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/json-writer.h"
  18 #include "qapi/qmp/qjson.h"
  19 #include "qapi/qmp/qbool.h"
  20 #include "qapi/qmp/qdict.h"
  21 #include "qapi/qmp/qlist.h"
  22 #include "qapi/qmp/qnum.h"
  23 #include "qapi/qmp/qstring.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(JSONWriter *writer, const char *name,
 153                     const QObject *obj)
 154 {
 155     switch (qobject_type(obj)) {
 156     case QTYPE_QNULL:
 157         json_writer_null(writer, name);
 158         break;
 159     case QTYPE_QNUM: {
 160         QNum *val = qobject_to(QNum, obj);
 161
 162         switch (val->kind) {
 163         case QNUM_I64:
 164             json_writer_int64(writer, name, val->u.i64);
 165             break;
 166         case QNUM_U64:
 167             json_writer_uint64(writer, name, val->u.u64);
 168             break;
 169         case QNUM_DOUBLE:
 170             json_writer_double(writer, name, val->u.dbl);
 171             break;
 172         default:
 173             abort();
 174         }
 175         break;
 176     }
 177     case QTYPE_QSTRING: {
 178         QString *val = qobject_to(QString, obj);
 179
 180         json_writer_str(writer, name, qstring_get_str(val));
 181         break;
 182     }
 183     case QTYPE_QDICT: {
 184         QDict *val = qobject_to(QDict, obj);
 185         const QDictEntry *entry;
 186
 187         json_writer_start_object(writer, name);
 188
 189         for (entry = qdict_first(val);
 190              entry;
 191              entry = qdict_next(val, entry)) {
 192             to_json(writer, qdict_entry_key(entry), qdict_entry_value(entry));
 193         }
 194
 195         json_writer_end_object(writer);
 196         break;
 197     }
 198     case QTYPE_QLIST: {
 199         QList *val = qobject_to(QList, obj);
 200         QListEntry *entry;
 201
 202         json_writer_start_array(writer, name);
 203
 204         QLIST_FOREACH_ENTRY(val, entry) {
 205             to_json(writer, NULL, qlist_entry_obj(entry));
 206         }
 207
 208         json_writer_end_array(writer);
 209         break;
 210     }
 211     case QTYPE_QBOOL: {
 212         QBool *val = qobject_to(QBool, obj);
 213
 214         json_writer_bool(writer, name, qbool_get_bool(val));
 215         break;
 216     }
 217     default:
 218         abort();
 219     }
 220 }
 221
 222 GString *qobject_to_json_pretty(const QObject *obj, bool pretty)
 223 {
 224     JSONWriter *writer = json_writer_new(pretty);
 225
 226     to_json(writer, NULL, obj);
 227     return json_writer_get_and_free(writer);
 228 }
 229
 230 GString *qobject_to_json(const QObject *obj)
 231 {
 232     return qobject_to_json_pretty(obj, false);
 233 }