--- /dev/null
+#!/usr/bin/perl
+
+use strict;
+use File::Spec;
+
+$ENV{PATH} = '/opt/git/bin';
+my $acl_git = '/vcs/acls.git';
+my $acl_branch = 'refs/heads/master';
+my $debug = 0;
+
+=doc
+Invoked as: update refname old-sha1 new-sha1
+
+This script is run by git-receive-pack once for each ref that the
+client is trying to modify. If we exit with a non-zero exit value
+then the update for that particular ref is denied, but updates for
+other refs in the same run of receive-pack may still be allowed.
+
+We are run after the objects have been uploaded, but before the
+ref is actually modified. We take advantage of that fact when we
+look for "new" commits and tags (the new objects won't show up in
+`rev-list --all`).
+
+This script loads and parses the content of the config file
+"users/$this_user.acl" from the $acl_branch commit of $acl_git ODB.
+The acl file is a git-config style file, but uses a slightly more
+restricted syntax as the Perl parser contained within this script
+is not nearly as permissive as git-config.
+
+Example:
+
+ [user]
+ committer = John Doe <john.doe@example.com>
+ committer = John R. Doe <john.doe@example.com>
+
+ [repository "acls"]
+ allow = heads/master
+ allow = CDUR for heads/jd/
+ allow = C for ^tags/v\\d+$
+
+For all new commit or tag objects the committer (or tagger) line
+within the object must exactly match one of the user.committer
+values listed in the acl file ("HEAD:users/$this_user.acl").
+
+For a branch to be modified an allow line within the matching
+repository section must be matched for both the refname and the
+opcode.
+
+Repository sections are matched on the basename of the repository
+(after removing the .git suffix).
+
+The opcode abbrevations are:
+
+ C: create new ref
+ D: delete existing ref
+ U: fast-forward existing ref (no commit loss)
+ R: rewind/rebase existing ref (commit loss)
+
+if no opcodes are listed before the "for" keyword then "U" (for
+fast-forward update only) is assumed as this is the most common
+usage.
+
+Refnames are matched by always assuming a prefix of "refs/".
+This hook forbids pushing or deleting anything not under "refs/".
+
+Refnames that start with ^ are Perl regular expressions, and the ^
+is kept as part of the regexp. \\ is needed to get just one \, so
+\\d expands to \d in Perl. The 3rd allow line above is an example.
+
+Refnames that don't start with ^ but that end with / are prefix
+matches (2nd allow line above); all other refnames are strict
+equality matches (1st allow line).
+
+Anything pushed to "heads/" (ok, really "refs/heads/") must be
+a commit. Tags are not permitted here.
+
+Anything pushed to "tags/" (err, really "refs/tags/") must be an
+annotated tag. Commits, blobs, trees, etc. are not permitted here.
+Annotated tag signatures aren't checked, nor are they required.
+
+The special subrepository of 'info/new-commit-check' can
+be created and used to allow users to push new commits and
+tags from another local repository to this one, even if they
+aren't the committer/tagger of those objects. In a nut shell
+the info/new-commit-check directory is a Git repository whose
+objects/info/alternates file lists this repository and all other
+possible sources, and whose refs subdirectory contains symlinks
+to this repository's refs subdirectory, and to all other possible
+sources refs subdirectories. Yes, this means that you cannot
+use packed-refs in those repositories as they won't be resolved
+correctly.
+
+=cut
+
+my $git_dir = $ENV{GIT_DIR};
+my $new_commit_check = "$git_dir/info/new-commit-check";
+my $ref = $ARGV[0];
+my $old = $ARGV[1];
+my $new = $ARGV[2];
+my $new_type;
+my ($this_user) = getpwuid $<; # REAL_USER_ID
+my $repository_name;
+my %user_committer;
+my @allow_rules;
+
+sub deny ($) {
+ print STDERR "-Deny- $_[0]\n" if $debug;
+ print STDERR "\ndenied: $_[0]\n\n";
+ exit 1;
+}
+
+sub grant ($) {
+ print STDERR "-Grant- $_[0]\n" if $debug;
+ exit 0;
+}
+
+sub info ($) {
+ print STDERR "-Info- $_[0]\n" if $debug;
+}
+
+sub parse_config ($$) {
+ my ($data, $fn) = @_;
+ info "Loading $fn";
+ open(I,'-|','git',"--git-dir=$acl_git",'cat-file','blob',$fn);
+ my $section = '';
+ while (<I>) {
+ chomp;
+ if (/^\s*$/ || /^\s*#/) {
+ } elsif (/^\[([a-z]+)\]$/i) {
+ $section = $1;
+ } elsif (/^\[([a-z]+)\s+"(.*)"\]$/i) {
+ $section = "$1.$2";
+ } elsif (/^\s*([a-z][a-z0-9]+)\s*=\s*(.*?)\s*$/i) {
+ push @{$data->{"$section.$1"}}, $2;
+ } else {
+ deny "bad config file line $. in $fn";
+ }
+ }
+ close I;
+}
+
+sub all_new_committers () {
+ local $ENV{GIT_DIR} = $git_dir;
+ $ENV{GIT_DIR} = $new_commit_check if -d $new_commit_check;
+
+ info "Getting committers of new commits.";
+ my %used;
+ open(T,'-|','git','rev-list','--pretty=raw',$new,'--not','--all');
+ while (<T>) {
+ next unless s/^committer //;
+ chop;
+ s/>.*$/>/;
+ info "Found $_." unless $used{$_}++;
+ }
+ close T;
+ info "No new commits." unless %used;
+ keys %used;
+}
+
+sub all_new_taggers () {
+ my %exists;
+ open(T,'-|','git','for-each-ref','--format=%(objectname)','refs/tags');
+ while (<T>) {
+ chop;
+ $exists{$_} = 1;
+ }
+ close T;
+
+ info "Getting taggers of new tags.";
+ my %used;
+ my $obj = $new;
+ my $obj_type = $new_type;
+ while ($obj_type eq 'tag') {
+ last if $exists{$obj};
+ $obj_type = '';
+ open(T,'-|','git','cat-file','tag',$obj);
+ while (<T>) {
+ chop;
+ if (/^object ([a-z0-9]{40})$/) {
+ $obj = $1;
+ } elsif (/^type (.+)$/) {
+ $obj_type = $1;
+ } elsif (s/^tagger //) {
+ s/>.*$/>/;
+ info "Found $_." unless $used{$_}++;
+ last;
+ }
+ }
+ close T;
+ }
+ info "No new tags." unless %used;
+ keys %used;
+}
+
+sub check_committers (@) {
+ my @bad;
+ foreach (@_) { push @bad, $_ unless $user_committer{$_}; }
+ if (@bad) {
+ print STDERR "\n";
+ print STDERR "You are not $_.\n" foreach (sort @bad);
+ deny "You cannot push changes not committed by you.";
+ }
+}
+
+sub git_value (@) {
+ open(T,'-|','git',@_); local $_ = <T>; chop; close T;
+ $_;
+}
+
+deny "No GIT_DIR inherited from caller" unless $git_dir;
+deny "Need a ref name" unless $ref;
+deny "Refusing funny ref $ref" unless $ref =~ s,^refs/,,;
+deny "Bad old value $old" unless $old =~ /^[a-z0-9]{40}$/;
+deny "Bad new value $new" unless $new =~ /^[a-z0-9]{40}$/;
+deny "Cannot determine who you are." unless $this_user;
+
+$repository_name = File::Spec->rel2abs($git_dir);
+$repository_name =~ m,/([^/]+)(?:\.git|/\.git)$,;
+$repository_name = $1;
+info "Updating in '$repository_name'.";
+
+my $op;
+if ($old =~ /^0{40}$/) { $op = 'C'; }
+elsif ($new =~ /^0{40}$/) { $op = 'D'; }
+else { $op = 'R'; }
+
+# This is really an update (fast-forward) if the
+# merge base of $old and $new is $old.
+#
+$op = 'U' if ($op eq 'R'
+ && $ref =~ m,^heads/,
+ && $old eq git_value('merge-base',$old,$new));
+
+# Load the user's ACL file.
+{
+ my %data = ('user.committer' => []);
+ parse_config(\%data, "$acl_branch:users/$this_user.acl");
+ %user_committer = map {$_ => $_} @{$data{'user.committer'}};
+ my $rules = $data{"repository.$repository_name.allow"} || [];
+ foreach (@$rules) {
+ if (/^([CDRU ]+)\s+for\s+([^\s]+)$/) {
+ my $ops = $1;
+ my $ref = $2;
+ $ops =~ s/ //g;
+ $ref =~ s/\\\\/\\/g;
+ push @allow_rules, [$ops, $ref];
+ } elsif (/^for\s+([^\s]+)$/) {
+ # Mentioned, but nothing granted?
+ } elsif (/^[^\s]+$/) {
+ s/\\\\/\\/g;
+ push @allow_rules, ['U', $_];
+ }
+ }
+}
+
+if ($op ne 'D') {
+ $new_type = git_value('cat-file','-t',$new);
+
+ if ($ref =~ m,^heads/,) {
+ deny "$ref must be a commit." unless $new_type eq 'commit';
+ } elsif ($ref =~ m,^tags/,) {
+ deny "$ref must be an annotated tag." unless $new_type eq 'tag';
+ }
+
+ check_committers (all_new_committers);
+ check_committers (all_new_taggers) if $new_type eq 'tag';
+}
+
+info "$this_user wants $op for $ref";
+foreach my $acl_entry (@allow_rules) {
+ my ($acl_ops, $acl_n) = @$acl_entry;
+ next unless $acl_ops =~ /^[CDRU]+$/; # Uhh.... shouldn't happen.
+ next unless $acl_n;
+ next unless $op =~ /^[$acl_ops]$/;
+
+ grant "Allowed by: $acl_ops for $acl_n"
+ if (
+ ($acl_n eq $ref)
+ || ($acl_n =~ m,/$, && substr($ref,0,length $acl_n) eq $acl_n)
+ || ($acl_n =~ m,^\^, && $ref =~ m:$acl_n:)
+ );
+}
+close A;
+deny "You are not permitted to $op $ref";