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