git-checkout.sh

   1 #!/bin/sh
   2
   3 USAGE='[-f] [-b <new_branch>] [<branch>] [<paths>...]'
   4 SUBDIRECTORY_OK=Sometimes
   5 . git-sh-setup
   6
   7 old=$(git-rev-parse HEAD)
   8 new=
   9 force=
  10 branch=
  11 newbranch=
  12 while [ "$#" != "0" ]; do
  13     arg="$1"
  14     shift
  15     case "$arg" in
  16         "-b")
  17                 newbranch="$1"
  18                 shift
  19                 [ -z "$newbranch" ] &&
  20                         die "git checkout: -b needs a branch name"
  21                 [ -e "$GIT_DIR/refs/heads/$newbranch" ] &&
  22                         die "git checkout: branch $newbranch already exists"
  23                 git-check-ref-format "heads/$newbranch" ||
  24                         die "we do not like '$newbranch' as a branch name."
  25                 ;;
  26         "-f")
  27                 force=1
  28                 ;;
  29         --)
  30                 break
  31                 ;;
  32         -*)
  33                 usage
  34                 ;;
  35         *)
  36                 if rev=$(git-rev-parse --verify "$arg^0" 2>/dev/null)
  37                 then
  38                         if [ -z "$rev" ]; then
  39                                 echo "unknown flag $arg"
  40                                 exit 1
  41                         fi
  42                         new="$rev"
  43                         if [ -f "$GIT_DIR/refs/heads/$arg" ]; then
  44                                 branch="$arg"
  45                         fi
  46                 elif rev=$(git-rev-parse --verify "$arg^{tree}" 2>/dev/null)
  47                 then
  48                         # checking out selected paths from a tree-ish.
  49                         new="$rev"
  50                         branch=
  51                 else
  52                         new=
  53                         branch=
  54                         set x "$arg" "$@"
  55                         shift
  56                 fi
  57                 break
  58                 ;;
  59     esac
  60 done
  61
  62 # The behaviour of the command with and without explicit path
  63 # parameters is quite different.
  64 #
  65 # Without paths, we are checking out everything in the work tree,
  66 # possibly switching branches.  This is the traditional behaviour.
  67 #
  68 # With paths, we are _never_ switching branch, but checking out
  69 # the named paths from either index (when no rev is given),
  70 # or the named tree-ish (when rev is given).
  71
  72 if test "$#" -ge 1
  73 then
  74         if test '' != "$newbranch$force"
  75         then
  76                 die "updating paths and switching branches or forcing are incompatible."
  77         fi
  78         if test '' != "$new"
  79         then
  80                 # from a specific tree-ish; note that this is for
  81                 # rescuing paths and is never meant to remove what
  82                 # is not in the named tree-ish.
  83                 git-ls-tree --full-name -r "$new" "$@" |
  84                 git-update-index --index-info || exit $?
  85         fi
  86         git-checkout-index -f -u -- "$@"
  87         exit $?
  88 else
  89         # Make sure we did not fall back on $arg^{tree} codepath
  90         # since we are not checking out from an arbitrary tree-ish,
  91         # but switching branches.
  92         if test '' != "$new"
  93         then
  94                 git-rev-parse --verify "$new^{commit}" >/dev/null 2>&1 ||
  95                 die "Cannot switch branch to a non-commit."
  96         fi
  97 fi
  98
  99 # We are switching branches and checking out trees, so
 100 # we *NEED* to be at the toplevel.
 101 cdup=$(git-rev-parse --show-cdup)
 102 if test ! -z "$cdup"
 103 then
 104         cd "$cdup"
 105 fi
 106
 107 [ -z "$new" ] && new=$old
 108
 109 # If we don't have an old branch that we're switching to,
 110 # and we don't have a new branch name for the target we
 111 # are switching to, then we'd better just be checking out
 112 # what we already had
 113
 114 [ -z "$branch$newbranch" ] &&
 115         [ "$new" != "$old" ] &&
 116         die "git checkout: you need to specify a new branch name"
 117
 118 if [ "$force" ]
 119 then
 120     git-read-tree --reset $new &&
 121         git-checkout-index -q -f -u -a
 122 else
 123     git-update-index --refresh >/dev/null
 124     git-read-tree -m -u $old $new || (
 125         echo >&2 -n "Try automerge [y/N]? "
 126         read yesno
 127         case "$yesno" in [yY]*) ;; *) exit 1 ;; esac
 128
 129         # NEEDSWORK: We may want to reset the index from the $new for
 130         # these paths after the automerge happens, but it is not done
 131         # yet.  Probably we need to leave unmerged ones alone, and
 132         # yank the object name & mode from $new for cleanly merged
 133         # paths and stuff them in the index.
 134
 135         names=`git diff-files --name-only`
 136         case "$names" in
 137         '')     ;;
 138         *)
 139                 echo "$names" | git update-index --remove --stdin ;;
 140         esac
 141
 142         work=`git write-tree` &&
 143         git read-tree -m -u $old $work $new || exit
 144         if result=`git write-tree 2>/dev/null`
 145         then
 146             echo >&2 "Trivially automerged." ;# can this even happen?
 147             exit 0
 148         fi
 149         git merge-index -o git-merge-one-file -a
 150     )
 151 fi
 152
 153 #
 154 # Switch the HEAD pointer to the new branch if we
 155 # checked out a branch head, and remove any potential
 156 # old MERGE_HEAD's (subsequent commits will clearly not
 157 # be based on them, since we re-set the index)
 158 #
 159 if [ "$?" -eq 0 ]; then
 160         if [ "$newbranch" ]; then
 161                 leading=`expr "refs/heads/$newbranch" : '\(.*\)/'` &&
 162                 mkdir -p "$GIT_DIR/$leading" &&
 163                 echo $new >"$GIT_DIR/refs/heads/$newbranch" || exit
 164                 branch="$newbranch"
 165         fi
 166         [ "$branch" ] &&
 167         GIT_DIR="$GIT_DIR" git-symbolic-ref HEAD "refs/heads/$branch"
 168         rm -f "$GIT_DIR/MERGE_HEAD"
 169 else
 170         exit 1
 171 fi