hash: require hash algorithm in `empty_tree_oid_hex()`
[git/gitster.git] / templates / hooks--pre-rebase.sample
blobdb5feab8a1ee6433108ade9e165956678a3e260b
1 #!/bin/sh
3 # Copyright (c) 2006, 2008 Junio C Hamano
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.
9 # The hook is called with the following parameters:
11 # $1 -- the upstream the series was forked from.
12 # $2 -- the branch being rebased (or empty when rebasing the current branch).
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.
18 publish=next
19 basebranch="$1"
20 if test "$#" = 2
21 then
22 topic="refs/heads/$2"
23 else
24 topic=`git symbolic-ref HEAD` ||
25 exit 0 ;# we do not interrupt rebasing detached HEAD
28 case "$topic" in
29 refs/heads/??/*)
32 exit 0 ;# we do not interrupt others.
34 esac
36 # Now we are dealing with a topic branch being rebased
37 # on top of master. Is it OK to rebase it?
39 # Does the topic really exist?
40 git show-ref -q "$topic" || {
41 echo >&2 "No such branch $topic"
42 exit 1
45 # Is topic fully merged to master?
46 not_in_master=`git rev-list --pretty=oneline ^master "$topic"`
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.
53 # Is topic ever merged to next? If so you should not be rebasing it.
54 only_next_1=`git rev-list ^master "^$topic" ${publish} | sort`
55 only_next_2=`git rev-list ^master ${publish} | sort`
56 if test "$only_next_1" = "$only_next_2"
57 then
58 not_in_topic=`git rev-list "^$topic" master`
59 if test -z "$not_in_topic"
60 then
61 echo >&2 "$topic is already up to date with master"
62 exit 1 ;# we could allow it, but there is no point.
63 else
64 exit 0
66 else
67 not_in_next=`git rev-list --pretty=oneline ^${publish} "$topic"`
68 @PERL_PATH@ -e '
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;
84 print STDERR " $elem->[1]\n";
87 ' "$topic" "$not_in_next" "$not_in_master"
88 exit 1
91 <<\DOC_END
93 This sample hook safeguards topic branches that have been
94 published from being rewound.
96 The workflow assumed here is:
98 * Once a topic branch forks from "master", "master" is never
99 merged into it again (either directly or indirectly).
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.
107 * Whenever you need to test or publish your changes to topic
108 branches, merge them into "next" branch.
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.
114 With this workflow, you would want to know:
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.
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".
131 Let's look at this example:
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"
144 A, B and C are topic branches.
146 * A has one fix since it was merged up to "next".
148 * B has finished. It has been fully merged up to "master" and "next",
149 and is ready to be deleted.
151 * C has not merged to "next" at all.
153 We would want to allow C to be rebased, refuse A, and encourage
154 B to be deleted.
156 To compute (1):
158 git rev-list ^master ^topic next
159 git rev-list ^master next
161 if these match, topic has not merged in next at all.
163 To compute (2):
165 git rev-list master..topic
167 if this is empty, it is fully merged to "master".
169 DOC_END