inline JsonParseErrorType parse_scalar(JsonLexContext *lex, JsonSemAction *sem);
static JsonParseErrorType parse_object_field(JsonLexContext *lex, JsonSemAction *sem);
static JsonParseErrorType parse_object(JsonLexContext *lex, JsonSemAction *sem);
static JsonParseErrorType parse_array_element(JsonLexContext *lex, JsonSemAction *sem);
static JsonParseErrorType parse_array(JsonLexContext *lex, JsonSemAction *sem);
static JsonParseErrorType report_parse_error(JsonParseContext ctx, JsonLexContext *lex);
/* the null action object used for pure validation */
JsonSemAction nullSemAction =
{
NULL, NULL, NULL, NULL, NULL,
NULL, NULL, NULL, NULL, NULL
};
/* Recursive Descent parser support routines */
/*
* lex_peek
*
* what is the current look_ahead token?
*/
static inline JsonTokenType
lex_peek(JsonLexContext *lex)
{
return lex->token_type;
}
/*
* lex_expect
*
* move the lexer to the next token if the current look_ahead token matches
* the parameter token. Otherwise, report an error.
*/
static inline JsonParseErrorType
lex_expect(JsonParseContext ctx, JsonLexContext *lex, JsonTokenType token)
{
if (lex_peek(lex) == token)
return json_lex(lex);
else
return report_parse_error(ctx, lex);
}
/* chars to consider as part of an alphanumeric token */
#define JSON_ALPHANUMERIC_CHAR(c) \
(((c) >= 'a' && (c) <= 'z') || \
((c) >= 'A' && (c) <= 'Z') || \
((c) >= '0' && (c) <= '9') || \
(c) == '_' || \
IS_HIGHBIT_SET(c))
/*
* Utility function to check if a string is a valid JSON number.
*
* str is of length len, and need not be null-terminated.
*/
bool
IsValidJsonNumber(const char *str, int len)
{
bool numeric_error;
int total_len;
JsonLexContext dummy_lex;
if (len <= 0)
return false;
/*
* json_lex_number expects a leading '-' to have been eaten already.
*
* having to cast away the constness of str is ugly, but there's not much
* easy alternative.
*/
if (*str == '-')
{
dummy_lex.input = unconstify(char *, str) + 1;
dummy_lex.input_length = len - 1;
}
else
{
dummy_lex.input = unconstify(char *, str);
dummy_lex.input_length = len;
}
json_lex_number(&dummy_lex, dummy_lex.input, &numeric_error, &total_len);
return (!numeric_error) && (total_len == dummy_lex.input_length);
}
/*
* makeJsonLexContextCstringLen
*
* lex constructor, with or without StringInfo object for de-escaped lexemes.
*
* Without is better as it makes the processing faster, so only make one
* if really required.
*/
JsonLexContext *
makeJsonLexContextCstringLen(char *json, int len, int encoding, bool need_escapes)
{
JsonLexContext *lex = palloc0(sizeof(JsonLexContext));
lex->input = lex->token_terminator = lex->line_start = json;
lex->line_number = 1;
lex->input_length = len;
lex->input_encoding = encoding;
if (need_escapes)
lex->strval = makeStringInfo();
return lex;
}
/*
* pg_parse_json
*
* Publicly visible entry point for the JSON parser.
*
* lex is a lexing context, set up for the json to be processed by calling
* makeJsonLexContext(). sem is a structure of function pointers to semantic
* action routines to be called at appropriate spots during parsing, and a
* pointer to a state object to be passed to those routines.
*/
JsonParseErrorType
pg_parse_json(JsonLexContext *lex, JsonSemAction *sem)
{
JsonTokenType tok;
JsonParseErrorType result;
/* get the initial token */
result = json_lex(lex);
if (result != JSON_SUCCESS)
return result;
tok = lex_peek(lex);
/* parse by recursive descent */
switch (tok)
{
case JSON_TOKEN_OBJECT_START:
result = parse_object(lex, sem);
break;
case JSON_TOKEN_ARRAY_START:
result = parse_array(lex, sem);
break;
default:
result = parse_scalar(lex, sem); /* json can be a bare scalar */
}
if (result == JSON_SUCCESS)
result = lex_expect(JSON_PARSE_END, lex, JSON_TOKEN_END);
return result;
}
/*
* json_count_array_elements
*
* Returns number of array elements in lex context at start of array token
* until end of array token at same nesting level.
*
* Designed to be called from array_start routines.
*/
JsonParseErrorType
json_count_array_elements(JsonLexContext *lex, int *elements)
{
JsonLexContext copylex;
int count;
JsonParseErrorType result;
/*
* It's safe to do this with a shallow copy because the lexical routines
* don't scribble on the input. They do scribble on the other pointers
* etc, so doing this with a copy makes that safe.
*/
memcpy(©lex, lex, sizeof(JsonLexContext));
copylex.strval = NULL; /* not interested in values here */
copylex.lex_level++;
count = 0;
result = lex_expect(JSON_PARSE_ARRAY_START, ©lex,
JSON_TOKEN_ARRAY_START);
if (result != JSON_SUCCESS)
return result;
if (lex_peek(©lex) != JSON_TOKEN_ARRAY_END)
{
while (1)
{
count++;
result = parse_array_element(©lex, &nullSemAction);
if (result != JSON_SUCCESS)
return result;
if (copylex.token_type != JSON_TOKEN_COMMA)
break;
result = json_lex(©lex);
if (result != JSON_SUCCESS)
return result;
}
}
result = lex_expect(JSON_PARSE_ARRAY_NEXT, ©lex,
JSON_TOKEN_ARRAY_END);
if (result != JSON_SUCCESS)
return result;
*elements = count;
return JSON_SUCCESS;
}
/*
* Recursive Descent parse routines. There is one for each structural
* element in a json document:
* - scalar (string, number, true, false, null)
* - array ( [ ] )
* - array element
* - object ( { } )
* - object field
*/
static inline JsonParseErrorType
parse_scalar(JsonLexContext *lex, JsonSemAction *sem)
{
char *val = NULL;
json_scalar_action sfunc = sem->scalar;
JsonTokenType tok = lex_peek(lex);
JsonParseErrorType result;
/* a scalar must be a string, a number, true, false, or null */
if (tok != JSON_TOKEN_STRING && tok != JSON_TOKEN_NUMBER &&
tok != JSON_TOKEN_TRUE && tok != JSON_TOKEN_FALSE &&
tok != JSON_TOKEN_NULL)
return report_parse_error(JSON_PARSE_VALUE, lex);
/* if no semantic function, just consume the token */
if (sfunc == NULL)
return json_lex(lex);
/* extract the de-escaped string value, or the raw lexeme */
if (lex_peek(lex) == JSON_TOKEN_STRING)
{
if (lex->strval != NULL)
val = pstrdup(lex->strval->data);
}
else
{
int len = (lex->token_terminator - lex->token_start);
val = palloc(len + 1);
memcpy(val, lex->token_start, len);
val[len] = '\0';
}
/* consume the token */
result = json_lex(lex);
if (result != JSON_SUCCESS)
return result;
/* invoke the callback */
result = (*sfunc) (sem->semstate, val, tok);
return result;
}
static JsonParseErrorType
parse_object_field(JsonLexContext *lex, JsonSemAction *sem)
{
/*
* An object field is "fieldname" : value where value can be a scalar,
* object or array. Note: in user-facing docs and error messages, we
* generally call a field name a "key".
*/
char *fname = NULL; /* keep compiler quiet */
json_ofield_action ostart = sem->object_field_start;
json_ofield_action oend = sem->object_field_end;
bool isnull;
JsonTokenType tok;
JsonParseErrorType result;
if (lex_peek(lex) != JSON_TOKEN_STRING)
return report_parse_error(JSON_PARSE_STRING, lex);
if ((ostart != NULL || oend != NULL) && lex->strval != NULL)
fname = pstrdup(lex->strval->data);
result = json_lex(lex);
if (result != JSON_SUCCESS)
return result;
result = lex_expect(JSON_PARSE_OBJECT_LABEL, lex, JSON_TOKEN_COLON);
if (result != JSON_SUCCESS)
return result;
tok = lex_peek(lex);
isnull = tok == JSON_TOKEN_NULL;
if (ostart != NULL)
{
result = (*ostart) (sem->semstate, fname, isnull);
if (result != JSON_SUCCESS)
return result;
}
switch (tok)
{
case JSON_TOKEN_OBJECT_START:
result = parse_object(lex, sem);
break;
case JSON_TOKEN_ARRAY_START:
result = parse_array(lex, sem);
break;
default:
result = parse_scalar(lex, sem);
}
if (result != JSON_SUCCESS)
return result;
if (oend != NULL)
{
result = (*oend) (sem->semstate, fname, isnull);
if (result != JSON_SUCCESS)
return result;
}
return JSON_SUCCESS;
}
static JsonParseErrorType
parse_object(JsonLexContext *lex, JsonSemAction *sem)
{
/*
* an object is a possibly empty sequence of object fields, separated by
* commas and surrounded by curly braces.
*/
json_struct_action ostart = sem->object_start;
json_struct_action oend = sem->object_end;
JsonTokenType tok;
JsonParseErrorType result;
#ifndef FRONTEND
check_stack_depth();
#endif
if (ostart != NULL)
{
result = (*ostart) (sem->semstate);
if (result != JSON_SUCCESS)
return result;
}
/*
* Data inside an object is at a higher nesting level than the object
* itself. Note that we increment this after we call the semantic routine
* for the object start and restore it before we call the routine for the
* object end.
*/
lex->lex_level++;
Assert(lex_peek(lex) == JSON_TOKEN_OBJECT_START);
result = json_lex(lex);
if (result != JSON_SUCCESS)
return result;
tok = lex_peek(lex);
switch (tok)
{
case JSON_TOKEN_STRING:
result = parse_object_field(lex, sem);
while (result == JSON_SUCCESS && lex_peek(lex) == JSON_TOKEN_COMMA)
{
result = json_lex(lex);
if (result != JSON_SUCCESS)
break;
result = parse_object_field(lex, sem);
}
break;
case JSON_TOKEN_OBJECT_END:
break;
default:
/* case of an invalid initial token inside the object */
result = report_parse_error(JSON_PARSE_OBJECT_START, lex);
}
if (result != JSON_SUCCESS)
return result;
result = lex_expect(JSON_PARSE_OBJECT_NEXT, lex, JSON_TOKEN_OBJECT_END);
if (result != JSON_SUCCESS)
return result;
lex->lex_level--;
if (oend != NULL)
{
result = (*oend) (sem->semstate);
if (result != JSON_SUCCESS)
return result;
}
return JSON_SUCCESS;
}
static JsonParseErrorType
parse_array_element(JsonLexContext *lex, JsonSemAction *sem)
{
json_aelem_action astart = sem->array_element_start;
json_aelem_action aend = sem->array_element_end;
JsonTokenType tok = lex_peek(lex);
JsonParseErrorType result;
bool isnull;
isnull = tok == JSON_TOKEN_NULL;
if (astart != NULL)
{
result = (*astart) (sem->semstate, isnull);
if (result != JSON_SUCCESS)
return result;
}
/* an array element is any object, array or scalar */
switch (tok)
{
case JSON_TOKEN_OBJECT_START:
result = parse_object(lex, sem);
break;
case JSON_TOKEN_ARRAY_START:
result = parse_array(lex, sem);
break;
default:
result = parse_scalar(lex, sem);
}
if (result != JSON_SUCCESS)
return result;
if (aend != NULL)
{
result = (*aend) (sem->semstate, isnull);
if (result != JSON_SUCCESS)
return result;
}
return JSON_SUCCESS;
}
static JsonParseErrorType
parse_array(JsonLexContext *lex, JsonSemAction *sem)
{
/*
* an array is a possibly empty sequence of array elements, separated by
* commas and surrounded by square brackets.
*/
json_struct_action astart = sem->array_start;
json_struct_action aend = sem->array_end;
JsonParseErrorType result;
#ifndef FRONTEND
check_stack_depth();
#endif
if (astart != NULL)
{
result = (*astart) (sem->semstate);
if (result != JSON_SUCCESS)
return result;
}
/*
* Data inside an array is at a higher nesting level than the array
* itself. Note that we increment this after we call the semantic routine
* for the array start and restore it before we call the routine for the
* array end.
*/
lex->lex_level++;
result = lex_expect(JSON_PARSE_ARRAY_START, lex, JSON_TOKEN_ARRAY_START);
if (result == JSON_SUCCESS && lex_peek(lex) != JSON_TOKEN_ARRAY_END)
{
result = parse_array_element(lex, sem);
while (result == JSON_SUCCESS && lex_peek(lex) == JSON_TOKEN_COMMA)
{
result = json_lex(lex);
if (result != JSON_SUCCESS)
break;
result = parse_array_element(lex, sem);
}
}
if (result != JSON_SUCCESS)
return result;
result = lex_expect(JSON_PARSE_ARRAY_NEXT, lex, JSON_TOKEN_ARRAY_END);
if (result != JSON_SUCCESS)
return result;
lex->lex_level--;
if (aend != NULL)
{
result = (*aend) (sem->semstate);
if (result != JSON_SUCCESS)
return result;
}
return JSON_SUCCESS;
}
/*
* Lex one token from the input stream.
*/
JsonParseErrorType
json_lex(JsonLexContext *lex)
{
char *s;
char *const end = lex->input + lex->input_length;
JsonParseErrorType result;
/* Skip leading whitespace. */
s = lex->token_terminator;
while (s < end && (*s == ' ' || *s == '\t' || *s == '\n' || *s == '\r'))
{
if (*s++ == '\n')
{
++lex->line_number;
lex->line_start = s;
}
}
lex->token_start = s;
/* Determine token type. */
if (s >= end)
{
lex->token_start = NULL;
lex->prev_token_terminator = lex->token_terminator;
lex->token_terminator = s;
lex->token_type = JSON_TOKEN_END;
}
else
{
switch (*s)
{
/* Single-character token, some kind of punctuation mark. */
case '{':
lex->prev_token_terminator = lex->token_terminator;
lex->token_terminator = s + 1;
lex->token_type = JSON_TOKEN_OBJECT_START;
break;
case '}':
lex->prev_token_terminator = lex->token_terminator;
lex->token_terminator = s + 1;
lex->token_type = JSON_TOKEN_OBJECT_END;
break;
case '[':
lex->prev_token_terminator = lex->token_terminator;
lex->token_terminator = s + 1;
lex->token_type = JSON_TOKEN_ARRAY_START;
break;
case ']':
lex->prev_token_terminator = lex->token_terminator;
lex->token_terminator = s + 1;
lex->token_type = JSON_TOKEN_ARRAY_END;
break;
case ',':
lex->prev_token_terminator = lex->token_terminator;
lex->token_terminator = s + 1;
lex->token_type = JSON_TOKEN_COMMA;
break;
case ':':
lex->prev_token_terminator = lex->token_terminator;
lex->token_terminator = s + 1;
lex->token_type = JSON_TOKEN_COLON;
break;
case '"':
/* string */
result = json_lex_string(lex);
if (result != JSON_SUCCESS)
return result;
lex->token_type = JSON_TOKEN_STRING;
break;
case '-':
/* Negative number. */
result = json_lex_number(lex, s + 1, NULL, NULL);
if (result != JSON_SUCCESS)
return result;
lex->token_type = JSON_TOKEN_NUMBER;
break;
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
/* Positive number. */
result = json_lex_number(lex, s, NULL, NULL);
if (result != JSON_SUCCESS)
return result;
lex->token_type = JSON_TOKEN_NUMBER;
break;
default:
{
char *p;
/*
* We're not dealing with a string, number, legal
* punctuation mark, or end of string. The only legal
* tokens we might find here are true, false, and null,
* but for error reporting purposes we scan until we see a
* non-alphanumeric character. That way, we can report
* the whole word as an unexpected token, rather than just
* some unintuitive prefix thereof.
*/
for (p = s; p < end && JSON_ALPHANUMERIC_CHAR(*p); p++)
/* skip */ ;
/*
* We got some sort of unexpected punctuation or an
* otherwise unexpected character, so just complain about
* that one character.
*/
if (p == s)
{
lex->prev_token_terminator = lex->token_terminator;
lex->token_terminator = s + 1;
return JSON_INVALID_TOKEN;
}
/*
* We've got a real alphanumeric token here. If it
* happens to be true, false, or null, all is well. If
* not, error out.
*/
lex->prev_token_terminator = lex->token_terminator;
lex->token_terminator = p;
if (p - s == 4)
{
if (memcmp(s, "true", 4) == 0)
lex->token_type = JSON_TOKEN_TRUE;
else if (memcmp(s, "null", 4) == 0)
lex->token_type = JSON_TOKEN_NULL;
else
return JSON_INVALID_TOKEN;
}
else if (p - s == 5 && memcmp(s, "false", 5) == 0)
lex->token_type = JSON_TOKEN_FALSE;
else
return JSON_INVALID_TOKEN;
}
} /* end of switch */
}
return JSON_SUCCESS;
}
/*
* The next token in the input stream is known to be a string; lex it.
*
* If lex->strval isn't NULL, fill it with the decoded string.
* Set lex->token_terminator to the end of the decoded input, and in
* success cases, transfer its previous value to lex->prev_token_terminator.
* Return JSON_SUCCESS or an error code.
*
* Note: be careful that all error exits advance lex->token_terminator
* to the point after the character we detected the error on.
*/
static inline JsonParseErrorType
json_lex_string(JsonLexContext *lex)
{
char *s;
char *const end = lex->input + lex->input_length;
int hi_surrogate = -1;
/* Convenience macros for error exits */
#define FAIL_AT_CHAR_START(code) \
do { \
lex->token_terminator = s; \
return code; \
} while (0)
#define FAIL_AT_CHAR_END(code) \
do { \
lex->token_terminator = \
s + pg_encoding_mblen_bounded(lex->input_encoding, s); \
return code; \
} while (0)
if (lex->strval != NULL)
resetStringInfo(lex->strval);
Assert(lex->input_length > 0);
s = lex->token_start;
for (;;)
{
s++;
/* Premature end of the string. */
if (s >= end)
FAIL_AT_CHAR_START(JSON_INVALID_TOKEN);
else if (*s == '"')
break;
else if (*s == '\\')
{
/* OK, we have an escape character. */
s++;
if (s >= end)
FAIL_AT_CHAR_START(JSON_INVALID_TOKEN);
else if (*s == 'u')
{
int i;
int ch = 0;
for (i = 1; i <= 4; i++)
{
s++;
if (s >= end)
FAIL_AT_CHAR_START(JSON_INVALID_TOKEN);
else if (*s >= '0' && *s <= '9')
ch = (ch * 16) + (*s - '0');
else if (*s >= 'a' && *s <= 'f')
ch = (ch * 16) + (*s - 'a') + 10;
else if (*s >= 'A' && *s <= 'F')
ch = (ch * 16) + (*s - 'A') + 10;
else
FAIL_AT_CHAR_END(JSON_UNICODE_ESCAPE_FORMAT);
}
if (lex->strval != NULL)
{
/*
* Combine surrogate pairs.
*/
if (is_utf16_surrogate_first(ch))
{
if (hi_surrogate != -1)
FAIL_AT_CHAR_END(JSON_UNICODE_HIGH_SURROGATE);
hi_surrogate = ch;
continue;
}
else if (is_utf16_surrogate_second(ch))
{
if (hi_surrogate == -1)
FAIL_AT_CHAR_END(JSON_UNICODE_LOW_SURROGATE);
ch = surrogate_pair_to_codepoint(hi_surrogate, ch);
hi_surrogate = -1;
}
if (hi_surrogate != -1)
FAIL_AT_CHAR_END(JSON_UNICODE_LOW_SURROGATE);
/*
* Reject invalid cases. We can't have a value above
* 0xFFFF here (since we only accepted 4 hex digits
* above), so no need to test for out-of-range chars.
*/
if (ch == 0)
{
/* We can't allow this, since our TEXT type doesn't */
FAIL_AT_CHAR_END(JSON_UNICODE_CODE_POINT_ZERO);
}
/*
* Add the represented character to lex->strval. In the
* backend, we can let pg_unicode_to_server_noerror()
* handle any required character set conversion; in
* frontend, we can only deal with trivial conversions.
*/
#ifndef FRONTEND
{
char cbuf[MAX_UNICODE_EQUIVALENT_STRING + 1];
if (!pg_unicode_to_server_noerror(ch, (unsigned char *) cbuf))
FAIL_AT_CHAR_END(JSON_UNICODE_UNTRANSLATABLE);
appendStringInfoString(lex->strval, cbuf);
}
#else
if (lex->input_encoding == PG_UTF8)
{
/* OK, we can map the code point to UTF8 easily */
char utf8str[5];
int utf8len;
unicode_to_utf8(ch, (unsigned char *) utf8str);
utf8len = pg_utf_mblen((unsigned char *) utf8str);
appendBinaryStringInfo(lex->strval, utf8str, utf8len);
}
else if (ch <= 0x007f)
{
/* The ASCII range is the same in all encodings */
appendStringInfoChar(lex->strval, (char) ch);
}
else
FAIL_AT_CHAR_END(JSON_UNICODE_HIGH_ESCAPE);
#endif /* FRONTEND */
}
}
else if (lex->strval != NULL)
{
if (hi_surrogate != -1)
FAIL_AT_CHAR_END(JSON_UNICODE_LOW_SURROGATE);
switch (*s)
{
case '"':
case '\\':
case '/':
appendStringInfoChar(lex->strval, *s);
break;
case 'b':
appendStringInfoChar(lex->strval, '\b');
break;
case 'f':
appendStringInfoChar(lex->strval, '\f');
break;
case 'n':
appendStringInfoChar(lex->strval, '\n');
break;
case 'r':
appendStringInfoChar(lex->strval, '\r');
break;
case 't':
appendStringInfoChar(lex->strval, '\t');
break;
default:
/*
* Not a valid string escape, so signal error. We
* adjust token_start so that just the escape sequence
* is reported, not the whole string.
*/
lex->token_start = s;
FAIL_AT_CHAR_END(JSON_ESCAPING_INVALID);
}
}
else if (strchr("\"\\/bfnrt", *s) == NULL)
{
/*
* Simpler processing if we're not bothered about de-escaping
*
* It's very tempting to remove the strchr() call here and
* replace it with a switch statement, but testing so far has
* shown it's not a performance win.
*/
lex->token_start = s;
FAIL_AT_CHAR_END(JSON_ESCAPING_INVALID);
}
}
else
{
char *p = s;
if (hi_surrogate != -1)
FAIL_AT_CHAR_END(JSON_UNICODE_LOW_SURROGATE);
/*
* Skip to the first byte that requires special handling, so we
* can batch calls to appendBinaryStringInfo.
*/
while (p < end - sizeof(Vector8) &&
!pg_lfind8('\\', (uint8 *) p, sizeof(Vector8)) &&
!pg_lfind8('"', (uint8 *) p, sizeof(Vector8)) &&
!pg_lfind8_le(31, (uint8 *) p, sizeof(Vector8)))
p += sizeof(Vector8);
for (; p < end; p++)
{
if (*p == '\\' || *p == '"')
break;
else if ((unsigned char) *p <= 31)
{
/* Per RFC4627, these characters MUST be escaped. */
/*
* Since *p isn't printable, exclude it from the context
* string
*/
lex->token_terminator = p;
return JSON_ESCAPING_REQUIRED;
}
}
if (lex->strval != NULL)
appendBinaryStringInfo(lex->strval, s, p - s);
/*
* s will be incremented at the top of the loop, so set it to just
* behind our lookahead position
*/
s = p - 1;
}
}
if (hi_surrogate != -1)
{
lex->token_terminator = s + 1;
return JSON_UNICODE_LOW_SURROGATE;
}
/* Hooray, we found the end of the string! */
lex->prev_token_terminator = lex->token_terminator;
lex->token_terminator = s + 1;
return JSON_SUCCESS;
#undef FAIL_AT_CHAR_START
#undef FAIL_AT_CHAR_END
}
/*
* The next token in the input stream is known to be a number; lex it.
*
* In JSON, a number consists of four parts:
*
* (1) An optional minus sign ('-').
*
* (2) Either a single '0', or a string of one or more digits that does not
* begin with a '0'.
*
* (3) An optional decimal part, consisting of a period ('.') followed by
* one or more digits. (Note: While this part can be omitted
* completely, it's not OK to have only the decimal point without
* any digits afterwards.)
*
* (4) An optional exponent part, consisting of 'e' or 'E', optionally
* followed by '+' or '-', followed by one or more digits. (Note:
* As with the decimal part, if 'e' or 'E' is present, it must be
* followed by at least one digit.)
*
* The 's' argument to this function points to the ostensible beginning
* of part 2 - i.e. the character after any optional minus sign, or the
* first character of the string if there is none.
*
* If num_err is not NULL, we return an error flag to *num_err rather than
* raising an error for a badly-formed number. Also, if total_len is not NULL
* the distance from lex->input to the token end+1 is returned to *total_len.
*/
static inline JsonParseErrorType
json_lex_number(JsonLexContext *lex, char *s,
bool *num_err, int *total_len)
{
bool error = false;
int len = s - lex->input;
/* Part (1): leading sign indicator. */
/* Caller already did this for us; so do nothing. */
/* Part (2): parse main digit string. */
if (len < lex->input_length && *s == '0')
{
s++;
len++;
}
else if (len < lex->input_length && *s >= '1' && *s <= '9')
{
do
{
s++;
len++;
} while (len < lex->input_length && *s >= '0' && *s <= '9');
}
else
error = true;
/* Part (3): parse optional decimal portion. */
if (len < lex->input_length && *s == '.')
{
s++;
len++;
if (len == lex->input_length || *s < '0' || *s > '9')
error = true;
else
{
do
{
s++;
len++;
} while (len < lex->input_length && *s >= '0' && *s <= '9');
}
}
/* Part (4): parse optional exponent. */
if (len < lex->input_length && (*s == 'e' || *s == 'E'))
{
s++;
len++;
if (len < lex->input_length && (*s == '+' || *s == '-'))
{
s++;
len++;
}
if (len == lex->input_length || *s < '0' || *s > '9')
error = true;
else
{
do
{
s++;
len++;
} while (len < lex->input_length && *s >= '0' && *s <= '9');
}
}
/*
* Check for trailing garbage. As in json_lex(), any alphanumeric stuff
* here should be considered part of the token for error-reporting
* purposes.
*/
for (; len < lex->input_length && JSON_ALPHANUMERIC_CHAR(*s); s++, len++)
error = true;
if (total_len != NULL)
*total_len = len;
if (num_err != NULL)
{
/* let the caller handle any error */
*num_err = error;
}
else
{
/* return token endpoint */
lex->prev_token_terminator = lex->token_terminator;
lex->token_terminator = s;
/* handle error if any */
if (error)
return JSON_INVALID_TOKEN;
}
return JSON_SUCCESS;
}
/*
* Report a parse error.
*
* lex->token_start and lex->token_terminator must identify the current token.
*/
static JsonParseErrorType
report_parse_error(JsonParseContext ctx, JsonLexContext *lex)
{
/* Handle case where the input ended prematurely. */
if (lex->token_start == NULL || lex->token_type == JSON_TOKEN_END)
return JSON_EXPECTED_MORE;
/* Otherwise choose the error type based on the parsing context. */
switch (ctx)
{
case JSON_PARSE_END:
return JSON_EXPECTED_END;
case JSON_PARSE_VALUE:
return JSON_EXPECTED_JSON;
case JSON_PARSE_STRING:
return JSON_EXPECTED_STRING;
case JSON_PARSE_ARRAY_START:
return JSON_EXPECTED_ARRAY_FIRST;
case JSON_PARSE_ARRAY_NEXT:
return JSON_EXPECTED_ARRAY_NEXT;
case JSON_PARSE_OBJECT_START:
return JSON_EXPECTED_OBJECT_FIRST;
case JSON_PARSE_OBJECT_LABEL:
return JSON_EXPECTED_COLON;
case JSON_PARSE_OBJECT_NEXT:
return JSON_EXPECTED_OBJECT_NEXT;
case JSON_PARSE_OBJECT_COMMA:
return JSON_EXPECTED_STRING;
}
/*
* We don't use a default: case, so that the compiler will warn about
* unhandled enum values.
*/
Assert(false);
return JSON_SUCCESS; /* silence stupider compilers */
}
#ifndef FRONTEND
/*
* Extract the current token from a lexing context, for error reporting.
*/
static char *
extract_token(JsonLexContext *lex)
{
int toklen = lex->token_terminator - lex->token_start;
char *token = palloc(toklen + 1);
memcpy(token, lex->token_start, toklen);
token[toklen] = '\0';
return token;
}
/*
* Construct an (already translated) detail message for a JSON error.
*
* Note that the error message generated by this routine may not be
* palloc'd, making it unsafe for frontend code as there is no way to
* know if this can be safely pfree'd or not.
*/
char *
json_errdetail(JsonParseErrorType error, JsonLexContext *lex)
{
switch (error)
{
case JSON_SUCCESS:
/* fall through to the error code after switch */
break;
case JSON_ESCAPING_INVALID:
return psprintf(_("Escape sequence \"\\%s\" is invalid."),
extract_token(lex));
case JSON_ESCAPING_REQUIRED:
return psprintf(_("Character with value 0x%02x must be escaped."),
(unsigned char) *(lex->token_terminator));
case JSON_EXPECTED_END:
return psprintf(_("Expected end of input, but found \"%s\"."),
extract_token(lex));
case JSON_EXPECTED_ARRAY_FIRST:
return psprintf(_("Expected array element or \"]\", but found \"%s\"."),
extract_token(lex));
case JSON_EXPECTED_ARRAY_NEXT:
return psprintf(_("Expected \",\" or \"]\", but found \"%s\"."),
extract_token(lex));
case JSON_EXPECTED_COLON:
return psprintf(_("Expected \":\", but found \"%s\"."),
extract_token(lex));
case JSON_EXPECTED_JSON:
return psprintf(_("Expected JSON value, but found \"%s\"."),
extract_token(lex));
case JSON_EXPECTED_MORE:
return _("The input string ended unexpectedly.");
case JSON_EXPECTED_OBJECT_FIRST:
return psprintf(_("Expected string or \"}\", but found \"%s\"."),
extract_token(lex));
case JSON_EXPECTED_OBJECT_NEXT:
return psprintf(_("Expected \",\" or \"}\", but found \"%s\"."),
extract_token(lex));
case JSON_EXPECTED_STRING:
return psprintf(_("Expected string, but found \"%s\"."),
extract_token(lex));
case JSON_INVALID_TOKEN:
return psprintf(_("Token \"%s\" is invalid."),
extract_token(lex));
case JSON_UNICODE_CODE_POINT_ZERO:
return _("\\u0000 cannot be converted to text.");
case JSON_UNICODE_ESCAPE_FORMAT:
return _("\"\\u\" must be followed by four hexadecimal digits.");
case JSON_UNICODE_HIGH_ESCAPE:
/* note: this case is only reachable in frontend not backend */
return _("Unicode escape values cannot be used for code point values above 007F when the encoding is not UTF8.");
case JSON_UNICODE_UNTRANSLATABLE:
/* note: this case is only reachable in backend not frontend */
return psprintf(_("Unicode escape value could not be translated to the server's encoding %s."),
GetDatabaseEncodingName());
case JSON_UNICODE_HIGH_SURROGATE:
return _("Unicode high surrogate must not follow a high surrogate.");
case JSON_UNICODE_LOW_SURROGATE:
return _("Unicode low surrogate must follow a high surrogate.");
case JSON_SEM_ACTION_FAILED:
/* fall through to the error code after switch */
break;
}
/*
* We don't use a default: case, so that the compiler will warn about
* unhandled enum values. But this needs to be here anyway to cover the
* possibility of an incorrect input.
*/
elog(ERROR, "unexpected json parse error type: %d", (int) error);
return NULL;
}
#endif
|