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This queue is for tickets about the JSON-XS CPAN distribution.

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The Basics
Id: 97196
Status: resolved
Priority: 0/
Queue: JSON-XS

People
Owner: Nobody in particular
Requestors: dcmertens.perl [...] gmail.com
Cc: dcmertens.perl [...] gmail.com
AdminCc:

Bug Information
Severity: Normal
Broken in: 3.01
Fixed in: (no value)



CC: dcmertens.perl [...] gmail.com
Subject: decode in list context, with filter_json_single_key_object, causes Perl to panic
I encountered a strange error in the behavior of JSON::XS, not present in JSON::PP. It can be avoided via user work-arounds, as I explain below, but should probably be addressed to avoid confusion, especially by users who are debugging their JSON-using code. The most likely situation in which this will trigger a problem is in code such as: ... my $json = JSON->new->filter_json_single_key_object ... ... print Dumper($json->decode($json_text)); ... It seems that the key ingredients include: 1) Must have a filter_json_single_key_object that gets used during the decoding 2) Must evaluate the decode method in list context. The attached script produces the following output from Perl for me: panic: attempt to copy freed scalar 7fde41139a38 to 7fde41029d88 at test.pl line 6. I have confirmed (via environment variables) that this is indeed using JSON::XS. A simple user work-around to avoid this is to always assign the result of the decode method to a scalar, or to wrap calls to "decode" in a strictly scalar context.
Subject: test.pl
use JSON; my $json = '[{ "foo": "bar" }]'; use Data::Dumper; print Dumper(scalar(JSON ->new ->filter_json_single_key_object( foo => sub { 1 } ) ->decode($json)));
Sorry, I somehow uploaded a revised version of the test script that does not trigger the failure. Here is what I meant to send: use JSON; my $json = '[{ "foo": "bar" }]'; my @objects = JSON ->new ->filter_json_single_key_object( foo => sub { 1 } ) ->decode($json);
Subject: Re: [rt.cpan.org #97196] decode in list context, with filter_json_single_key_object, causes Perl to panic
Date: Mon, 14 Jul 2014 15:24:22 +0200
To: David Mertens via RT <bug-JSON-XS [...] rt.cpan.org>
From: Marc Lehmann <schmorp [...] schmorp.de>
Hi! Please send your bug report it to the official contact/author address for the module in question (or send it to rt.cpan.org@schmorp.de, that's fine as well). What follows is the rationale for this request, you don't have to read it if you don't care. Why is this necessary? rt.cpan.org has many deficiencies which makes it tedious and hard to use, increasing the workload on the people who provide all the perl modules you probably appreciate (and that is really to be avoided - module authors should be able to invest all their time into improving their modules and not fighting with rt.cpan.org's bugs). Still, for some people, rt.cpan.org is useful to have, and some people even like it and really want to use it. That is fine, too. Unfortunately, the designers of rt.cpan.org didn't make their "service" optional - you can neither opt-in nor opt-out of rt.cpan.org as a module author. Just like a spammer, rt.cpan.org forces its "service" (whether wanted or unwanted) on everybody. Just like a spammer, they don't care for the people they actively hurt. Just like a spammer, they don't don't care to fix these issues and make their "service" ethically acceptable. You cannot even configure it to redirect tickets to somewhere else. Unfortunately, ignoring rt.cpan.org is not an option either: for people reporting possible bugs there is no indication that their report will be ignored, and for module authors it means they miss potentially vital bug reports such as yours (and of course it's a great impression if rt.cpan.org has lots of bug reports that are unanswered, making a module look unmaintained when in fact the opposite might be true). I am sorry that this wasted a bit of your time, but please understand that I am just as much a victim as you are - the problem is the unethical stance of the rt.cpan.org providers who force their "service" on everybody. Please redirect your bug report as stated in the beginning of this mail, and please consider petitioning the rt.cpan.org providers to stop their unethical behaviour and allow opt-in, opt-out, or some redirect option. One last issue: many people mail me that this can be "fixed" by including the bugtracker element in my module meta file. This is not true: 1. This field only affects search.cpan.org and maybe similar services. (Many people confuse rt.cpan.org with search.cpan.org for some reason). 2. It doesn't even work (there are still links to rt.cpan.org displayed). 3. Even if search.cpan.org does no longer display the link, it doesn't actually affect rt.cpan.org (and tests have shown that people go to rt.cpan.org regardless) Even *iff* rt.cpan.org would start listening on the bugtracker field, however, it's still wrong. I have a lot of modules, and each time a service like rt.cpan.org comes out, I would have to make dummy releases for all my modules. This not only creates a lot of extra work for me (I take releases very seriously) but also users, who would wonder why there is a new release. Thanks a lot, Marc Lehmann <rt.cpan.org@schmorp.de> Last updated: 2012-04-22