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 json_pretty_newline(GString *accu, bool pretty, int indent)
 153 {
 154     if (pretty) {
 155         g_string_append_printf(accu, "\n%*s", indent * 4, "");
 156     }
 157 }
 158
 159 static void to_json(const QObject *obj, GString *accu, bool pretty, int indent)
 160 {
 161     switch (qobject_type(obj)) {
 162     case QTYPE_QNULL:
 163         g_string_append(accu, "null");
 164         break;
 165     case QTYPE_QNUM: {
 166         QNum *val = qobject_to(QNum, obj);
 167         char *buffer = qnum_to_string(val);
 168         g_string_append(accu, buffer);
 169         g_free(buffer);
 170         break;
 171     }
 172     case QTYPE_QSTRING: {
 173         QString *val = qobject_to(QString, obj);
 174         const char *ptr;
 175         int cp;
 176         char *end;
 177
 178         ptr = qstring_get_str(val);
 179         g_string_append_c(accu, '"');
 180
 181         for (; *ptr; ptr = end) {
 182             cp = mod_utf8_codepoint(ptr, 6, &end);
 183             switch (cp) {
 184             case '\"':
 185                 g_string_append(accu, "\\\"");
 186                 break;
 187             case '\\':
 188                 g_string_append(accu, "\\\\");
 189                 break;
 190             case '\b':
 191                 g_string_append(accu, "\\b");
 192                 break;
 193             case '\f':
 194                 g_string_append(accu, "\\f");
 195                 break;
 196             case '\n':
 197                 g_string_append(accu, "\\n");
 198                 break;
 199             case '\r':
 200                 g_string_append(accu, "\\r");
 201                 break;
 202             case '\t':
 203                 g_string_append(accu, "\\t");
 204                 break;
 205             default:
 206                 if (cp < 0) {
 207                     cp = 0xFFFD; /* replacement character */
 208                 }
 209                 if (cp > 0xFFFF) {
 210                     /* beyond BMP; need a surrogate pair */
 211                     g_string_append_printf(accu, "\\u%04X\\u%04X",
 212                                            0xD800 + ((cp - 0x10000) >> 10),
 213                                            0xDC00 + ((cp - 0x10000) & 0x3FF));
 214                 } else if (cp < 0x20 || cp >= 0x7F) {
 215                     g_string_append_printf(accu, "\\u%04X", cp);
 216                 } else {
 217                     g_string_append_c(accu, cp);
 218                 }
 219             }
 220         };
 221
 222         g_string_append_c(accu, '"');
 223         break;
 224     }
 225     case QTYPE_QDICT: {
 226         QDict *val = qobject_to(QDict, obj);
 227         const char *comma = pretty ? "," : ", ";
 228         const char *sep = "";
 229         const QDictEntry *entry;
 230         QString *qkey;
 231
 232         g_string_append_c(accu, '{');
 233
 234         for (entry = qdict_first(val);
 235              entry;
 236              entry = qdict_next(val, entry)) {
 237             g_string_append(accu, sep);
 238             json_pretty_newline(accu, pretty, indent + 1);
 239
 240             qkey = qstring_from_str(qdict_entry_key(entry));
 241             to_json(QOBJECT(qkey), accu, pretty, indent + 1);
 242             qobject_unref(qkey);
 243
 244             g_string_append(accu, ": ");
 245             to_json(qdict_entry_value(entry), accu, pretty, indent + 1);
 246             sep = comma;
 247         }
 248
 249         json_pretty_newline(accu, pretty, indent);
 250         g_string_append_c(accu, '}');
 251         break;
 252     }
 253     case QTYPE_QLIST: {
 254         QList *val = qobject_to(QList, obj);
 255         const char *comma = pretty ? "," : ", ";
 256         const char *sep = "";
 257         QListEntry *entry;
 258
 259         g_string_append_c(accu, '[');
 260
 261         QLIST_FOREACH_ENTRY(val, entry) {
 262             g_string_append(accu, sep);
 263             json_pretty_newline(accu, pretty, indent + 1);
 264             to_json(qlist_entry_obj(entry), accu, pretty, indent + 1);
 265             sep = comma;
 266         }
 267
 268         json_pretty_newline(accu, pretty, indent);
 269         g_string_append_c(accu, ']');
 270         break;
 271     }
 272     case QTYPE_QBOOL: {
 273         QBool *val = qobject_to(QBool, obj);
 274
 275         if (qbool_get_bool(val)) {
 276             g_string_append(accu, "true");
 277         } else {
 278             g_string_append(accu, "false");
 279         }
 280         break;
 281     }
 282     default:
 283         abort();
 284     }
 285 }
 286
 287 QString *qobject_to_json_pretty(const QObject *obj, bool pretty)
 288 {
 289     GString *accu = g_string_new(NULL);
 290
 291     to_json(obj, accu, pretty, 0);
 292     return qstring_from_gstring(accu);
 293 }
 294
 295 QString *qobject_to_json(const QObject *obj)
 296 {
 297     return qobject_to_json_pretty(obj, false);
 298 }