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