git-checkout.sh

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