Marc-André Lureau <marcandre.lur...@gmail.com> writes:
> Hi
>
> On Tue, Jul 17, 2018 at 9:06 AM, Markus Armbruster <arm...@redhat.com> wrote:
>> Marc-André Lureau <marcandre.lur...@redhat.com> writes:
>>
>>> Let's make json_parser_parse_err() suck less, and simplify caller
>>> error handling.
>>
>> Missing:
>>
>> * monitor.c handle_qmp_command(): drop workaround
>>
>>> * qga/main.c process_event() doesn't need further changes after
>>> previous cleanup.
>>
>> "Doesn't need further changes" yes, but I think it could use one.
>> Consider:
>>
>> obj = json_parser_parse_err(tokens, NULL, &err);
>> if (err) {
>> goto err;
>> }
>> qdict = qobject_to(QDict, obj);
>> if (!qdict) {
>> error_setg(&err, QERR_JSON_PARSING);
>> goto err;
>> }
>>
>> Before this patch, we get to the error_setg() when
>> json_parser_parse_err() fails without setting an error, and when it
>> succeeds but returns anything but a dictionary. QERR_JSON_PARSING is
>> appropriate for the first case, but not the second.
>>
>> This patch removes the first case. Please improve the error message.
>>
>
> ok, replaced with
>
> error_setg(&err, "Input must be a JSON object");
Works for me.
>>> * qobject/json-parser.c json_parser_parse()
>>> Ignores the error.
>>
>> Stupid wrapper that's used exactly once, in libqtest.c. Let's use
>> json_parser_parse_err() there, and drop the wrapper. Let's rename
>> json_parser_parse_err() to json_parser_parse() then.
>>
>>> * qobject/qjson.c qobject_from_jsonv() via parse_json()
>>> - qobject_from_json()
>>> ~ block.c parse_json_filename() - removed workaround
>>> ~ block/rbd.c - abort (generated json - should never fail)
>>> ~ qapi/qobject-input-visitor.c - removed workaround
>>> ~ tests/check-qjson.c - abort, ok
>>
>> To be precise, we pass &error_abort and either assert or crash when it
>> returns null. Okay. Same for other instances of "abort, ok" below.
>>
>> There are a few instances that don't abort. First one when !utf8_out:
>>
>> obj = qobject_from_json(json_in, utf8_out ? &error_abort : NULL);
>> if (utf8_out) {
>> str = qobject_to(QString, obj);
>> g_assert(str);
>> g_assert_cmpstr(qstring_get_str(str), ==, utf8_out);
>> } else {
>> g_assert(!obj);
>> }
>> qobject_unref(obj);
>>
>> It ignores the error. Okay.
>>
>> Next one:
>>
>> static void unterminated_string(void)
>> {
>> Error *err = NULL;
>> QObject *obj = qobject_from_json("\"abc", &err);
>> g_assert(!err); /* BUG */
>> g_assert(obj == NULL);
>> }
>>
>> This patch should fix the BUG. We'll see at [*] below why it doens't.
>>
>>> ~ tests/test-visitor-serialization.c - abort, ok
>>>
>>> - qobject_from_jsonf()
>>
>> This is called qobject_from_jsonf_nofail() since commit f3e9cc9f7a1, and
>> became the obvious wrapper around qobject_from_vjsonf_nofail() in commit
>> 74670550ee0. Please mention both new names.
>
> Hmm this is not upstream yet :)
Uh, I applied your series on top of my "[PATCH 00/20] tests:
Compile-time format string checking for libqtest.h" for review, then
promptly forgot my base isn't upstream, yet.
I consider my series ready, but decided to hold onto it until 3.1 opens
up.
Hope we'll remember these semantic conflicts when we assemble our series
for 3.1.
>> I guess the commit message needs more updates for these recent changes
>> below, but I'm glossing over that now, along with much of the patch,
>> because I think I've found something more serious, explained at the end
>> of the patch.
>>
>>> Now dies in error_handle_fatal() instead of the assertion.
>>
>> Which assertion? Ah, the one in qobject_from_vjsonf_nofail().
>>
>> The assertion is now dead, isn't it?
>
> not upstream at least
I applied to master and tried to determine "the assertion" by squinting
at the code, no luck. No need to help me with it, I'll simply try again
with your respin.
>>> Only used in tests, ok.
>>>
>>> - tests/test-qobject-input-visitor.c
>>> - tests/libqtest.c qmp_fd_sendv()
>>> Passes &error_abort, does nothing when qobject_from_jsonv() returns
>>> null. The fix makes this catch invalid JSON instead of silently
>>> ignoring it.
>>>
>>> Signed-off-by: Marc-André Lureau <marcandre.lur...@redhat.com>
>>> ---
>>> block.c | 5 -----
>>> monitor.c | 4 ----
>>> qapi/qobject-input-visitor.c | 5 -----
>>> qobject/json-parser.c | 8 +++++++-
>>> 4 files changed, 7 insertions(+), 15 deletions(-)
>>>
>>> diff --git a/block.c b/block.c
>>> index ac8b3a3511..9046d66465 100644
>>> --- a/block.c
>>> +++ b/block.c
>>> @@ -1478,11 +1478,6 @@ static QDict *parse_json_filename(const char
>>> *filename, Error **errp)
>>>
>>> options_obj = qobject_from_json(filename, errp);
>>> if (!options_obj) {
>>> - /* Work around qobject_from_json() lossage TODO fix that */
>>> - if (errp && !*errp) {
>>> - error_setg(errp, "Could not parse the JSON options");
>>> - return NULL;
>>> - }
>>> error_prepend(errp, "Could not parse the JSON options: ");
>>> return NULL;
>>> }
>>> diff --git a/monitor.c b/monitor.c
>>> index ec40a80d81..a3efe96d1d 100644
>>> --- a/monitor.c
>>> +++ b/monitor.c
>>> @@ -4112,10 +4112,6 @@ static void handle_qmp_command(JSONMessageParser
>>> *parser, GQueue *tokens)
>>> QMPRequest *req_obj;
>>>
>>> req = json_parser_parse_err(tokens, NULL, &err);
>>> - if (!req && !err) {
>>> - /* json_parser_parse_err() sucks: can fail without setting @err */
>>> - error_setg(&err, QERR_JSON_PARSING);
>>> - }
>>>
>>> qdict = qobject_to(QDict, req);
>>> if (qdict) {
>>> diff --git a/qapi/qobject-input-visitor.c b/qapi/qobject-input-visitor.c
>>> index da57f4cc24..3e88b27f9e 100644
>>> --- a/qapi/qobject-input-visitor.c
>>> +++ b/qapi/qobject-input-visitor.c
>>> @@ -725,11 +725,6 @@ Visitor *qobject_input_visitor_new_str(const char *str,
>>> if (is_json) {
>>> obj = qobject_from_json(str, errp);
>>> if (!obj) {
>>> - /* Work around qobject_from_json() lossage TODO fix that */
>>> - if (errp && !*errp) {
>>> - error_setg(errp, "JSON parse error");
>>> - return NULL;
>>> - }
>>> return NULL;
>>> }
>>> args = qobject_to(QDict, obj);
>>> diff --git a/qobject/json-parser.c b/qobject/json-parser.c
>>> index a5aa790d62..82c3167629 100644
>>> --- a/qobject/json-parser.c
>>> +++ b/qobject/json-parser.c
>>> @@ -24,6 +24,7 @@
>>> #include "qapi/qmp/json-parser.h"
>>> #include "qapi/qmp/json-lexer.h"
>>> #include "qapi/qmp/json-streamer.h"
>>> +#include "qapi/qmp/qerror.h"
>>>
>>> typedef struct JSONParserContext
>>> {
>>> @@ -591,7 +592,12 @@ QObject *json_parser_parse_err(GQueue *tokens, va_list
>>> *ap, Error **errp)
>> QObject *json_parser_parse_err(GQueue *tokens, va_list *ap, Error **errp)
>> {
>> JSONParserContext *ctxt = parser_context_new(tokens);
>> QObject *result;
>>
>> if (!ctxt) {
>> return NULL;
>>
>> [*] Still returns null without setting an error. Two cases lumped into
>> one: "no tokens due to empty input (not an error)", and "no tokens due
>> to lexical error". This is not the spot to distinguish the two, it
>> needs to be done in its callers. I figure the sane contract for
>
> I tried to tackle that in the next iteration, but it's harder than it
> looks like somehow ;)
Doesn't surprise me.
>> json_parser_parse_err() would be
>>
>> * If @tokens is null, return null.
>> * Else if @tokens parse okay, return the parse tree.
>> * Else set an error and return null.
>>
>> But then "always set an error if return NULL" is not possible. Ideas?
>
> That's okay, I'll document the function that way
>
>
>>
>> }
>>>
>>> result = parse_value(ctxt, ap);
>>>
>>> - error_propagate(errp, ctxt->err);
>>> + if (!result && !ctxt->err) {
>>> + /* TODO: improve error reporting */
>>> + error_setg(errp, QERR_JSON_PARSING);
>>> + } else {
>>> + error_propagate(errp, ctxt->err);
>>> + }
>>>
>>> parser_context_free(ctxt);
>>
