checkout: merge local modifications while switching branches.
[git/git.git] / git-checkout.sh
1 #!/bin/sh
2
3 USAGE='[-f] [-b <new_branch>] [-m] [<branch>] [<paths>...]'
4 SUBDIRECTORY_OK=Sometimes
5 . git-sh-setup
6
7 old=$(git-rev-parse HEAD)
8 new=
9 force=
10 branch=
11 newbranch=
12 merge=
13 while [ "$#" != "0" ]; do
14 arg="$1"
15 shift
16 case "$arg" in
17 "-b")
18 newbranch="$1"
19 shift
20 [ -z "$newbranch" ] &&
21 die "git checkout: -b needs a branch name"
22 [ -e "$GIT_DIR/refs/heads/$newbranch" ] &&
23 die "git checkout: branch $newbranch already exists"
24 git-check-ref-format "heads/$newbranch" ||
25 die "we do not like '$newbranch' as a branch name."
26 ;;
27 "-f")
28 force=1
29 ;;
30 -m)
31 merge=1
32 ;;
33 --)
34 break
35 ;;
36 -*)
37 usage
38 ;;
39 *)
40 if rev=$(git-rev-parse --verify "$arg^0" 2>/dev/null)
41 then
42 if [ -z "$rev" ]; then
43 echo "unknown flag $arg"
44 exit 1
45 fi
46 new="$rev"
47 if [ -f "$GIT_DIR/refs/heads/$arg" ]; then
48 branch="$arg"
49 fi
50 elif rev=$(git-rev-parse --verify "$arg^{tree}" 2>/dev/null)
51 then
52 # checking out selected paths from a tree-ish.
53 new="$rev"
54 branch=
55 else
56 new=
57 branch=
58 set x "$arg" "$@"
59 shift
60 fi
61 break
62 ;;
63 esac
64 done
65
66 # The behaviour of the command with and without explicit path
67 # parameters is quite different.
68 #
69 # Without paths, we are checking out everything in the work tree,
70 # possibly switching branches. This is the traditional behaviour.
71 #
72 # With paths, we are _never_ switching branch, but checking out
73 # the named paths from either index (when no rev is given),
74 # or the named tree-ish (when rev is given).
75
76 if test "$#" -ge 1
77 then
78 if test '' != "$newbranch$force$merge"
79 then
80 die "updating paths and switching branches or forcing are incompatible."
81 fi
82 if test '' != "$new"
83 then
84 # from a specific tree-ish; note that this is for
85 # rescuing paths and is never meant to remove what
86 # is not in the named tree-ish.
87 git-ls-tree --full-name -r "$new" "$@" |
88 git-update-index --index-info || exit $?
89 fi
90 git-checkout-index -f -u -- "$@"
91 exit $?
92 else
93 # Make sure we did not fall back on $arg^{tree} codepath
94 # since we are not checking out from an arbitrary tree-ish,
95 # but switching branches.
96 if test '' != "$new"
97 then
98 git-rev-parse --verify "$new^{commit}" >/dev/null 2>&1 ||
99 die "Cannot switch branch to a non-commit."
100 fi
101 fi
102
103 # We are switching branches and checking out trees, so
104 # we *NEED* to be at the toplevel.
105 cdup=$(git-rev-parse --show-cdup)
106 if test ! -z "$cdup"
107 then
108 cd "$cdup"
109 fi
110
111 [ -z "$new" ] && new=$old
112
113 # If we don't have an old branch that we're switching to,
114 # and we don't have a new branch name for the target we
115 # are switching to, then we'd better just be checking out
116 # what we already had
117
118 [ -z "$branch$newbranch" ] &&
119 [ "$new" != "$old" ] &&
120 die "git checkout: you need to specify a new branch name"
121
122 if [ "$force" ]
123 then
124 git-read-tree --reset $new &&
125 git-checkout-index -q -f -u -a
126 else
127 git-update-index --refresh >/dev/null
128 merge_error=$(git-read-tree -m -u $old $new 2>&1) || (
129 case "$merge" in
130 '')
131 echo >&2 "$merge_error"
132 exit 1 ;;
133 esac
134
135 # Match the index to the working tree, and do a three-way.
136 git diff-files --name-only | git update-index --remove --stdin &&
137 work=`git write-tree` &&
138 git read-tree --reset $new &&
139 git checkout-index -f -u -q -a &&
140 git read-tree -m -u $old $new $work || exit
141
142 if result=`git write-tree 2>/dev/null`
143 then
144 echo >&2 "Trivially automerged."
145 else
146 git merge-index -o git-merge-one-file -a
147 fi
148
149 # Do not register the cleanly merged paths in the index yet.
150 # this is not a real merge before committing, but just carrying
151 # the working tree changes along.
152 unmerged=`git ls-files -u`
153 git read-tree --reset $new
154 case "$unmerged" in
155 '') ;;
156 *)
157 (
158 z40=0000000000000000000000000000000000000000
159 echo "$unmerged" |
160 sed -e 's/^[0-7]* [0-9a-f]* /'"0 $z40 /"
161 echo "$unmerged"
162 ) | git update-index --index-info
163 ;;
164 esac
165 exit 0
166 )
167 fi
168
169 #
170 # Switch the HEAD pointer to the new branch if we
171 # checked out a branch head, and remove any potential
172 # old MERGE_HEAD's (subsequent commits will clearly not
173 # be based on them, since we re-set the index)
174 #
175 if [ "$?" -eq 0 ]; then
176 if [ "$newbranch" ]; then
177 leading=`expr "refs/heads/$newbranch" : '\(.*\)/'` &&
178 mkdir -p "$GIT_DIR/$leading" &&
179 echo $new >"$GIT_DIR/refs/heads/$newbranch" || exit
180 branch="$newbranch"
181 fi
182 [ "$branch" ] &&
183 GIT_DIR="$GIT_DIR" git-symbolic-ref HEAD "refs/heads/$branch"
184 rm -f "$GIT_DIR/MERGE_HEAD"
185 else
186 exit 1
187 fi