I can confirm this using zsh 4.3.17 in Ubuntu Precise:
mkdir /tmp/foo
mkdir /tmp/bar
sudo mount -o bind /tmp/foo /tmp/bar
cd /tmp/bar
unset PWD
zsh
pwd
=> /tmp/foo
** Changed in: zsh (Ubuntu)
Importance: Undecided => Low
** Changed in: zsh (Ubuntu)
Status: Confirmed => Triaged
** Description changed:
When starting zsh in a subdirectory mounted using a bind mount, without
the PWD variable being set, zsh becomes confused, and is unable to
determine its working directory. Moreover, during the attempt to find
out its working directory, it moves to a different place.
In order to test 32-bit software on my 64-bit system, I've set up a
chroot under /home/chroot/ubuntu-8.04-i386 under which I've mounted the
real home using mount -o bind:
mount -o bind /home /home/chroot/ubuntu-8.04-i386/home
When I cd into any subdirectory of a subdirectory of
/home/chroot/ubuntu-8.04-i386/home , unset PWD, and start zsh, zsh
becomes confused as soon as its pwd algorithm crosses the bind
mountpoint.
Other shells, such as bash, handle this situation just fine.
In the "wild" this situation happens when using schroot to execute a zsh
in my 32 bit chroot environment (because by default, schroot unsets PWD
before calling the shell). However, as shown above, the reason for the
behavior is unrelated to the chroot system call, but can be reproduced
with bind mounts alone.
I suspect that the reason for this bug is some bogus "optimization" on
how zsh detects mountpoints. Rather than assuming a mountpoint as soon
as none of the inode numbers of the subdirectories of the parent match
that of the current directory, zsh relies solely on a comparison of the
device number of parent and current. However, in case of a bind mount
both may match, even though a mountpoint is present.
-----------------------------
> lsb_release -rd
Description: Ubuntu 8.04.1
Release: 8.04
> apt-cache policy zsh
zsh:
- Installé : 4.3.4-24ubuntu1
- Candidat : 4.3.4-24ubuntu1
- Table de version :
- *** 4.3.4-24ubuntu1 0
- 500 http://be.archive.ubuntu.com hardy/main Packages
- 100 /var/lib/dpkg/status
+ Installé : 4.3.4-24ubuntu1
+ Candidat : 4.3.4-24ubuntu1
+ Table de version :
+ *** 4.3.4-24ubuntu1 0
+ 500 http://be.archive.ubuntu.com hardy/main Packages
+ 100 /var/lib/dpkg/status
How to reproduce:
----------------------------
mkdir -p /home/alain/tmp
mkdir -p /home /home/chroot/ubuntu-8.04-i386/home
mount -o bind /home /home/chroot/ubuntu-8.04-i386/home
cd /home /home/chroot/ubuntu-8.04-i386/home/alain/tmp
unset PWD
zsh
What I expect to happen:
---------------------------------------
zsh's current dir should be
/home/chroot/ubuntu-8.0.4-i386/home/alain/tmp , and pwd should show same
What happened instead:
-------------------------------------
zsh's current dir is /home/chroot/ubuntu-8.0.4-i386/home , and pwd shows
"."
+
+
+ TEST CASE:
+ mkdir /tmp/foo
+ mkdir /tmp/bar
+ sudo mount -o bind /tmp/foo /tmp/bar
+ cd /tmp/bar
+ unset PWD
+ zsh
+ pwd
+
+ => /tmp/foo
+ But should be /tmp/bar
** Summary changed:
- zsh's pwd gets confused by bind mounts
+ zsh's pwd gets confused with $PWD unset in mounted dir (bind/nfs)
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https://bugs.launchpad.net/bugs/312156
Title:
zsh's pwd gets confused with $PWD unset in mounted dir (bind/nfs)
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