From:             jketterl at chipxonio dot de
Operating system: linux (ubuntu)
PHP version:      5.2.11
PHP Bug Type:     Filesystem function related
Bug description:  ftell()/fseek() inconsistency when using stream filters

Description:
------------
exact php version: PHP 5.2.11-0.dotdeb.1 with Suhosin-Patch 0.9.7 (cli)
(built: Sep 20 2009 09:41:43)
this bug is also be filter-/stream-related. i just believe it might be
easier to fix on the filesystem side, that's why i chose that category.

when using a php stream filter to convert input from utf-16 into iso8859
(or most probably from any 2byte-encoded charset into any
single-byte-encode charset) the ftell() and fseek() functions start to
behave inconsistently.

more precisely: fseek() jumps to exact offsets ignoring the
2byte-encoding, whereas ftell() seems to return the number of bytes read
*after* the filter has been applied. thus it is not possible to fseek()
back to a certain offset that has been stored with ftell() before.

the content of the testfile used in the code examples is as follows:
Line 01
Line 02
Line 03
Line 04

Reproduce code:
---------------
$file = 'test.csv';

$fp = fopen($file, 'r');
stream_filter_append($fp, 'convert.iconv.utf16/iso8859-15');
$line = fgets($fp);
var_dump($line);
$line = fgets($fp);
var_dump($line);
fclose($fp);

$fp = fopen($file, 'r');
stream_filter_append($fp, 'convert.iconv.utf16/iso8859-15');
$line = fgets($fp);
var_dump($line);
fseek($fp, ftell($fp)); // this shouldn't move anything - but it does...
$line = fgets($fp);
var_dump($line);
fclose($fp);

Expected result:
----------------
string(8) "Line 01
"
string(8) "Line 02
"
string(8) "Line 01
"
string(8) "Line 02
"

Actual result:
--------------
string(8) "Line 01
"
string(8) "Line 02
"
string(8) "Line 01
"
string(4) " 01
"

-- 
Edit bug report at http://bugs.php.net/?id=49874&edit=1
-- 
Try a snapshot (PHP 5.2):            
http://bugs.php.net/fix.php?id=49874&r=trysnapshot52
Try a snapshot (PHP 5.3):            
http://bugs.php.net/fix.php?id=49874&r=trysnapshot53
Try a snapshot (PHP 6.0):            
http://bugs.php.net/fix.php?id=49874&r=trysnapshot60
Fixed in SVN:                        
http://bugs.php.net/fix.php?id=49874&r=fixed
Fixed in SVN and need be documented: 
http://bugs.php.net/fix.php?id=49874&r=needdocs
Fixed in release:                    
http://bugs.php.net/fix.php?id=49874&r=alreadyfixed
Need backtrace:                      
http://bugs.php.net/fix.php?id=49874&r=needtrace
Need Reproduce Script:               
http://bugs.php.net/fix.php?id=49874&r=needscript
Try newer version:                   
http://bugs.php.net/fix.php?id=49874&r=oldversion
Not developer issue:                 
http://bugs.php.net/fix.php?id=49874&r=support
Expected behavior:                   
http://bugs.php.net/fix.php?id=49874&r=notwrong
Not enough info:                     
http://bugs.php.net/fix.php?id=49874&r=notenoughinfo
Submitted twice:                     
http://bugs.php.net/fix.php?id=49874&r=submittedtwice
register_globals:                    
http://bugs.php.net/fix.php?id=49874&r=globals
PHP 4 support discontinued:          http://bugs.php.net/fix.php?id=49874&r=php4
Daylight Savings:                    http://bugs.php.net/fix.php?id=49874&r=dst
IIS Stability:                       
http://bugs.php.net/fix.php?id=49874&r=isapi
Install GNU Sed:                     
http://bugs.php.net/fix.php?id=49874&r=gnused
Floating point limitations:          
http://bugs.php.net/fix.php?id=49874&r=float
No Zend Extensions:                  
http://bugs.php.net/fix.php?id=49874&r=nozend
MySQL Configuration Error:           
http://bugs.php.net/fix.php?id=49874&r=mysqlcfg

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