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Diffstat (limited to 'documents.git/hooks/pre-rebase.sample')
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1 files changed, 169 insertions, 0 deletions
diff --git a/documents.git/hooks/pre-rebase.sample b/documents.git/hooks/pre-rebase.sample new file mode 100644 index 00000000..6cbef5c3 --- /dev/null +++ b/documents.git/hooks/pre-rebase.sample @@ -0,0 +1,169 @@ +#!/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 + +<<\DOC_END + +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". + +DOC_END |