Provided by: libsvn-hooks-perl_1.36-1_all 
NAME
SVN::Hooks - Framework for implementing Subversion hooks
VERSION
version 1.36
SYNOPSIS
A single script can implement several hooks:
#!/usr/bin/perl
use SVN::Hooks;
START_COMMIT {
my ($repo_path, $username, $capabilities, $txn_name) = @_;
# ...
};
PRE_COMMIT {
my ($svnlook) = @_;
# ...
};
run_hook($0, @ARGV);
Or you can use already implemented hooks via plugins:
#!/usr/bin/perl
use SVN::Hooks;
use SVN::Hooks::DenyFilenames;
use SVN::Hooks::DenyChanges;
use SVN::Hooks::CheckProperty;
...
run_hook($0, @ARGV);
INTRODUCTION
In order to really understand what this is all about you need to understand Subversion
<http://subversion.apache.org/> and its hooks. You can read everything about this in the
svnbook, a.k.a. Version Control with Subversion, at
<http://svnbook.red-bean.com/nightly/en/index.html>.
Subversion is a version control system, and as such it is used to keep historical
revisions of files and directories. Each revision maintains information about all the
changes introduced since the previous one: date, author, log message, files changed, files
renamed, etc.
Subversion uses a client/server model. The server maintains the repository, which is the
database containing all the historical information we talked about above. Users use a
Subversion client tool to query and change the repository but also to maintain one or more
working areas. A working area is a directory in the user machine containing a copy of a
particular revision of the repository. The user can use the client tool to make all sorts
of changes in his working area and to "commit" them all in an atomic operation that bumps
the repository to a new revision.
A hook is a specifically named program that is called by the Subversion server during the
execution of some operations. There are exactly nine hooks which must reside under the
"hooks" directory in the repository. When you create a new repository, you get nine
template files in this directory, all of them having the ".tmpl" suffix and helpful
instructions inside explaining how to convert them into working hooks.
When Subversion is performing a commit operation on behalf of a client, for example, it
calls the "start-commit" hook, then the "pre-commit" hook, and then the "post-commit"
hook. The first two can gather all sorts of information about the specific commit
transaction being performed and decide to reject it in case it doesn't comply to specified
policies. The "post-commit" can be used to log or alert interested parties about the
commit just done.
IMPORTANT NOTE from the svnbook: "For security reasons, the Subversion repository executes
hook programs with an empty environment---that is, no environment variables are set at
all, not even $PATH (or %PATH%, under Windows). Because of this, many administrators are
baffled when their hook program runs fine by hand, but doesn't work when run by
Subversion. Be sure to explicitly set any necessary environment variables in your hook
program and/or use absolute paths to programs."
Not even the current directory where the hooks run is specified by Subversion. However,
the hooks executed by the SVN::Hooks framework run with their currect directory set to the
repository's root directory in the server. This can be useful sometimes.
There are several useful hook scripts available elsewhere
<http://svn.apache.org/repos/asf/subversion/trunk/contrib/hook-scripts/>, mainly for those
three associated with the commit operation. However, when you try to combine the
functionality of two or more of those scripts in a single hook you normally end up facing
two problems.
Complexity
In order to integrate the funcionality of more than one script you have to write a
driver script that's called by Subversion and calls all the other scripts in order,
passing to them the arguments they need. Moreover, some of those scripts may have
configuration files to read and you may have to maintain several of them.
Inefficiency
This arrangement is inefficient in two ways. First because each script runs as a
separate process, which usually have a high startup cost because they are, well,
scripts and not binaries. And second, because as each script is called in turn they
have no memory of the scripts called before and have to gather the information about
the transaction again and again, normally by calling the "svnlook" command, which
spawns yet another process.
SVN::Hooks is a framework for implementing Subversion hooks that tries to solve these
problems.
Instead of having separate scripts implementing different functionality you have a single
script implementing all the funcionality you need either directly or using some of the
existing plugins, which are implemented by Perl modules in the SVN::Hooks:: namespace.
This single script can be used to implement all nine standard hooks, because each hook
knows when to perform based on the context in which the script was called.
USAGE
In the Subversion server, go to the "hooks" directory under the directory where the
repository was created. You should see there the nine hook templates. Create a script
there using the SVN::Hooks module.
$ cd /path/to/repo/hooks
$ cat >svn-hooks.pl <<END_OF_SCRIPT
#!/usr/bin/perl
use SVN::Hooks;
run_hook($0, @ARGV);
END_OF_SCRIPT
$ chmod +x svn-hooks.pl
This script will serve for any hook. Create symbolic links pointing to it for each hook
you are interested in. (You may create symbolic links for all nine hooks, but this will
make Subversion call the script for all hooked operations, even for those that you may not
be interested in. Nothing wrong will happen, but the server will be doing extra work for
nothing.)
$ ln -s svn-hooks.pl start-commit
$ ln -s svn-hooks.pl pre-commit
$ ln -s svn-hooks.pl post-commit
$ ln -s svn-hooks.pl pre-revprop-change
As is the script won't do anything. You have to implement some hooks or use some of the
existing ones implemented as plugins. Either way, the script should end with a call to
"run_hooks" passing to it the name with which it wass called ($0) and all the arguments it
received (@ARGV).
Implementing Hooks
Implement hooks using one of the nine hook directives below. Each one of them get a single
block (anonymous function) as argument. The block will be called by "run_hook" with proper
arguments, as indicated below. These arguments are the ones gotten from @ARGV, with the
exception of the ones identified by "SVN::Look". These are SVN::Look objects which can be
used to grok detailed information about the repository and the current transaction.
(Please, refer to the SVN::Look documentation to know how to use it.)
• POST_COMMIT(SVN::Look)
• POST_LOCK(repos-path, username)
• POST_REVPROP_CHANGE(SVN::Look, username, property-name, action)
• POST_UNLOCK(repos-path, username)
• PRE_COMMIT(SVN::Look)
• PRE_LOCK(repos-path, path, username, comment, steal-lock-flag)
• PRE_REVPROP_CHANGE(SVN::Look, username, property-name, action)
• PRE_UNLOCK(repos-path, path, username, lock-token, break-unlock-flag)
• START_COMMIT(repos-path, username, capabilities, txn-name)
This is an example of a script implementing two hooks:
#!/usr/bin/perl
use SVN::Hooks;
# ...
START_COMMIT {
my ($repos_path, $username, $capabilities, $txn_name) = @_;
exists $committers{$username}
or die "User '$username' is not allowed to commit.\n";
$capabilities =~ /mergeinfo/
or die "Your Subversion client does not support mergeinfo capability.\n";
};
PRE_COMMIT {
my ($svnlook) = @_;
foreach my $added ($svnlook->added()) {
$added !~ /\.(exe|o|jar|zip)$/
or die "Please, don't commit binary files such as '$added'.\n";
}
};
run_hook($0, @ARGV);
Note that the hook directives resemble function definitions but they're not. They are
function calls, and as such must end with a semi-colon.
Most of the "start-commit" and "pre-*" hooks are used to check some condition. If the
condition holds, they must simply end without returning anything. Otherwise, they must
"die" with a suitable error message.
Also note that each hook directive can be called more than once if you need to implement
more than one specific hook. The hooks will run in the order they were defined.
Using Plugins
There are several hooks already implemented as plugin modules under the namespace
"SVN::Hooks::", which you can use. The main ones are described succinctly below. Please,
see their own documentation for more details.
SVN::Hooks::AllowPropChange
Allow only specified users make changes in revision properties.
SVN::Hooks::CheckCapability
Check if the Subversion client implements the required capabilities.
SVN::Hooks::CheckJira
Integrate Subversion with the JIRA <http://www.atlassian.com/software/jira/> ticketing
system.
SVN::Hooks::CheckLog
Check if the log message in a commit conforms to a Regexp.
SVN::Hooks::CheckMimeTypes
Check if the files added to the repository have the "svn:mime-type" property set.
Moreover, for text files, check if the properties "svn:eol-style" and "svn:keywords"
are also set.
SVN::Hooks::CheckProperty
Check for specific properties for specific kinds of files.
SVN::Hooks::CheckStructure
Check if the files and directories being added to the repository conform to a specific
structure.
SVN::Hooks::DenyChanges
Deny the addition, modification, or deletion of specific files and directories in the
repository. Usually used to deny modifications in the "tags" directory.
SVN::Hooks::DenyFilenames
Deny the addition of files which file names doesn't comply with a Regexp. Usually used
to disallow some characteres in the filenames.
SVN::Hooks::Notify
Sends notification emails after successful commits.
SVN::Hooks::UpdateConfFile
Allows you to maintain Subversion configuration files versioned in the same repository
where they are used. Usually used to maintain the configuration file for the hooks and
the repository access control file.
This is an example of a script using some plugins:
#!/usr/bin/perl
use SVN::Hooks;
use SVN::Hooks::CheckProperty;
use SVN::Hooks::DenyChanges;
use SVN::Hooks::DenyFilenames;
# Accept only letters, digits, underlines, periods, and hifens
DENY_FILENAMES(qr/[^-\/\.\w]/i);
# Disallow modifications in the tags directory
DENY_UPDATE(qr:^tags:);
# OpenOffice.org documents need locks
CHECK_PROPERTY(qr/\.(?:od[bcfgimpst]|ot[ghpst])$/i => 'svn:needs-lock');
run_hook($0, @ARGV);
Those directives are implemented and exported by the hooks. Note that using hooks you
don't need to be explicit about which one of the nine hooks will be triggered by the
directives. This is on purpose, because some plugins can trigger more than one hook. The
plugin documentation should tell you which hooks can be triggered so that you know which
symbolic links you need to create in the hooks repository directory.
Configuration file
Before calling the hooks, the function "run_hook" evaluates a file called svn-hooks.conf
under the conf directory in the repository, if it exists. Hence, you can choose to put all
the directives in this file and not in the script under the hooks directory.
The advantage of this is that you can then manage the configuration file with the
"SVN::Hooks::UpdateConfFile" and have it versioned under the same repository that it
controls.
One way to do this is to use this hook script:
#!/usr/bin/perl
use SVN::Hooks;
use SVN::Hooks::UpdateConfFile;
use ...
UPDATE_CONF_FILE(
'conf/svn-hooks.conf' => 'svn-hooks.conf',
validator => [qw(/usr/bin/perl -c)],
rotate => 2,
);
run_hook($0, @ARGV);
Use this hook script and create a directory called conf at the root of the repository
(besides the common trunk, branches, and tags directories). Add the svn-hooks.conf file
under the conf directory. Then, whenever you commit a new version of the file, the pre-
commit hook will validate it sintactically ("/usr/bin/perl -c") and copy its new version
to the conf/svn-hooks.conf file in the repository. (Read the SVN::Hooks::UpdateConfFile
documentation to understand it in details.)
Being a Perl script, it's possible to get fancy with the configuration file, using
variables, functions, and whatever. But for most purposes it consists just in a series of
configuration directives.
Don't forget to end it with the "1;" statement, though, because it's evaluated with a "do"
statement and needs to end with a true expression.
Please, see the plugins documentation to know about the directives.
PLUGIN DEVELOPER TUTORIAL
Yet to do.
EXPORT
run_hook
This is responsible to invoke the right plugins depending on the context in which it was
called.
Its first argument must be the name of the hook that was called. Usually you just pass $0
to it, since it knows to extract the basename of the parameter.
Its second argument must be the path to the directory where the repository was created.
The remaining arguments depend on the hook for which it's being called, like this:
• start-commit repo-path user capabilities txn-name
• pre-commit repo-path txn
• post-commit repo-path rev
• pre-lock repo-path path user
• post-lock repo-path user
• pre-unlock repo-path path user
• post-unlock repo-path user
• pre-revprop-change repo-path rev user propname action
• post-revprop-change repo-path rev user propname action
But as these are exactly the arguments Subversion passes when it calls the hooks, you
usually call "run_hook" like this:
run_hook($0, @ARGV);
REPOSITORY
<https://github.com/gnustavo/SVN-Hooks>
AUTHOR
Gustavo L. de M. Chaves <gnustavo@cpan.org>
COPYRIGHT AND LICENSE
This software is copyright (c) 2022 by CPqD <www.cpqd.com.br>.
This is free software; you can redistribute it and/or modify it under the same terms as
the Perl 5 programming language system itself.