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