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

From: Anand Mohanadoss
Subject: bug#20079: Fwd: Memory leak from seek/ftell with files larger than 2GB
Date: Wed, 11 Mar 2015 18:08:18 +0530


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...


---------- Forwarded message ----------
From: Anand Mohanadoss <address@hidden>
Date: Wed, Feb 25, 2015 at 9:35 PM
Subject: Memory leak from seek/ftell with files larger than 2GB
To: address@hidden


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?

(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)

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