Last modified: 2011-04-18 13:26:07 UTC

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Bug 28586 - YAML: strings that are the same as boolean literals
YAML: strings that are the same as boolean literals
Status: RESOLVED FIXED
Product: MediaWiki
Classification: Unclassified
API (Other open bugs)
unspecified
All All
: Normal normal (vote)
: ---
Assigned To: Roan Kattouw
:
Depends on:
Blocks:
  Show dependency treegraph
 
Reported: 2011-04-17 20:58 UTC by wgh
Modified: 2011-04-18 13:26 UTC (History)
6 users (show)

See Also:
Web browser: ---
Mobile Platform: ---
Assignee Huggle Beta Tester: ---


Attachments

Description wgh 2011-04-17 20:58:43 UTC
For example, http://en.wikipedia.org/w/api.php?action=query&titles=False&format=yamlfm

Try to parse it using pyyaml, and you'll get 
{'query': {'pages': [{'ns': 0, 'pageid': 228749, 'title': False}]}}

That's because False is unquoted, and, according to specs,
http://www.yaml.org/spec/1.2/spec.html#id2803629
it's boolean literal, when it should be a string instead.

It also doesn't escape other boolean literals found in older 1.1 specs
http://yaml.org/type/bool.html
Comment 1 Sam Reed (reedy) 2011-04-18 09:08:14 UTC
This is really a spyc bug, and probably should be dealt with upstream (ie http://code.google.com/p/spyc/)

It does list that it supports the 1.0 spec, no mention of 1.1 or 2. The code does also say ""It currently supports a very limited subsection of the YAML spec."

Although in core we are using a base of 0.23, I just borrowed the 0.4.5-svn from Translate, and it makes some minor changes to the output

I know we run a condensed version in core due to security constraints etc (See r42547), we have also made a few minor bugfixes to it

Might be worth getting Tim (or looking what he did) to look over the newer version, and look at forward porting it in some capacity...

Other options include using a different library (seemingly only Symfonys YAML library in PHP), else, the rest are all PHP extensions...
Comment 2 Niklas Laxström 2011-04-18 09:45:24 UTC
As far as I know the security concerns related to the behavior of the parse function have long since been fixed. My experience with different yaml implementations is that they are all broken in different, annoying ways.
Comment 3 Sam Reed (reedy) 2011-04-18 09:49:50 UTC
Please see also bug 28591
Comment 4 Sam Reed (reedy) 2011-04-18 10:03:07 UTC
Seemingly symfony does this correctly

require_once( "./sfYamlDumper.php" );

$yaml = new sfYamlDumper();

$php = 'a:1:{s:5:"query";a:1:{s:5:"pages";a:1:{i:228749;a:3:{s:6:"pageid";i:228$

var_dump( $yaml->dump( unserialize( $php ) ) );

reedy@ubuntu64-esxi:~$ php test.php
string(75) "{ query: { pages: { 228749: { pageid: 228749, ns: 0, title: 'False' } } } }"
Comment 5 Tim Starling 2011-04-18 11:04:06 UTC
The simple fix is to remove YAML support. It's a really terrible format for computer-to-computer communications, because the spec is difficult to implement and there are lots of silly little cases like this one that need special handling. I noticed this bug in spyc last time I reviewed it, but I didn't bother reporting it because there were so many other similar bugs. 

If we really have to have YAML support, I recommend writing our own formatter which uses a JSON-like subset of YAML and skips all the cute features which trip up parsers. It should stick to quoted strings and "flow collections", i.e. arrays delimited with brackets or braces. In fact if we move to YAML 1.2, we can just use FormatJson::encode(), since JSON is a subset of YAML 1.2.
Comment 6 Sam Reed (reedy) 2011-04-18 11:42:58 UTC
r86305
Comment 7 wgh 2011-04-18 13:21:48 UTC
Did you mean r86302 ?
Comment 8 Sam Reed (reedy) 2011-04-18 13:22:51 UTC
Yup. No need to reopen for that
Comment 9 wgh 2011-04-18 13:25:24 UTC
Reedy, I'm deeply sorry. Somehow selector below had "REOPENED" choice by default.
Comment 10 Sam Reed (reedy) 2011-04-18 13:26:07 UTC
Oh, weird

No harm done :)

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