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9a111c91 JH |
1 | #!/bin/sh |
2 | # | |
ba2d0f4f | 3 | # Copyright (c) 2006, 2008 Junio C Hamano |
9a111c91 | 4 | # |
100e762a | 5 | # The "pre-rebase" hook is run just before "git rebase" starts doing |
ba2d0f4f JH |
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. | |
9a111c91 JH |
17 | |
18 | publish=next | |
19 | basebranch="$1" | |
20 | if test "$#" = 2 | |
21 | then | |
22 | topic="refs/heads/$2" | |
23 | else | |
ba2d0f4f JH |
24 | topic=`git symbolic-ref HEAD` || |
25 | exit 0 ;# we do not interrupt rebasing detached HEAD | |
9a111c91 JH |
26 | fi |
27 | ||
ba2d0f4f JH |
28 | case "$topic" in |
29 | refs/heads/??/*) | |
9a111c91 JH |
30 | ;; |
31 | *) | |
32 | exit 0 ;# we do not interrupt others. | |
33 | ;; | |
34 | esac | |
35 | ||
36 | # Now we are dealing with a topic branch being rebased | |
37 | # on top of master. Is it OK to rebase it? | |
38 | ||
ba2d0f4f JH |
39 | # Does the topic really exist? |
40 | git show-ref -q "$topic" || { | |
41 | echo >&2 "No such branch $topic" | |
42 | exit 1 | |
43 | } | |
44 | ||
9a111c91 | 45 | # Is topic fully merged to master? |
100e762a | 46 | not_in_master=`git rev-list --pretty=oneline ^master "$topic"` |
9a111c91 JH |
47 | if test -z "$not_in_master" |
48 | then | |
49 | echo >&2 "$topic is fully merged to master; better remove it." | |
50 | exit 1 ;# we could allow it, but there is no point. | |
51 | fi | |
52 | ||
53 | # Is topic ever merged to next? If so you should not be rebasing it. | |
100e762a BW |
54 | only_next_1=`git rev-list ^master "^$topic" ${publish} | sort` |
55 | only_next_2=`git rev-list ^master ${publish} | sort` | |
9a111c91 JH |
56 | if test "$only_next_1" = "$only_next_2" |
57 | then | |
100e762a | 58 | not_in_topic=`git rev-list "^$topic" master` |
9a111c91 JH |
59 | if test -z "$not_in_topic" |
60 | then | |
7560f547 | 61 | echo >&2 "$topic is already up to date with master" |
9a111c91 JH |
62 | exit 1 ;# we could allow it, but there is no point. |
63 | else | |
64 | exit 0 | |
65 | fi | |
66 | else | |
100e762a | 67 | not_in_next=`git rev-list --pretty=oneline ^${publish} "$topic"` |
502be959 | 68 | @PERL_PATH@ -e ' |
9a111c91 JH |
69 | my $topic = $ARGV[0]; |
70 | my $msg = "* $topic has 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" | |
88 | exit 1 | |
89 | fi | |
90 | ||
8db1ae57 | 91 | <<\DOC_END |
9a111c91 JH |
92 | |
93 | This sample hook safeguards topic branches that have been | |
94 | published from being rewound. | |
95 | ||
96 | The workflow assumed here is: | |
97 | ||
98 | * Once a topic branch forks from "master", "master" is never | |
99 | merged into it again (either directly or indirectly). | |
100 | ||
101 | * Once a topic branch is fully cooked and merged into "master", | |
102 | it is deleted. If you need to build on top of it to correct | |
103 | earlier mistakes, a new topic branch is created by forking at | |
104 | the tip of the "master". This is not strictly necessary, but | |
105 | it makes it easier to keep your history simple. | |
106 | ||
107 | * Whenever you need to test or publish your changes to topic | |
108 | branches, merge them into "next" branch. | |
109 | ||
110 | The script, being an example, hardcodes the publish branch name | |
111 | to be "next", but it is trivial to make it configurable via | |
112 | $GIT_DIR/config mechanism. | |
113 | ||
114 | With this workflow, you would want to know: | |
115 | ||
116 | (1) ... if a topic branch has ever been merged to "next". Young | |
117 | topic branches can have stupid mistakes you would rather | |
118 | clean up before publishing, and things that have not been | |
119 | merged into other branches can be easily rebased without | |
120 | affecting other people. But once it is published, you would | |
121 | not want to rewind it. | |
122 | ||
123 | (2) ... if a topic branch has been fully merged to "master". | |
124 | Then you can delete it. More importantly, you should not | |
125 | build on top of it -- other people may already want to | |
126 | change things related to the topic as patches against your | |
127 | "master", so if you need further changes, it is better to | |
128 | fork the topic (perhaps with the same name) afresh from the | |
129 | tip of "master". | |
130 | ||
131 | Let's look at this example: | |
132 | ||
133 | o---o---o---o---o---o---o---o---o---o "next" | |
134 | / / / / | |
135 | / a---a---b A / / | |
136 | / / / / | |
137 | / / c---c---c---c B / | |
138 | / / / \ / | |
139 | / / / b---b C \ / | |
140 | / / / / \ / | |
141 | ---o---o---o---o---o---o---o---o---o---o---o "master" | |
142 | ||
143 | ||
144 | A, B and C are topic branches. | |
145 | ||
146 | * A has one fix since it was merged up to "next". | |
147 | ||
148 | * B has finished. It has been fully merged up to "master" and "next", | |
149 | and is ready to be deleted. | |
150 | ||
151 | * C has not merged to "next" at all. | |
152 | ||
153 | We would want to allow C to be rebased, refuse A, and encourage | |
154 | B to be deleted. | |
155 | ||
156 | To compute (1): | |
157 | ||
100e762a BW |
158 | git rev-list ^master ^topic next |
159 | git rev-list ^master next | |
9a111c91 JH |
160 | |
161 | if these match, topic has not merged in next at all. | |
162 | ||
163 | To compute (2): | |
164 | ||
100e762a | 165 | git rev-list master..topic |
9a111c91 JH |
166 | |
167 | if this is empty, it is fully merged to "master". | |
8db1ae57 JN |
168 | |
169 | DOC_END |