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 '$newbranch' as a branch name."
  22                 ;;
  23         "-f")
  24                 force=1
  25                 ;;
  26         --)
  27                 break
  28                 ;;
  29         *)
  30                 if rev=$(git-rev-parse --verify "$arg^0" 2>/dev/null)
  31                 then
  32                         if [ -z "$rev" ]; then
  33                                 echo "unknown flag $arg"
  34                                 exit 1
  35                         fi
  36                         new="$rev"
  37                         if [ -f "$GIT_DIR/refs/heads/$arg" ]; then
  38                                 branch="$arg"
  39                         fi
  40                 elif rev=$(git-rev-parse --verify "$arg^{tree}" 2>/dev/null)
  41                 then
  42                         # checking out selected paths from a tree-ish.
  43                         new="$rev"
  44                         branch=
  45                 else
  46                         new=
  47                         branch=
  48                         set x "$arg" "$@"
  49                         shift
  50                 fi
  51                 break
  52                 ;;
  53     esac
  54 done
  55
  56 # The behaviour of the command with and without explicit path
  57 # parameters is quite different.
  58 #
  59 # Without paths, we are checking out everything in the work tree,
  60 # possibly switching branches.  This is the traditional behaviour.
  61 #
  62 # With paths, we are _never_ switching branch, but checking out
  63 # the named paths from either index (when no rev is given),
  64 # or the named tree-ish (when rev is given).
  65
  66 if test "$#" -ge 1
  67 then
  68         if test '' != "$newbranch$force"
  69         then
  70                 die "updating paths and switching branches or forcing are incompatible."
  71         fi
  72         if test '' != "$new"
  73         then
  74                 # from a specific tree-ish; note that this is for
  75                 # rescuing paths and is never meant to remove what
  76                 # is not in the named tree-ish.
  77                 git-ls-tree -r "$new" "$@" |
  78                 sed -ne 's/^\([0-7]*\) blob \(.*\)$/\1 \2/p' |
  79                 git-update-index --index-info || exit $?
  80         fi
  81         git-checkout-index -f -u -- "$@"
  82         exit $?
  83 else
  84         # Make sure we did not fall back on $arg^{tree} codepath
  85         # since we are not checking out from an arbitrary tree-ish,
  86         # but switching branches.
  87         if test '' != "$new"
  88         then
  89                 git-rev-parse --verify "$new^{commit}" >/dev/null 2>&1 ||
  90                 die "Cannot switch branch to a non-commit."
  91         fi
  92 fi
  93
  94 [ -z "$new" ] && new=$old
  95
  96 # If we don't have an old branch that we're switching to,
  97 # and we don't have a new branch name for the target we
  98 # are switching to, then we'd better just be checking out
  99 # what we already had
 100
 101 [ -z "$branch$newbranch" ] &&
 102         [ "$new" != "$old" ] &&
 103         die "git checkout: you need to specify a new branch name"
 104
 105 if [ "$force" ]
 106 then
 107     git-read-tree --reset $new &&
 108         git-checkout-index -q -f -u -a
 109 else
 110     git-update-index --refresh >/dev/null
 111     git-read-tree -m -u $old $new
 112 fi
 113
 114 #
 115 # Switch the HEAD pointer to the new branch if it we
 116 # checked out a branch head, and remove any potential
 117 # old MERGE_HEAD's (subsequent commits will clearly not
 118 # be based on them, since we re-set the index)
 119 #
 120 if [ "$?" -eq 0 ]; then
 121         if [ "$newbranch" ]; then
 122                 echo $new > "$GIT_DIR/refs/heads/$newbranch"
 123                 branch="$newbranch"
 124         fi
 125         [ "$branch" ] &&
 126         GIT_DIR="$GIT_DIR" git-symbolic-ref HEAD "refs/heads/$branch"
 127         rm -f "$GIT_DIR/MERGE_HEAD"
 128 else
 129         exit 1
 130 fi