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     JSONMessageParser parser;
  27     QObject *result;
  28     Error *err;
  29 } JSONParsingState;
  30
  31 static void consume_json(void *opaque, QObject *json, Error *err)
  32 {
  33     JSONParsingState *s = opaque;
  34
  35     assert(!json != !err);
  36     assert(!s->result || !s->err);
  37
  38     if (s->result) {
  39         qobject_unref(s->result);
  40         s->result = NULL;
  41         error_setg(&s->err, "Expecting at most one JSON value");
  42     }
  43     if (s->err) {
  44         qobject_unref(json);
  45         error_free(err);
  46         return;
  47     }
  48     s->result = json;
  49     s->err = err;
  50 }
  51
  52 /*
  53  * Parse @string as JSON value.
  54  * If @ap is non-null, interpolate %-escapes.
  55  * Takes ownership of %p arguments.
  56  * On success, return the JSON value.
  57  * On failure, store an error through @errp and return NULL.
  58  * Ownership of %p arguments becomes indeterminate then.  To avoid
  59  * leaks, callers passing %p must terminate on error, e.g. by passing
  60  * &error_abort.
  61  */
  62 static QObject *qobject_from_jsonv(const char *string, va_list *ap,
  63                                    Error **errp)
  64 {
  65     JSONParsingState state = {};
  66
  67     json_message_parser_init(&state.parser, consume_json, &state, ap);
  68     json_message_parser_feed(&state.parser, string, strlen(string));
  69     json_message_parser_flush(&state.parser);
  70     json_message_parser_destroy(&state.parser);
  71
  72     if (!state.result && !state.err) {
  73         error_setg(&state.err, "Expecting a JSON value");
  74     }
  75
  76     error_propagate(errp, state.err);
  77     return state.result;
  78 }
  79
  80 QObject *qobject_from_json(const char *string, Error **errp)
  81 {
  82     return qobject_from_jsonv(string, NULL, errp);
  83 }
  84
  85 /*
  86  * Parse @string as JSON value with %-escapes interpolated.
  87  * Abort on error.  Do not use with untrusted @string.
  88  * Return the resulting QObject.  It is never null.
  89  */
  90 QObject *qobject_from_vjsonf_nofail(const char *string, va_list ap)
  91 {
  92     va_list ap_copy;
  93     QObject *obj;
  94
  95     /* va_copy() is needed when va_list is an array type */
  96     va_copy(ap_copy, ap);
  97     obj = qobject_from_jsonv(string, &ap_copy, &error_abort);
  98     va_end(ap_copy);
  99
 100     assert(obj);
 101     return obj;
 102 }
 103
 104 /*
 105  * Parse @string as JSON value with %-escapes interpolated.
 106  * Abort on error.  Do not use with untrusted @string.
 107  * Return the resulting QObject.  It is never null.
 108  */
 109 QObject *qobject_from_jsonf_nofail(const char *string, ...)
 110 {
 111     QObject *obj;
 112     va_list ap;
 113
 114     va_start(ap, string);
 115     obj = qobject_from_vjsonf_nofail(string, ap);
 116     va_end(ap);
 117
 118     return obj;
 119 }
 120
 121 /*
 122  * Parse @string as JSON object with %-escapes interpolated.
 123  * Abort on error.  Do not use with untrusted @string.
 124  * Return the resulting QDict.  It is never null.
 125  */
 126 QDict *qdict_from_vjsonf_nofail(const char *string, va_list ap)
 127 {
 128     QDict *qdict;
 129
 130     qdict = qobject_to(QDict, qobject_from_vjsonf_nofail(string, ap));
 131     assert(qdict);
 132     return qdict;
 133 }
 134
 135 /*
 136  * Parse @string as JSON object with %-escapes interpolated.
 137  * Abort on error.  Do not use with untrusted @string.
 138  * Return the resulting QDict.  It is never null.
 139  */
 140 QDict *qdict_from_jsonf_nofail(const char *string, ...)
 141 {
 142     QDict *qdict;
 143     va_list ap;
 144
 145     va_start(ap, string);
 146     qdict = qdict_from_vjsonf_nofail(string, ap);
 147     va_end(ap);
 148     return qdict;
 149 }
 150
 151 static void to_json(JSONWriter *writer, const char *name,
 152                     const QObject *obj)
 153 {
 154     switch (qobject_type(obj)) {
 155     case QTYPE_QNULL:
 156         json_writer_null(writer, name);
 157         break;
 158     case QTYPE_QNUM: {
 159         QNum *val = qobject_to(QNum, obj);
 160
 161         switch (val->kind) {
 162         case QNUM_I64:
 163             json_writer_int64(writer, name, val->u.i64);
 164             break;
 165         case QNUM_U64:
 166             json_writer_uint64(writer, name, val->u.u64);
 167             break;
 168         case QNUM_DOUBLE:
 169             json_writer_double(writer, name, val->u.dbl);
 170             break;
 171         default:
 172             abort();
 173         }
 174         break;
 175     }
 176     case QTYPE_QSTRING: {
 177         QString *val = qobject_to(QString, obj);
 178
 179         json_writer_str(writer, name, qstring_get_str(val));
 180         break;
 181     }
 182     case QTYPE_QDICT: {
 183         QDict *val = qobject_to(QDict, obj);
 184         const QDictEntry *entry;
 185
 186         json_writer_start_object(writer, name);
 187
 188         for (entry = qdict_first(val);
 189              entry;
 190              entry = qdict_next(val, entry)) {
 191             to_json(writer, qdict_entry_key(entry), qdict_entry_value(entry));
 192         }
 193
 194         json_writer_end_object(writer);
 195         break;
 196     }
 197     case QTYPE_QLIST: {
 198         QList *val = qobject_to(QList, obj);
 199         QListEntry *entry;
 200
 201         json_writer_start_array(writer, name);
 202
 203         QLIST_FOREACH_ENTRY(val, entry) {
 204             to_json(writer, NULL, qlist_entry_obj(entry));
 205         }
 206
 207         json_writer_end_array(writer);
 208         break;
 209     }
 210     case QTYPE_QBOOL: {
 211         QBool *val = qobject_to(QBool, obj);
 212
 213         json_writer_bool(writer, name, qbool_get_bool(val));
 214         break;
 215     }
 216     default:
 217         abort();
 218     }
 219 }
 220
 221 GString *qobject_to_json_pretty(const QObject *obj, bool pretty)
 222 {
 223     JSONWriter *writer = json_writer_new(pretty);
 224
 225     to_json(writer, NULL, obj);
 226     return json_writer_get_and_free(writer);
 227 }
 228
 229 GString *qobject_to_json(const QObject *obj)
 230 {
 231     return qobject_to_json_pretty(obj, false);
 232 }