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/qmp/json-lexer.h"
  16 #include "qapi/qmp/json-parser.h"
  17 #include "qapi/qmp/json-streamer.h"
  18 #include "qapi/qmp/qjson.h"
  19 #include "qapi/qmp/qint.h"
  20 #include "qapi/qmp/qlist.h"
  21 #include "qapi/qmp/qbool.h"
  22 #include "qapi/qmp/qfloat.h"
  23 #include "qapi/qmp/qdict.h"
  24
  25 typedef struct JSONParsingState
  26 {
  27     JSONMessageParser parser;
  28     va_list *ap;
  29     QObject *result;
  30 } JSONParsingState;
  31
  32 static void parse_json(JSONMessageParser *parser, GQueue *tokens)
  33 {
  34     JSONParsingState *s = container_of(parser, JSONParsingState, parser);
  35     s->result = json_parser_parse(tokens, s->ap);
  36 }
  37
  38 QObject *qobject_from_jsonv(const char *string, va_list *ap)
  39 {
  40     JSONParsingState state = {};
  41
  42     state.ap = ap;
  43
  44     json_message_parser_init(&state.parser, parse_json);
  45     json_message_parser_feed(&state.parser, string, strlen(string));
  46     json_message_parser_flush(&state.parser);
  47     json_message_parser_destroy(&state.parser);
  48
  49     return state.result;
  50 }
  51
  52 QObject *qobject_from_json(const char *string)
  53 {
  54     return qobject_from_jsonv(string, NULL);
  55 }
  56
  57 /*
  58  * IMPORTANT: This function aborts on error, thus it must not
  59  * be used with untrusted arguments.
  60  */
  61 QObject *qobject_from_jsonf(const char *string, ...)
  62 {
  63     QObject *obj;
  64     va_list ap;
  65
  66     va_start(ap, string);
  67     obj = qobject_from_jsonv(string, &ap);
  68     va_end(ap);
  69
  70     assert(obj != NULL);
  71     return obj;
  72 }
  73
  74 typedef struct ToJsonIterState
  75 {
  76     int indent;
  77     int pretty;
  78     int count;
  79     QString *str;
  80 } ToJsonIterState;
  81
  82 static void to_json(const QObject *obj, QString *str, int pretty, int indent);
  83
  84 static void to_json_dict_iter(const char *key, QObject *obj, void *opaque)
  85 {
  86     ToJsonIterState *s = opaque;
  87     QString *qkey;
  88     int j;
  89
  90     if (s->count) {
  91         qstring_append(s->str, s->pretty ? "," : ", ");
  92     }
  93
  94     if (s->pretty) {
  95         qstring_append(s->str, "\n");
  96         for (j = 0 ; j < s->indent ; j++)
  97             qstring_append(s->str, "    ");
  98     }
  99
 100     qkey = qstring_from_str(key);
 101     to_json(QOBJECT(qkey), s->str, s->pretty, s->indent);
 102     QDECREF(qkey);
 103
 104     qstring_append(s->str, ": ");
 105     to_json(obj, s->str, s->pretty, s->indent);
 106     s->count++;
 107 }
 108
 109 static void to_json_list_iter(QObject *obj, void *opaque)
 110 {
 111     ToJsonIterState *s = opaque;
 112     int j;
 113
 114     if (s->count) {
 115         qstring_append(s->str, s->pretty ? "," : ", ");
 116     }
 117
 118     if (s->pretty) {
 119         qstring_append(s->str, "\n");
 120         for (j = 0 ; j < s->indent ; j++)
 121             qstring_append(s->str, "    ");
 122     }
 123
 124     to_json(obj, s->str, s->pretty, s->indent);
 125     s->count++;
 126 }
 127
 128 static void to_json(const QObject *obj, QString *str, int pretty, int indent)
 129 {
 130     switch (qobject_type(obj)) {
 131     case QTYPE_QNULL:
 132         qstring_append(str, "null");
 133         break;
 134     case QTYPE_QINT: {
 135         QInt *val = qobject_to_qint(obj);
 136         char buffer[1024];
 137
 138         snprintf(buffer, sizeof(buffer), "%" PRId64, qint_get_int(val));
 139         qstring_append(str, buffer);
 140         break;
 141     }
 142     case QTYPE_QSTRING: {
 143         QString *val = qobject_to_qstring(obj);
 144         const char *ptr;
 145         int cp;
 146         char buf[16];
 147         char *end;
 148
 149         ptr = qstring_get_str(val);
 150         qstring_append(str, "\"");
 151
 152         for (; *ptr; ptr = end) {
 153             cp = mod_utf8_codepoint(ptr, 6, &end);
 154             switch (cp) {
 155             case '\"':
 156                 qstring_append(str, "\\\"");
 157                 break;
 158             case '\\':
 159                 qstring_append(str, "\\\\");
 160                 break;
 161             case '\b':
 162                 qstring_append(str, "\\b");
 163                 break;
 164             case '\f':
 165                 qstring_append(str, "\\f");
 166                 break;
 167             case '\n':
 168                 qstring_append(str, "\\n");
 169                 break;
 170             case '\r':
 171                 qstring_append(str, "\\r");
 172                 break;
 173             case '\t':
 174                 qstring_append(str, "\\t");
 175                 break;
 176             default:
 177                 if (cp < 0) {
 178                     cp = 0xFFFD; /* replacement character */
 179                 }
 180                 if (cp > 0xFFFF) {
 181                     /* beyond BMP; need a surrogate pair */
 182                     snprintf(buf, sizeof(buf), "\\u%04X\\u%04X",
 183                              0xD800 + ((cp - 0x10000) >> 10),
 184                              0xDC00 + ((cp - 0x10000) & 0x3FF));
 185                 } else if (cp < 0x20 || cp >= 0x7F) {
 186                     snprintf(buf, sizeof(buf), "\\u%04X", cp);
 187                 } else {
 188                     buf[0] = cp;
 189                     buf[1] = 0;
 190                 }
 191                 qstring_append(str, buf);
 192             }
 193         };
 194
 195         qstring_append(str, "\"");
 196         break;
 197     }
 198     case QTYPE_QDICT: {
 199         ToJsonIterState s;
 200         QDict *val = qobject_to_qdict(obj);
 201
 202         s.count = 0;
 203         s.str = str;
 204         s.indent = indent + 1;
 205         s.pretty = pretty;
 206         qstring_append(str, "{");
 207         qdict_iter(val, to_json_dict_iter, &s);
 208         if (pretty) {
 209             int j;
 210             qstring_append(str, "\n");
 211             for (j = 0 ; j < indent ; j++)
 212                 qstring_append(str, "    ");
 213         }
 214         qstring_append(str, "}");
 215         break;
 216     }
 217     case QTYPE_QLIST: {
 218         ToJsonIterState s;
 219         QList *val = qobject_to_qlist(obj);
 220
 221         s.count = 0;
 222         s.str = str;
 223         s.indent = indent + 1;
 224         s.pretty = pretty;
 225         qstring_append(str, "[");
 226         qlist_iter(val, (void *)to_json_list_iter, &s);
 227         if (pretty) {
 228             int j;
 229             qstring_append(str, "\n");
 230             for (j = 0 ; j < indent ; j++)
 231                 qstring_append(str, "    ");
 232         }
 233         qstring_append(str, "]");
 234         break;
 235     }
 236     case QTYPE_QFLOAT: {
 237         QFloat *val = qobject_to_qfloat(obj);
 238         char buffer[1024];
 239         int len;
 240
 241         /* FIXME: snprintf() is locale dependent; but JSON requires
 242          * numbers to be formatted as if in the C locale. Dependence
 243          * on C locale is a pervasive issue in QEMU. */
 244         /* FIXME: This risks printing Inf or NaN, which are not valid
 245          * JSON values. */
 246         /* FIXME: the default precision of 6 for %f often causes
 247          * rounding errors; we should be using DBL_DECIMAL_DIG (17),
 248          * and only rounding to a shorter number if the result would
 249          * still produce the same floating point value.  */
 250         len = snprintf(buffer, sizeof(buffer), "%f", qfloat_get_double(val));
 251         while (len > 0 && buffer[len - 1] == '0') {
 252             len--;
 253         }
 254
 255         if (len && buffer[len - 1] == '.') {
 256             buffer[len - 1] = 0;
 257         } else {
 258             buffer[len] = 0;
 259         }
 260
 261         qstring_append(str, buffer);
 262         break;
 263     }
 264     case QTYPE_QBOOL: {
 265         QBool *val = qobject_to_qbool(obj);
 266
 267         if (qbool_get_bool(val)) {
 268             qstring_append(str, "true");
 269         } else {
 270             qstring_append(str, "false");
 271         }
 272         break;
 273     }
 274     default:
 275         abort();
 276     }
 277 }
 278
 279 QString *qobject_to_json(const QObject *obj)
 280 {
 281     QString *str = qstring_new();
 282
 283     to_json(obj, str, 0, 0);
 284
 285     return str;
 286 }
 287
 288 QString *qobject_to_json_pretty(const QObject *obj)
 289 {
 290     QString *str = qstring_new();
 291
 292     to_json(obj, str, 1, 0);
 293
 294     return str;
 295 }