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 $newbranch already exists"
  20                 git-check-ref-format "heads/$newbranch" ||
  21                         die "we do not like '$newbranch' as a branch name."
  22                 ;;
  23         "-f")
  24                 force=1
  25                 ;;
  26         *)
  27                 rev=$(git-rev-parse --verify "$arg^0" 2>/dev/null) ||
  28                         die "I don't know any '$arg'."
  29                 if [ -z "$rev" ]; then
  30                         echo "unknown flag $arg"
  31                         exit 1
  32                 fi
  33                 if [ "$new" ]; then
  34                         echo "Multiple revisions?"
  35                         exit 1
  36                 fi
  37                 new="$rev"
  38                 if [ -f "$GIT_DIR/refs/heads/$arg" ]; then
  39                         branch="$arg"
  40                 fi
  41                 ;;
  42     esac
  43 done
  44 [ -z "$new" ] && new=$old
  45
  46 #
  47 # If we don't have an old branch that we're switching to,
  48 # and we don't have a new branch name for the target we
  49 # are switching to, then we'd better just be checking out
  50 # what we already had
  51 #
  52 [ -z "$branch$newbranch" ] &&
  53         [ "$new" != "$old" ] &&
  54         die "git checkout: you need to specify a new branch name"
  55
  56 if [ "$force" ]
  57 then
  58     git-read-tree --reset $new &&
  59         git-checkout-index -q -f -u -a
  60 else
  61     git-update-index --refresh >/dev/null
  62     git-read-tree -m -u $old $new
  63 fi
  64
  65 #
  66 # Switch the HEAD pointer to the new branch if it we
  67 # checked out a branch head, and remove any potential
  68 # old MERGE_HEAD's (subsequent commits will clearly not
  69 # be based on them, since we re-set the index)
  70 #
  71 if [ "$?" -eq 0 ]; then
  72         if [ "$newbranch" ]; then
  73                 echo $new > "$GIT_DIR/refs/heads/$newbranch"
  74                 branch="$newbranch"
  75         fi
  76         [ "$branch" ] &&
  77         GIT_DIR="$GIT_DIR" git-symbolic-ref HEAD "refs/heads/$branch"
  78         rm -f "$GIT_DIR/MERGE_HEAD"
  79 else
  80         exit 1
  81 fi