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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 "qapi/error.h" | |
16 | #include "qemu-common.h" | |
17 | #include "qapi/qmp/types.h" | |
18 | #include "qapi/qmp/json-parser.h" | |
19 | #include "qapi/qmp/json-lexer.h" | |
20 | #include "qapi/qmp/json-streamer.h" | |
21 | ||
22 | typedef struct JSONParserContext | |
23 | { | |
24 | Error *err; | |
25 | JSONToken *current; | |
26 | GQueue *buf; | |
27 | } JSONParserContext; | |
28 | ||
29 | #define BUG_ON(cond) assert(!(cond)) | |
30 | ||
31 | /** | |
32 | * TODO | |
33 | * | |
34 | * 0) make errors meaningful again | |
35 | * 1) add geometry information to tokens | |
36 | * 3) should we return a parsed size? | |
37 | * 4) deal with premature EOI | |
38 | */ | |
39 | ||
40 | static QObject *parse_value(JSONParserContext *ctxt, va_list *ap); | |
41 | ||
42 | /** | |
43 | * Error handler | |
44 | */ | |
45 | static void GCC_FMT_ATTR(3, 4) parse_error(JSONParserContext *ctxt, | |
46 | JSONToken *token, const char *msg, ...) | |
47 | { | |
48 | va_list ap; | |
49 | char message[1024]; | |
50 | va_start(ap, msg); | |
51 | vsnprintf(message, sizeof(message), msg, ap); | |
52 | va_end(ap); | |
53 | if (ctxt->err) { | |
54 | error_free(ctxt->err); | |
55 | ctxt->err = NULL; | |
56 | } | |
57 | error_setg(&ctxt->err, "JSON parse error, %s", message); | |
58 | } | |
59 | ||
60 | /** | |
61 | * String helpers | |
62 | * | |
63 | * These helpers are used to unescape strings. | |
64 | */ | |
65 | static void wchar_to_utf8(uint16_t wchar, char *buffer, size_t buffer_length) | |
66 | { | |
67 | if (wchar <= 0x007F) { | |
68 | BUG_ON(buffer_length < 2); | |
69 | ||
70 | buffer[0] = wchar & 0x7F; | |
71 | buffer[1] = 0; | |
72 | } else if (wchar <= 0x07FF) { | |
73 | BUG_ON(buffer_length < 3); | |
74 | ||
75 | buffer[0] = 0xC0 | ((wchar >> 6) & 0x1F); | |
76 | buffer[1] = 0x80 | (wchar & 0x3F); | |
77 | buffer[2] = 0; | |
78 | } else { | |
79 | BUG_ON(buffer_length < 4); | |
80 | ||
81 | buffer[0] = 0xE0 | ((wchar >> 12) & 0x0F); | |
82 | buffer[1] = 0x80 | ((wchar >> 6) & 0x3F); | |
83 | buffer[2] = 0x80 | (wchar & 0x3F); | |
84 | buffer[3] = 0; | |
85 | } | |
86 | } | |
87 | ||
88 | static int hex2decimal(char ch) | |
89 | { | |
90 | if (ch >= '0' && ch <= '9') { | |
91 | return (ch - '0'); | |
92 | } else if (ch >= 'a' && ch <= 'f') { | |
93 | return 10 + (ch - 'a'); | |
94 | } else if (ch >= 'A' && ch <= 'F') { | |
95 | return 10 + (ch - 'A'); | |
96 | } | |
97 | ||
98 | return -1; | |
99 | } | |
100 | ||
101 | /** | |
102 | * parse_string(): Parse a json string and return a QObject | |
103 | * | |
104 | * string | |
105 | * "" | |
106 | * " chars " | |
107 | * chars | |
108 | * char | |
109 | * char chars | |
110 | * char | |
111 | * any-Unicode-character- | |
112 | * except-"-or-\-or- | |
113 | * control-character | |
114 | * \" | |
115 | * \\ | |
116 | * \/ | |
117 | * \b | |
118 | * \f | |
119 | * \n | |
120 | * \r | |
121 | * \t | |
122 | * \u four-hex-digits | |
123 | */ | |
124 | static QString *qstring_from_escaped_str(JSONParserContext *ctxt, | |
125 | JSONToken *token) | |
126 | { | |
127 | const char *ptr = token->str; | |
128 | QString *str; | |
129 | int double_quote = 1; | |
130 | ||
131 | if (*ptr == '"') { | |
132 | double_quote = 1; | |
133 | } else { | |
134 | double_quote = 0; | |
135 | } | |
136 | ptr++; | |
137 | ||
138 | str = qstring_new(); | |
139 | while (*ptr && | |
140 | ((double_quote && *ptr != '"') || (!double_quote && *ptr != '\''))) { | |
141 | if (*ptr == '\\') { | |
142 | ptr++; | |
143 | ||
144 | switch (*ptr) { | |
145 | case '"': | |
146 | qstring_append(str, "\""); | |
147 | ptr++; | |
148 | break; | |
149 | case '\'': | |
150 | qstring_append(str, "'"); | |
151 | ptr++; | |
152 | break; | |
153 | case '\\': | |
154 | qstring_append(str, "\\"); | |
155 | ptr++; | |
156 | break; | |
157 | case '/': | |
158 | qstring_append(str, "/"); | |
159 | ptr++; | |
160 | break; | |
161 | case 'b': | |
162 | qstring_append(str, "\b"); | |
163 | ptr++; | |
164 | break; | |
165 | case 'f': | |
166 | qstring_append(str, "\f"); | |
167 | ptr++; | |
168 | break; | |
169 | case 'n': | |
170 | qstring_append(str, "\n"); | |
171 | ptr++; | |
172 | break; | |
173 | case 'r': | |
174 | qstring_append(str, "\r"); | |
175 | ptr++; | |
176 | break; | |
177 | case 't': | |
178 | qstring_append(str, "\t"); | |
179 | ptr++; | |
180 | break; | |
181 | case 'u': { | |
182 | uint16_t unicode_char = 0; | |
183 | char utf8_char[4]; | |
184 | int i = 0; | |
185 | ||
186 | ptr++; | |
187 | ||
188 | for (i = 0; i < 4; i++) { | |
189 | if (qemu_isxdigit(*ptr)) { | |
190 | unicode_char |= hex2decimal(*ptr) << ((3 - i) * 4); | |
191 | } else { | |
192 | parse_error(ctxt, token, | |
193 | "invalid hex escape sequence in string"); | |
194 | goto out; | |
195 | } | |
196 | ptr++; | |
197 | } | |
198 | ||
199 | wchar_to_utf8(unicode_char, utf8_char, sizeof(utf8_char)); | |
200 | qstring_append(str, utf8_char); | |
201 | } break; | |
202 | default: | |
203 | parse_error(ctxt, token, "invalid escape sequence in string"); | |
204 | goto out; | |
205 | } | |
206 | } else { | |
207 | char dummy[2]; | |
208 | ||
209 | dummy[0] = *ptr++; | |
210 | dummy[1] = 0; | |
211 | ||
212 | qstring_append(str, dummy); | |
213 | } | |
214 | } | |
215 | ||
216 | return str; | |
217 | ||
218 | out: | |
219 | QDECREF(str); | |
220 | return NULL; | |
221 | } | |
222 | ||
223 | /* Note: the token object returned by parser_context_peek_token or | |
224 | * parser_context_pop_token is deleted as soon as parser_context_pop_token | |
225 | * is called again. | |
226 | */ | |
227 | static JSONToken *parser_context_pop_token(JSONParserContext *ctxt) | |
228 | { | |
229 | g_free(ctxt->current); | |
230 | assert(!g_queue_is_empty(ctxt->buf)); | |
231 | ctxt->current = g_queue_pop_head(ctxt->buf); | |
232 | return ctxt->current; | |
233 | } | |
234 | ||
235 | static JSONToken *parser_context_peek_token(JSONParserContext *ctxt) | |
236 | { | |
237 | assert(!g_queue_is_empty(ctxt->buf)); | |
238 | return g_queue_peek_head(ctxt->buf); | |
239 | } | |
240 | ||
241 | static JSONParserContext *parser_context_new(GQueue *tokens) | |
242 | { | |
243 | JSONParserContext *ctxt; | |
244 | ||
245 | if (!tokens) { | |
246 | return NULL; | |
247 | } | |
248 | ||
249 | ctxt = g_malloc0(sizeof(JSONParserContext)); | |
250 | ctxt->buf = tokens; | |
251 | ||
252 | return ctxt; | |
253 | } | |
254 | ||
255 | /* to support error propagation, ctxt->err must be freed separately */ | |
256 | static void parser_context_free(JSONParserContext *ctxt) | |
257 | { | |
258 | if (ctxt) { | |
259 | while (!g_queue_is_empty(ctxt->buf)) { | |
260 | parser_context_pop_token(ctxt); | |
261 | } | |
262 | g_free(ctxt->current); | |
263 | g_queue_free(ctxt->buf); | |
264 | g_free(ctxt); | |
265 | } | |
266 | } | |
267 | ||
268 | /** | |
269 | * Parsing rules | |
270 | */ | |
271 | static int parse_pair(JSONParserContext *ctxt, QDict *dict, va_list *ap) | |
272 | { | |
273 | QObject *key = NULL, *value; | |
274 | JSONToken *peek, *token; | |
275 | ||
276 | peek = parser_context_peek_token(ctxt); | |
277 | if (peek == NULL) { | |
278 | parse_error(ctxt, NULL, "premature EOI"); | |
279 | goto out; | |
280 | } | |
281 | ||
282 | key = parse_value(ctxt, ap); | |
283 | if (!key || qobject_type(key) != QTYPE_QSTRING) { | |
284 | parse_error(ctxt, peek, "key is not a string in object"); | |
285 | goto out; | |
286 | } | |
287 | ||
288 | token = parser_context_pop_token(ctxt); | |
289 | if (token == NULL) { | |
290 | parse_error(ctxt, NULL, "premature EOI"); | |
291 | goto out; | |
292 | } | |
293 | ||
294 | if (token->type != JSON_COLON) { | |
295 | parse_error(ctxt, token, "missing : in object pair"); | |
296 | goto out; | |
297 | } | |
298 | ||
299 | value = parse_value(ctxt, ap); | |
300 | if (value == NULL) { | |
301 | parse_error(ctxt, token, "Missing value in dict"); | |
302 | goto out; | |
303 | } | |
304 | ||
305 | qdict_put_obj(dict, qstring_get_str(qobject_to_qstring(key)), value); | |
306 | ||
307 | qobject_decref(key); | |
308 | ||
309 | return 0; | |
310 | ||
311 | out: | |
312 | qobject_decref(key); | |
313 | ||
314 | return -1; | |
315 | } | |
316 | ||
317 | static QObject *parse_object(JSONParserContext *ctxt, va_list *ap) | |
318 | { | |
319 | QDict *dict = NULL; | |
320 | JSONToken *token, *peek; | |
321 | ||
322 | token = parser_context_pop_token(ctxt); | |
323 | assert(token && token->type == JSON_LCURLY); | |
324 | ||
325 | dict = qdict_new(); | |
326 | ||
327 | peek = parser_context_peek_token(ctxt); | |
328 | if (peek == NULL) { | |
329 | parse_error(ctxt, NULL, "premature EOI"); | |
330 | goto out; | |
331 | } | |
332 | ||
333 | if (peek->type != JSON_RCURLY) { | |
334 | if (parse_pair(ctxt, dict, ap) == -1) { | |
335 | goto out; | |
336 | } | |
337 | ||
338 | token = parser_context_pop_token(ctxt); | |
339 | if (token == NULL) { | |
340 | parse_error(ctxt, NULL, "premature EOI"); | |
341 | goto out; | |
342 | } | |
343 | ||
344 | while (token->type != JSON_RCURLY) { | |
345 | if (token->type != JSON_COMMA) { | |
346 | parse_error(ctxt, token, "expected separator in dict"); | |
347 | goto out; | |
348 | } | |
349 | ||
350 | if (parse_pair(ctxt, dict, ap) == -1) { | |
351 | goto out; | |
352 | } | |
353 | ||
354 | token = parser_context_pop_token(ctxt); | |
355 | if (token == NULL) { | |
356 | parse_error(ctxt, NULL, "premature EOI"); | |
357 | goto out; | |
358 | } | |
359 | } | |
360 | } else { | |
361 | (void)parser_context_pop_token(ctxt); | |
362 | } | |
363 | ||
364 | return QOBJECT(dict); | |
365 | ||
366 | out: | |
367 | QDECREF(dict); | |
368 | return NULL; | |
369 | } | |
370 | ||
371 | static QObject *parse_array(JSONParserContext *ctxt, va_list *ap) | |
372 | { | |
373 | QList *list = NULL; | |
374 | JSONToken *token, *peek; | |
375 | ||
376 | token = parser_context_pop_token(ctxt); | |
377 | assert(token && token->type == JSON_LSQUARE); | |
378 | ||
379 | list = qlist_new(); | |
380 | ||
381 | peek = parser_context_peek_token(ctxt); | |
382 | if (peek == NULL) { | |
383 | parse_error(ctxt, NULL, "premature EOI"); | |
384 | goto out; | |
385 | } | |
386 | ||
387 | if (peek->type != JSON_RSQUARE) { | |
388 | QObject *obj; | |
389 | ||
390 | obj = parse_value(ctxt, ap); | |
391 | if (obj == NULL) { | |
392 | parse_error(ctxt, token, "expecting value"); | |
393 | goto out; | |
394 | } | |
395 | ||
396 | qlist_append_obj(list, obj); | |
397 | ||
398 | token = parser_context_pop_token(ctxt); | |
399 | if (token == NULL) { | |
400 | parse_error(ctxt, NULL, "premature EOI"); | |
401 | goto out; | |
402 | } | |
403 | ||
404 | while (token->type != JSON_RSQUARE) { | |
405 | if (token->type != JSON_COMMA) { | |
406 | parse_error(ctxt, token, "expected separator in list"); | |
407 | goto out; | |
408 | } | |
409 | ||
410 | obj = parse_value(ctxt, ap); | |
411 | if (obj == NULL) { | |
412 | parse_error(ctxt, token, "expecting value"); | |
413 | goto out; | |
414 | } | |
415 | ||
416 | qlist_append_obj(list, obj); | |
417 | ||
418 | token = parser_context_pop_token(ctxt); | |
419 | if (token == NULL) { | |
420 | parse_error(ctxt, NULL, "premature EOI"); | |
421 | goto out; | |
422 | } | |
423 | } | |
424 | } else { | |
425 | (void)parser_context_pop_token(ctxt); | |
426 | } | |
427 | ||
428 | return QOBJECT(list); | |
429 | ||
430 | out: | |
431 | QDECREF(list); | |
432 | return NULL; | |
433 | } | |
434 | ||
435 | static QObject *parse_keyword(JSONParserContext *ctxt) | |
436 | { | |
437 | JSONToken *token; | |
438 | ||
439 | token = parser_context_pop_token(ctxt); | |
440 | assert(token && token->type == JSON_KEYWORD); | |
441 | ||
442 | if (!strcmp(token->str, "true")) { | |
443 | return QOBJECT(qbool_from_bool(true)); | |
444 | } else if (!strcmp(token->str, "false")) { | |
445 | return QOBJECT(qbool_from_bool(false)); | |
446 | } else if (!strcmp(token->str, "null")) { | |
447 | return qnull(); | |
448 | } | |
449 | parse_error(ctxt, token, "invalid keyword '%s'", token->str); | |
450 | return NULL; | |
451 | } | |
452 | ||
453 | static QObject *parse_escape(JSONParserContext *ctxt, va_list *ap) | |
454 | { | |
455 | JSONToken *token; | |
456 | ||
457 | if (ap == NULL) { | |
458 | return NULL; | |
459 | } | |
460 | ||
461 | token = parser_context_pop_token(ctxt); | |
462 | assert(token && token->type == JSON_ESCAPE); | |
463 | ||
464 | if (!strcmp(token->str, "%p")) { | |
465 | return va_arg(*ap, QObject *); | |
466 | } else if (!strcmp(token->str, "%i")) { | |
467 | return QOBJECT(qbool_from_bool(va_arg(*ap, int))); | |
468 | } else if (!strcmp(token->str, "%d")) { | |
469 | return QOBJECT(qint_from_int(va_arg(*ap, int))); | |
470 | } else if (!strcmp(token->str, "%ld")) { | |
471 | return QOBJECT(qint_from_int(va_arg(*ap, long))); | |
472 | } else if (!strcmp(token->str, "%lld") || | |
473 | !strcmp(token->str, "%I64d")) { | |
474 | return QOBJECT(qint_from_int(va_arg(*ap, long long))); | |
475 | } else if (!strcmp(token->str, "%s")) { | |
476 | return QOBJECT(qstring_from_str(va_arg(*ap, const char *))); | |
477 | } else if (!strcmp(token->str, "%f")) { | |
478 | return QOBJECT(qfloat_from_double(va_arg(*ap, double))); | |
479 | } | |
480 | return NULL; | |
481 | } | |
482 | ||
483 | static QObject *parse_literal(JSONParserContext *ctxt) | |
484 | { | |
485 | JSONToken *token; | |
486 | ||
487 | token = parser_context_pop_token(ctxt); | |
488 | assert(token); | |
489 | ||
490 | switch (token->type) { | |
491 | case JSON_STRING: | |
492 | return QOBJECT(qstring_from_escaped_str(ctxt, token)); | |
493 | case JSON_INTEGER: { | |
494 | /* A possibility exists that this is a whole-valued float where the | |
495 | * fractional part was left out due to being 0 (.0). It's not a big | |
496 | * deal to treat these as ints in the parser, so long as users of the | |
497 | * resulting QObject know to expect a QInt in place of a QFloat in | |
498 | * cases like these. | |
499 | * | |
500 | * However, in some cases these values will overflow/underflow a | |
501 | * QInt/int64 container, thus we should assume these are to be handled | |
502 | * as QFloats/doubles rather than silently changing their values. | |
503 | * | |
504 | * strtoll() indicates these instances by setting errno to ERANGE | |
505 | */ | |
506 | int64_t value; | |
507 | ||
508 | errno = 0; /* strtoll doesn't set errno on success */ | |
509 | value = strtoll(token->str, NULL, 10); | |
510 | if (errno != ERANGE) { | |
511 | return QOBJECT(qint_from_int(value)); | |
512 | } | |
513 | /* fall through to JSON_FLOAT */ | |
514 | } | |
515 | case JSON_FLOAT: | |
516 | /* FIXME dependent on locale; a pervasive issue in QEMU */ | |
517 | /* FIXME our lexer matches RFC 7159 in forbidding Inf or NaN, | |
518 | * but those might be useful extensions beyond JSON */ | |
519 | return QOBJECT(qfloat_from_double(strtod(token->str, NULL))); | |
520 | default: | |
521 | abort(); | |
522 | } | |
523 | } | |
524 | ||
525 | static QObject *parse_value(JSONParserContext *ctxt, va_list *ap) | |
526 | { | |
527 | JSONToken *token; | |
528 | ||
529 | token = parser_context_peek_token(ctxt); | |
530 | if (token == NULL) { | |
531 | parse_error(ctxt, NULL, "premature EOI"); | |
532 | return NULL; | |
533 | } | |
534 | ||
535 | switch (token->type) { | |
536 | case JSON_LCURLY: | |
537 | return parse_object(ctxt, ap); | |
538 | case JSON_LSQUARE: | |
539 | return parse_array(ctxt, ap); | |
540 | case JSON_ESCAPE: | |
541 | return parse_escape(ctxt, ap); | |
542 | case JSON_INTEGER: | |
543 | case JSON_FLOAT: | |
544 | case JSON_STRING: | |
545 | return parse_literal(ctxt); | |
546 | case JSON_KEYWORD: | |
547 | return parse_keyword(ctxt); | |
548 | default: | |
549 | parse_error(ctxt, token, "expecting value"); | |
550 | return NULL; | |
551 | } | |
552 | } | |
553 | ||
554 | QObject *json_parser_parse(GQueue *tokens, va_list *ap) | |
555 | { | |
556 | return json_parser_parse_err(tokens, ap, NULL); | |
557 | } | |
558 | ||
559 | QObject *json_parser_parse_err(GQueue *tokens, va_list *ap, Error **errp) | |
560 | { | |
561 | JSONParserContext *ctxt = parser_context_new(tokens); | |
562 | QObject *result; | |
563 | ||
564 | if (!ctxt) { | |
565 | return NULL; | |
566 | } | |
567 | ||
568 | result = parse_value(ctxt, ap); | |
569 | ||
570 | error_propagate(errp, ctxt->err); | |
571 | ||
572 | parser_context_free(ctxt); | |
573 | ||
574 | return result; | |
575 | } |