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