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 #include "qemu/unicode.h"
  25
  26 typedef struct JSONParsingState
  27 {
  28     JSONMessageParser parser;
  29     va_list *ap;
  30     QObject *result;
  31 } JSONParsingState;
  32
  33 static void parse_json(JSONMessageParser *parser, GQueue *tokens)
  34 {
  35     JSONParsingState *s = container_of(parser, JSONParsingState, parser);
  36     s->result = json_parser_parse(tokens, s->ap);
  37 }
  38
  39 QObject *qobject_from_jsonv(const char *string, va_list *ap)
  40 {
  41     JSONParsingState state = {};
  42
  43     state.ap = ap;
  44
  45     json_message_parser_init(&state.parser, parse_json);
  46     json_message_parser_feed(&state.parser, string, strlen(string));
  47     json_message_parser_flush(&state.parser);
  48     json_message_parser_destroy(&state.parser);
  49
  50     return state.result;
  51 }
  52
  53 QObject *qobject_from_json(const char *string)
  54 {
  55     return qobject_from_jsonv(string, NULL);
  56 }
  57
  58 /*
  59  * IMPORTANT: This function aborts on error, thus it must not
  60  * be used with untrusted arguments.
  61  */
  62 QObject *qobject_from_jsonf(const char *string, ...)
  63 {
  64     QObject *obj;
  65     va_list ap;
  66
  67     va_start(ap, string);
  68     obj = qobject_from_jsonv(string, &ap);
  69     va_end(ap);
  70
  71     assert(obj != NULL);
  72     return obj;
  73 }
  74
  75 typedef struct ToJsonIterState
  76 {
  77     int indent;
  78     int pretty;
  79     int count;
  80     QString *str;
  81 } ToJsonIterState;
  82
  83 static void to_json(const QObject *obj, QString *str, int pretty, int indent);
  84
  85 static void to_json_dict_iter(const char *key, QObject *obj, void *opaque)
  86 {
  87     ToJsonIterState *s = opaque;
  88     QString *qkey;
  89     int j;
  90
  91     if (s->count) {
  92         qstring_append(s->str, s->pretty ? "," : ", ");
  93     }
  94
  95     if (s->pretty) {
  96         qstring_append(s->str, "\n");
  97         for (j = 0 ; j < s->indent ; j++)
  98             qstring_append(s->str, "    ");
  99     }
 100
 101     qkey = qstring_from_str(key);
 102     to_json(QOBJECT(qkey), s->str, s->pretty, s->indent);
 103     QDECREF(qkey);
 104
 105     qstring_append(s->str, ": ");
 106     to_json(obj, s->str, s->pretty, s->indent);
 107     s->count++;
 108 }
 109
 110 static void to_json_list_iter(QObject *obj, void *opaque)
 111 {
 112     ToJsonIterState *s = opaque;
 113     int j;
 114
 115     if (s->count) {
 116         qstring_append(s->str, s->pretty ? "," : ", ");
 117     }
 118
 119     if (s->pretty) {
 120         qstring_append(s->str, "\n");
 121         for (j = 0 ; j < s->indent ; j++)
 122             qstring_append(s->str, "    ");
 123     }
 124
 125     to_json(obj, s->str, s->pretty, s->indent);
 126     s->count++;
 127 }
 128
 129 static void to_json(const QObject *obj, QString *str, int pretty, int indent)
 130 {
 131     switch (qobject_type(obj)) {
 132     case QTYPE_QNULL:
 133         qstring_append(str, "null");
 134         break;
 135     case QTYPE_QINT: {
 136         QInt *val = qobject_to_qint(obj);
 137         char buffer[1024];
 138
 139         snprintf(buffer, sizeof(buffer), "%" PRId64, qint_get_int(val));
 140         qstring_append(str, buffer);
 141         break;
 142     }
 143     case QTYPE_QSTRING: {
 144         QString *val = qobject_to_qstring(obj);
 145         const char *ptr;
 146         int cp;
 147         char buf[16];
 148         char *end;
 149
 150         ptr = qstring_get_str(val);
 151         qstring_append(str, "\"");
 152
 153         for (; *ptr; ptr = end) {
 154             cp = mod_utf8_codepoint(ptr, 6, &end);
 155             switch (cp) {
 156             case '\"':
 157                 qstring_append(str, "\\\"");
 158                 break;
 159             case '\\':
 160                 qstring_append(str, "\\\\");
 161                 break;
 162             case '\b':
 163                 qstring_append(str, "\\b");
 164                 break;
 165             case '\f':
 166                 qstring_append(str, "\\f");
 167                 break;
 168             case '\n':
 169                 qstring_append(str, "\\n");
 170                 break;
 171             case '\r':
 172                 qstring_append(str, "\\r");
 173                 break;
 174             case '\t':
 175                 qstring_append(str, "\\t");
 176                 break;
 177             default:
 178                 if (cp < 0) {
 179                     cp = 0xFFFD; /* replacement character */
 180                 }
 181                 if (cp > 0xFFFF) {
 182                     /* beyond BMP; need a surrogate pair */
 183                     snprintf(buf, sizeof(buf), "\\u%04X\\u%04X",
 184                              0xD800 + ((cp - 0x10000) >> 10),
 185                              0xDC00 + ((cp - 0x10000) & 0x3FF));
 186                 } else if (cp < 0x20 || cp >= 0x7F) {
 187                     snprintf(buf, sizeof(buf), "\\u%04X", cp);
 188                 } else {
 189                     buf[0] = cp;
 190                     buf[1] = 0;
 191                 }
 192                 qstring_append(str, buf);
 193             }
 194         };
 195
 196         qstring_append(str, "\"");
 197         break;
 198     }
 199     case QTYPE_QDICT: {
 200         ToJsonIterState s;
 201         QDict *val = qobject_to_qdict(obj);
 202
 203         s.count = 0;
 204         s.str = str;
 205         s.indent = indent + 1;
 206         s.pretty = pretty;
 207         qstring_append(str, "{");
 208         qdict_iter(val, to_json_dict_iter, &s);
 209         if (pretty) {
 210             int j;
 211             qstring_append(str, "\n");
 212             for (j = 0 ; j < indent ; j++)
 213                 qstring_append(str, "    ");
 214         }
 215         qstring_append(str, "}");
 216         break;
 217     }
 218     case QTYPE_QLIST: {
 219         ToJsonIterState s;
 220         QList *val = qobject_to_qlist(obj);
 221
 222         s.count = 0;
 223         s.str = str;
 224         s.indent = indent + 1;
 225         s.pretty = pretty;
 226         qstring_append(str, "[");
 227         qlist_iter(val, (void *)to_json_list_iter, &s);
 228         if (pretty) {
 229             int j;
 230             qstring_append(str, "\n");
 231             for (j = 0 ; j < indent ; j++)
 232                 qstring_append(str, "    ");
 233         }
 234         qstring_append(str, "]");
 235         break;
 236     }
 237     case QTYPE_QFLOAT: {
 238         QFloat *val = qobject_to_qfloat(obj);
 239         char buffer[1024];
 240         int len;
 241
 242         /* FIXME: snprintf() is locale dependent; but JSON requires
 243          * numbers to be formatted as if in the C locale. Dependence
 244          * on C locale is a pervasive issue in QEMU. */
 245         /* FIXME: This risks printing Inf or NaN, which are not valid
 246          * JSON values. */
 247         /* FIXME: the default precision of 6 for %f often causes
 248          * rounding errors; we should be using DBL_DECIMAL_DIG (17),
 249          * and only rounding to a shorter number if the result would
 250          * still produce the same floating point value.  */
 251         len = snprintf(buffer, sizeof(buffer), "%f", qfloat_get_double(val));
 252         while (len > 0 && buffer[len - 1] == '0') {
 253             len--;
 254         }
 255
 256         if (len && buffer[len - 1] == '.') {
 257             buffer[len - 1] = 0;
 258         } else {
 259             buffer[len] = 0;
 260         }
 261
 262         qstring_append(str, buffer);
 263         break;
 264     }
 265     case QTYPE_QBOOL: {
 266         QBool *val = qobject_to_qbool(obj);
 267
 268         if (qbool_get_bool(val)) {
 269             qstring_append(str, "true");
 270         } else {
 271             qstring_append(str, "false");
 272         }
 273         break;
 274     }
 275     default:
 276         abort();
 277     }
 278 }
 279
 280 QString *qobject_to_json(const QObject *obj)
 281 {
 282     QString *str = qstring_new();
 283
 284     to_json(obj, str, 0, 0);
 285
 286     return str;
 287 }
 288
 289 QString *qobject_to_json_pretty(const QObject *obj)
 290 {
 291     QString *str = qstring_new();
 292
 293     to_json(obj, str, 1, 0);
 294
 295     return str;
 296 }