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