git-checkout.sh

   1 #!/bin/sh
   2
   3 USAGE='[-q] [-f] [-b <new_branch>] [-m] [<branch>] [<paths>...]'
   4 SUBDIRECTORY_OK=Sometimes
   5 . git-sh-setup
   6 require_work_tree
   7
   8 old_name=HEAD
   9 old=$(git-rev-parse --verify $old_name 2>/dev/null)
  10 oldbranch=$(git-symbolic-ref $old_name 2>/dev/null)
  11 new=
  12 new_name=
  13 force=
  14 branch=
  15 track=
  16 newbranch=
  17 newbranch_log=
  18 merge=
  19 quiet=
  20 v=-v
  21 LF='
  22 '
  23 while [ "$#" != "0" ]; do
  24     arg="$1"
  25     shift
  26     case "$arg" in
  27         "-b")
  28                 newbranch="$1"
  29                 shift
  30                 [ -z "$newbranch" ] &&
  31                         die "git checkout: -b needs a branch name"
  32                 git-show-ref --verify --quiet -- "refs/heads/$newbranch" &&
  33                         die "git checkout: branch $newbranch already exists"
  34                 git-check-ref-format "heads/$newbranch" ||
  35                         die "git checkout: we do not like '$newbranch' as a branch name."
  36                 ;;
  37         "-l")
  38                 newbranch_log=-l
  39                 ;;
  40         "--track"|"--no-track")
  41                 track="$arg"
  42                 ;;
  43         "-f")
  44                 force=1
  45                 ;;
  46         -m)
  47                 merge=1
  48                 ;;
  49         "-q")
  50                 quiet=1
  51                 v=
  52                 ;;
  53         --)
  54                 break
  55                 ;;
  56         -*)
  57                 usage
  58                 ;;
  59         *)
  60                 if rev=$(git-rev-parse --verify "$arg^0" 2>/dev/null)
  61                 then
  62                         if [ -z "$rev" ]; then
  63                                 echo "unknown flag $arg"
  64                                 exit 1
  65                         fi
  66                         new="$rev"
  67                         new_name="$arg"
  68                         if git-show-ref --verify --quiet -- "refs/heads/$arg"
  69                         then
  70                                 branch="$arg"
  71                         fi
  72                 elif rev=$(git-rev-parse --verify "$arg^{tree}" 2>/dev/null)
  73                 then
  74                         # checking out selected paths from a tree-ish.
  75                         new="$rev"
  76                         new_name="$arg^{tree}"
  77                         branch=
  78                 else
  79                         new=
  80                         new_name=
  81                         branch=
  82                         set x "$arg" "$@"
  83                         shift
  84                 fi
  85                 case "$1" in
  86                 --)
  87                         shift ;;
  88                 esac
  89                 break
  90                 ;;
  91     esac
  92 done
  93
  94 case "$newbranch,$track" in
  95 ,--*)
  96         die "git checkout: --track and --no-track require -b"
  97 esac
  98
  99 case "$force$merge" in
 100 11)
 101         die "git checkout: -f and -m are incompatible"
 102 esac
 103
 104 # The behaviour of the command with and without explicit path
 105 # parameters is quite different.
 106 #
 107 # Without paths, we are checking out everything in the work tree,
 108 # possibly switching branches.  This is the traditional behaviour.
 109 #
 110 # With paths, we are _never_ switching branch, but checking out
 111 # the named paths from either index (when no rev is given),
 112 # or the named tree-ish (when rev is given).
 113
 114 if test "$#" -ge 1
 115 then
 116         hint=
 117         if test "$#" -eq 1
 118         then
 119                 hint="
 120 Did you intend to checkout '$@' which can not be resolved as commit?"
 121         fi
 122         if test '' != "$newbranch$force$merge"
 123         then
 124                 die "git checkout: updating paths is incompatible with switching branches/forcing$hint"
 125         fi
 126         if test '' != "$new"
 127         then
 128                 # from a specific tree-ish; note that this is for
 129                 # rescuing paths and is never meant to remove what
 130                 # is not in the named tree-ish.
 131                 git-ls-tree --full-name -r "$new" "$@" |
 132                 git-update-index --index-info || exit $?
 133         fi
 134
 135         # Make sure the request is about existing paths.
 136         git-ls-files --error-unmatch -- "$@" >/dev/null || exit
 137         git-ls-files -- "$@" |
 138         git-checkout-index -f -u --stdin
 139         exit $?
 140 else
 141         # Make sure we did not fall back on $arg^{tree} codepath
 142         # since we are not checking out from an arbitrary tree-ish,
 143         # but switching branches.
 144         if test '' != "$new"
 145         then
 146                 git-rev-parse --verify "$new^{commit}" >/dev/null 2>&1 ||
 147                 die "Cannot switch branch to a non-commit."
 148         fi
 149 fi
 150
 151 # We are switching branches and checking out trees, so
 152 # we *NEED* to be at the toplevel.
 153 cd_to_toplevel
 154
 155 [ -z "$new" ] && new=$old && new_name="$old_name"
 156
 157 # If we don't have an existing branch that we're switching to,
 158 # and we don't have a new branch name for the target we
 159 # are switching to, then we are detaching our HEAD from any
 160 # branch.  However, if "git checkout HEAD" detaches the HEAD
 161 # from the current branch, even though that may be logically
 162 # correct, it feels somewhat funny.  More importantly, we do not
 163 # want "git checkout" nor "git checkout -f" to detach HEAD.
 164
 165 detached=
 166 detach_warn=
 167
 168 describe_detached_head () {
 169         test -n "$quiet" || {
 170                 printf >&2 "$1 "
 171                 GIT_PAGER= git log >&2 -1 --pretty=oneline --abbrev-commit "$2"
 172         }
 173 }
 174
 175 if test -z "$branch$newbranch" && test "$new_name" != "$old_name"
 176 then
 177         detached="$new"
 178         if test -n "$oldbranch" && test -z "$quiet"
 179         then
 180                 detach_warn="Note: moving to \"$new_name\" which isn't a local branch
 181 If you want to create a new branch from this checkout, you may do so
 182 (now or later) by using -b with the checkout command again. Example:
 183   git checkout -b <new_branch_name>"
 184         fi
 185 elif test -z "$oldbranch" && test "$new" != "$old"
 186 then
 187         describe_detached_head 'Previous HEAD position was' "$old"
 188 fi
 189
 190 if [ "X$old" = X ]
 191 then
 192         if test -z "$quiet"
 193         then
 194                 echo >&2 "warning: You appear to be on a branch yet to be born."
 195                 echo >&2 "warning: Forcing checkout of $new_name."
 196         fi
 197         force=1
 198 fi
 199
 200 if [ "$force" ]
 201 then
 202     git-read-tree $v --reset -u $new
 203 else
 204     git-update-index --refresh >/dev/null
 205     merge_error=$(git-read-tree -m -u --exclude-per-directory=.gitignore $old $new 2>&1) || (
 206         case "$merge" in
 207         '')
 208                 echo >&2 "$merge_error"
 209                 exit 1 ;;
 210         esac
 211
 212         # Match the index to the working tree, and do a three-way.
 213         git diff-files --name-only | git update-index --remove --stdin &&
 214         work=`git write-tree` &&
 215         git read-tree $v --reset -u $new || exit
 216
 217         eval GITHEAD_$new='${new_name:-${branch:-$new}}' &&
 218         eval GITHEAD_$work=local &&
 219         export GITHEAD_$new GITHEAD_$work &&
 220         git merge-recursive $old -- $new $work
 221
 222         # Do not register the cleanly merged paths in the index yet.
 223         # this is not a real merge before committing, but just carrying
 224         # the working tree changes along.
 225         unmerged=`git ls-files -u`
 226         git read-tree $v --reset $new
 227         case "$unmerged" in
 228         '')     ;;
 229         *)
 230                 (
 231                         z40=0000000000000000000000000000000000000000
 232                         echo "$unmerged" |
 233                         sed -e 's/^[0-7]* [0-9a-f]* /'"0 $z40 /"
 234                         echo "$unmerged"
 235                 ) | git update-index --index-info
 236                 ;;
 237         esac
 238         exit 0
 239     )
 240     saved_err=$?
 241     if test "$saved_err" = 0 && test -z "$quiet"
 242     then
 243         git diff-index --name-status "$new"
 244     fi
 245     (exit $saved_err)
 246 fi
 247
 248 #
 249 # Switch the HEAD pointer to the new branch if we
 250 # checked out a branch head, and remove any potential
 251 # old MERGE_HEAD's (subsequent commits will clearly not
 252 # be based on them, since we re-set the index)
 253 #
 254 if [ "$?" -eq 0 ]; then
 255         if [ "$newbranch" ]; then
 256                 git-branch $track $newbranch_log "$newbranch" "$new_name" || exit
 257                 branch="$newbranch"
 258         fi
 259         if test -n "$branch"
 260         then
 261                 GIT_DIR="$GIT_DIR" git-symbolic-ref -m "checkout: moving to $branch" HEAD "refs/heads/$branch"
 262                 if test -n "$quiet"
 263                 then
 264                         true    # nothing
 265                 elif test "refs/heads/$branch" = "$oldbranch"
 266                 then
 267                         echo >&2 "Already on branch \"$branch\""
 268                 else
 269                         echo >&2 "Switched to${newbranch:+ a new} branch \"$branch\""
 270                 fi
 271         elif test -n "$detached"
 272         then
 273                 # NEEDSWORK: we would want a command to detach the HEAD
 274                 # atomically, instead of this handcrafted command sequence.
 275                 # Perhaps:
 276                 #       git update-ref --detach HEAD $new
 277                 # or something like that...
 278                 #
 279                 git-rev-parse HEAD >"$GIT_DIR/HEAD.new" &&
 280                 mv "$GIT_DIR/HEAD.new" "$GIT_DIR/HEAD" &&
 281                 git-update-ref -m "checkout: moving to $arg" HEAD "$detached" ||
 282                         die "Cannot detach HEAD"
 283                 if test -n "$detach_warn"
 284                 then
 285                         echo >&2 "$detach_warn"
 286                 fi
 287                 describe_detached_head 'HEAD is now at' HEAD
 288         fi
 289         rm -f "$GIT_DIR/MERGE_HEAD"
 290 else
 291         exit 1
 292 fi