"hooklets" -- play nice with any number of site-local 'update' hooks

(yes, I made up the name.  Deal with it!)

contrib/update.detect-dup-pubkeys

@@ -0,0 +1,74 @@
+#!/bin/bash
+
+# update "hooklet" to detect duplicate public keys
+
+# This particular hooklet also serves as an example for people writing others.
+# [It should be quite easy to figure out what parts apply to any hooklet and
+# what parts are specific to *this* hooklet and its function.]
+
+# see hooks/common/update.secondary.sample for instructions on *enabling*
+# hooklets
+
+# a hooklet is called as follows:
+#   git-receive-pack --> 'update' --> 'update.secondary' --> this script
+# note: the same three arguments that git passes to the update hook are passed
+# along to each hooklet.
+
+# the update hook, and therefore the hooklets, are called for *every* repo out
+# there.  If you want this hooklet to run only for certain repos, here's how:
+[ "$GL_REPO" = "gitolite-admin" ] || exit 0
+
+# superfluous, since update.secondary already did it, but I'd like to
+# emphasise that all output MUST go to STDERR
+exec >&2
+
+# ----
+
+# the main functionality of the hooklet starts here.  In this one (and I
+# suspect many others) we want to examine the actual files from the commit
+# that was pushed.
+
+# get the tip commit being pushed
+sha=$3
+
+# git sets this; and we don't want it at this point...
+unset GIT_DIR
+
+# paranoia
+set -e
+
+# setup the temp area
+export TMPDIR=$GL_REPO_BASE_ABS
+export tmp=$(mktemp -d -t gl-internal-temp-repo.XXXXXXXXXX);
+trap "rm -rf $tmp" EXIT;
+
+# now get the files into $tmp.
+    # (note: if your task does not require the actual files, and you can
+    # manage with "git cat-file -s" and so on, then you may not even need a
+    # $tmp; you may be able to do it all right in the repo.git directory)
+
+git archive $sha keydir | tar -C $tmp -xf -
+    # DO NOT try, say, 'GIT_WORK_TREE=$tmp git checkout $sha'.  It'll screw up
+    # both the 'index' and 'HEAD' of the repo.git.  Screwing up the index is
+    # BAD because now it goes out of sync with $GL_ADMINDIR.  Think of a push
+    # that had a deleted pubkey but failed a hooklet for some reason.  A
+    # subsequent push that fixes the error will now result in a $GL_ADMINDIR
+    # that still *has* that deleted pubkey!!
+
+    # And this is equally applicable to cases where you're using a
+    # post-receive or similar hook to live update a web site or something,
+    # which is a pretty common usage, I am given to understand.
+
+cd $tmp
+
+# ----
+
+# *finally*, the actual check you need to do in this hook: look for duplicate
+# pubkeys and exit 1 if dups are found
+for f in `find keydir -name "*.pub"`
+do
+    ssh-keygen -l -f "$f"
+done | perl -ane '
+    die "$F[2] is a duplicate of $seen{$F[1]}\n" if $seen{$F[1]};
+    $seen{$F[1]} = $F[2];
+'

contrib/update.email-check

@@ -4,9 +4,7 @@
 
     # Gitolite specific script to check "author email" field of every commit
     # pushed and to disallow if this email does not match the email that the
-    # user pushing is expected to have.  Needs to be renamed to
+    # user pushing is expected to have.
-    # "update.secondary"; see gitolite docs for how to propagate this to all
-    # repos.
 
     # Use without gitolite is also possible; just substitute your access
     # control system's notion of "user" for the env var GL_USER in the code

doc/2-admin.mkd

@@ -148,6 +148,10 @@ if such a hook exists.  People wishing to do exotic things on the server side
 when the admin repo is pushed should see doc/shell-games.notes for how to
 exploit this :-)
 
+In addition, gitolite now contains the basic infrastructure to support
+multiple such hooks without having to remember to chain them yourself.  You
+can look in `hooks/common/update.secondary.sample` for instructions.
+
 Finally, these names (`update.secondary` and `post-update.secondary`) are
 merely the defaults.  You can change them to anything you want; look in
 conf/example.gitolite.rc for details.

hooks/common/update

@@ -86,14 +86,14 @@ if (exists $repos{$ENV{GL_REPO}}{NAME_LIMITS}) {
 my $log_refex = check_ref(\@allowed_refs, $ENV{GL_REPO}, (shift @refs), $att_acc);
 check_ref                (\@allowed_refs, $ENV{GL_REPO}, $_           , $att_acc) for @refs;
 
-# if we returned at all, all the checks succeeded, so we log the action and exit 0
+# if we returned at all, all the checks succeeded.  Check secondary hooks now
+$UPDATE_CHAINS_TO ||= 'hooks/update.secondary';
+( -f $UPDATE_CHAINS_TO or -l $UPDATE_CHAINS_TO )
+    and system ( $UPDATE_CHAINS_TO, @ARGV )
+    and die "$UPDATE_CHAINS_TO died\n";
 
+# now log it and exit 0 so git can get on with it
 log_it("", "$att_acc\t" .  substr($oldsha, 0, 14) . "\t" . substr($newsha, 0, 14) .
     "\t$reported_repo\t$ref\t$log_refex");
 
-# now chain to the local admin defined update hook, if present
-$UPDATE_CHAINS_TO ||= 'hooks/update.secondary';
-exec $UPDATE_CHAINS_TO, @ARGV
-    if -f $UPDATE_CHAINS_TO or -l $UPDATE_CHAINS_TO;
-
 exit 0;

hooks/common/update.secondary.sample

@@ -0,0 +1,44 @@
+#!/bin/bash
+
+# driver script to run multiple update "hooklets".  Each "hooklet" performs a
+# specific (possibly site-local) check, and they *all* have to succeed for the
+# push to succeed.
+
+# HOW TO USE:
+
+# (1) clone gitolite as you would for an upgrade (or install)
+# (2) rename this file to remove the .sample extension
+# (3) make the renamed file executable (chmod +x)
+# (4) create a directory called update.secondary.d in hooks/common
+# (5) copy all the update "hooklets" you want (like update.detect-dup-pubkeys)
+#     from contrib or wherever, to that directory
+# (6) make them also executable (chmod +x)
+# (7) install/upgrade gitolite as normal so all these files go to the server
+
+# rules for writing a hooklet are in the sample hooklet called
+# "update.detect-dup-pubkeys" in contrib
+
+# ----
+
+# NOTE: a hooklet runs under the same assumptions as the 'update' hook, so the
+# starting directory must be maintained and arguments must be passed on.
+
+[ -d hooks/update.secondary.d ] || exit 0
+
+# all output from these "hooklets" must go to STDERR to avoid confusing the client
+exec >&2
+
+for i in hooks/update.secondary.d/*
+do
+    [ -x "$i" ] || continue
+    # call the hooklet with the same arguments we got
+    "$i" "$@"   || {
+        # hooklet failed; we need to log it...
+        echo hooklet $i failed
+        perl -I$GL_BINDIR -Mgitolite -e "log_it('hooklet $i failed')"
+        # ...and send back some non-zero exit code ;-)
+        exit 1
+    }
+done
+
+exit 0