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Bug #80285 strspn $length argument may no longer exceed the string bounds
Submitted: 2020-10-26 16:11 UTC Modified: 2020-10-27 10:45 UTC
From: paul dot crovella at gmail dot com Assigned: nikic (profile)
Status: Closed Package: Unknown/Other Function
PHP Version: 8.0.0RC2 OS:
Private report: No CVE-ID: None
 [2020-10-26 16:11 UTC] paul dot crovella at gmail dot com
Description:
------------
This commit[1] changed not just out-of-bounds offsets of strspn to throw ValueError, but lengths that exceed the string bounds as well.

Given that a positive $length argument functions as a max-length for the match attempt, the prior behavior of accepting a length beyond the string bounds makes sense and reverting to it would realign with substr whose length parameter serves a similar purpose.

Is something gained by breaking existing code and requiring:

strspn($subject, $mask, $start, min($length, strlen($subject) - $start))

where:

strspn($subject, $mask, $start, $length)

seemed to work fine as intended prior?

[1] https://github.com/php/php-src/commit/5d9ab53a5d53f11a18ae11ed31b17ff87c8d52a7

Test script:
---------------
<?php

var_dump(
    strspn("foo", "asdf", 0, 4),
    strspn("fffff", "asdf", 0, 4)
);

Expected result:
----------------
int(1)
int(4)

Actual result:
--------------
Fatal error: Uncaught ValueError: strspn(): Argument #4 ($length) must be contained in argument #1 ($str) in /in/J05AD:4

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 [2020-10-27 10:45 UTC] nikic@php.net
-Status: Open +Status: Closed -Assigned To: +Assigned To: nikic
 [2020-10-27 10:45 UTC] nikic@php.net
This is the second independent report of this issue, so I've decided to undo the change in https://github.com/php/php-src/commit/d776d25a8e6763bfe8cc283a4693d7d417d50ddd. The behavior should be strictly identical to doing a substr in advance now.
 
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