1#!/bin/sh 2# 3# Copyright (c) 2006, 2008 Junio C Hamano 4# 5# The "pre-rebase" hook is run just before "git rebase" starts doing 6# its job, and can prevent the command from running by exiting with 7# non-zero status. 8# 9# The hook is called with the following parameters: 10# 11# $1 -- the upstream the series was forked from. 12# $2 -- the branch being rebased (or empty when rebasing the current branch). 13# 14# This sample shows how to prevent topic branches that are already 15# merged to 'next' branch from getting rebased, because allowing it 16# would result in rebasing already published history. 17 18publish=next 19basebranch="$1" 20iftest"$#"=2 21then 22 topic="refs/heads/$2" 23else 24 topic=`git symbolic-ref HEAD`|| 25exit0;# we do not interrupt rebasing detached HEAD 26fi 27 28case"$topic"in 29refs/heads/??/*) 30;; 31*) 32exit0;# we do not interrupt others. 33;; 34esac 35 36# Now we are dealing with a topic branch being rebased 37# on top of master. Is it OK to rebase it? 38 39# Does the topic really exist? 40git show-ref -q"$topic"|| { 41echo>&2"No such branch$topic" 42exit1 43} 44 45# Is topic fully merged to master? 46not_in_master=`git rev-list --pretty=oneline ^master "$topic"` 47iftest -z"$not_in_master" 48then 49echo>&2"$topicis fully merged to master; better remove it." 50exit1;# we could allow it, but there is no point. 51fi 52 53# Is topic ever merged to next? If so you should not be rebasing it. 54only_next_1=`git rev-list ^master "^$topic"${publish}| sort` 55only_next_2=`git rev-list ^master${publish}| sort` 56iftest"$only_next_1"="$only_next_2" 57then 58 not_in_topic=`git rev-list "^$topic" master` 59iftest -z"$not_in_topic" 60then 61echo>&2"$topicis already up-to-date with master" 62exit1;# we could allow it, but there is no point. 63else 64exit0 65fi 66else 67 not_in_next=`git rev-list --pretty=oneline ^${publish}"$topic"` 68 @PERL_PATH@ -e' 69 my$topic=$ARGV[0]; 70 my$msg= "*$topichas commits already merged to public branch:\n"; 71 my (%not_in_next) = map { 72 /^([0-9a-f]+) /; 73 ($1=> 1); 74 } split(/\n/,$ARGV[1]); 75 for my$elem(map { 76 /^([0-9a-f]+) (.*)$/; 77 [$1=>$2]; 78 } split(/\n/,$ARGV[2])) { 79 if (!exists$not_in_next{$elem->[0]}) { 80 if ($msg) { 81 print STDERR$msg; 82 undef$msg; 83 } 84 print STDERR "$elem->[1]\n"; 85 } 86 } 87 '"$topic""$not_in_next""$not_in_master" 88exit1 89fi 90 91exit0 92 93################################################################ 94 95This sample hook safeguards topic branches that have been 96published from being rewound. 97 98The workflow assumed here is: 99 100* Once a topic branch forks from "master","master" is never 101 merged into it again (either directly or indirectly). 102 103* Once a topic branch is fully cooked and merged into "master", 104 it is deleted. If you need to build on top of it to correct 105 earlier mistakes, a new topic branch is created by forking at 106 the tip of the "master". This is not strictly necessary, but 107 it makes it easier to keep your history simple. 108 109* Whenever you need to test or publish your changes to topic 110 branches, merge them into "next" branch. 111 112The script, being an example, hardcodes the publish branch name 113to be "next", but it is trivial to make it configurable via 114$GIT_DIR/config mechanism. 115 116With this workflow, you would want to know: 117 118(1) ... if a topic branch has ever been merged to "next". Young 119 topic branches can have stupid mistakes you would rather 120 clean up before publishing, and things that have not been 121 merged into other branches can be easily rebased without 122 affecting other people. But once it is published, you would 123 not want to rewind it. 124 125(2) ... if a topic branch has been fully merged to "master". 126 Then you can delete it. More importantly, you should not 127 build on top of it -- other people may already want to 128 change things related to the topic as patches against your 129"master", so if you need further changes, it is better to 130 fork the topic (perhaps with the same name) afresh from the 131 tip of "master". 132 133Let's look at this example: 134 135 o---o---o---o---o---o---o---o---o---o "next" 136 / / / / 137 / a---a---b A / / 138 / / / / 139 / / c---c---c---c B / 140 / / / \ / 141 / / / b---b C \ / 142 / / / / \ / 143 ---o---o---o---o---o---o---o---o---o---o---o "master" 144 145 146A, B and C are topic branches. 147 148 * A has one fix since it was merged up to "next". 149 150 * B has finished. It has been fully merged up to "master" and "next", 151 and is ready to be deleted. 152 153 * C has not merged to "next" at all. 154 155We would want to allow C to be rebased, refuse A, and encourage 156B to be deleted. 157 158To compute (1): 159 160 git rev-list ^master ^topic next 161 git rev-list ^master next 162 163 if these match, topic has not merged in next at all. 164 165To compute (2): 166 167 git rev-list master..topic 168 169 if this is empty, it is fully merged to "master".