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Request #54902 fseek inconsistencies with large (>2GB) files
Submitted: 2011-05-22 05:24 UTC Modified: 2011-05-22 05:50 UTC
Votes:3
Avg. Score:5.0 ± 0.0
Reproduced:3 of 3 (100.0%)
Same Version:0 (0.0%)
Same OS:1 (33.3%)
From: zingaburga at hotmail dot com Assigned:
Status: Open Package: Filesystem function related
PHP Version: 5.3.6 OS: Windows 7
Private report: No CVE-ID: None
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 [2011-05-22 05:24 UTC] zingaburga at hotmail dot com
Description:
------------
Firstly, I'm aware that fseek/ftell doesn't necessarily work correctly with >2GB files with 32-bit PHP due to integer range constraints, however, fseek operates rather inconsistently when passing 2GB, which would be nice if fixed (note that I've put this as a feature request, as it's a nice to have, and unsure if you'd classify this as a bug).

I'm using the 32-bit Windows build from here: http://windows.php.net/download/

See example script [ http://pastebin.com/Zb0vRgWX ] with comments for more info.
I haven't looked at PHP's source code, but from the behaviour of the script, I'm guessing that fseek does some checks, and because it's overflowing, it won't allow certain operations.  I'm not sure about the weird 8192 byte limit though.
As fread allows overflows, would it be possible to allow fseek to overflow too?

(PS first time I've submitted a "bug" - I hope I've done it correctly >_>)


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 [2011-05-22 05:50 UTC] zingaburga at hotmail dot com
If you're wondering, I'm using the following function to try to get around the fseek limitations.  It works, but it's really slow for large seeks.  If the 8KB limitation could be lifted, then this function could be serveral times faster.

http://pastebin.com/xWiQxgSB
 
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