bug#20079: Fwd: Memory leak from seek/ftell with files larger than 2GB

[Andy Wingo <wingo@pobox.com>]

Hi,

Thank you very much for this one!  Turns out we had an incredibly
embarrassing bug in which we forgot to attach finalizers for bignums
created by scm_from_{uint64,int64} on 32-bit platforms.  Fixed in master
and stable-2.0.

Cheers,

Andy

On Wed 11 Mar 2015 13:38, Anand Mohanadoss <anand108@gmail.com> writes:

> Hi,
>
> I had sent the following to the user forum and did not receive any
> comments. I am reposting it in the bug forum with the hope that one of
> the experts may be able to comment...
>
> Thanks,
> Anand
>
> ---------- Forwarded message ----------
> From: Anand Mohanadoss <anand108@gmail.com>
> Date: Wed, Feb 25, 2015 at 9:35 PM
> Subject: Memory leak from seek/ftell with files larger than 2GB
> To: guile-user@gnu.org
>
> Hi,
>
> We are seeing an issue with seek and ftell leaking memory with files
> larger than 2GB.
>
> We are using 2.0.11 guile built as a 32-bit application with large
> file support enabled (guile was built using gcc 4.4.0 for Linux with
> flags _FILE_OFFSET_BITS=64, _LARGEFILE_SOURCE and _
> LARGEFILE64_SOURCE). The issue also appears to happen with guile 2.2.
>
> The memory leaks start only after the offset exceeds maximum positive
> value for a 32-bit signed integer. ftell and seek do work as expected
> (given how lseek should work with large file support).
>
> Appended is a program that illustrates the problem. The first seek
> simply skips the part of the file where you won't see a memory leak.
> If you comment out ftell and the second seek lines and un-comment the
> lines that follow them, there is no memory leak. 
>
> Is this a bug in guile or should we be doing things differently? If
> this is a known issue, is there a recommended work around?
>
> Thanks,
> Anand
>
> (define MAX_SIGNED_INT 2147483647)
> (define BYTES_TO_READ 10)
>
> (define file "/tmp/test.pcap") ;sample file greater than 2.5GB
>
> (define (traverse file)
> (let* ((port (open-input-file file #:binary #t))
> (file-sz (stat:size (stat port)))
> (ua (make-bytevector BYTES_TO_READ 0))
> (cur-offset 0))
> (seek port (- MAX_UNSIGNED_INT 1000) SEEK_CUR)
> (while (< (ftell port) (- file-sz BYTES_TO_READ))
> ;(while (< cur-offset (- file-sz BYTES_TO_READ))
> (seek port BYTES_TO_READ SEEK_CUR)
> ;(get-bytevector-n! port ua 0 BYTES_TO_READ)
> (set! cur-offset (+ BYTES_TO_READ cur-offset)))
> (close-port port))) 
>
> (traverse file)