git-checkout: allow "checkout HEAD -- path"
[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=$(git-rev-parse HEAD)
8 old_name=HEAD
9 new=
10 new_name=
11 force=
12 branch=
13 newbranch=
14 newbranch_log=
15 merge=
16 while [ "$#" != "0" ]; do
17 arg="$1"
18 shift
19 case "$arg" in
20 "-b")
21 newbranch="$1"
22 shift
23 [ -z "$newbranch" ] &&
24 die "git checkout: -b needs a branch name"
25 [ -e "$GIT_DIR/refs/heads/$newbranch" ] &&
26 die "git checkout: branch $newbranch already exists"
27 git-check-ref-format "heads/$newbranch" ||
28 die "git checkout: we do not like '$newbranch' as a branch name."
29 ;;
30 "-l")
31 newbranch_log=1
32 ;;
33 "-f")
34 force=1
35 ;;
36 -m)
37 merge=1
38 ;;
39 --)
40 break
41 ;;
42 -*)
43 usage
44 ;;
45 *)
46 if rev=$(git-rev-parse --verify "$arg^0" 2>/dev/null)
47 then
48 if [ -z "$rev" ]; then
49 echo "unknown flag $arg"
50 exit 1
51 fi
52 new="$rev"
53 new_name="$arg^0"
54 if [ -f "$GIT_DIR/refs/heads/$arg" ]; then
55 branch="$arg"
56 fi
57 elif rev=$(git-rev-parse --verify "$arg^{tree}" 2>/dev/null)
58 then
59 # checking out selected paths from a tree-ish.
60 new="$rev"
61 new_name="$arg^{tree}"
62 branch=
63 else
64 new=
65 new_name=
66 branch=
67 set x "$arg" "$@"
68 shift
69 fi
70 case "$1" in
71 --)
72 shift ;;
73 esac
74 break
75 ;;
76 esac
77 done
78
79 # The behaviour of the command with and without explicit path
80 # parameters is quite different.
81 #
82 # Without paths, we are checking out everything in the work tree,
83 # possibly switching branches. This is the traditional behaviour.
84 #
85 # With paths, we are _never_ switching branch, but checking out
86 # the named paths from either index (when no rev is given),
87 # or the named tree-ish (when rev is given).
88
89 if test "$#" -ge 1
90 then
91 hint=
92 if test "$#" -eq 1
93 then
94 hint="
95 Did you intend to checkout '$@' which can not be resolved as commit?"
96 fi
97 if test '' != "$newbranch$force$merge"
98 then
99 die "git checkout: updating paths is incompatible with switching branches/forcing$hint"
100 fi
101 if test '' != "$new"
102 then
103 # from a specific tree-ish; note that this is for
104 # rescuing paths and is never meant to remove what
105 # is not in the named tree-ish.
106 git-ls-tree --full-name -r "$new" "$@" |
107 git-update-index --index-info || exit $?
108 fi
109 git-checkout-index -f -u -- "$@"
110 exit $?
111 else
112 # Make sure we did not fall back on $arg^{tree} codepath
113 # since we are not checking out from an arbitrary tree-ish,
114 # but switching branches.
115 if test '' != "$new"
116 then
117 git-rev-parse --verify "$new^{commit}" >/dev/null 2>&1 ||
118 die "Cannot switch branch to a non-commit."
119 fi
120 fi
121
122 # We are switching branches and checking out trees, so
123 # we *NEED* to be at the toplevel.
124 cdup=$(git-rev-parse --show-cdup)
125 if test ! -z "$cdup"
126 then
127 cd "$cdup"
128 fi
129
130 [ -z "$new" ] && new=$old && new_name="$old_name"
131
132 # If we don't have an old branch that we're switching to,
133 # and we don't have a new branch name for the target we
134 # are switching to, then we'd better just be checking out
135 # what we already had
136
137 [ -z "$branch$newbranch" ] &&
138 [ "$new" != "$old" ] &&
139 die "git checkout: to checkout the requested commit you need to specify
140 a name for a new branch which is created and switched to"
141
142 if [ "$force" ]
143 then
144 git-read-tree --reset -u $new
145 else
146 git-update-index --refresh >/dev/null
147 merge_error=$(git-read-tree -m -u $old $new 2>&1) || (
148 case "$merge" in
149 '')
150 echo >&2 "$merge_error"
151 exit 1 ;;
152 esac
153
154 # Match the index to the working tree, and do a three-way.
155 git diff-files --name-only | git update-index --remove --stdin &&
156 work=`git write-tree` &&
157 git read-tree --reset -u $new &&
158 git read-tree -m -u --aggressive $old $new $work || exit
159
160 if result=`git write-tree 2>/dev/null`
161 then
162 echo >&2 "Trivially automerged."
163 else
164 git merge-index -o git-merge-one-file -a
165 fi
166
167 # Do not register the cleanly merged paths in the index yet.
168 # this is not a real merge before committing, but just carrying
169 # the working tree changes along.
170 unmerged=`git ls-files -u`
171 git read-tree --reset $new
172 case "$unmerged" in
173 '') ;;
174 *)
175 (
176 z40=0000000000000000000000000000000000000000
177 echo "$unmerged" |
178 sed -e 's/^[0-7]* [0-9a-f]* /'"0 $z40 /"
179 echo "$unmerged"
180 ) | git update-index --index-info
181 ;;
182 esac
183 exit 0
184 )
185 saved_err=$?
186 if test "$saved_err" = 0
187 then
188 test "$new" = "$old" || git diff-index --name-status "$new"
189 fi
190 (exit $saved_err)
191 fi
192
193 #
194 # Switch the HEAD pointer to the new branch if we
195 # checked out a branch head, and remove any potential
196 # old MERGE_HEAD's (subsequent commits will clearly not
197 # be based on them, since we re-set the index)
198 #
199 if [ "$?" -eq 0 ]; then
200 if [ "$newbranch" ]; then
201 if [ "$newbranch_log" ]; then
202 mkdir -p $(dirname "$GIT_DIR/logs/refs/heads/$newbranch")
203 touch "$GIT_DIR/logs/refs/heads/$newbranch"
204 fi
205 git-update-ref -m "checkout: Created from $new_name" "refs/heads/$newbranch" $new || exit
206 branch="$newbranch"
207 fi
208 [ "$branch" ] &&
209 GIT_DIR="$GIT_DIR" git-symbolic-ref HEAD "refs/heads/$branch"
210 rm -f "$GIT_DIR/MERGE_HEAD"
211 else
212 exit 1
213 fi