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 require_work_tree
   7
   8 old_name=HEAD
   9 old=$(git-rev-parse --verify $old_name 2>/dev/null)
  10 oldbranch=$(git-symbolic-ref $old_name 2>/dev/null)
  11 new=
  12 new_name=
  13 force=
  14 branch=
  15 newbranch=
  16 newbranch_log=
  17 merge=
  18 LF='
  19 '
  20 while [ "$#" != "0" ]; do
  21     arg="$1"
  22     shift
  23     case "$arg" in
  24         "-b")
  25                 newbranch="$1"
  26                 shift
  27                 [ -z "$newbranch" ] &&
  28                         die "git checkout: -b needs a branch name"
  29                 git-show-ref --verify --quiet -- "refs/heads/$newbranch" &&
  30                         die "git checkout: branch $newbranch already exists"
  31                 git-check-ref-format "heads/$newbranch" ||
  32                         die "git checkout: we do not like '$newbranch' as a branch name."
  33                 ;;
  34         "-l")
  35                 newbranch_log=1
  36                 ;;
  37         "-f")
  38                 force=1
  39                 ;;
  40         -m)
  41                 merge=1
  42                 ;;
  43         --)
  44                 break
  45                 ;;
  46         -*)
  47                 usage
  48                 ;;
  49         *)
  50                 if rev=$(git-rev-parse --verify "$arg^0" 2>/dev/null)
  51                 then
  52                         if [ -z "$rev" ]; then
  53                                 echo "unknown flag $arg"
  54                                 exit 1
  55                         fi
  56                         new="$rev"
  57                         new_name="$arg"
  58                         if git-show-ref --verify --quiet -- "refs/heads/$arg"
  59                         then
  60                                 branch="$arg"
  61                         fi
  62                 elif rev=$(git-rev-parse --verify "$arg^{tree}" 2>/dev/null)
  63                 then
  64                         # checking out selected paths from a tree-ish.
  65                         new="$rev"
  66                         new_name="$arg^{tree}"
  67                         branch=
  68                 else
  69                         new=
  70                         new_name=
  71                         branch=
  72                         set x "$arg" "$@"
  73                         shift
  74                 fi
  75                 case "$1" in
  76                 --)
  77                         shift ;;
  78                 esac
  79                 break
  80                 ;;
  81     esac
  82 done
  83
  84 case "$force$merge" in
  85 11)
  86         die "git checkout: -f and -m are incompatible"
  87 esac
  88
  89 # The behaviour of the command with and without explicit path
  90 # parameters is quite different.
  91 #
  92 # Without paths, we are checking out everything in the work tree,
  93 # possibly switching branches.  This is the traditional behaviour.
  94 #
  95 # With paths, we are _never_ switching branch, but checking out
  96 # the named paths from either index (when no rev is given),
  97 # or the named tree-ish (when rev is given).
  98
  99 if test "$#" -ge 1
 100 then
 101         hint=
 102         if test "$#" -eq 1
 103         then
 104                 hint="
 105 Did you intend to checkout '$@' which can not be resolved as commit?"
 106         fi
 107         if test '' != "$newbranch$force$merge"
 108         then
 109                 die "git checkout: updating paths is incompatible with switching branches/forcing$hint"
 110         fi
 111         if test '' != "$new"
 112         then
 113                 # from a specific tree-ish; note that this is for
 114                 # rescuing paths and is never meant to remove what
 115                 # is not in the named tree-ish.
 116                 git-ls-tree --full-name -r "$new" "$@" |
 117                 git-update-index --index-info || exit $?
 118         fi
 119
 120         # Make sure the request is about existing paths.
 121         git-ls-files --error-unmatch -- "$@" >/dev/null || exit
 122         git-ls-files -- "$@" |
 123         git-checkout-index -f -u --stdin
 124         exit $?
 125 else
 126         # Make sure we did not fall back on $arg^{tree} codepath
 127         # since we are not checking out from an arbitrary tree-ish,
 128         # but switching branches.
 129         if test '' != "$new"
 130         then
 131                 git-rev-parse --verify "$new^{commit}" >/dev/null 2>&1 ||
 132                 die "Cannot switch branch to a non-commit."
 133         fi
 134 fi
 135
 136 # We are switching branches and checking out trees, so
 137 # we *NEED* to be at the toplevel.
 138 cd_to_toplevel
 139
 140 [ -z "$new" ] && new=$old && new_name="$old_name"
 141
 142 # If we don't have an existing 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 are detaching our HEAD from any
 145 # branch.  However, if "git checkout HEAD" detaches the HEAD
 146 # from the current branch, even though that may be logically
 147 # correct, it feels somewhat funny.  More importantly, we do not
 148 # want "git checkout" nor "git checkout -f" to detach HEAD.
 149
 150 detached=
 151 detach_warn=
 152
 153 if test -z "$branch$newbranch" && test "$new" != "$old"
 154 then
 155         detached="$new"
 156         if test -n "$oldbranch"
 157         then
 158                 detach_warn="warning: you are not on ANY branch anymore.
 159 If you meant to create a new branch from the commit, you need -b to
 160 associate a new branch with the wanted checkout.  Example:
 161   git checkout -b <new_branch_name> $arg"
 162         fi
 163 elif test -z "$oldbranch" && test -n "$branch"
 164 then
 165         # Coming back...
 166         if test -z "$force"
 167         then
 168                 git show-ref -d -s | grep "$old" >/dev/null || {
 169                         echo >&2 \
 170 "You are not on any branch and switching to branch '$new_name'
 171 may lose your changes.  At this point, you can do one of two things:
 172  (1) Decide it is Ok and say 'git checkout -f $new_name';
 173  (2) Start a new branch from the current commit, by saying
 174      'git checkout -b <branch-name>'.
 175 Leaving your HEAD detached; not switching to branch '$new_name'."
 176                         exit 1;
 177                 }
 178         fi
 179 fi
 180
 181 if [ "X$old" = X ]
 182 then
 183         echo >&2 "warning: You appear to be on a branch yet to be born."
 184         echo >&2 "warning: Forcing checkout of $new_name."
 185         force=1
 186 fi
 187
 188 if [ "$force" ]
 189 then
 190     git-read-tree --reset -u $new
 191 else
 192     git-update-index --refresh >/dev/null
 193     merge_error=$(git-read-tree -m -u --exclude-per-directory=.gitignore $old $new 2>&1) || (
 194         case "$merge" in
 195         '')
 196                 echo >&2 "$merge_error"
 197                 exit 1 ;;
 198         esac
 199
 200         # Match the index to the working tree, and do a three-way.
 201         git diff-files --name-only | git update-index --remove --stdin &&
 202         work=`git write-tree` &&
 203         git read-tree --reset -u $new &&
 204         git read-tree -m -u --aggressive --exclude-per-directory=.gitignore $old $new $work ||
 205         exit
 206
 207         if result=`git write-tree 2>/dev/null`
 208         then
 209             echo >&2 "Trivially automerged."
 210         else
 211             git merge-index -o git-merge-one-file -a
 212         fi
 213
 214         # Do not register the cleanly merged paths in the index yet.
 215         # this is not a real merge before committing, but just carrying
 216         # the working tree changes along.
 217         unmerged=`git ls-files -u`
 218         git read-tree --reset $new
 219         case "$unmerged" in
 220         '')     ;;
 221         *)
 222                 (
 223                         z40=0000000000000000000000000000000000000000
 224                         echo "$unmerged" |
 225                         sed -e 's/^[0-7]* [0-9a-f]* /'"0 $z40 /"
 226                         echo "$unmerged"
 227                 ) | git update-index --index-info
 228                 ;;
 229         esac
 230         exit 0
 231     )
 232     saved_err=$?
 233     if test "$saved_err" = 0
 234     then
 235         test "$new" = "$old" || git diff-index --name-status "$new"
 236     fi
 237     (exit $saved_err)
 238 fi
 239
 240 #
 241 # Switch the HEAD pointer to the new branch if we
 242 # checked out a branch head, and remove any potential
 243 # old MERGE_HEAD's (subsequent commits will clearly not
 244 # be based on them, since we re-set the index)
 245 #
 246 if [ "$?" -eq 0 ]; then
 247         if [ "$newbranch" ]; then
 248                 if [ "$newbranch_log" ]; then
 249                         mkdir -p $(dirname "$GIT_DIR/logs/refs/heads/$newbranch")
 250                         touch "$GIT_DIR/logs/refs/heads/$newbranch"
 251                 fi
 252                 git-update-ref -m "checkout: Created from $new_name" "refs/heads/$newbranch" $new || exit
 253                 branch="$newbranch"
 254         fi
 255         if test -n "$branch"
 256         then
 257                 GIT_DIR="$GIT_DIR" git-symbolic-ref HEAD "refs/heads/$branch"
 258         elif test -n "$detached"
 259         then
 260                 # NEEDSWORK: we would want a command to detach the HEAD
 261                 # atomically, instead of this handcrafted command sequence.
 262                 # Perhaps:
 263                 #       git update-ref --detach HEAD $new
 264                 # or something like that...
 265                 #
 266                 echo "$detached" >"$GIT_DIR/HEAD.new" &&
 267                 mv "$GIT_DIR/HEAD.new" "$GIT_DIR/HEAD" ||
 268                         die "Cannot detach HEAD"
 269                 if test -n "$detach_warn"
 270                 then
 271                         echo >&2 "$detach_warn"
 272                 fi
 273         fi
 274         rm -f "$GIT_DIR/MERGE_HEAD"
 275 else
 276         exit 1
 277 fi