Req #69213 [Nab]: consecutivly issued fseek don't work properly when together over PHP_MAX_INT

Edit report at https://bugs.php.net/bug.php?id=69213&edit=1 ID: 69213 Updated by: ab@php.net Reported by: johnregphpbug at stefanie dot de Summary: consecutivly issued fseek don't work properly when together over PHP_MAX_INT Status: Not a bug Type: Feature/Change Request Package: Filesystem function related Operating System: Win 7 Home Premium SP1 PHP Version: Irrelevant Block user comment: N Private report: N New Comment: Typo: in 32 bit runtime, offset is "signed long". Previous Comments: ------------------------------------------------------------------------ [2015-03-11 07:58:08] ab@php.net Hi, thanks for following. Just looking at your php code - it's horrible :) Even if it seems to work, I'd rather call it bug itself. In the C run time, the 32 bit offset is an unsigned long. Tho manual is clearly states offset to expect an integer, not a double. Are you sure the data you seek() to is correct? Some unpleasant surprise is to expect, I'd highly discourage you from using this in production. About how to try snap - the easiest is just to get a zipball and try on console. If you wish to use it with some webserver - IIS and Apache will sure work. For Apache, if your XAMPP is a vc11-x64 build - maybe yes, otherwise get an appropriate build from apachelounge.com, but in both cases use php7_module directive in the httpd.conf Thanks. ------------------------------------------------------------------------ [2015-03-10 15:39:15] johnregphpbug at stefanie dot de I will try to install a 64 bit version. The manual is just not really clear at this. 1. The answers on I got on stackoverflow can't be entirly correct, and other people have come accross the restriction, too: 2. Reading over the PHP_MAX_INT treshhold is possible. But the workaround found at least in one user-comment on the manual of fseek and another old bugreport that shows a workaround for the workaround don't work as expected. I'm very sure there is a bug in that php-version. Of course it might really just be undocumented behaviour outside the defintions. (But then it should throw an error; which it doesn't.) (Can I just download a 64 bit build from the snapshots and put in my xampp installation instead of old php version?) If you find time, you might want to test the workaround I tried: <?php $testdata = ''; // C:\xampp\todrivei\germany-latest.osm 42.651.795.559 , 42651795559 file size from last year $filenameandpath = 'C:\xampp\todrivei\germany-latest.osm'; $seekto = 42651795559 - 2000;; // PHP_INT_MAX: 2147483647; function my_fseek($fp,$pos,$first=0) { if($first) fseek($fp,0,SEEK_SET); $pos=floatval($pos); // within limits, use normal fseek if($pos<=PHP_INT_MAX) { fseek($fp,$pos,SEEK_CUR); } // out of limits, use recursive fseek else { fseek($fp,PHP_INT_MAX,SEEK_CUR); $pos -= PHP_INT_MAX; $tempchar = fread($fp,1); // ."\n\r"; $pos -= 1; my_fseek($fp,$pos); } } $testdata = 'PHP_INT_MAX: '.PHP_INT_MAX."\n\r"; $testdata .= 'seekto: ' . $seekto."\n\r"; $handle = fopen($filenameandpath,'r'); my_fseek($handle, floatval($seekto),1); $testdata .= fread($handle,62000); fclose($handle); echo $testdata; ?> I can even try to seek over the file size (like I set seekto to 400GByte) and fread still returns data of the file. ------------------------------------------------------------------------ [2015-03-10 14:40:19] ab@php.net Thank you for taking the time to write to us, but this is not a bug. Please double-check the documentation available at http://www.php.net/manual/ and the instructions on how to report a bug at http://bugs.php.net/how-to-report.php Thanks for the report. PHP before 7 on Windows doesn't support large file operations. All the APIs used are 32 bit APIs. Same for integers. Und anyway much less in the 32 bit build, no matter what bitness the OS has. Instead, it'd be really appreciable you to take some latest snapshot http://windows.php.net/downloads/snaps/master/ to test the functionality you've described. It is the highest time for that now :) Though note that you'll need a 64 bit build for LFS. Thanks. ------------------------------------------------------------------------ [2015-03-10 13:57:01] johnregphpbug at stefanie dot de Description: ------------ (This is my first ever bug report on php.) (PHP 5.6.3 doesn't show up on the drop down list on the bug report form, so I choose "irrelevant".) I have Win 7, 64 bit. Latest XAMPP version, that has a 32 bit php 5.6.3. On testing http://php.net/manual/en/function.fseek.php#112647 for a very big file (bigger than PHP_MAX_INT 2147483647) I'm now pretty sure, that the consecutivly following fseeks are summed up before really executed on the filepointer. The result is that those fseeks only seek up to PHP_MAX_INT ahead from the current filepointer-position. I found a workaround for that, as putting a fread between two originally consecutivly following fseeks seems to stop the aggregation. (Though that workaround needs a second small workaround, as fread can't be called with 0 bytes read length, so I have to fread one byte and put this in the calculation for breaking up the big number seek to smaller seeks.) (Another bug: Once the filepointer is over PHP_MAX_INT then ftell will give back a negative number.) ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=69213&edit=1