Merge branch 'jc/cache-tree'
[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 "git checkout: 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 "$#" -ge 1
77 then
78         hint=
79         if test "$#" -eq 1
80         then
81                 hint="
82 Did you intend to checkout '$@' which can not be resolved as commit?"
83         fi
84         if test '' != "$newbranch$force$merge"
85         then
86                 die "git checkout: updating paths is incompatible with switching branches/forcing$hint"
87         fi
88         if test '' != "$new"
89         then
90                 # from a specific tree-ish; note that this is for
91                 # rescuing paths and is never meant to remove what
92                 # is not in the named tree-ish.
93                 git-ls-tree --full-name -r "$new" "$@" |
94                 git-update-index --index-info || exit $?
95         fi
96         git-checkout-index -f -u -- "$@"
97         exit $?
98 else
99         # Make sure we did not fall back on $arg^{tree} codepath
100         # since we are not checking out from an arbitrary tree-ish,
101         # but switching branches.
102         if test '' != "$new"
103         then
104                 git-rev-parse --verify "$new^{commit}" >/dev/null 2>&1 ||
105                 die "Cannot switch branch to a non-commit."
106         fi
107 fi
108
109 # We are switching branches and checking out trees, so
110 # we *NEED* to be at the toplevel.
111 cdup=$(git-rev-parse --show-cdup)
112 if test ! -z "$cdup"
113 then
114         cd "$cdup"
115 fi
116
117 [ -z "$new" ] && new=$old
118
119 # If we don't have an old branch that we're switching to,
120 # and we don't have a new branch name for the target we
121 # are switching to, then we'd better just be checking out
122 # what we already had
123
124 [ -z "$branch$newbranch" ] &&
125         [ "$new" != "$old" ] &&
126         die "git checkout: to checkout the requested commit you need to specify 
127               a name for a new branch which is created and switched to"
128
129 if [ "$force" ]
130 then
131     git-read-tree --reset $new &&
132         git-checkout-index -q -f -u -a
133 else
134     git-update-index --refresh >/dev/null
135     merge_error=$(git-read-tree -m -u $old $new 2>&1) || (
136         case "$merge" in
137         '')
138                 echo >&2 "$merge_error"
139                 exit 1 ;;
140         esac
141
142         # Match the index to the working tree, and do a three-way.
143         git diff-files --name-only | git update-index --remove --stdin &&
144         work=`git write-tree` &&
145         git read-tree --reset $new &&
146         git checkout-index -f -u -q -a &&
147         git read-tree -m -u --aggressive $old $new $work || exit
148
149         if result=`git write-tree 2>/dev/null`
150         then
151             echo >&2 "Trivially automerged."
152         else
153             git merge-index -o git-merge-one-file -a
154         fi
155
156         # Do not register the cleanly merged paths in the index yet.
157         # this is not a real merge before committing, but just carrying
158         # the working tree changes along.
159         unmerged=`git ls-files -u`
160         git read-tree --reset $new
161         case "$unmerged" in
162         '')     ;;
163         *)
164                 (
165                         z40=0000000000000000000000000000000000000000
166                         echo "$unmerged" |
167                         sed -e 's/^[0-7]* [0-9a-f]* /'"0 $z40 /"
168                         echo "$unmerged"
169                 ) | git update-index --index-info
170                 ;;
171         esac
172         exit 0
173     )
174     saved_err=$?
175     if test "$saved_err" = 0
176     then
177         test "$new" = "$old" || git diff-index --name-status "$new"
178     fi
179     (exit $saved_err)
180 fi
181
182
183 # Switch the HEAD pointer to the new branch if we
184 # checked out a branch head, and remove any potential
185 # old MERGE_HEAD's (subsequent commits will clearly not
186 # be based on them, since we re-set the index)
187 #
188 if [ "$?" -eq 0 ]; then
189         if [ "$newbranch" ]; then
190                 leading=`expr "refs/heads/$newbranch" : '\(.*\)/'` &&
191                 mkdir -p "$GIT_DIR/$leading" &&
192                 echo $new >"$GIT_DIR/refs/heads/$newbranch" || exit
193                 branch="$newbranch"
194         fi
195         [ "$branch" ] &&
196         GIT_DIR="$GIT_DIR" git-symbolic-ref HEAD "refs/heads/$branch"
197         rm -f "$GIT_DIR/MERGE_HEAD"
198 else
199         exit 1
200 fi