Bug#578852: prohibit usage of Breaks for file conflicts
Guillem Jover guil...@debian.org writes: Hi! On Fri, 2010-04-23 at 10:51:56 +0200, Goswin von Brederlow wrote: Package: debian-policy Version: 3.8.4.0 Severity: normal to test the actual behaviour of dpkg for this situation I created the following 5 packages: [...] In conclusion: == On downgrades using Replaces with Breaks triggers a long standing dpkg bug or can cause files to disapear. So it might indeed be wise for policy to prohibit the use of Breaks for file conflicts. Even if the dpkg bug is fixed it still risks loosing files when reverting a partial upgrade and downgrading to the old versions. There's the problem with downgrades and versioned Replaces, and there's the other problem with disappearing the wrong replaced/replacing package on reverse installation order and losing track of package ownership of files, fixed also in 1.15.7 with: http://git.debian.org/?p=dpkg/dpkg.git;a=commit;h=0958a9f9 Neither of these are triggered by Breaks nor Conflicts. These test-cases can be found in: http://git.debian.org/?p=dpkg/pkg-tests.git;a=tree regards, guillem % dpkg --version Debian `dpkg' package management program version 1.15.7.1 (amd64). This is free software; see the GNU General Public License version 2 or later for copying conditions. There is NO warranty. % dpkg -S /usr/share/doc/foo/foo.control foo: /usr/share/doc/foo/foo.control % sudo dpkg --auto-deconfigure --unpack bar_2_all.deb dpkg: considering deconfiguration of foo, which would be broken by installation of bar ... dpkg: yes, will deconfigure foo (broken by bar). (Reading database ... 176362 files and directories currently installed.) Preparing to replace bar 1 (using bar_2_all.deb) ... De-configuring foo ... Unpacking replacement bar ... Replacing files in old package foo ... % dpkg -S /usr/share/doc/foo/foo.control bar: /usr/share/doc/foo/foo.control % sudo dpkg -i bar_1_all.deb (Reading database ... 176362 files and directories currently installed.) Preparing to replace bar 2 (using bar_1_all.deb) ... Unpacking replacement bar ... Setting up bar (1) ... % sudo dpkg --configure -a Setting up foo (1) ... % dpkg -S /usr/share/doc/foo/foo.control dpkg: /usr/share/doc/foo/foo.control not found. With Replaces files disapear on downgrade unless the replaced package is also reinstalled (after the downgrade). As long as dpkg does not keep a backup of replaced files and restores them on downgrades that can not be fixed. This is not really a bug as I think that is just how Replaces is specified. Replaces just isn't a reversible (downgradable) feature. MfG Goswin -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org
Bug#578852: prohibit usage of Breaks for file conflicts
Hi! On Fri, 2010-04-23 at 10:51:56 +0200, Goswin von Brederlow wrote: Package: debian-policy Version: 3.8.4.0 Severity: normal to test the actual behaviour of dpkg for this situation I created the following 5 packages: [...] Test 1 == I start with version 1 installed and update to version 2/2b/2c without problems. Then on downgrade: m...@frosties:~/t% sudo dpkg -i foo_1_all.deb dpkg: warning: downgrading foo from 2 to 1. (Reading database ... 176361 files and directories currently installed.) Preparing to replace foo 2 (using foo_1_all.deb) ... Unpacking replacement foo ... dpkg: error processing foo_1_all.deb (--install): trying to overwrite '/usr/share/doc/foo/foo.control', which is also in package bar 0:2b Errors were encountered while processing: foo_1_all.deb SEE http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=20471 No, this is #568566, and fixed in 1.15.7 with: http://git.debian.org/?p=dpkg/dpkg.git;a=commit;h=418e1fc0 I found out this bug some weeks ago by code staring, and only matched it against an actual bug report recently, initially thought it would fix some failing test-cases about disappearing packages in the dpkg's pkg-tests.git functional test suite, but it ended up being something different. This was “introduced” in dpkg 1.13.2 (2005-03-18) when fixing #164595 by forgetting to handle the versioned downgrade case, for something that had not been supported before. In conclusion: == On downgrades using Replaces with Breaks triggers a long standing dpkg bug or can cause files to disapear. So it might indeed be wise for policy to prohibit the use of Breaks for file conflicts. Even if the dpkg bug is fixed it still risks loosing files when reverting a partial upgrade and downgrading to the old versions. There's the problem with downgrades and versioned Replaces, and there's the other problem with disappearing the wrong replaced/replacing package on reverse installation order and losing track of package ownership of files, fixed also in 1.15.7 with: http://git.debian.org/?p=dpkg/dpkg.git;a=commit;h=0958a9f9 Neither of these are triggered by Breaks nor Conflicts. These test-cases can be found in: http://git.debian.org/?p=dpkg/pkg-tests.git;a=tree regards, guillem -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org
Bug#578852: prohibit usage of Breaks for file conflicts
Package: debian-policy Version: 3.8.4.0 Severity: normal Hi, to test the actual behaviour of dpkg for this situation I created the following 5 packages: Package: foo Version: 1 Architecture: all -rw-r--r-- root/root 227 2010-04-23 10:39 ./usr/share/doc/foo/foo-1.control Package: bar Version: 1 Architecture: all empty Package: foo Version: 2 Architecture: all empty Package: bar Version: 2b Architecture: all Breaks: foo (= 1) Replaces: foo (= 1) -rw-r--r-- mrvn/mrvn 180 2010-04-23 09:41 ./usr/share/doc/foo/foo.control Package: bar Version: 2c Architecture: all Conflicts: foo (= 1) Replaces: foo (= 1) -rw-r--r-- mrvn/mrvn 180 2010-04-23 09:41 ./usr/share/doc/foo/foo.control The foo.control file moves from foo to bar between version 1 and 2b/2c. Test 1 == I start with version 1 installed and update to version 2/2b/2c without problems. Then on downgrade: m...@frosties:~/t% dpkg -s bar Package: bar Status: install ok installed Priority: optional Section: misc Installed-Size: 44 Maintainer: Goswin von Brederlow goswin-...@web.de Architecture: all Version: 2b Replaces: foo (= 1) Breaks: foo (= 1) Description: dummy foo dummy package to test m...@frosties:~/t% sudo dpkg -i foo_1_all.deb dpkg: warning: downgrading foo from 2 to 1. (Reading database ... 176361 files and directories currently installed.) Preparing to replace foo 2 (using foo_1_all.deb) ... Unpacking replacement foo ... dpkg: error processing foo_1_all.deb (--install): trying to overwrite '/usr/share/doc/foo/foo.control', which is also in package bar 0:2b Errors were encountered while processing: foo_1_all.deb SEE http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=20471 m...@frosties:~/t% dpkg -s bar Package: bar Status: install ok installed Priority: optional Section: misc Installed-Size: 44 Maintainer: Goswin von Brederlow goswin-...@web.de Architecture: all Version: 2c Replaces: foo (= 1) Conflicts: foo (= 1) Description: dummy foo dummy package to test m...@frosties:~/t% sudo dpkg -i foo_1_all.deb dpkg: warning: downgrading foo from 2 to 1. dpkg: regarding foo_1_all.deb containing foo: bar conflicts with foo (= 1) foo (version 1) is to be installed. dpkg: error processing foo_1_all.deb (--install): conflicting packages - not installing foo Errors were encountered while processing: foo_1_all.deb This is as expected. Test 2 == Again I start with version 1 installed. m...@frosties:~/t% sudo dpkg --auto-deconfigure --unpack bar_2b_all.deb dpkg: considering deconfiguration of foo, which would be broken by installation of bar ... dpkg: yes, will deconfigure foo (broken by bar). (Reading database ... 176361 files and directories currently installed.) Preparing to replace bar 1 (using bar_2b_all.deb) ... De-configuring foo ... Unpacking replacement bar ... Replacing files in old package foo ... m...@frosties:~/t% sudo dpkg -i bar_1_all.deb (Reading database ... 176361 files and directories currently installed.) Preparing to replace bar 2 (using bar_1_all.deb) ... Unpacking replacement bar ... Setting up bar (1) ... m...@frosties:~/t% sudo dpkg --configure -a Setting up foo (1) ... m...@frosties:~/t% ls -lh /usr/share/doc/foo/foo.control ls: cannot access /usr/share/doc/foo/foo.control: No such file or directory This I believe is actualy according to specs. It just isn't a nice outcome. Test 3 == Again I start with version 1 installed. m...@frosties:~/t% sudo dpkg --unpack bar_2c_all.deb dpkg: considering removing foo in favour of bar ... dpkg: yes, will remove foo in favour of bar. (Reading database ... 176361 files and directories currently installed.) Preparing to replace bar 1 (using bar_2c_all.deb) ... Unpacking replacement bar ... m...@frosties:~/t% sudo dpkg -i bar_1_all.deb (Reading database ... 176358 files and directories currently installed.) Preparing to replace bar 2 (using bar_1_all.deb) ... Unpacking replacement bar ... Setting up bar (1) ... m...@frosties:~/t% sudo dpkg -i foo_1_all.deb Selecting previously deselected package foo. (Reading database ... 176356 files and directories currently installed.) Unpacking foo (from foo_1_all.deb) ... Setting up foo (1) ... m...@frosties:~/t% ls -lh /usr/share/doc/foo/foo.control -rw-r--r-- 1 root root 227 Apr 23 10:39 /usr/share/doc/foo/foo.control Since foo gets removed completly it must be reinstalled to get foo back. And then it gets its file back. In conclusion: == On downgrades using Replaces with Breaks triggers a long standing dpkg bug or can cause files to disapear. So it might indeed be wise for policy to prohibit the use of Breaks for file conflicts. Even if the dpkg bug is fixed it still risks loosing files when reverting a partial upgrade and downgrading to the old versions. MfG Goswin -- System Information: Debian Release: squeeze/sid APT prefers unstable APT policy: (500, 'unstable') Architecture: amd64 (x86_64) Kernel: Linux 2.6.31.6-xen-2010.02.18 (SMP w/4
