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Use "\z" instead of "$" to anchor validating regular expressions

Authored by epriestley on Mar 13 2014, 2:18 PM.



Via HackerOne. In regular expressions, "$" matches "end of input, or before terminating newline". This means that the expression /^A$/ matches two strings: "A", and "A\n".

When we care about this, use \z instead, which matches "end of input" only.

This allowed registration of "username\n" and similar.

Test Plan
  • Grepped codebase for all calls to preg_match() / preg_match_all().
  • Fixed the ones where this seemed like it could have an impact.
  • Added and executed unit tests.

Diff Detail

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Event Timeline

epriestley retitled this revision from to Use "\z" instead of "$" to anchor validating regular expressions.
epriestley updated this object.
epriestley edited the test plan for this revision. (Show Details)
epriestley added a reviewer: btrahan.
btrahan edited edge metadata.
This revision is now accepted and ready to land.Mar 13 2014, 5:38 PM
epriestley updated this revision to Diff 20210.

Closed by commit rP969d0c3e8de2 (authored by @epriestley).