git-tar-tree: no more void pointer arithmetic
[git.git] / git-checkout.sh
index 2c053a3..564117f 100755 (executable)
@@ -1,11 +1,18 @@
 #!/bin/sh
-. git-sh-setup || die "Not a git archive"
+
+USAGE='[-f] [-b <new_branch>] [-m] [<branch>] [<paths>...]'
+SUBDIRECTORY_OK=Sometimes
+. git-sh-setup
 
 old=$(git-rev-parse HEAD)
+old_name=HEAD
 new=
+new_name=
 force=
 branch=
 newbranch=
+newbranch_log=
+merge=
 while [ "$#" != "0" ]; do
     arg="$1"
     shift
@@ -18,40 +25,115 @@ while [ "$#" != "0" ]; do
                [ -e "$GIT_DIR/refs/heads/$newbranch" ] &&
                        die "git checkout: branch $newbranch already exists"
                git-check-ref-format "heads/$newbranch" ||
-                       die "we do not like '$newbranch' as a branch name."
+                       die "git checkout: we do not like '$newbranch' as a branch name."
+               ;;
+       "-l")
+               newbranch_log=1
                ;;
        "-f")
                force=1
                ;;
+       -m)
+               merge=1
+               ;;
+       --)
+               break
+               ;;
+       -*)
+               usage
+               ;;
        *)
-               rev=$(git-rev-parse --verify "$arg^0" 2>/dev/null) ||
-                       die "I don't know any '$arg'."
-               if [ -z "$rev" ]; then
-                       echo "unknown flag $arg"
-                       exit 1
-               fi
-               if [ "$new" ]; then
-                       echo "Multiple revisions?"
-                       exit 1
-               fi
-               new="$rev"
-               if [ -f "$GIT_DIR/refs/heads/$arg" ]; then
-                       branch="$arg"
+               if rev=$(git-rev-parse --verify "$arg^0" 2>/dev/null)
+               then
+                       if [ -z "$rev" ]; then
+                               echo "unknown flag $arg"
+                               exit 1
+                       fi
+                       new="$rev"
+                       new_name="$arg^0"
+                       if [ -f "$GIT_DIR/refs/heads/$arg" ]; then
+                               branch="$arg"
+                       fi
+               elif rev=$(git-rev-parse --verify "$arg^{tree}" 2>/dev/null)
+               then
+                       # checking out selected paths from a tree-ish.
+                       new="$rev"
+                       new_name="$arg^{tree}"
+                       branch=
+               else
+                       new=
+                       new_name=
+                       branch=
+                       set x "$arg" "$@"
+                       shift
                fi
+               break
                ;;
     esac
 done
-[ -z "$new" ] && new=$old
 
+# The behaviour of the command with and without explicit path
+# parameters is quite different.
+#
+# Without paths, we are checking out everything in the work tree,
+# possibly switching branches.  This is the traditional behaviour.
 #
+# With paths, we are _never_ switching branch, but checking out
+# the named paths from either index (when no rev is given),
+# or the named tree-ish (when rev is given).
+
+if test "$#" -ge 1
+then
+       hint=
+       if test "$#" -eq 1
+       then
+               hint="
+Did you intend to checkout '$@' which can not be resolved as commit?"
+       fi
+       if test '' != "$newbranch$force$merge"
+       then
+               die "git checkout: updating paths is incompatible with switching branches/forcing$hint"
+       fi
+       if test '' != "$new"
+       then
+               # from a specific tree-ish; note that this is for
+               # rescuing paths and is never meant to remove what
+               # is not in the named tree-ish.
+               git-ls-tree --full-name -r "$new" "$@" |
+               git-update-index --index-info || exit $?
+       fi
+       git-checkout-index -f -u -- "$@"
+       exit $?
+else
+       # Make sure we did not fall back on $arg^{tree} codepath
+       # since we are not checking out from an arbitrary tree-ish,
+       # but switching branches.
+       if test '' != "$new"
+       then
+               git-rev-parse --verify "$new^{commit}" >/dev/null 2>&1 ||
+               die "Cannot switch branch to a non-commit."
+       fi
+fi
+
+# We are switching branches and checking out trees, so
+# we *NEED* to be at the toplevel.
+cdup=$(git-rev-parse --show-cdup)
+if test ! -z "$cdup"
+then
+       cd "$cdup"
+fi
+
+[ -z "$new" ] && new=$old && new_name="$old_name"
+
 # If we don't have an old branch that we're switching to,
 # and we don't have a new branch name for the target we
 # are switching to, then we'd better just be checking out
 # what we already had
-#
+
 [ -z "$branch$newbranch" ] &&
        [ "$new" != "$old" ] &&
-       die "git checkout: you need to specify a new branch name"
+       die "git checkout: to checkout the requested commit you need to specify 
+              a name for a new branch which is created and switched to"
 
 if [ "$force" ]
 then
@@ -59,18 +141,66 @@ then
        git-checkout-index -q -f -u -a
 else
     git-update-index --refresh >/dev/null
-    git-read-tree -m -u $old $new
+    merge_error=$(git-read-tree -m -u $old $new 2>&1) || (
+       case "$merge" in
+       '')
+               echo >&2 "$merge_error"
+               exit 1 ;;
+       esac
+
+       # Match the index to the working tree, and do a three-way.
+       git diff-files --name-only | git update-index --remove --stdin &&
+       work=`git write-tree` &&
+       git read-tree --reset $new &&
+       git checkout-index -f -u -q -a &&
+       git read-tree -m -u --aggressive $old $new $work || exit
+
+       if result=`git write-tree 2>/dev/null`
+       then
+           echo >&2 "Trivially automerged."
+       else
+           git merge-index -o git-merge-one-file -a
+       fi
+
+       # Do not register the cleanly merged paths in the index yet.
+       # this is not a real merge before committing, but just carrying
+       # the working tree changes along.
+       unmerged=`git ls-files -u`
+       git read-tree --reset $new
+       case "$unmerged" in
+       '')     ;;
+       *)
+               (
+                       z40=0000000000000000000000000000000000000000
+                       echo "$unmerged" |
+                       sed -e 's/^[0-7]* [0-9a-f]* /'"0 $z40 /"
+                       echo "$unmerged"
+               ) | git update-index --index-info
+               ;;
+       esac
+       exit 0
+    )
+    saved_err=$?
+    if test "$saved_err" = 0
+    then
+       test "$new" = "$old" || git diff-index --name-status "$new"
+    fi
+    (exit $saved_err)
 fi
 
 # 
-# Switch the HEAD pointer to the new branch if it we
+# Switch the HEAD pointer to the new branch if we
 # checked out a branch head, and remove any potential
 # old MERGE_HEAD's (subsequent commits will clearly not
 # be based on them, since we re-set the index)
 #
 if [ "$?" -eq 0 ]; then
        if [ "$newbranch" ]; then
-               echo $new > "$GIT_DIR/refs/heads/$newbranch"
+               if [ "$newbranch_log" ]; then
+                       mkdir -p $(dirname "$GIT_DIR/logs/refs/heads/$newbranch")
+                       touch "$GIT_DIR/logs/refs/heads/$newbranch"
+               fi
+               git-update-ref -m "checkout: Created from $new_name" "refs/heads/$newbranch" $new || exit
                branch="$newbranch"
        fi
        [ "$branch" ] &&