block: Rename raw-{posix,win32} to file-*.c
[qemu.git] / qobject / json-lexer.c
1 /*
2 * JSON lexer
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-common.h"
16 #include "qapi/qmp/json-lexer.h"
17
18 #define MAX_TOKEN_SIZE (64ULL << 20)
19
20 /*
21 * Required by JSON (RFC 7159):
22 *
23 * \"([^\\\"]|\\[\"'\\/bfnrt]|\\u[0-9a-fA-F]{4})*\"
24 * -?(0|[1-9][0-9]*)(.[0-9]+)?([eE][-+]?[0-9]+)?
25 * [{}\[\],:]
26 * [a-z]+ # covers null, true, false
27 *
28 * Extension of '' strings:
29 *
30 * '([^\\']|\\[\"'\\/bfnrt]|\\u[0-9a-fA-F]{4})*'
31 *
32 * Extension for vararg handling in JSON construction:
33 *
34 * %((l|ll|I64)?d|[ipsf])
35 *
36 */
37
38 enum json_lexer_state {
39 IN_ERROR = 0, /* must really be 0, see json_lexer[] */
40 IN_DQ_UCODE3,
41 IN_DQ_UCODE2,
42 IN_DQ_UCODE1,
43 IN_DQ_UCODE0,
44 IN_DQ_STRING_ESCAPE,
45 IN_DQ_STRING,
46 IN_SQ_UCODE3,
47 IN_SQ_UCODE2,
48 IN_SQ_UCODE1,
49 IN_SQ_UCODE0,
50 IN_SQ_STRING_ESCAPE,
51 IN_SQ_STRING,
52 IN_ZERO,
53 IN_DIGITS,
54 IN_DIGIT,
55 IN_EXP_E,
56 IN_MANTISSA,
57 IN_MANTISSA_DIGITS,
58 IN_NONZERO_NUMBER,
59 IN_NEG_NONZERO_NUMBER,
60 IN_KEYWORD,
61 IN_ESCAPE,
62 IN_ESCAPE_L,
63 IN_ESCAPE_LL,
64 IN_ESCAPE_I,
65 IN_ESCAPE_I6,
66 IN_ESCAPE_I64,
67 IN_WHITESPACE,
68 IN_START,
69 };
70
71 QEMU_BUILD_BUG_ON((int)JSON_MIN <= (int)IN_START);
72
73 #define TERMINAL(state) [0 ... 0x7F] = (state)
74
75 /* Return whether TERMINAL is a terminal state and the transition to it
76 from OLD_STATE required lookahead. This happens whenever the table
77 below uses the TERMINAL macro. */
78 #define TERMINAL_NEEDED_LOOKAHEAD(old_state, terminal) \
79 (json_lexer[(old_state)][0] == (terminal))
80
81 static const uint8_t json_lexer[][256] = {
82 /* Relies on default initialization to IN_ERROR! */
83
84 /* double quote string */
85 [IN_DQ_UCODE3] = {
86 ['0' ... '9'] = IN_DQ_STRING,
87 ['a' ... 'f'] = IN_DQ_STRING,
88 ['A' ... 'F'] = IN_DQ_STRING,
89 },
90 [IN_DQ_UCODE2] = {
91 ['0' ... '9'] = IN_DQ_UCODE3,
92 ['a' ... 'f'] = IN_DQ_UCODE3,
93 ['A' ... 'F'] = IN_DQ_UCODE3,
94 },
95 [IN_DQ_UCODE1] = {
96 ['0' ... '9'] = IN_DQ_UCODE2,
97 ['a' ... 'f'] = IN_DQ_UCODE2,
98 ['A' ... 'F'] = IN_DQ_UCODE2,
99 },
100 [IN_DQ_UCODE0] = {
101 ['0' ... '9'] = IN_DQ_UCODE1,
102 ['a' ... 'f'] = IN_DQ_UCODE1,
103 ['A' ... 'F'] = IN_DQ_UCODE1,
104 },
105 [IN_DQ_STRING_ESCAPE] = {
106 ['b'] = IN_DQ_STRING,
107 ['f'] = IN_DQ_STRING,
108 ['n'] = IN_DQ_STRING,
109 ['r'] = IN_DQ_STRING,
110 ['t'] = IN_DQ_STRING,
111 ['/'] = IN_DQ_STRING,
112 ['\\'] = IN_DQ_STRING,
113 ['\''] = IN_DQ_STRING,
114 ['\"'] = IN_DQ_STRING,
115 ['u'] = IN_DQ_UCODE0,
116 },
117 [IN_DQ_STRING] = {
118 [1 ... 0xBF] = IN_DQ_STRING,
119 [0xC2 ... 0xF4] = IN_DQ_STRING,
120 ['\\'] = IN_DQ_STRING_ESCAPE,
121 ['"'] = JSON_STRING,
122 },
123
124 /* single quote string */
125 [IN_SQ_UCODE3] = {
126 ['0' ... '9'] = IN_SQ_STRING,
127 ['a' ... 'f'] = IN_SQ_STRING,
128 ['A' ... 'F'] = IN_SQ_STRING,
129 },
130 [IN_SQ_UCODE2] = {
131 ['0' ... '9'] = IN_SQ_UCODE3,
132 ['a' ... 'f'] = IN_SQ_UCODE3,
133 ['A' ... 'F'] = IN_SQ_UCODE3,
134 },
135 [IN_SQ_UCODE1] = {
136 ['0' ... '9'] = IN_SQ_UCODE2,
137 ['a' ... 'f'] = IN_SQ_UCODE2,
138 ['A' ... 'F'] = IN_SQ_UCODE2,
139 },
140 [IN_SQ_UCODE0] = {
141 ['0' ... '9'] = IN_SQ_UCODE1,
142 ['a' ... 'f'] = IN_SQ_UCODE1,
143 ['A' ... 'F'] = IN_SQ_UCODE1,
144 },
145 [IN_SQ_STRING_ESCAPE] = {
146 ['b'] = IN_SQ_STRING,
147 ['f'] = IN_SQ_STRING,
148 ['n'] = IN_SQ_STRING,
149 ['r'] = IN_SQ_STRING,
150 ['t'] = IN_SQ_STRING,
151 ['/'] = IN_SQ_STRING,
152 ['\\'] = IN_SQ_STRING,
153 ['\''] = IN_SQ_STRING,
154 ['\"'] = IN_SQ_STRING,
155 ['u'] = IN_SQ_UCODE0,
156 },
157 [IN_SQ_STRING] = {
158 [1 ... 0xBF] = IN_SQ_STRING,
159 [0xC2 ... 0xF4] = IN_SQ_STRING,
160 ['\\'] = IN_SQ_STRING_ESCAPE,
161 ['\''] = JSON_STRING,
162 },
163
164 /* Zero */
165 [IN_ZERO] = {
166 TERMINAL(JSON_INTEGER),
167 ['0' ... '9'] = IN_ERROR,
168 ['.'] = IN_MANTISSA,
169 },
170
171 /* Float */
172 [IN_DIGITS] = {
173 TERMINAL(JSON_FLOAT),
174 ['0' ... '9'] = IN_DIGITS,
175 },
176
177 [IN_DIGIT] = {
178 ['0' ... '9'] = IN_DIGITS,
179 },
180
181 [IN_EXP_E] = {
182 ['-'] = IN_DIGIT,
183 ['+'] = IN_DIGIT,
184 ['0' ... '9'] = IN_DIGITS,
185 },
186
187 [IN_MANTISSA_DIGITS] = {
188 TERMINAL(JSON_FLOAT),
189 ['0' ... '9'] = IN_MANTISSA_DIGITS,
190 ['e'] = IN_EXP_E,
191 ['E'] = IN_EXP_E,
192 },
193
194 [IN_MANTISSA] = {
195 ['0' ... '9'] = IN_MANTISSA_DIGITS,
196 },
197
198 /* Number */
199 [IN_NONZERO_NUMBER] = {
200 TERMINAL(JSON_INTEGER),
201 ['0' ... '9'] = IN_NONZERO_NUMBER,
202 ['e'] = IN_EXP_E,
203 ['E'] = IN_EXP_E,
204 ['.'] = IN_MANTISSA,
205 },
206
207 [IN_NEG_NONZERO_NUMBER] = {
208 ['0'] = IN_ZERO,
209 ['1' ... '9'] = IN_NONZERO_NUMBER,
210 },
211
212 /* keywords */
213 [IN_KEYWORD] = {
214 TERMINAL(JSON_KEYWORD),
215 ['a' ... 'z'] = IN_KEYWORD,
216 },
217
218 /* whitespace */
219 [IN_WHITESPACE] = {
220 TERMINAL(JSON_SKIP),
221 [' '] = IN_WHITESPACE,
222 ['\t'] = IN_WHITESPACE,
223 ['\r'] = IN_WHITESPACE,
224 ['\n'] = IN_WHITESPACE,
225 },
226
227 /* escape */
228 [IN_ESCAPE_LL] = {
229 ['d'] = JSON_ESCAPE,
230 },
231
232 [IN_ESCAPE_L] = {
233 ['d'] = JSON_ESCAPE,
234 ['l'] = IN_ESCAPE_LL,
235 },
236
237 [IN_ESCAPE_I64] = {
238 ['d'] = JSON_ESCAPE,
239 },
240
241 [IN_ESCAPE_I6] = {
242 ['4'] = IN_ESCAPE_I64,
243 },
244
245 [IN_ESCAPE_I] = {
246 ['6'] = IN_ESCAPE_I6,
247 },
248
249 [IN_ESCAPE] = {
250 ['d'] = JSON_ESCAPE,
251 ['i'] = JSON_ESCAPE,
252 ['p'] = JSON_ESCAPE,
253 ['s'] = JSON_ESCAPE,
254 ['f'] = JSON_ESCAPE,
255 ['l'] = IN_ESCAPE_L,
256 ['I'] = IN_ESCAPE_I,
257 },
258
259 /* top level rule */
260 [IN_START] = {
261 ['"'] = IN_DQ_STRING,
262 ['\''] = IN_SQ_STRING,
263 ['0'] = IN_ZERO,
264 ['1' ... '9'] = IN_NONZERO_NUMBER,
265 ['-'] = IN_NEG_NONZERO_NUMBER,
266 ['{'] = JSON_LCURLY,
267 ['}'] = JSON_RCURLY,
268 ['['] = JSON_LSQUARE,
269 [']'] = JSON_RSQUARE,
270 [','] = JSON_COMMA,
271 [':'] = JSON_COLON,
272 ['a' ... 'z'] = IN_KEYWORD,
273 ['%'] = IN_ESCAPE,
274 [' '] = IN_WHITESPACE,
275 ['\t'] = IN_WHITESPACE,
276 ['\r'] = IN_WHITESPACE,
277 ['\n'] = IN_WHITESPACE,
278 },
279 };
280
281 void json_lexer_init(JSONLexer *lexer, JSONLexerEmitter func)
282 {
283 lexer->emit = func;
284 lexer->state = IN_START;
285 lexer->token = g_string_sized_new(3);
286 lexer->x = lexer->y = 0;
287 }
288
289 static int json_lexer_feed_char(JSONLexer *lexer, char ch, bool flush)
290 {
291 int char_consumed, new_state;
292
293 lexer->x++;
294 if (ch == '\n') {
295 lexer->x = 0;
296 lexer->y++;
297 }
298
299 do {
300 assert(lexer->state <= ARRAY_SIZE(json_lexer));
301 new_state = json_lexer[lexer->state][(uint8_t)ch];
302 char_consumed = !TERMINAL_NEEDED_LOOKAHEAD(lexer->state, new_state);
303 if (char_consumed) {
304 g_string_append_c(lexer->token, ch);
305 }
306
307 switch (new_state) {
308 case JSON_LCURLY:
309 case JSON_RCURLY:
310 case JSON_LSQUARE:
311 case JSON_RSQUARE:
312 case JSON_COLON:
313 case JSON_COMMA:
314 case JSON_ESCAPE:
315 case JSON_INTEGER:
316 case JSON_FLOAT:
317 case JSON_KEYWORD:
318 case JSON_STRING:
319 lexer->emit(lexer, lexer->token, new_state, lexer->x, lexer->y);
320 /* fall through */
321 case JSON_SKIP:
322 g_string_truncate(lexer->token, 0);
323 new_state = IN_START;
324 break;
325 case IN_ERROR:
326 /* XXX: To avoid having previous bad input leaving the parser in an
327 * unresponsive state where we consume unpredictable amounts of
328 * subsequent "good" input, percolate this error state up to the
329 * tokenizer/parser by forcing a NULL object to be emitted, then
330 * reset state.
331 *
332 * Also note that this handling is required for reliable channel
333 * negotiation between QMP and the guest agent, since chr(0xFF)
334 * is placed at the beginning of certain events to ensure proper
335 * delivery when the channel is in an unknown state. chr(0xFF) is
336 * never a valid ASCII/UTF-8 sequence, so this should reliably
337 * induce an error/flush state.
338 */
339 lexer->emit(lexer, lexer->token, JSON_ERROR, lexer->x, lexer->y);
340 g_string_truncate(lexer->token, 0);
341 new_state = IN_START;
342 lexer->state = new_state;
343 return 0;
344 default:
345 break;
346 }
347 lexer->state = new_state;
348 } while (!char_consumed && !flush);
349
350 /* Do not let a single token grow to an arbitrarily large size,
351 * this is a security consideration.
352 */
353 if (lexer->token->len > MAX_TOKEN_SIZE) {
354 lexer->emit(lexer, lexer->token, lexer->state, lexer->x, lexer->y);
355 g_string_truncate(lexer->token, 0);
356 lexer->state = IN_START;
357 }
358
359 return 0;
360 }
361
362 int json_lexer_feed(JSONLexer *lexer, const char *buffer, size_t size)
363 {
364 size_t i;
365
366 for (i = 0; i < size; i++) {
367 int err;
368
369 err = json_lexer_feed_char(lexer, buffer[i], false);
370 if (err < 0) {
371 return err;
372 }
373 }
374
375 return 0;
376 }
377
378 int json_lexer_flush(JSONLexer *lexer)
379 {
380 return lexer->state == IN_START ? 0 : json_lexer_feed_char(lexer, 0, true);
381 }
382
383 void json_lexer_destroy(JSONLexer *lexer)
384 {
385 g_string_free(lexer->token, true);
386 }