git-checkout.sh

   1 #!/bin/sh
   2
   3 USAGE='[-f] [-b <new_branch>] [-m] [<branch>] [<paths>...]'
   4 SUBDIRECTORY_OK=Sometimes
   5 . git-sh-setup
   6
   7 old_name=HEAD
   8 old=$(git-rev-parse --verify $old_name 2>/dev/null)
   9 oldbranch=$(git-symbolic-ref $old_name 2>/dev/null)
  10 new=
  11 new_name=
  12 force=
  13 branch=
  14 newbranch=
  15 newbranch_log=
  16 merge=
  17 while [ "$#" != "0" ]; do
  18     arg="$1"
  19     shift
  20     case "$arg" in
  21         "-b")
  22                 newbranch="$1"
  23                 shift
  24                 [ -z "$newbranch" ] &&
  25                         die "git checkout: -b needs a branch name"
  26                 git-show-ref --verify --quiet -- "refs/heads/$newbranch" &&
  27                         die "git checkout: branch $newbranch already exists"
  28                 git-check-ref-format "heads/$newbranch" ||
  29                         die "git checkout: we do not like '$newbranch' as a branch name."
  30                 ;;
  31         "-l")
  32                 newbranch_log=1
  33                 ;;
  34         "-f")
  35                 force=1
  36                 ;;
  37         -m)
  38                 merge=1
  39                 ;;
  40         --)
  41                 break
  42                 ;;
  43         -*)
  44                 usage
  45                 ;;
  46         *)
  47                 if rev=$(git-rev-parse --verify "$arg^0" 2>/dev/null)
  48                 then
  49                         if [ -z "$rev" ]; then
  50                                 echo "unknown flag $arg"
  51                                 exit 1
  52                         fi
  53                         new="$rev"
  54                         new_name="$arg^0"
  55                         if git-show-ref --verify --quiet -- "refs/heads/$arg"
  56                         then
  57                                 branch="$arg"
  58                         fi
  59                 elif rev=$(git-rev-parse --verify "$arg^{tree}" 2>/dev/null)
  60                 then
  61                         # checking out selected paths from a tree-ish.
  62                         new="$rev"
  63                         new_name="$arg^{tree}"
  64                         branch=
  65                 else
  66                         new=
  67                         new_name=
  68                         branch=
  69                         set x "$arg" "$@"
  70                         shift
  71                 fi
  72                 case "$1" in
  73                 --)
  74                         shift ;;
  75                 esac
  76                 break
  77                 ;;
  78     esac
  79 done
  80
  81 case "$force$merge" in
  82 11)
  83         die "git checkout: -f and -m are incompatible"
  84 esac
  85
  86 # The behaviour of the command with and without explicit path
  87 # parameters is quite different.
  88 #
  89 # Without paths, we are checking out everything in the work tree,
  90 # possibly switching branches.  This is the traditional behaviour.
  91 #
  92 # With paths, we are _never_ switching branch, but checking out
  93 # the named paths from either index (when no rev is given),
  94 # or the named tree-ish (when rev is given).
  95
  96 if test "$#" -ge 1
  97 then
  98         hint=
  99         if test "$#" -eq 1
 100         then
 101                 hint="
 102 Did you intend to checkout '$@' which can not be resolved as commit?"
 103         fi
 104         if test '' != "$newbranch$force$merge"
 105         then
 106                 die "git checkout: updating paths is incompatible with switching branches/forcing$hint"
 107         fi
 108         if test '' != "$new"
 109         then
 110                 # from a specific tree-ish; note that this is for
 111                 # rescuing paths and is never meant to remove what
 112                 # is not in the named tree-ish.
 113                 git-ls-tree --full-name -r "$new" "$@" |
 114                 git-update-index --index-info || exit $?
 115         fi
 116
 117         # Make sure the request is about existing paths.
 118         git-ls-files --error-unmatch -- "$@" >/dev/null || exit
 119         git-ls-files -- "$@" |
 120         git-checkout-index -f -u --stdin
 121         exit $?
 122 else
 123         # Make sure we did not fall back on $arg^{tree} codepath
 124         # since we are not checking out from an arbitrary tree-ish,
 125         # but switching branches.
 126         if test '' != "$new"
 127         then
 128                 git-rev-parse --verify "$new^{commit}" >/dev/null 2>&1 ||
 129                 die "Cannot switch branch to a non-commit."
 130         fi
 131 fi
 132
 133 # We are switching branches and checking out trees, so
 134 # we *NEED* to be at the toplevel.
 135 cdup=$(git-rev-parse --show-cdup)
 136 if test ! -z "$cdup"
 137 then
 138         cd "$cdup"
 139 fi
 140
 141 [ -z "$new" ] && new=$old && new_name="$old_name"
 142
 143 # If we don't have an existing branch that we're switching to,
 144 # and we don't have a new branch name for the target we
 145 # are switching to, then we are detaching our HEAD from any
 146 # branch.  However, if "git checkout HEAD" detaches the HEAD
 147 # from the current branch, even though that may be logically
 148 # correct, it feels somewhat funny.  More importantly, we do not
 149 # want "git checkout" nor "git checkout -f" to detach HEAD.
 150
 151 if test -z "$branch$newbranch" && test "$new" != "$old"
 152 then
 153         # NEEDSWORK: we would want to have a command here
 154         # that allows us to detach the HEAD atomically.  Perhaps
 155         # something like "git update-ref --detach HEAD $new"
 156         echo "$new" >"$GIT_DIR/HEAD.new" &&
 157         mv "$GIT_DIR/HEAD.new" "$GIT_DIR/HEAD" || die "Cannot detach HEAD"
 158
 159         if test -n "$oldbranch"
 160         then
 161                 echo >&2 "warning: you are not on ANY branch anymore.
 162 If you meant to create a new branch from the commit, you need -b to
 163 associate a new branch with the wanted checkout.  Example:
 164   git checkout -b <new_branch_name> $arg
 165 "
 166         fi
 167 fi
 168
 169 if [ "X$old" = X ]
 170 then
 171         echo >&2 "warning: You appear to be on a branch yet to be born."
 172         echo >&2 "warning: Forcing checkout of $new_name."
 173         force=1
 174 fi
 175
 176 if [ "$force" ]
 177 then
 178     git-read-tree --reset -u $new
 179 else
 180     git-update-index --refresh >/dev/null
 181     merge_error=$(git-read-tree -m -u --exclude-per-directory=.gitignore $old $new 2>&1) || (
 182         case "$merge" in
 183         '')
 184                 echo >&2 "$merge_error"
 185                 exit 1 ;;
 186         esac
 187
 188         # Match the index to the working tree, and do a three-way.
 189         git diff-files --name-only | git update-index --remove --stdin &&
 190         work=`git write-tree` &&
 191         git read-tree --reset -u $new &&
 192         git read-tree -m -u --aggressive --exclude-per-directory=.gitignore $old $new $work ||
 193         exit
 194
 195         if result=`git write-tree 2>/dev/null`
 196         then
 197             echo >&2 "Trivially automerged."
 198         else
 199             git merge-index -o git-merge-one-file -a
 200         fi
 201
 202         # Do not register the cleanly merged paths in the index yet.
 203         # this is not a real merge before committing, but just carrying
 204         # the working tree changes along.
 205         unmerged=`git ls-files -u`
 206         git read-tree --reset $new
 207         case "$unmerged" in
 208         '')     ;;
 209         *)
 210                 (
 211                         z40=0000000000000000000000000000000000000000
 212                         echo "$unmerged" |
 213                         sed -e 's/^[0-7]* [0-9a-f]* /'"0 $z40 /"
 214                         echo "$unmerged"
 215                 ) | git update-index --index-info
 216                 ;;
 217         esac
 218         exit 0
 219     )
 220     saved_err=$?
 221     if test "$saved_err" = 0
 222     then
 223         test "$new" = "$old" || git diff-index --name-status "$new"
 224     fi
 225     (exit $saved_err)
 226 fi
 227
 228 #
 229 # Switch the HEAD pointer to the new branch if we
 230 # checked out a branch head, and remove any potential
 231 # old MERGE_HEAD's (subsequent commits will clearly not
 232 # be based on them, since we re-set the index)
 233 #
 234 if [ "$?" -eq 0 ]; then
 235         if [ "$newbranch" ]; then
 236                 if [ "$newbranch_log" ]; then
 237                         mkdir -p $(dirname "$GIT_DIR/logs/refs/heads/$newbranch")
 238                         touch "$GIT_DIR/logs/refs/heads/$newbranch"
 239                 fi
 240                 git-update-ref -m "checkout: Created from $new_name" "refs/heads/$newbranch" $new || exit
 241                 branch="$newbranch"
 242         fi
 243         [ "$branch" ] &&
 244         GIT_DIR="$GIT_DIR" git-symbolic-ref HEAD "refs/heads/$branch"
 245         rm -f "$GIT_DIR/MERGE_HEAD"
 246 else
 247         exit 1
 248 fi