git-checkout.sh

   1 #!/bin/sh
   2 . git-sh-setup || die "Not a git archive"
   3
   4 usage () {
   5     die "usage: git checkout [-f] [-b <new_branch>] [<branch>] [<paths>...]"
   6 }
   7
   8 old=$(git-rev-parse HEAD)
   9 new=
  10 force=
  11 branch=
  12 newbranch=
  13 while [ "$#" != "0" ]; do
  14     arg="$1"
  15     shift
  16     case "$arg" in
  17         "-b")
  18                 newbranch="$1"
  19                 shift
  20                 [ -z "$newbranch" ] &&
  21                         die "git checkout: -b needs a branch name"
  22                 [ -e "$GIT_DIR/refs/heads/$newbranch" ] &&
  23                         die "git checkout: branch $newbranch already exists"
  24                 git-check-ref-format "heads/$newbranch" ||
  25                         die "we do not like '$newbranch' as a branch name."
  26                 ;;
  27         "-f")
  28                 force=1
  29                 ;;
  30         --)
  31                 break
  32                 ;;
  33         -*)
  34                 usage
  35                 ;;
  36         *)
  37                 if rev=$(git-rev-parse --verify "$arg^0" 2>/dev/null)
  38                 then
  39                         if [ -z "$rev" ]; then
  40                                 echo "unknown flag $arg"
  41                                 exit 1
  42                         fi
  43                         new="$rev"
  44                         if [ -f "$GIT_DIR/refs/heads/$arg" ]; then
  45                                 branch="$arg"
  46                         fi
  47                 elif rev=$(git-rev-parse --verify "$arg^{tree}" 2>/dev/null)
  48                 then
  49                         # checking out selected paths from a tree-ish.
  50                         new="$rev"
  51                         branch=
  52                 else
  53                         new=
  54                         branch=
  55                         set x "$arg" "$@"
  56                         shift
  57                 fi
  58                 break
  59                 ;;
  60     esac
  61 done
  62
  63 # The behaviour of the command with and without explicit path
  64 # parameters is quite different.
  65 #
  66 # Without paths, we are checking out everything in the work tree,
  67 # possibly switching branches.  This is the traditional behaviour.
  68 #
  69 # With paths, we are _never_ switching branch, but checking out
  70 # the named paths from either index (when no rev is given),
  71 # or the named tree-ish (when rev is given).
  72
  73 if test "$#" -ge 1
  74 then
  75         if test '' != "$newbranch$force"
  76         then
  77                 die "updating paths and switching branches or forcing are incompatible."
  78         fi
  79         if test '' != "$new"
  80         then
  81                 # from a specific tree-ish; note that this is for
  82                 # rescuing paths and is never meant to remove what
  83                 # is not in the named tree-ish.
  84                 git-ls-tree -r "$new" "$@" |
  85                 sed -ne 's/^\([0-7]*\) blob \(.*\)$/\1 \2/p' |
  86                 git-update-index --index-info || exit $?
  87         fi
  88         git-checkout-index -f -u -- "$@"
  89         exit $?
  90 else
  91         # Make sure we did not fall back on $arg^{tree} codepath
  92         # since we are not checking out from an arbitrary tree-ish,
  93         # but switching branches.
  94         if test '' != "$new"
  95         then
  96                 git-rev-parse --verify "$new^{commit}" >/dev/null 2>&1 ||
  97                 die "Cannot switch branch to a non-commit."
  98         fi
  99 fi
 100
 101 [ -z "$new" ] && new=$old
 102
 103 # If we don't have an old branch that we're switching to,
 104 # and we don't have a new branch name for the target we
 105 # are switching to, then we'd better just be checking out
 106 # what we already had
 107
 108 [ -z "$branch$newbranch" ] &&
 109         [ "$new" != "$old" ] &&
 110         die "git checkout: you need to specify a new branch name"
 111
 112 if [ "$force" ]
 113 then
 114     git-read-tree --reset $new &&
 115         git-checkout-index -q -f -u -a
 116 else
 117     git-update-index --refresh >/dev/null
 118     git-read-tree -m -u $old $new
 119 fi
 120
 121 #
 122 # Switch the HEAD pointer to the new branch if it we
 123 # checked out a branch head, and remove any potential
 124 # old MERGE_HEAD's (subsequent commits will clearly not
 125 # be based on them, since we re-set the index)
 126 #
 127 if [ "$?" -eq 0 ]; then
 128         if [ "$newbranch" ]; then
 129                 leading=`expr "refs/heads/$newbranch" : '\(.*\)/'` &&
 130                 mkdir -p "$GIT_DIR/$leading" &&
 131                 echo $new >"$GIT_DIR/refs/heads/$newbranch" || exit
 132                 branch="$newbranch"
 133         fi
 134         [ "$branch" ] &&
 135         GIT_DIR="$GIT_DIR" git-symbolic-ref HEAD "refs/heads/$branch"
 136         rm -f "$GIT_DIR/MERGE_HEAD"
 137 else
 138         exit 1
 139 fi