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 "qemu/ctype.h"
16 #include "qemu/cutils.h"
17 #include "qemu/unicode.h"
18 #include "qapi/error.h"
19 #include "qapi/qmp/qbool.h"
20 #include "qapi/qmp/qdict.h"
21 #include "qapi/qmp/qlist.h"
22 #include "qapi/qmp/qnull.h"
23 #include "qapi/qmp/qnum.h"
24 #include "qapi/qmp/qstring.h"
25 #include "json-parser-int.h"
26
27 struct JSONToken {
28 JSONTokenType type;
29 int x;
30 int y;
31 char str[];
32 };
33
34 typedef struct JSONParserContext {
35 Error *err;
36 JSONToken *current;
37 GQueue *buf;
38 va_list *ap;
39 } JSONParserContext;
40
41 #define BUG_ON(cond) assert(!(cond))
42
43 /**
44 * TODO
45 *
46 * 0) make errors meaningful again
47 * 1) add geometry information to tokens
48 * 3) should we return a parsed size?
49 * 4) deal with premature EOI
50 */
51
52 static QObject *parse_value(JSONParserContext *ctxt);
53
54 /**
55 * Error handler
56 */
parse_error(JSONParserContext * ctxt,JSONToken * token,const char * msg,...)57 static void G_GNUC_PRINTF(3, 4) parse_error(JSONParserContext *ctxt,
58 JSONToken *token, const char *msg, ...)
59 {
60 va_list ap;
61 char message[1024];
62
63 if (ctxt->err) {
64 return;
65 }
66 va_start(ap, msg);
67 vsnprintf(message, sizeof(message), msg, ap);
68 va_end(ap);
69 error_setg(&ctxt->err, "JSON parse error, %s", message);
70 }
71
cvt4hex(const char * s)72 static int cvt4hex(const char *s)
73 {
74 int cp, i;
75
76 cp = 0;
77 for (i = 0; i < 4; i++) {
78 if (!qemu_isxdigit(s[i])) {
79 return -1;
80 }
81 cp <<= 4;
82 if (s[i] >= '0' && s[i] <= '9') {
83 cp |= s[i] - '0';
84 } else if (s[i] >= 'a' && s[i] <= 'f') {
85 cp |= 10 + s[i] - 'a';
86 } else if (s[i] >= 'A' && s[i] <= 'F') {
87 cp |= 10 + s[i] - 'A';
88 } else {
89 return -1;
90 }
91 }
92 return cp;
93 }
94
95 /**
96 * parse_string(): Parse a JSON string
97 *
98 * From RFC 8259 "The JavaScript Object Notation (JSON) Data
99 * Interchange Format":
100 *
101 * char = unescaped /
102 * escape (
103 * %x22 / ; " quotation mark U+0022
104 * %x5C / ; \ reverse solidus U+005C
105 * %x2F / ; / solidus U+002F
106 * %x62 / ; b backspace U+0008
107 * %x66 / ; f form feed U+000C
108 * %x6E / ; n line feed U+000A
109 * %x72 / ; r carriage return U+000D
110 * %x74 / ; t tab U+0009
111 * %x75 4HEXDIG ) ; uXXXX U+XXXX
112 * escape = %x5C ; \
113 * quotation-mark = %x22 ; "
114 * unescaped = %x20-21 / %x23-5B / %x5D-10FFFF
115 *
116 * Extensions over RFC 8259:
117 * - Extra escape sequence in strings:
118 * 0x27 (apostrophe) is recognized after escape, too
119 * - Single-quoted strings:
120 * Like double-quoted strings, except they're delimited by %x27
121 * (apostrophe) instead of %x22 (quotation mark), and can't contain
122 * unescaped apostrophe, but can contain unescaped quotation mark.
123 *
124 * Note:
125 * - Encoding is modified UTF-8.
126 * - Invalid Unicode characters are rejected.
127 * - Control characters \x00..\x1F are rejected by the lexer.
128 */
parse_string(JSONParserContext * ctxt,JSONToken * token)129 static QString *parse_string(JSONParserContext *ctxt, JSONToken *token)
130 {
131 const char *ptr = token->str;
132 GString *str;
133 char quote;
134 const char *beg;
135 int cp, trailing;
136 char *end;
137 ssize_t len;
138 char utf8_buf[5];
139
140 assert(*ptr == '"' || *ptr == '\'');
141 quote = *ptr++;
142 str = g_string_new(NULL);
143
144 while (*ptr != quote) {
145 assert(*ptr);
146 switch (*ptr) {
147 case '\\':
148 beg = ptr++;
149 switch (*ptr++) {
150 case '"':
151 g_string_append_c(str, '"');
152 break;
153 case '\'':
154 g_string_append_c(str, '\'');
155 break;
156 case '\\':
157 g_string_append_c(str, '\\');
158 break;
159 case '/':
160 g_string_append_c(str, '/');
161 break;
162 case 'b':
163 g_string_append_c(str, '\b');
164 break;
165 case 'f':
166 g_string_append_c(str, '\f');
167 break;
168 case 'n':
169 g_string_append_c(str, '\n');
170 break;
171 case 'r':
172 g_string_append_c(str, '\r');
173 break;
174 case 't':
175 g_string_append_c(str, '\t');
176 break;
177 case 'u':
178 cp = cvt4hex(ptr);
179 ptr += 4;
180
181 /* handle surrogate pairs */
182 if (cp >= 0xD800 && cp <= 0xDBFF
183 && ptr[0] == '\\' && ptr[1] == 'u') {
184 /* leading surrogate followed by \u */
185 cp = 0x10000 + ((cp & 0x3FF) << 10);
186 trailing = cvt4hex(ptr + 2);
187 if (trailing >= 0xDC00 && trailing <= 0xDFFF) {
188 /* followed by trailing surrogate */
189 cp |= trailing & 0x3FF;
190 ptr += 6;
191 } else {
192 cp = -1; /* invalid */
193 }
194 }
195
196 if (mod_utf8_encode(utf8_buf, sizeof(utf8_buf), cp) < 0) {
197 parse_error(ctxt, token,
198 "%.*s is not a valid Unicode character",
199 (int)(ptr - beg), beg);
200 goto out;
201 }
202 g_string_append(str, utf8_buf);
203 break;
204 default:
205 parse_error(ctxt, token, "invalid escape sequence in string");
206 goto out;
207 }
208 break;
209 case '%':
210 if (ctxt->ap) {
211 if (ptr[1] != '%') {
212 parse_error(ctxt, token, "can't interpolate into string");
213 goto out;
214 }
215 ptr++;
216 }
217 /* fall through */
218 default:
219 cp = mod_utf8_codepoint(ptr, 6, &end);
220 if (cp < 0) {
221 parse_error(ctxt, token, "invalid UTF-8 sequence in string");
222 goto out;
223 }
224 ptr = end;
225 len = mod_utf8_encode(utf8_buf, sizeof(utf8_buf), cp);
226 assert(len >= 0);
227 g_string_append(str, utf8_buf);
228 }
229 }
230
231 return qstring_from_gstring(str);
232
233 out:
234 g_string_free(str, true);
235 return NULL;
236 }
237
238 /* Note: the token object returned by parser_context_peek_token or
239 * parser_context_pop_token is deleted as soon as parser_context_pop_token
240 * is called again.
241 */
parser_context_pop_token(JSONParserContext * ctxt)242 static JSONToken *parser_context_pop_token(JSONParserContext *ctxt)
243 {
244 g_free(ctxt->current);
245 ctxt->current = g_queue_pop_head(ctxt->buf);
246 return ctxt->current;
247 }
248
parser_context_peek_token(JSONParserContext * ctxt)249 static JSONToken *parser_context_peek_token(JSONParserContext *ctxt)
250 {
251 return g_queue_peek_head(ctxt->buf);
252 }
253
254 /**
255 * Parsing rules
256 */
parse_pair(JSONParserContext * ctxt,QDict * dict)257 static int parse_pair(JSONParserContext *ctxt, QDict *dict)
258 {
259 QObject *key_obj = NULL;
260 QString *key;
261 QObject *value;
262 JSONToken *peek, *token;
263
264 peek = parser_context_peek_token(ctxt);
265 if (peek == NULL) {
266 parse_error(ctxt, NULL, "premature EOI");
267 goto out;
268 }
269
270 key_obj = parse_value(ctxt);
271 key = qobject_to(QString, key_obj);
272 if (!key) {
273 parse_error(ctxt, peek, "key is not a string in object");
274 goto out;
275 }
276
277 token = parser_context_pop_token(ctxt);
278 if (token == NULL) {
279 parse_error(ctxt, NULL, "premature EOI");
280 goto out;
281 }
282
283 if (token->type != JSON_COLON) {
284 parse_error(ctxt, token, "missing : in object pair");
285 goto out;
286 }
287
288 value = parse_value(ctxt);
289 if (value == NULL) {
290 parse_error(ctxt, token, "Missing value in dict");
291 goto out;
292 }
293
294 if (qdict_haskey(dict, qstring_get_str(key))) {
295 parse_error(ctxt, token, "duplicate key");
296 goto out;
297 }
298
299 qdict_put_obj(dict, qstring_get_str(key), value);
300
301 qobject_unref(key_obj);
302 return 0;
303
304 out:
305 qobject_unref(key_obj);
306 return -1;
307 }
308
parse_object(JSONParserContext * ctxt)309 static QObject *parse_object(JSONParserContext *ctxt)
310 {
311 QDict *dict = NULL;
312 JSONToken *token, *peek;
313
314 token = parser_context_pop_token(ctxt);
315 assert(token && token->type == JSON_LCURLY);
316
317 dict = qdict_new();
318
319 peek = parser_context_peek_token(ctxt);
320 if (peek == NULL) {
321 parse_error(ctxt, NULL, "premature EOI");
322 goto out;
323 }
324
325 if (peek->type != JSON_RCURLY) {
326 if (parse_pair(ctxt, dict) == -1) {
327 goto out;
328 }
329
330 token = parser_context_pop_token(ctxt);
331 if (token == NULL) {
332 parse_error(ctxt, NULL, "premature EOI");
333 goto out;
334 }
335
336 while (token->type != JSON_RCURLY) {
337 if (token->type != JSON_COMMA) {
338 parse_error(ctxt, token, "expected separator in dict");
339 goto out;
340 }
341
342 if (parse_pair(ctxt, dict) == -1) {
343 goto out;
344 }
345
346 token = parser_context_pop_token(ctxt);
347 if (token == NULL) {
348 parse_error(ctxt, NULL, "premature EOI");
349 goto out;
350 }
351 }
352 } else {
353 (void)parser_context_pop_token(ctxt);
354 }
355
356 return QOBJECT(dict);
357
358 out:
359 qobject_unref(dict);
360 return NULL;
361 }
362
parse_array(JSONParserContext * ctxt)363 static QObject *parse_array(JSONParserContext *ctxt)
364 {
365 QList *list = NULL;
366 JSONToken *token, *peek;
367
368 token = parser_context_pop_token(ctxt);
369 assert(token && token->type == JSON_LSQUARE);
370
371 list = qlist_new();
372
373 peek = parser_context_peek_token(ctxt);
374 if (peek == NULL) {
375 parse_error(ctxt, NULL, "premature EOI");
376 goto out;
377 }
378
379 if (peek->type != JSON_RSQUARE) {
380 QObject *obj;
381
382 obj = parse_value(ctxt);
383 if (obj == NULL) {
384 parse_error(ctxt, token, "expecting value");
385 goto out;
386 }
387
388 qlist_append_obj(list, obj);
389
390 token = parser_context_pop_token(ctxt);
391 if (token == NULL) {
392 parse_error(ctxt, NULL, "premature EOI");
393 goto out;
394 }
395
396 while (token->type != JSON_RSQUARE) {
397 if (token->type != JSON_COMMA) {
398 parse_error(ctxt, token, "expected separator in list");
399 goto out;
400 }
401
402 obj = parse_value(ctxt);
403 if (obj == NULL) {
404 parse_error(ctxt, token, "expecting value");
405 goto out;
406 }
407
408 qlist_append_obj(list, obj);
409
410 token = parser_context_pop_token(ctxt);
411 if (token == NULL) {
412 parse_error(ctxt, NULL, "premature EOI");
413 goto out;
414 }
415 }
416 } else {
417 (void)parser_context_pop_token(ctxt);
418 }
419
420 return QOBJECT(list);
421
422 out:
423 qobject_unref(list);
424 return NULL;
425 }
426
parse_keyword(JSONParserContext * ctxt)427 static QObject *parse_keyword(JSONParserContext *ctxt)
428 {
429 JSONToken *token;
430
431 token = parser_context_pop_token(ctxt);
432 assert(token && token->type == JSON_KEYWORD);
433
434 if (!strcmp(token->str, "true")) {
435 return QOBJECT(qbool_from_bool(true));
436 } else if (!strcmp(token->str, "false")) {
437 return QOBJECT(qbool_from_bool(false));
438 } else if (!strcmp(token->str, "null")) {
439 return QOBJECT(qnull());
440 }
441 parse_error(ctxt, token, "invalid keyword '%s'", token->str);
442 return NULL;
443 }
444
parse_interpolation(JSONParserContext * ctxt)445 static QObject *parse_interpolation(JSONParserContext *ctxt)
446 {
447 JSONToken *token;
448
449 token = parser_context_pop_token(ctxt);
450 assert(token && token->type == JSON_INTERP);
451
452 if (!strcmp(token->str, "%p")) {
453 return va_arg(*ctxt->ap, QObject *);
454 } else if (!strcmp(token->str, "%i")) {
455 return QOBJECT(qbool_from_bool(va_arg(*ctxt->ap, int)));
456 } else if (!strcmp(token->str, "%d")) {
457 return QOBJECT(qnum_from_int(va_arg(*ctxt->ap, int)));
458 } else if (!strcmp(token->str, "%ld")) {
459 return QOBJECT(qnum_from_int(va_arg(*ctxt->ap, long)));
460 } else if (!strcmp(token->str, "%lld")) {
461 return QOBJECT(qnum_from_int(va_arg(*ctxt->ap, long long)));
462 } else if (!strcmp(token->str, "%" PRId64)) {
463 return QOBJECT(qnum_from_int(va_arg(*ctxt->ap, int64_t)));
464 } else if (!strcmp(token->str, "%u")) {
465 return QOBJECT(qnum_from_uint(va_arg(*ctxt->ap, unsigned int)));
466 } else if (!strcmp(token->str, "%lu")) {
467 return QOBJECT(qnum_from_uint(va_arg(*ctxt->ap, unsigned long)));
468 } else if (!strcmp(token->str, "%llu")) {
469 return QOBJECT(qnum_from_uint(va_arg(*ctxt->ap, unsigned long long)));
470 } else if (!strcmp(token->str, "%" PRIu64)) {
471 return QOBJECT(qnum_from_uint(va_arg(*ctxt->ap, uint64_t)));
472 } else if (!strcmp(token->str, "%s")) {
473 return QOBJECT(qstring_from_str(va_arg(*ctxt->ap, const char *)));
474 } else if (!strcmp(token->str, "%f")) {
475 return QOBJECT(qnum_from_double(va_arg(*ctxt->ap, double)));
476 }
477 parse_error(ctxt, token, "invalid interpolation '%s'", token->str);
478 return NULL;
479 }
480
parse_literal(JSONParserContext * ctxt)481 static QObject *parse_literal(JSONParserContext *ctxt)
482 {
483 JSONToken *token;
484
485 token = parser_context_pop_token(ctxt);
486 assert(token);
487
488 switch (token->type) {
489 case JSON_STRING:
490 return QOBJECT(parse_string(ctxt, token));
491 case JSON_INTEGER: {
492 /*
493 * Represent JSON_INTEGER as QNUM_I64 if possible, else as
494 * QNUM_U64, else as QNUM_DOUBLE. Note that qemu_strtoi64()
495 * and qemu_strtou64() fail with ERANGE when it's not
496 * possible.
497 *
498 * qnum_get_int() will then work for any signed 64-bit
499 * JSON_INTEGER, qnum_get_uint() for any unsigned 64-bit
500 * integer, and qnum_get_double() both for any JSON_INTEGER
501 * and any JSON_FLOAT (with precision loss for integers beyond
502 * 53 bits)
503 */
504 int ret;
505 int64_t value;
506 uint64_t uvalue;
507
508 ret = qemu_strtoi64(token->str, NULL, 10, &value);
509 if (!ret) {
510 return QOBJECT(qnum_from_int(value));
511 }
512 assert(ret == -ERANGE);
513
514 if (token->str[0] != '-') {
515 ret = qemu_strtou64(token->str, NULL, 10, &uvalue);
516 if (!ret) {
517 return QOBJECT(qnum_from_uint(uvalue));
518 }
519 assert(ret == -ERANGE);
520 }
521 }
522 /* fall through to JSON_FLOAT */
523 case JSON_FLOAT:
524 /* FIXME dependent on locale; a pervasive issue in QEMU */
525 /* FIXME our lexer matches RFC 8259 in forbidding Inf or NaN,
526 * but those might be useful extensions beyond JSON */
527 return QOBJECT(qnum_from_double(strtod(token->str, NULL)));
528 default:
529 abort();
530 }
531 }
532
parse_value(JSONParserContext * ctxt)533 static QObject *parse_value(JSONParserContext *ctxt)
534 {
535 JSONToken *token;
536
537 token = parser_context_peek_token(ctxt);
538 if (token == NULL) {
539 parse_error(ctxt, NULL, "premature EOI");
540 return NULL;
541 }
542
543 switch (token->type) {
544 case JSON_LCURLY:
545 return parse_object(ctxt);
546 case JSON_LSQUARE:
547 return parse_array(ctxt);
548 case JSON_INTERP:
549 return parse_interpolation(ctxt);
550 case JSON_INTEGER:
551 case JSON_FLOAT:
552 case JSON_STRING:
553 return parse_literal(ctxt);
554 case JSON_KEYWORD:
555 return parse_keyword(ctxt);
556 default:
557 parse_error(ctxt, token, "expecting value");
558 return NULL;
559 }
560 }
561
json_token(JSONTokenType type,int x,int y,GString * tokstr)562 JSONToken *json_token(JSONTokenType type, int x, int y, GString *tokstr)
563 {
564 JSONToken *token = g_malloc(sizeof(JSONToken) + tokstr->len + 1);
565
566 token->type = type;
567 memcpy(token->str, tokstr->str, tokstr->len);
568 token->str[tokstr->len] = 0;
569 token->x = x;
570 token->y = y;
571 return token;
572 }
573
json_parser_parse(GQueue * tokens,va_list * ap,Error ** errp)574 QObject *json_parser_parse(GQueue *tokens, va_list *ap, Error **errp)
575 {
576 JSONParserContext ctxt = { .buf = tokens, .ap = ap };
577 QObject *result;
578
579 result = parse_value(&ctxt);
580 assert(ctxt.err || g_queue_is_empty(ctxt.buf));
581
582 error_propagate(errp, ctxt.err);
583
584 while (!g_queue_is_empty(ctxt.buf)) {
585 parser_context_pop_token(&ctxt);
586 }
587 g_free(ctxt.current);
588
589 return result;
590 }
591