Debian Bug report logs - #134758
dpkg-query: Make -S handle unowned symlinks resolving to owned pathnames

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Message #5 received at submit@bugs.debian.org (full text, mbox, reply):

From: Richard Kettlewell <rjk@greenend.org.uk>

To: submit@bugs.debian.org

Subject: 'dpkg -S' and symlinks

Date: Tue, 19 Feb 2002 22:23:20 +0000 (GMT)

Package: dpkg
Version: 1.9.19
Severity: wishlist

dpkg -S only compares filenames lexically: so symlinks can lead to
annoying false negatives, as in the following example:

    lyonesse$ type xterm
    xterm is /usr/bin/X11/xterm
    lyonesse$ dpkg -S /usr/bin/X11/xterm
    dpkg: /usr/bin/X11/xterm not found.
    lyonesse$ realpath /usr/bin/X11/xterm
    /usr/X11R6/bin/xterm
    lyonesse$ dpkg -S /usr/X11R6/bin/xterm
    xterm: /usr/X11R6/bin/xterm

However, realpathing the search term doesn't solve the problem:
consider the case where the operator has replaced some standard
directory such as /usr/sbin with a symlink (e.g. to split up /usr over
several partitions due to space constraints, or to identify /usr/sbin
with /usr/bin).  Then realpathing the search term would result in
*nothing* in /usr/sbin matching, which is even worse than the current
behaviour.

realpathing filenames as they are written to PACKAGE.list at
install time would solve this, but would break the ability of the
operator to move bits of filesystem around leaving links behind to
keep the standard names working without telling dpkg about it, which
is surely an unreasonable imposition.

realpathing them as they are read from PACKAGE.list in the process of
implementing -S would work better, but dpkg -S is far too slow
already.  Even with caching, this would amount to 100,000 or more
lstat() calls on a reasonably package-heavy system.

Anyone got any better ideas?

A solution to the exact example quoted above would be to insist that
PATH entries be the same as the path found in debfiles, (so
e.g. /etc/profile would have /usr/X11R6/bin where it now has
/usr/bin/X11).  However this is not a general solution.

ttfn/rjk

Message #10 received at 134758@bugs.debian.org (full text, mbox, reply):

From: Rolf Leggewie <debian-bugs@rolf.leggewie.biz>

To: Debian Bug Tracking System <134758@bugs.debian.org>

Subject: /usr/bin/dpkg: #134758: 'dpkg -S' and symlinks

Date: Fri, 29 Apr 2005 12:54:53 +0200

Package: dpkg
Version: 1.10.27
Followup-For: Bug #134758

Hi,

I do not know much about realpath, I have never used it previously.  
I assume that using which instead of realpath would not solve the 
speed problem, would it?

Regards

Rolf

-- System Information:
Debian Release: 3.1
  APT prefers testing
  APT policy: (500, 'testing')
Architecture: i386 (i686)
Kernel: Linux 2.4.26.desktop041204
Locale: LANG=de_DE@euro, LC_CTYPE=de_DE@euro (charmap=ISO-8859-15)

Versions of packages dpkg depends on:
ii  dselect                     1.10.27      a user tool to manage Debian packa
ii  libc6                       2.3.2.ds1-20 GNU C Library: Shared libraries an

-- no debconf information

Message #25 received at 134758@bugs.debian.org (full text, mbox, reply):

From: Raphael Hertzog <hertzog@debian.org>

To: 134758@bugs.debian.org

Cc: Helmut Grohne <helmut@subdivi.de>

Subject: dpkg -S and symlinks

Date: Mon, 12 Dec 2016 13:53:25 +0100

Hi,

Now that some users enabled "usrmerge" it has become more important
that "dpkg -S" deals sensibly with symlinks. I have thus raised the
severity of this bug to important (following the discussion
with Helmut in #843073).

Cheers,
-- 
Raphaël Hertzog ◈ Debian Developer

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