json-parser: fix handling of large whole number values

Currently our JSON parser assumes that numbers lacking a fractional
value are integers and attempts to store them as QInt/int64 values. This
breaks in the case where the number overflows/underflows int64 values (which
is still valid JSON)

Fix this by detecting such cases and using a QFloat to store the value
instead.
Signed-off-by: NMichael Roth <mdroth@linux.vnet.ibm.com>
Reviewed-by: NLaszlo Ersek <lersek@redhat.com>
Reviewed-by: NAmos Kong <akong@redhat.com>
Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>

qobject/json-parser.c

@@ -640,9 +640,29 @@ static QObject *parse_literal(JSONParserContext *ctxt)
     case JSON_STRING:
         obj = QOBJECT(qstring_from_escaped_str(ctxt, token));
         break;
-    case JSON_INTEGER:
-        obj = QOBJECT(qint_from_int(strtoll(token_get_value(token), NULL, 10)));
-        break;
+    case JSON_INTEGER: {
+        /* A possibility exists that this is a whole-valued float where the
+         * fractional part was left out due to being 0 (.0). It's not a big
+         * deal to treat these as ints in the parser, so long as users of the
+         * resulting QObject know to expect a QInt in place of a QFloat in
+         * cases like these.
+         *
+         * However, in some cases these values will overflow/underflow a
+         * QInt/int64 container, thus we should assume these are to be handled
+         * as QFloats/doubles rather than silently changing their values.
+         *
+         * strtoll() indicates these instances by setting errno to ERANGE
+         */
+        int64_t value;
+
+        errno = 0; /* strtoll doesn't set errno on success */
+        value = strtoll(token_get_value(token), NULL, 10);
+        if (errno != ERANGE) {
+            obj = QOBJECT(qint_from_int(value));
+            break;
+        }
+        /* fall through to JSON_FLOAT */
+    }
     case JSON_FLOAT:
         /* FIXME dependent on locale */
         obj = QOBJECT(qfloat_from_double(strtod(token_get_value(token), NULL)));