Package: dpkg Version: 1.17.23 Severity: grave Hi,
I've reproduced this behaviour on Debian/jessie with dpkg 1.17.23, but the original issue appeared on Debian/wheezy with dpkg 1.16.15 (and old-stable as well as unstable might be very probably affected as well). What happened (with anonymized data): a Debian package shipped a file called /srv/repository/release/myscript.sh. Its underlying directory /srv/repository on the file system of the host is a *symlink* pointing to a different directory (because the data is served via NFS from a different system). When the package gets removed/purged (or in a package update the file /srv/repository/release/myscript.sh is no longer provided) the symlink /srv/repository gets removed by dpkg, even though there are other files inside the directory. The original data behind the symlink isn't removed/touched/modified, so no data loss from that perspective. *But* by removing the symlink - even though there's still data inside the directory behind the symlink - this can cause serious service disruptions (and also conflicting data sets), as it happened at a customer of mine a few hours ago. [BTW, for the investigation it would have been nice if there would be some information about such removals in dpkg's logs, it was far from trivial to identify this behaviour.] Demonstration follows: ,---- [ simple example for reproducing ] | root@demo ~ # ls -la /symlinktarget | total 0 | drwxr-xr-x 3 root root 60 Feb 23 22:56 ./ | drwxr-xr-x 34 root root 300 Feb 23 22:56 ../ | drwxr-xr-x 2 root root 60 Feb 23 22:58 repository/ | root@demo ~ # ls -la /symlinktarget/repository | total 4 | drwxr-xr-x 2 root root 60 Feb 23 22:58 ./ | drwxr-xr-x 3 root root 60 Feb 23 22:56 ../ | -rw-r--r-- 1 root root 4 Feb 23 22:57 foo | root@demo ~ # | root@demo ~ # ln -s /symlinktarget/repository /srv/repository | root@demo ~ # ls -la /srv/repository | lrwxrwxrwx 1 root root 25 Feb 23 22:59 /srv/repository -> /symlinktarget/repository/ | root@demo ~ # | root@demo ~ # dpkg -i foobar-demo_0.0.2_all.deb | Selecting previously unselected package foobar-demo. | (Reading database ... 123190 files and directories currently installed.) | Preparing to unpack foobar-demo_0.0.2_all.deb ... | Unpacking foobar-demo (0.0.2) ... | Setting up foobar-demo (0.0.2) ... | root@demo ~ # ls -la /srv/repository/release/myscript.sh | total 32 | drwxr-xr-x 2 root root 100 Feb 23 22:59 ./ | drwxr-xr-x 3 root root 80 Feb 23 22:59 ../ | -rwxr-xr-x 1 root root 1855 Feb 23 22:49 myscript.sh | root@demo ~ # dpkg -S /srv/repository/release/myscript.sh | foobar-demo: /srv/repository/release/myscript.sh | root@demo ~ # echo foo > /srv/repository/foo | root@demo ~ # ls -la /srv/repository/ | total 4 | drwxr-xr-x 3 root root 80 Feb 23 22:59 ./ | drwxr-xr-x 3 root root 60 Feb 23 22:56 ../ | -rw-r--r-- 1 root root 4 Feb 23 22:59 foo | drwxr-xr-x 2 root root 100 Feb 23 22:59 release/ | root@demo ~ # ls -la /srv/repository/foo | -rw-r--r-- 1 root root 4 Feb 23 22:59 /srv/repository/foo | root@demo ~ # apt-get --purge remove foobar-demo | Reading package lists... Done | Building dependency tree | Reading state information... Done | The following packages will be REMOVED: | foobar-demo* | 0 upgraded, 0 newly installed, 1 to remove and 3 not upgraded. | After this operation, 152 kB disk space will be freed. | Do you want to continue? [Y/n] y | (Reading database ... 123223 files and directories currently installed.) | Removing foobar-demo (0.0.2) ... | root@demo ~ # ls -la /srv/repository/foo | ls: cannot access /srv/repository/foo: No such file or directory | root@demo ~ # ls -la /srv/repository | ls: cannot access /srv/repository: No such file or directory | root@demo ~ # ls -la /symlinktarget/repository | total 4 | drwxr-xr-x 2 root root 60 Feb 23 23:00 ./ | drwxr-xr-x 3 root root 60 Feb 23 22:56 ../ | -rw-r--r-- 1 root root 4 Feb 23 22:59 foo | root@demo ~ # `---- regards, -mika- -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: https://lists.debian.org/2015-02-24t00-15...@devnull.michael-prokop.at
