yading@10: #!/bin/sh
yading@10: #
yading@10: # Copyright (c) 2006, 2008 Junio C Hamano
yading@10: #
yading@10: # The "pre-rebase" hook is run just before "git rebase" starts doing
yading@10: # its job, and can prevent the command from running by exiting with
yading@10: # non-zero status.
yading@10: #
yading@10: # The hook is called with the following parameters:
yading@10: #
yading@10: # $1 -- the upstream the series was forked from.
yading@10: # $2 -- the branch being rebased (or empty when rebasing the current branch).
yading@10: #
yading@10: # This sample shows how to prevent topic branches that are already
yading@10: # merged to 'next' branch from getting rebased, because allowing it
yading@10: # would result in rebasing already published history.
yading@10: 
yading@10: publish=next
yading@10: basebranch="$1"
yading@10: if test "$#" = 2
yading@10: then
yading@10: 	topic="refs/heads/$2"
yading@10: else
yading@10: 	topic=`git symbolic-ref HEAD` ||
yading@10: 	exit 0 ;# we do not interrupt rebasing detached HEAD
yading@10: fi
yading@10: 
yading@10: case "$topic" in
yading@10: refs/heads/??/*)
yading@10: 	;;
yading@10: *)
yading@10: 	exit 0 ;# we do not interrupt others.
yading@10: 	;;
yading@10: esac
yading@10: 
yading@10: # Now we are dealing with a topic branch being rebased
yading@10: # on top of master.  Is it OK to rebase it?
yading@10: 
yading@10: # Does the topic really exist?
yading@10: git show-ref -q "$topic" || {
yading@10: 	echo >&2 "No such branch $topic"
yading@10: 	exit 1
yading@10: }
yading@10: 
yading@10: # Is topic fully merged to master?
yading@10: not_in_master=`git rev-list --pretty=oneline ^master "$topic"`
yading@10: if test -z "$not_in_master"
yading@10: then
yading@10: 	echo >&2 "$topic is fully merged to master; better remove it."
yading@10: 	exit 1 ;# we could allow it, but there is no point.
yading@10: fi
yading@10: 
yading@10: # Is topic ever merged to next?  If so you should not be rebasing it.
yading@10: only_next_1=`git rev-list ^master "^$topic" ${publish} | sort`
yading@10: only_next_2=`git rev-list ^master           ${publish} | sort`
yading@10: if test "$only_next_1" = "$only_next_2"
yading@10: then
yading@10: 	not_in_topic=`git rev-list "^$topic" master`
yading@10: 	if test -z "$not_in_topic"
yading@10: 	then
yading@10: 		echo >&2 "$topic is already up-to-date with master"
yading@10: 		exit 1 ;# we could allow it, but there is no point.
yading@10: 	else
yading@10: 		exit 0
yading@10: 	fi
yading@10: else
yading@10: 	not_in_next=`git rev-list --pretty=oneline ^${publish} "$topic"`
yading@10: 	/usr/bin/perl -e '
yading@10: 		my $topic = $ARGV[0];
yading@10: 		my $msg = "* $topic has commits already merged to public branch:\n";
yading@10: 		my (%not_in_next) = map {
yading@10: 			/^([0-9a-f]+) /;
yading@10: 			($1 => 1);
yading@10: 		} split(/\n/, $ARGV[1]);
yading@10: 		for my $elem (map {
yading@10: 				/^([0-9a-f]+) (.*)$/;
yading@10: 				[$1 => $2];
yading@10: 			} split(/\n/, $ARGV[2])) {
yading@10: 			if (!exists $not_in_next{$elem->[0]}) {
yading@10: 				if ($msg) {
yading@10: 					print STDERR $msg;
yading@10: 					undef $msg;
yading@10: 				}
yading@10: 				print STDERR " $elem->[1]\n";
yading@10: 			}
yading@10: 		}
yading@10: 	' "$topic" "$not_in_next" "$not_in_master"
yading@10: 	exit 1
yading@10: fi
yading@10: 
yading@10: exit 0
yading@10: 
yading@10: ################################################################
yading@10: 
yading@10: This sample hook safeguards topic branches that have been
yading@10: published from being rewound.
yading@10: 
yading@10: The workflow assumed here is:
yading@10: 
yading@10:  * Once a topic branch forks from "master", "master" is never
yading@10:    merged into it again (either directly or indirectly).
yading@10: 
yading@10:  * Once a topic branch is fully cooked and merged into "master",
yading@10:    it is deleted.  If you need to build on top of it to correct
yading@10:    earlier mistakes, a new topic branch is created by forking at
yading@10:    the tip of the "master".  This is not strictly necessary, but
yading@10:    it makes it easier to keep your history simple.
yading@10: 
yading@10:  * Whenever you need to test or publish your changes to topic
yading@10:    branches, merge them into "next" branch.
yading@10: 
yading@10: The script, being an example, hardcodes the publish branch name
yading@10: to be "next", but it is trivial to make it configurable via
yading@10: $GIT_DIR/config mechanism.
yading@10: 
yading@10: With this workflow, you would want to know:
yading@10: 
yading@10: (1) ... if a topic branch has ever been merged to "next".  Young
yading@10:     topic branches can have stupid mistakes you would rather
yading@10:     clean up before publishing, and things that have not been
yading@10:     merged into other branches can be easily rebased without
yading@10:     affecting other people.  But once it is published, you would
yading@10:     not want to rewind it.
yading@10: 
yading@10: (2) ... if a topic branch has been fully merged to "master".
yading@10:     Then you can delete it.  More importantly, you should not
yading@10:     build on top of it -- other people may already want to
yading@10:     change things related to the topic as patches against your
yading@10:     "master", so if you need further changes, it is better to
yading@10:     fork the topic (perhaps with the same name) afresh from the
yading@10:     tip of "master".
yading@10: 
yading@10: Let's look at this example:
yading@10: 
yading@10: 		   o---o---o---o---o---o---o---o---o---o "next"
yading@10: 		  /       /           /           /
yading@10: 		 /   a---a---b A     /           /
yading@10: 		/   /               /           /
yading@10: 	       /   /   c---c---c---c B         /
yading@10: 	      /   /   /             \         /
yading@10: 	     /   /   /   b---b C     \       /
yading@10: 	    /   /   /   /             \     /
yading@10:     ---o---o---o---o---o---o---o---o---o---o---o "master"
yading@10: 
yading@10: 
yading@10: A, B and C are topic branches.
yading@10: 
yading@10:  * A has one fix since it was merged up to "next".
yading@10: 
yading@10:  * B has finished.  It has been fully merged up to "master" and "next",
yading@10:    and is ready to be deleted.
yading@10: 
yading@10:  * C has not merged to "next" at all.
yading@10: 
yading@10: We would want to allow C to be rebased, refuse A, and encourage
yading@10: B to be deleted.
yading@10: 
yading@10: To compute (1):
yading@10: 
yading@10: 	git rev-list ^master ^topic next
yading@10: 	git rev-list ^master        next
yading@10: 
yading@10: 	if these match, topic has not merged in next at all.
yading@10: 
yading@10: To compute (2):
yading@10: 
yading@10: 	git rev-list master..topic
yading@10: 
yading@10: 	if this is empty, it is fully merged to "master".