rlm@11: #!/bin/sh
rlm@11: #
rlm@11: # Copyright (c) 2006, 2008 Junio C Hamano
rlm@11: #
rlm@11: # The "pre-rebase" hook is run just before "git-rebase" starts doing
rlm@11: # its job, and can prevent the command from running by exiting with
rlm@11: # non-zero status.
rlm@11: #
rlm@11: # The hook is called with the following parameters:
rlm@11: #
rlm@11: # $1 -- the upstream the series was forked from.
rlm@11: # $2 -- the branch being rebased (or empty when rebasing the current branch).
rlm@11: #
rlm@11: # This sample shows how to prevent topic branches that are already
rlm@11: # merged to 'next' branch from getting rebased, because allowing it
rlm@11: # would result in rebasing already published history.
rlm@11: 
rlm@11: publish=next
rlm@11: basebranch="$1"
rlm@11: if test "$#" = 2
rlm@11: then
rlm@11: 	topic="refs/heads/$2"
rlm@11: else
rlm@11: 	topic=`git symbolic-ref HEAD` ||
rlm@11: 	exit 0 ;# we do not interrupt rebasing detached HEAD
rlm@11: fi
rlm@11: 
rlm@11: case "$topic" in
rlm@11: refs/heads/??/*)
rlm@11: 	;;
rlm@11: *)
rlm@11: 	exit 0 ;# we do not interrupt others.
rlm@11: 	;;
rlm@11: esac
rlm@11: 
rlm@11: # Now we are dealing with a topic branch being rebased
rlm@11: # on top of master.  Is it OK to rebase it?
rlm@11: 
rlm@11: # Does the topic really exist?
rlm@11: git show-ref -q "$topic" || {
rlm@11: 	echo >&2 "No such branch $topic"
rlm@11: 	exit 1
rlm@11: }
rlm@11: 
rlm@11: # Is topic fully merged to master?
rlm@11: not_in_master=`git-rev-list --pretty=oneline ^master "$topic"`
rlm@11: if test -z "$not_in_master"
rlm@11: then
rlm@11: 	echo >&2 "$topic is fully merged to master; better remove it."
rlm@11: 	exit 1 ;# we could allow it, but there is no point.
rlm@11: fi
rlm@11: 
rlm@11: # Is topic ever merged to next?  If so you should not be rebasing it.
rlm@11: only_next_1=`git-rev-list ^master "^$topic" ${publish} | sort`
rlm@11: only_next_2=`git-rev-list ^master           ${publish} | sort`
rlm@11: if test "$only_next_1" = "$only_next_2"
rlm@11: then
rlm@11: 	not_in_topic=`git-rev-list "^$topic" master`
rlm@11: 	if test -z "$not_in_topic"
rlm@11: 	then
rlm@11: 		echo >&2 "$topic is already up-to-date with master"
rlm@11: 		exit 1 ;# we could allow it, but there is no point.
rlm@11: 	else
rlm@11: 		exit 0
rlm@11: 	fi
rlm@11: else
rlm@11: 	not_in_next=`git-rev-list --pretty=oneline ^${publish} "$topic"`
rlm@11: 	perl -e '
rlm@11: 		my $topic = $ARGV[0];
rlm@11: 		my $msg = "* $topic has commits already merged to public branch:\n";
rlm@11: 		my (%not_in_next) = map {
rlm@11: 			/^([0-9a-f]+) /;
rlm@11: 			($1 => 1);
rlm@11: 		} split(/\n/, $ARGV[1]);
rlm@11: 		for my $elem (map {
rlm@11: 				/^([0-9a-f]+) (.*)$/;
rlm@11: 				[$1 => $2];
rlm@11: 			} split(/\n/, $ARGV[2])) {
rlm@11: 			if (!exists $not_in_next{$elem->[0]}) {
rlm@11: 				if ($msg) {
rlm@11: 					print STDERR $msg;
rlm@11: 					undef $msg;
rlm@11: 				}
rlm@11: 				print STDERR " $elem->[1]\n";
rlm@11: 			}
rlm@11: 		}
rlm@11: 	' "$topic" "$not_in_next" "$not_in_master"
rlm@11: 	exit 1
rlm@11: fi
rlm@11: 
rlm@11: exit 0
rlm@11: 
rlm@11: ################################################################
rlm@11: 
rlm@11: This sample hook safeguards topic branches that have been
rlm@11: published from being rewound.
rlm@11: 
rlm@11: The workflow assumed here is:
rlm@11: 
rlm@11:  * Once a topic branch forks from "master", "master" is never
rlm@11:    merged into it again (either directly or indirectly).
rlm@11: 
rlm@11:  * Once a topic branch is fully cooked and merged into "master",
rlm@11:    it is deleted.  If you need to build on top of it to correct
rlm@11:    earlier mistakes, a new topic branch is created by forking at
rlm@11:    the tip of the "master".  This is not strictly necessary, but
rlm@11:    it makes it easier to keep your history simple.
rlm@11: 
rlm@11:  * Whenever you need to test or publish your changes to topic
rlm@11:    branches, merge them into "next" branch.
rlm@11: 
rlm@11: The script, being an example, hardcodes the publish branch name
rlm@11: to be "next", but it is trivial to make it configurable via
rlm@11: $GIT_DIR/config mechanism.
rlm@11: 
rlm@11: With this workflow, you would want to know:
rlm@11: 
rlm@11: (1) ... if a topic branch has ever been merged to "next".  Young
rlm@11:     topic branches can have stupid mistakes you would rather
rlm@11:     clean up before publishing, and things that have not been
rlm@11:     merged into other branches can be easily rebased without
rlm@11:     affecting other people.  But once it is published, you would
rlm@11:     not want to rewind it.
rlm@11: 
rlm@11: (2) ... if a topic branch has been fully merged to "master".
rlm@11:     Then you can delete it.  More importantly, you should not
rlm@11:     build on top of it -- other people may already want to
rlm@11:     change things related to the topic as patches against your
rlm@11:     "master", so if you need further changes, it is better to
rlm@11:     fork the topic (perhaps with the same name) afresh from the
rlm@11:     tip of "master".
rlm@11: 
rlm@11: Let's look at this example:
rlm@11: 
rlm@11: 		   o---o---o---o---o---o---o---o---o---o "next"
rlm@11: 		  /       /           /           /
rlm@11: 		 /   a---a---b A     /           /
rlm@11: 		/   /               /           /
rlm@11: 	       /   /   c---c---c---c B         /
rlm@11: 	      /   /   /             \         /
rlm@11: 	     /   /   /   b---b C     \       /
rlm@11: 	    /   /   /   /             \     /
rlm@11:     ---o---o---o---o---o---o---o---o---o---o---o "master"
rlm@11: 
rlm@11: 
rlm@11: A, B and C are topic branches.
rlm@11: 
rlm@11:  * A has one fix since it was merged up to "next".
rlm@11: 
rlm@11:  * B has finished.  It has been fully merged up to "master" and "next",
rlm@11:    and is ready to be deleted.
rlm@11: 
rlm@11:  * C has not merged to "next" at all.
rlm@11: 
rlm@11: We would want to allow C to be rebased, refuse A, and encourage
rlm@11: B to be deleted.
rlm@11: 
rlm@11: To compute (1):
rlm@11: 
rlm@11: 	git-rev-list ^master ^topic next
rlm@11: 	git-rev-list ^master        next
rlm@11: 
rlm@11: 	if these match, topic has not merged in next at all.
rlm@11: 
rlm@11: To compute (2):
rlm@11: 
rlm@11: 	git-rev-list master..topic
rlm@11: 
rlm@11: 	if this is empty, it is fully merged to "master".