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