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