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