qobject/qjson.c

   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 static void to_json(const QObject *obj, QString *str, int pretty, int indent);
 153
 154 static void json_pretty_newline(QString *str, bool pretty, int indent)
 155 {
 156     int i;
 157
 158     if (pretty) {
 159         qstring_append(str, "\n");
 160         for (i = 0; i < indent; i++) {
 161             qstring_append(str, "    ");
 162         }
 163     }
 164 }
 165
 166 static void to_json(const QObject *obj, QString *str, int pretty, int indent)
 167 {
 168     switch (qobject_type(obj)) {
 169     case QTYPE_QNULL:
 170         qstring_append(str, "null");
 171         break;
 172     case QTYPE_QNUM: {
 173         QNum *val = qobject_to(QNum, obj);
 174         char *buffer = qnum_to_string(val);
 175         qstring_append(str, buffer);
 176         g_free(buffer);
 177         break;
 178     }
 179     case QTYPE_QSTRING: {
 180         QString *val = qobject_to(QString, obj);
 181         const char *ptr;
 182         int cp;
 183         char buf[16];
 184         char *end;
 185
 186         ptr = qstring_get_str(val);
 187         qstring_append(str, "\"");
 188
 189         for (; *ptr; ptr = end) {
 190             cp = mod_utf8_codepoint(ptr, 6, &end);
 191             switch (cp) {
 192             case '\"':
 193                 qstring_append(str, "\\\"");
 194                 break;
 195             case '\\':
 196                 qstring_append(str, "\\\\");
 197                 break;
 198             case '\b':
 199                 qstring_append(str, "\\b");
 200                 break;
 201             case '\f':
 202                 qstring_append(str, "\\f");
 203                 break;
 204             case '\n':
 205                 qstring_append(str, "\\n");
 206                 break;
 207             case '\r':
 208                 qstring_append(str, "\\r");
 209                 break;
 210             case '\t':
 211                 qstring_append(str, "\\t");
 212                 break;
 213             default:
 214                 if (cp < 0) {
 215                     cp = 0xFFFD; /* replacement character */
 216                 }
 217                 if (cp > 0xFFFF) {
 218                     /* beyond BMP; need a surrogate pair */
 219                     snprintf(buf, sizeof(buf), "\\u%04X\\u%04X",
 220                              0xD800 + ((cp - 0x10000) >> 10),
 221                              0xDC00 + ((cp - 0x10000) & 0x3FF));
 222                 } else if (cp < 0x20 || cp >= 0x7F) {
 223                     snprintf(buf, sizeof(buf), "\\u%04X", cp);
 224                 } else {
 225                     buf[0] = cp;
 226                     buf[1] = 0;
 227                 }
 228                 qstring_append(str, buf);
 229             }
 230         };
 231
 232         qstring_append(str, "\"");
 233         break;
 234     }
 235     case QTYPE_QDICT: {
 236         QDict *val = qobject_to(QDict, obj);
 237         const char *comma = pretty ? "," : ", ";
 238         const char *sep = "";
 239         const QDictEntry *entry;
 240         QString *qkey;
 241
 242         qstring_append(str, "{");
 243
 244         for (entry = qdict_first(val);
 245              entry;
 246              entry = qdict_next(val, entry)) {
 247             qstring_append(str, sep);
 248             json_pretty_newline(str, pretty, indent + 1);
 249
 250             qkey = qstring_from_str(qdict_entry_key(entry));
 251             to_json(QOBJECT(qkey), str, pretty, indent + 1);
 252             qobject_unref(qkey);
 253
 254             qstring_append(str, ": ");
 255             to_json(qdict_entry_value(entry), str, pretty, indent + 1);
 256             sep = comma;
 257         }
 258
 259         json_pretty_newline(str, pretty, indent);
 260         qstring_append(str, "}");
 261         break;
 262     }
 263     case QTYPE_QLIST: {
 264         QList *val = qobject_to(QList, obj);
 265         const char *comma = pretty ? "," : ", ";
 266         const char *sep = "";
 267         QListEntry *entry;
 268
 269         qstring_append(str, "[");
 270
 271         QLIST_FOREACH_ENTRY(val, entry) {
 272             qstring_append(str, sep);
 273             json_pretty_newline(str, pretty, indent + 1);
 274             to_json(qlist_entry_obj(entry), str, pretty, indent + 1);
 275             sep = comma;
 276         }
 277
 278         json_pretty_newline(str, pretty, indent);
 279         qstring_append(str, "]");
 280         break;
 281     }
 282     case QTYPE_QBOOL: {
 283         QBool *val = qobject_to(QBool, obj);
 284
 285         if (qbool_get_bool(val)) {
 286             qstring_append(str, "true");
 287         } else {
 288             qstring_append(str, "false");
 289         }
 290         break;
 291     }
 292     default:
 293         abort();
 294     }
 295 }
 296
 297 QString *qobject_to_json(const QObject *obj)
 298 {
 299     QString *str = qstring_new();
 300
 301     to_json(obj, str, 0, 0);
 302
 303     return str;
 304 }
 305
 306 QString *qobject_to_json_pretty(const QObject *obj)
 307 {
 308     QString *str = qstring_new();
 309
 310     to_json(obj, str, 1, 0);
 311
 312     return str;
 313 }