Bug 162765

Summary:

[patch] lseek(2) may return successful although no seek operation was actually performed

Product:

Documentation

Reporter:

Alexander Best <arundel>

Component:

Manual Pages

Assignee:

Gordon Bergling <gbe>

Status:

Closed FIXED

Severity:

Affects Only Me

CC:

doc, gbe

Priority:

Normal

Keywords:

patch

Version:

Latest

Hardware:

Any

OS:

Any

See Also:

https://reviews.freebsd.org/D25646

Attachments:

Description	Flags
file.diff	none
lseek.2.diff3	none

Description Alexander Best freebsd_committer

2011-11-22 20:40:01 UTC

in certain situations lseek() will return successful although no seek was performed. this can happen when operating on devices that don't support seeking (older tape drives) or when operating on changeable media devices (such as DVD or Blu-ray devices) without a medium inserted.

the attached patch fixes the lseek(2) man page by adding several entries to the BUGS section, along with updating the POSIX compliance to the latest specifications.

please note that the real issue doesn't seem fixable atm. lseek() was never designed to confirm a seek operation, but to merely request it.

the issue was extensively discussion in this thread:

http://lists.freebsd.org/pipermail/freebsd-hackers/2011-November/036842.html (alternative link: http://docs.freebsd.org/cgi/mid.cgi?20111115202450.GA73512)

cheers.
alex

Fix: Patch attached with submission follows:

Comment 1 Alexander Best freebsd_committer

2011-11-22 20:45:29 UTC

Responsible Changed
From-To: freebsd-bugs->freebsd-doc

Over to maintainer(s).

Comment 2 Alexander Best freebsd_committer

2011-11-22 21:52:56 UTC

here's a revised patch (comma removed after "confirm"), as suggested by warren
block. thanks. :)

cheers.
alex

Comment 3 Eitan Adler freebsd_committer

2012-03-04 04:31:47 UTC

Responsible Changed
From-To: freebsd-doc->eadler

I'll take it.

Comment 4 Eitan Adler freebsd_committer

2012-09-02 17:52:36 UTC

Responsible Changed
From-To: eadler->freebsd-doc

I won't be looking at this PR for a while and I need to clear some out 
of my queue

Comment 5 Eitan Adler freebsd_committer

2017-12-31 08:00:50 UTC

For bugs matching the following criteria:

Status: In Progress Changed: (is less than) 2014-06-01

Reset to default assignee and clear in-progress tags.

Mail being skipped

Comment 6 commit-hook freebsd_committer

2020-07-13 15:53:53 UTC

A commit references this bug:

Author: gbe
Date: Mon Jul 13 15:52:58 UTC 2020
New revision: 363156
URL: https://svnweb.freebsd.org/changeset/base/363156

Log:
  lseek(2): Document the seek behavior better and update the POSIX compliance

  In certain situations lseek(2) will return successful although if no seek
  was performed. This can happen when operating on devices that don't support
  seeking (older tape drives) or when operating on changeable media devices
  (such as DVD or Blu-ray devices) without a medium inserted.

  Document this within the man page and update the POSIX compliance while here.

  PR:		162765
  Submitted by:	arundel@
  Reported by:	arundel@
  Reviewed by:	bcr (mentor)
  Approved by:	bcr (mentor)
  MFC after:	1 week
  Differential Revision:	https://reviews.freebsd.org/D25646

Changes:
  head/lib/libc/sys/lseek.2

Comment 7 commit-hook freebsd_committer

2020-07-20 16:48:54 UTC

A commit references this bug:

Author: gbe
Date: Mon Jul 20 16:48:46 UTC 2020
New revision: 363370
URL: https://svnweb.freebsd.org/changeset/base/363370

Log:
  MFC r363156: lseek(2): Document the seek behavior better and update the POSIX compliance

  PR:		162765
  Submitted by:	arundel@
  Reported by:	arundel@
  Reviewed by:	bcr (mentor)
  Approved by:	bcr (mentor)
  MFC after:	1 week
  Differential Revision:	https://reviews.freebsd.org/D25646

Changes:
_U  stable/12/
  stable/12/lib/libc/sys/lseek.2