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