Rpm filetriggers

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[edit] Introduction

Filetriggers allow to run some scripts when some file has been added or removed.

The typical use cases are:

  • updating /etc/ld.so.cache when some libraries have been added/removed in /usr/lib or /lib
  • running update-menus to update menus of non-XDG compliant desktops when some *.desktop have been added/removed in /usr/share/applications

[edit] Usage

Add the following to your macros to enable filetriggers: 

%_filetriggers_dir /var/lib/rpm/filetriggers

Then install your watchers: 

% cat /var/lib/rpm/filetriggers/ldconfig.filter
^.(/lib|/usr/lib)/[^/]*\.so\.
% cat /var/lib/rpm/filetriggers/ldconfig.script
#!/bin/sh
ldconfig -X
% cat /var/lib/rpm/filetriggers/gtk-icon-cache-hicolor.filter
^./usr/share/icons/hicolor/
% cat /var/lib/rpm/filetriggers/gtk-icon-cache-hicolor.script
#!/bin/sh
/usr/bin/gtk-update-icon-cache --force --quiet /usr/share/icons/hicolor

Note the "." in the regexp which matches both "+" and "-", and so matches both install and uninstall.

[edit] Implementation

A simple patch on rpm. Description:

[edit] files-awaiting-filetriggers

When a package is successfully installed (or removed), rpm will append the installed (resp. removed) files to /var/lib/rpm/files-awaiting-filetriggers.

The format is quite simple: <installed-or-removed> <filename>

where <installed-or-removed> ::= "+" | "-"

For example, after installing hexedit: 

+/usr/bin/hexedit
+/usr/share/doc/hexedit
+/usr/share/doc/hexedit/COPYING
+/usr/share/doc/hexedit/TODO
+/usr/share/doc/hexedit/hexedit-1.2.12.lsm
+/usr/share/man/man1/hexedit.1.lzma

[edit] rpmRunFileTriggers

This function is called before running %posttrans scriptlets. It can be disabled using --noscripts or --notriggers (no special command line option introduced for now).

For each %_filetriggers_dir/*.filter, the regexp (POSIX Extended Regular Expression) on the first line is applied on files-awaiting-filetriggers. If some files match, the corresponding %_filetriggers_dir/<name>.script is called, with matching lines passed in stdin.

Note that this is done in parallel, so multiple <name>.script may be running at the same time.

When it's done, /var/lib/rpm/files-awaiting-filetriggers is removed.

[edit] Comments

Characteristics of this implementation :

  • if the transaction is aborted, the next successful transaction will run on every succesful package installation/removal. This is due to files-awaiting-filetriggers which allows to keep state of what is done or not.
  • it needs only a light patch in rpm
  • files-awaiting-filetriggers may be getting big (eg: 5MB on a big transaction of 1000 packages)
  • not fully integrated in rpm:
    • --nofiletriggers and RPMTRANS_FLAG_NOFILETRIGGERS should be added
    • a new command rpm --run-filetriggers would be useful to force running filetriggers, and only them.

[edit] Suggestions

Filetriggers has been merged with some improvements and additional in rpm5 [HEAD http://rpm5.org/cvs/rlog?f=rpm/lib/filetriggers.c]:

  • Use miRE in stead of regex(3)
  • Pass filename as argument to filetrigger script so they can replace filetriggers requiring file arguments. (room for improval)
    • info-install proposal: 
[root@localhost filetriggers]# cat install_info.filter
^\+/usr/share/info/.*\.info.*
[root@localhost filetriggers]# cat install_info.script
#!/bin/sh
/sbin/install-info $1 --dir=/usr/share/info/dir

[root@localhost filetriggers]# cat remove_install_info.filter
^\-/usr/share/info/.*\.info.*
[root@localhost filetriggers]# cat remove_install_info.script
#!/bin/sh
if [ ! -f $1 ]; then
        echo /sbin/install-info $1 --dir=/usr/share/info/dir --remove
fi

[edit] Candidates

  • emacs elisp
  • fc-cache
  • gtk-update-icon-cache
  • install-info [Proposed]
  • ldconfig [Support in place]
  • python .pyo
  • scrollkeeper-update
  • tetex
  • update-desktop-database
  • update-icon-caches
  • update-menus [Support in place]
  • update-mime-database

[edit] External links

Some links about filetriggers:

Retrieved from "http://wiki.mandriva.com/en/Rpm_filetriggers"
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