qemu/qobject/qjson.c
Markus Armbruster 998da0b158 qobject: Factor JSON writer out of qobject_to_json()
We have two JSON writers written in C: qobject/qjson.c provides
qobject_to_json(), and migration/qjson.c provides a more low level
imperative interface.  They don't share code.  The latter tacitly
limits numbers to int64_t, and strings contents to characters that
don't need escaping.

Factor out qobject_to_json()'s JSON writer as qobject/json-writer.c.
Straightforward, except for numbers: since the writer is to be
independent of QObject, it can't use qnum_to_string().  Open-code it
instead.  This is actually an improvement of sorts, because it
liberates qnum_to_string() from JSON's needs: its JSON-related FIXMEs
move to the JSON writer, where they belong.

The next commit will replace migration/qjson.c.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20201211171152.146877-16-armbru@redhat.com>
2020-12-19 10:39:16 +01:00

234 lines
5.7 KiB
C

/*
* QObject JSON integration
*
* Copyright IBM, Corp. 2009
*
* Authors:
* Anthony Liguori <aliguori@us.ibm.com>
*
* This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
* See the COPYING.LIB file in the top-level directory.
*
*/
#include "qemu/osdep.h"
#include "qapi/error.h"
#include "qapi/qmp/json-parser.h"
#include "qapi/qmp/json-writer.h"
#include "qapi/qmp/qjson.h"
#include "qapi/qmp/qbool.h"
#include "qapi/qmp/qdict.h"
#include "qapi/qmp/qlist.h"
#include "qapi/qmp/qnum.h"
#include "qapi/qmp/qstring.h"
typedef struct JSONParsingState
{
JSONMessageParser parser;
QObject *result;
Error *err;
} JSONParsingState;
static void consume_json(void *opaque, QObject *json, Error *err)
{
JSONParsingState *s = opaque;
assert(!json != !err);
assert(!s->result || !s->err);
if (s->result) {
qobject_unref(s->result);
s->result = NULL;
error_setg(&s->err, "Expecting at most one JSON value");
}
if (s->err) {
qobject_unref(json);
error_free(err);
return;
}
s->result = json;
s->err = err;
}
/*
* Parse @string as JSON value.
* If @ap is non-null, interpolate %-escapes.
* Takes ownership of %p arguments.
* On success, return the JSON value.
* On failure, store an error through @errp and return NULL.
* Ownership of %p arguments becomes indeterminate then. To avoid
* leaks, callers passing %p must terminate on error, e.g. by passing
* &error_abort.
*/
static QObject *qobject_from_jsonv(const char *string, va_list *ap,
Error **errp)
{
JSONParsingState state = {};
json_message_parser_init(&state.parser, consume_json, &state, ap);
json_message_parser_feed(&state.parser, string, strlen(string));
json_message_parser_flush(&state.parser);
json_message_parser_destroy(&state.parser);
if (!state.result && !state.err) {
error_setg(&state.err, "Expecting a JSON value");
}
error_propagate(errp, state.err);
return state.result;
}
QObject *qobject_from_json(const char *string, Error **errp)
{
return qobject_from_jsonv(string, NULL, errp);
}
/*
* Parse @string as JSON value with %-escapes interpolated.
* Abort on error. Do not use with untrusted @string.
* Return the resulting QObject. It is never null.
*/
QObject *qobject_from_vjsonf_nofail(const char *string, va_list ap)
{
va_list ap_copy;
QObject *obj;
/* va_copy() is needed when va_list is an array type */
va_copy(ap_copy, ap);
obj = qobject_from_jsonv(string, &ap_copy, &error_abort);
va_end(ap_copy);
assert(obj);
return obj;
}
/*
* Parse @string as JSON value with %-escapes interpolated.
* Abort on error. Do not use with untrusted @string.
* Return the resulting QObject. It is never null.
*/
QObject *qobject_from_jsonf_nofail(const char *string, ...)
{
QObject *obj;
va_list ap;
va_start(ap, string);
obj = qobject_from_vjsonf_nofail(string, ap);
va_end(ap);
return obj;
}
/*
* Parse @string as JSON object with %-escapes interpolated.
* Abort on error. Do not use with untrusted @string.
* Return the resulting QDict. It is never null.
*/
QDict *qdict_from_vjsonf_nofail(const char *string, va_list ap)
{
QDict *qdict;
qdict = qobject_to(QDict, qobject_from_vjsonf_nofail(string, ap));
assert(qdict);
return qdict;
}
/*
* Parse @string as JSON object with %-escapes interpolated.
* Abort on error. Do not use with untrusted @string.
* Return the resulting QDict. It is never null.
*/
QDict *qdict_from_jsonf_nofail(const char *string, ...)
{
QDict *qdict;
va_list ap;
va_start(ap, string);
qdict = qdict_from_vjsonf_nofail(string, ap);
va_end(ap);
return qdict;
}
static void to_json(JSONWriter *writer, const char *name,
const QObject *obj)
{
switch (qobject_type(obj)) {
case QTYPE_QNULL:
json_writer_null(writer, name);
break;
case QTYPE_QNUM: {
QNum *val = qobject_to(QNum, obj);
switch (val->kind) {
case QNUM_I64:
json_writer_int64(writer, name, val->u.i64);
break;
case QNUM_U64:
json_writer_uint64(writer, name, val->u.u64);
break;
case QNUM_DOUBLE:
json_writer_double(writer, name, val->u.dbl);
break;
default:
abort();
}
break;
}
case QTYPE_QSTRING: {
QString *val = qobject_to(QString, obj);
json_writer_str(writer, name, qstring_get_str(val));
break;
}
case QTYPE_QDICT: {
QDict *val = qobject_to(QDict, obj);
const QDictEntry *entry;
json_writer_start_object(writer, name);
for (entry = qdict_first(val);
entry;
entry = qdict_next(val, entry)) {
to_json(writer, qdict_entry_key(entry), qdict_entry_value(entry));
}
json_writer_end_object(writer);
break;
}
case QTYPE_QLIST: {
QList *val = qobject_to(QList, obj);
QListEntry *entry;
json_writer_start_array(writer, name);
QLIST_FOREACH_ENTRY(val, entry) {
to_json(writer, NULL, qlist_entry_obj(entry));
}
json_writer_end_array(writer);
break;
}
case QTYPE_QBOOL: {
QBool *val = qobject_to(QBool, obj);
json_writer_bool(writer, name, qbool_get_bool(val));
break;
}
default:
abort();
}
}
GString *qobject_to_json_pretty(const QObject *obj, bool pretty)
{
JSONWriter *writer = json_writer_new(pretty);
to_json(writer, NULL, obj);
return json_writer_get_and_free(writer);
}
GString *qobject_to_json(const QObject *obj)
{
return qobject_to_json_pretty(obj, false);
}