xref: /qemu/qobject/qjson.c (revision 2f2ec111) 
1 /*
2  * QObject JSON integration
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 "qapi/qmp/json-parser.h"
17 #include "qapi/qmp/qjson.h"
18 #include "qapi/qmp/qbool.h"
19 #include "qapi/qmp/qdict.h"
20 #include "qapi/qmp/qlist.h"
21 #include "qapi/qmp/qnum.h"
22 #include "qapi/qmp/qstring.h"
23 #include "qemu/unicode.h"
24 
25 typedef struct JSONParsingState
26 {
27     JSONMessageParser parser;
28     QObject *result;
29     Error *err;
30 } JSONParsingState;
31 
32 static void consume_json(void *opaque, QObject *json, Error *err)
33 {
34     JSONParsingState *s = opaque;
35 
36     assert(!json != !err);
37     assert(!s->result || !s->err);
38 
39     if (s->result) {
40         qobject_unref(s->result);
41         s->result = NULL;
42         error_setg(&s->err, "Expecting at most one JSON value");
43     }
44     if (s->err) {
45         qobject_unref(json);
46         error_free(err);
47         return;
48     }
49     s->result = json;
50     s->err = err;
51 }
52 
53 /*
54  * Parse @string as JSON value.
55  * If @ap is non-null, interpolate %-escapes.
56  * Takes ownership of %p arguments.
57  * On success, return the JSON value.
58  * On failure, store an error through @errp and return NULL.
59  * Ownership of %p arguments becomes indeterminate then.  To avoid
60  * leaks, callers passing %p must terminate on error, e.g. by passing
61  * &error_abort.
62  */
63 static QObject *qobject_from_jsonv(const char *string, va_list *ap,
64                                    Error **errp)
65 {
66     JSONParsingState state = {};
67 
68     json_message_parser_init(&state.parser, consume_json, &state, ap);
69     json_message_parser_feed(&state.parser, string, strlen(string));
70     json_message_parser_flush(&state.parser);
71     json_message_parser_destroy(&state.parser);
72 
73     if (!state.result && !state.err) {
74         error_setg(&state.err, "Expecting a JSON value");
75     }
76 
77     error_propagate(errp, state.err);
78     return state.result;
79 }
80 
81 QObject *qobject_from_json(const char *string, Error **errp)
82 {
83     return qobject_from_jsonv(string, NULL, errp);
84 }
85 
86 /*
87  * Parse @string as JSON value with %-escapes interpolated.
88  * Abort on error.  Do not use with untrusted @string.
89  * Return the resulting QObject.  It is never null.
90  */
91 QObject *qobject_from_vjsonf_nofail(const char *string, va_list ap)
92 {
93     va_list ap_copy;
94     QObject *obj;
95 
96     /* va_copy() is needed when va_list is an array type */
97     va_copy(ap_copy, ap);
98     obj = qobject_from_jsonv(string, &ap_copy, &error_abort);
99     va_end(ap_copy);
100 
101     assert(obj);
102     return obj;
103 }
104 
105 /*
106  * Parse @string as JSON value with %-escapes interpolated.
107  * Abort on error.  Do not use with untrusted @string.
108  * Return the resulting QObject.  It is never null.
109  */
110 QObject *qobject_from_jsonf_nofail(const char *string, ...)
111 {
112     QObject *obj;
113     va_list ap;
114 
115     va_start(ap, string);
116     obj = qobject_from_vjsonf_nofail(string, ap);
117     va_end(ap);
118 
119     return obj;
120 }
121 
122 /*
123  * Parse @string as JSON object with %-escapes interpolated.
124  * Abort on error.  Do not use with untrusted @string.
125  * Return the resulting QDict.  It is never null.
126  */
127 QDict *qdict_from_vjsonf_nofail(const char *string, va_list ap)
128 {
129     QDict *qdict;
130 
131     qdict = qobject_to(QDict, qobject_from_vjsonf_nofail(string, ap));
132     assert(qdict);
133     return qdict;
134 }
135 
136 /*
137  * Parse @string as JSON object with %-escapes interpolated.
138  * Abort on error.  Do not use with untrusted @string.
139  * Return the resulting QDict.  It is never null.
140  */
141 QDict *qdict_from_jsonf_nofail(const char *string, ...)
142 {
143     QDict *qdict;
144     va_list ap;
145 
146     va_start(ap, string);
147     qdict = qdict_from_vjsonf_nofail(string, ap);
148     va_end(ap);
149     return qdict;
150 }
151 
152 typedef struct ToJsonIterState
153 {
154     int indent;
155     int pretty;
156     int count;
157     QString *str;
158 } ToJsonIterState;
159 
160 static void to_json(const QObject *obj, QString *str, int pretty, int indent);
161 
162 static void json_pretty_newline(QString *str, bool pretty, int indent)
163 {
164     int i;
165 
166     if (pretty) {
167         qstring_append(str, "\n");
168         for (i = 0; i < indent; i++) {
169             qstring_append(str, "    ");
170         }
171     }
172 }
173 
174 static void to_json_dict_iter(const char *key, QObject *obj, void *opaque)
175 {
176     ToJsonIterState *s = opaque;
177     QString *qkey;
178 
179     if (s->count) {
180         qstring_append(s->str, s->pretty ? "," : ", ");
181     }
182 
183     json_pretty_newline(s->str, s->pretty, s->indent);
184 
185     qkey = qstring_from_str(key);
186     to_json(QOBJECT(qkey), s->str, s->pretty, s->indent);
187     qobject_unref(qkey);
188 
189     qstring_append(s->str, ": ");
190     to_json(obj, s->str, s->pretty, s->indent);
191     s->count++;
192 }
193 
194 static void to_json(const QObject *obj, QString *str, int pretty, int indent)
195 {
196     switch (qobject_type(obj)) {
197     case QTYPE_QNULL:
198         qstring_append(str, "null");
199         break;
200     case QTYPE_QNUM: {
201         QNum *val = qobject_to(QNum, obj);
202         char *buffer = qnum_to_string(val);
203         qstring_append(str, buffer);
204         g_free(buffer);
205         break;
206     }
207     case QTYPE_QSTRING: {
208         QString *val = qobject_to(QString, obj);
209         const char *ptr;
210         int cp;
211         char buf[16];
212         char *end;
213 
214         ptr = qstring_get_str(val);
215         qstring_append(str, "\"");
216 
217         for (; *ptr; ptr = end) {
218             cp = mod_utf8_codepoint(ptr, 6, &end);
219             switch (cp) {
220             case '\"':
221                 qstring_append(str, "\\\"");
222                 break;
223             case '\\':
224                 qstring_append(str, "\\\\");
225                 break;
226             case '\b':
227                 qstring_append(str, "\\b");
228                 break;
229             case '\f':
230                 qstring_append(str, "\\f");
231                 break;
232             case '\n':
233                 qstring_append(str, "\\n");
234                 break;
235             case '\r':
236                 qstring_append(str, "\\r");
237                 break;
238             case '\t':
239                 qstring_append(str, "\\t");
240                 break;
241             default:
242                 if (cp < 0) {
243                     cp = 0xFFFD; /* replacement character */
244                 }
245                 if (cp > 0xFFFF) {
246                     /* beyond BMP; need a surrogate pair */
247                     snprintf(buf, sizeof(buf), "\\u%04X\\u%04X",
248                              0xD800 + ((cp - 0x10000) >> 10),
249                              0xDC00 + ((cp - 0x10000) & 0x3FF));
250                 } else if (cp < 0x20 || cp >= 0x7F) {
251                     snprintf(buf, sizeof(buf), "\\u%04X", cp);
252                 } else {
253                     buf[0] = cp;
254                     buf[1] = 0;
255                 }
256                 qstring_append(str, buf);
257             }
258         };
259 
260         qstring_append(str, "\"");
261         break;
262     }
263     case QTYPE_QDICT: {
264         ToJsonIterState s;
265         QDict *val = qobject_to(QDict, obj);
266 
267         s.count = 0;
268         s.str = str;
269         s.indent = indent + 1;
270         s.pretty = pretty;
271         qstring_append(str, "{");
272         qdict_iter(val, to_json_dict_iter, &s);
273         json_pretty_newline(str, pretty, indent);
274         qstring_append(str, "}");
275         break;
276     }
277     case QTYPE_QLIST: {
278         QList *val = qobject_to(QList, obj);
279         const char *comma = pretty ? "," : ", ";
280         const char *sep = "";
281         QListEntry *entry;
282 
283         qstring_append(str, "[");
284 
285         QLIST_FOREACH_ENTRY(val, entry) {
286             qstring_append(str, sep);
287             json_pretty_newline(str, pretty, indent + 1);
288             to_json(qlist_entry_obj(entry), str, pretty, indent + 1);
289             sep = comma;
290         }
291 
292         json_pretty_newline(str, pretty, indent);
293         qstring_append(str, "]");
294         break;
295     }
296     case QTYPE_QBOOL: {
297         QBool *val = qobject_to(QBool, obj);
298 
299         if (qbool_get_bool(val)) {
300             qstring_append(str, "true");
301         } else {
302             qstring_append(str, "false");
303         }
304         break;
305     }
306     default:
307         abort();
308     }
309 }
310 
311 QString *qobject_to_json(const QObject *obj)
312 {
313     QString *str = qstring_new();
314 
315     to_json(obj, str, 0, 0);
316 
317     return str;
318 }
319 
320 QString *qobject_to_json_pretty(const QObject *obj)
321 {
322     QString *str = qstring_new();
323 
324     to_json(obj, str, 1, 0);
325 
326     return str;
327 }
328