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 "$arg^0" 2>/dev/null) ||
  26                         die "I don't know any '$arg'."
  27                 if [ -z "$rev" ]; then
  28                         echo "unknown flag $arg"
  29                         exit 1
  30                 fi
  31                 if [ "$new" ]; then
  32                         echo "Multiple revisions?"
  33                         exit 1
  34                 fi
  35                 new="$rev"
  36                 if [ -f "$GIT_DIR/refs/heads/$arg" ]; then
  37                         branch="$arg"
  38                 fi
  39                 ;;
  40     esac
  41 done
  42 [ -z "$new" ] && new=$old
  43
  44 #
  45 # If we don't have an old branch that we're switching to,
  46 # and we don't have a new branch name for the target we
  47 # are switching to, then we'd better just be checking out
  48 # what we already had
  49 #
  50 [ -z "$branch$newbranch" ] &&
  51         [ "$new" != "$old" ] &&
  52         die "git checkout: you need to specify a new branch name"
  53
  54 if [ "$force" ]
  55 then
  56     git-read-tree --reset $new &&
  57         git-checkout-index -q -f -u -a
  58 else
  59     git-update-index --refresh >/dev/null
  60     git-read-tree -m -u $old $new
  61 fi
  62
  63 #
  64 # Switch the HEAD pointer to the new branch if it we
  65 # checked out a branch head, and remove any potential
  66 # old MERGE_HEAD's (subsequent commits will clearly not
  67 # be based on them, since we re-set the index)
  68 #
  69 if [ "$?" -eq 0 ]; then
  70         if [ "$newbranch" ]; then
  71                 echo $new > "$GIT_DIR/refs/heads/$newbranch"
  72                 branch="$newbranch"
  73         fi
  74         [ "$branch" ] && ln -sf "refs/heads/$branch" "$GIT_DIR/HEAD"
  75         rm -f "$GIT_DIR/MERGE_HEAD"
  76 else
  77         exit 1
  78 fi