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