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Bug #52731 mb_strpos reports needle position incorrectly
Submitted: 2010-08-29 17:05 UTC Modified: 2010-08-29 17:21 UTC
Votes:3
Avg. Score:3.0 ± 0.8
Reproduced:2 of 2 (100.0%)
Same Version:0 (0.0%)
Same OS:0 (0.0%)
From: tokul at users dot sourceforge dot net Assigned: moriyoshi
Status: Assigned Package: mbstring related
PHP Version: 5.3SVN-2010-08-29 (snap) OS:
Private report: No CVE-ID:
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 [2010-08-29 17:05 UTC] tokul at users dot sourceforge dot net
Description:
------------
If code sets incorrect character set (utf-8 instead of big5 in test case), mb_strpos() can incorrectly report needle position in some cases. It looks like $offset is calculated one way and results are calculated in some other way. See test code. mb_substr($str,$pos1,1,'utf-8') can be used to see character that is in reported needle position.

I understand that $str is not in UTF-8 charset, but position reported by mb_strpos() violates very basic strpos function behavior. Search is started after $offset position and result position is counted from string start. Result should not be lower than $offset or it should be boolean false.

php5.3-201008291230
compiled with /configure --prefix=/somepath --enable-cli --disable-all --enable-mbstring

Also tested PHP 5.2.0 (debian etch), 5.3.2-2 (debian squeeze) and 5.2.13 (standard PHP package). 5.2.13 and 5.3.2 results are the same. 5.2.0 results are a little bit different, but I was able to reproduce position calculation problem with more complex code.


Test script:
---------------
$str = "\xb7\x51 &\xb4\xa6\xb6\x7d";
$pos1 = mb_strpos($str,'&',0,'utf-8');
var_dump($pos1);
$pos2 = mb_strpos($str,'&',$pos1 + 1,'utf-8');
var_dump($pos2);

Expected result:
----------------
second var_dump() result should be higher than first one or should be boolean false.

result should not be lower than offset.


Actual result:
--------------
int(2)
int(2)

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 [2010-08-29 17:21 UTC] felipe@php.net
-Status: Open +Status: Assigned -Assigned To: +Assigned To: moriyoshi
 
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