refs: implement removal of ref storages

We're about to introduce logic to migrate ref storages. One part of the
migration will be to delete the files that are part of the old ref
storage format. We don't yet have a way to delete such data generically
across ref backends though.

Implement a new `delete` callback and expose it via a new
`ref_storage_delete()` function.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 52 insertions, 0 deletions

diff --git a/refs/reftable-backend.c b/refs/reftable-backend.c
index bffed9257f..da6b3162f3 100644
--- a/refs/reftable-backend.c
+++ b/refs/reftable-backend.c
@@ -1,6 +1,7 @@
 #include "../git-compat-util.h"
 #include "../abspath.h"
 #include "../chdir-notify.h"
+#include "../dir.h"
 #include "../environment.h"
 #include "../gettext.h"
 #include "../hash.h"
@@ -343,6 +344,56 @@ static int reftable_be_create_on_disk(struct ref_store *ref_store,
 	return 0;
 }
 
+static int reftable_be_remove_on_disk(struct ref_store *ref_store,
+				      struct strbuf *err)
+{
+	struct reftable_ref_store *refs =
+		reftable_be_downcast(ref_store, REF_STORE_WRITE, "remove");
+	struct strbuf sb = STRBUF_INIT;
+	int ret = 0;
+
+	/*
+	 * Release the ref store such that all stacks are closed. This is
+	 * required so that the "tables.list" file is not open anymore, which
+	 * would otherwise make it impossible to remove the file on Windows.
+	 */
+	reftable_be_release(ref_store);
+
+	strbuf_addf(&sb, "%s/reftable", refs->base.gitdir);
+	if (remove_dir_recursively(&sb, 0) < 0) {
+		strbuf_addf(err, "could not delete reftables: %s",
+			    strerror(errno));
+		ret = -1;
+	}
+	strbuf_reset(&sb);
+
+	strbuf_addf(&sb, "%s/HEAD", refs->base.gitdir);
+	if (unlink(sb.buf) < 0) {
+		strbuf_addf(err, "could not delete stub HEAD: %s",
+			    strerror(errno));
+		ret = -1;
+	}
+	strbuf_reset(&sb);
+
+	strbuf_addf(&sb, "%s/refs/heads", refs->base.gitdir);
+	if (unlink(sb.buf) < 0) {
+		strbuf_addf(err, "could not delete stub heads: %s",
+			    strerror(errno));
+		ret = -1;
+	}
+	strbuf_reset(&sb);
+
+	strbuf_addf(&sb, "%s/refs", refs->base.gitdir);
+	if (rmdir(sb.buf) < 0) {
+		strbuf_addf(err, "could not delete refs directory: %s",
+			    strerror(errno));
+		ret = -1;
+	}
+
+	strbuf_release(&sb);
+	return ret;
+}
+
 struct reftable_ref_iterator {
 	struct ref_iterator base;
 	struct reftable_ref_store *refs;
@@ -2196,6 +2247,7 @@ struct ref_storage_be refs_be_reftable = {
 	.init = reftable_be_init,
 	.release = reftable_be_release,
 	.create_on_disk = reftable_be_create_on_disk,
+	.remove_on_disk = reftable_be_remove_on_disk,
 
 	.transaction_prepare = reftable_be_transaction_prepare,
 	.transaction_finish = reftable_be_transaction_finish,