git-checkout.sh

   1 #!/bin/sh
   2 . git-sh-setup || die "Not a git archive"
   3
   4 old=$(git-rev-parse HEAD)
   5 new=
   6 force=
   7 branch=
   8 newbranch=
   9 while [ "$#" != "0" ]; do
  10     arg="$1"
  11     shift
  12     case "$arg" in
  13         "-b")
  14                 newbranch="$1"
  15                 shift
  16                 [ -z "$newbranch" ] &&
  17                         die "git checkout: -b needs a branch name"
  18                 [ -e "$GIT_DIR/refs/heads/$newbranch" ] &&
  19                         die "git checkout: branch $newbranch already exists"
  20                 ;;
  21         "-f")
  22                 force=1
  23                 ;;
  24         *)
  25                 rev=$(git-rev-parse --verify "$arg^0") || exit
  26                 if [ -z "$rev" ]; then
  27                         echo "unknown flag $arg"
  28                         exit 1
  29                 fi
  30                 if [ "$new" ]; then
  31                         echo "Multiple revisions?"
  32                         exit 1
  33                 fi
  34                 new="$rev"
  35                 if [ -f "$GIT_DIR/refs/heads/$arg" ]; then
  36                         branch="$arg"
  37                 fi
  38                 ;;
  39     esac
  40 done
  41 [ -z "$new" ] && new=$old
  42
  43 #
  44 # If we don't have an old branch that we're switching to,
  45 # and we don't have a new branch name for the target we
  46 # are switching to, then we'd better just be checking out
  47 # what we already had
  48 #
  49 [ -z "$branch$newbranch" ] &&
  50         [ "$new" != "$old" ] &&
  51         die "git checkout: you need to specify a new branch name"
  52
  53 if [ "$force" ]
  54 then
  55     git-read-tree --reset $new &&
  56         git-checkout-index -q -f -u -a
  57 else
  58     git-read-tree -m -u $old $new
  59 fi
  60
  61 #
  62 # Switch the HEAD pointer to the new branch if it we
  63 # checked out a branch head, and remove any potential
  64 # old MERGE_HEAD's (subsequent commits will clearly not
  65 # be based on them, since we re-set the index)
  66 #
  67 if [ "$?" -eq 0 ]; then
  68         if [ "$newbranch" ]; then
  69                 echo $new > "$GIT_DIR/refs/heads/$newbranch"
  70                 branch="$newbranch"
  71         fi
  72         [ "$branch" ] && ln -sf "refs/heads/$branch" "$GIT_DIR/HEAD"
  73         rm -f "$GIT_DIR/MERGE_HEAD"
  74 else
  75         exit 1
  76 fi