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In the answer realloc() for NUMA Systems using HWLOC, the parser breaks my URL link.

The URL was with __word__:


After parsing, it becomes (<a href is broken; no clickable link):


Short test:

http://example.com/_test_ -> test">http://example.com/test

Or if I put in a naked URL with _test_ just here: test">http://example.com/test

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So are you intentionally not using the markdown syntax for links? –  Cody Gray Aug 4 '11 at 9:29
markdown is harder, than just putting an url in the text –  osgx Aug 4 '11 at 9:31
And C++ is harder than Java. But at least it doesn't break when you use characters like underscores within the link that have a specific meaning in markdown syntax. –  Cody Gray Aug 4 '11 at 9:33
But naked urls have specific parsing in markdown; and italic will not work in urls, so, I think, parser should not to parse italic in naked urls. –  osgx Aug 4 '11 at 9:35
@Cody If it was just the link not being linkified, I'd agree with you and tell osgx to tough it up. But "> appearing out of the blue is a different matter; it makes me worry that there might a way to inject arbitrary HTML into the permitted markup (i.e. a security issue). –  Gilles Aug 4 '11 at 9:48
@Cody The HTML for the link-not-parsed-as-link is hwlocality_membinding.php#gade5e2c28ea8475a479bf2b1df36c6ccd">http://www.open-m‌​pi.de/projects/hwloc/doc/v1.2/group_<em>hwlocality</em>_membinding.php#gade5e2c28‌​ea8475a479bf2b1df36c6ccd –  Gilles Aug 4 '11 at 9:53
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2 Answers 2

up vote 10 down vote accepted

Too much of an edge condition.

Remember that Markdown does not support "naked" URLs officially, so you have your pick of non-naked URLs to use here:

<a href="http://example.com/foo__bar__baz#hash">link</a>  


see http://stackoverflow.com/editing-help

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YouTube is starting to put underscores in URLs, so I think we are only going to see an increase in these situations. –  CyberSkull Jan 3 '12 at 20:13
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This will work correctly from the next build on: client changeset, server changeset. The underscores will still cause some potentially unwanted styling of the displayed text1, but the link itself works.

1 Not anymore in most cases (including the one here), thanks to point 2. in this change.

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Aaand this broke Github. Probably Github's fault, but _ is not on the reserved characters list. Can the generated href attribute not be normalized? E.g. decode percent-encoded characters for non-reserved characters such as _? –  Martijn Pieters Apr 14 at 14:02
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