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-rwxr-xr-xgit-checkout.sh76
1 files changed, 76 insertions, 0 deletions
diff --git a/git-checkout.sh b/git-checkout.sh
new file mode 100755
index 0000000..4e7c57a
--- /dev/null
+++ b/git-checkout.sh
@@ -0,0 +1,76 @@
+#!/bin/sh
+. git-sh-setup || die "Not a git archive"
+
+old=$(git-rev-parse HEAD)
+new=
+force=
+branch=
+newbranch=
+while [ "$#" != "0" ]; do
+ arg="$1"
+ shift
+ case "$arg" in
+ "-b")
+ newbranch="$1"
+ shift
+ [ -z "$newbranch" ] &&
+ die "git checkout: -b needs a branch name"
+ [ -e "$GIT_DIR/refs/heads/$newbranch" ] &&
+ die "git checkout: branch $newbranch already exists"
+ ;;
+ "-f")
+ force=1
+ ;;
+ *)
+ rev=$(git-rev-parse --verify "$arg^0") || exit
+ if [ -z "$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"
+ fi
+ ;;
+ esac
+done
+[ -z "$new" ] && new=$old
+
+#
+# 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"
+
+if [ "$force" ]
+then
+ git-read-tree --reset $new &&
+ git-checkout-index -q -f -u -a
+else
+ git-read-tree -m -u $old $new
+fi
+
+#
+# Switch the HEAD pointer to the new branch if it we
+# checked out a branch head, and remove any potential
+# old MERGE_HEAD's (subsequent commits will clearly not
+# be based on them, since we re-set the index)
+#
+if [ "$?" -eq 0 ]; then
+ if [ "$newbranch" ]; then
+ echo $new > "$GIT_DIR/refs/heads/$newbranch"
+ branch="$newbranch"
+ fi
+ [ "$branch" ] && ln -sf "refs/heads/$branch" "$GIT_DIR/HEAD"
+ rm -f "$GIT_DIR/MERGE_HEAD"
+else
+ exit 1
+fi