1 files changed, 53 insertions, 0 deletions
diff --git a/reftable/reftable-blocksource.h b/reftable/reftable-blocksource.h
new file mode 100644
index 0000000000..f5ba867bd6
--- /dev/null
+++ b/reftable/reftable-blocksource.h
@@ -0,0 +1,53 @@
+/*
+ * Copyright 2020 Google LLC
+ *
+ * Use of this source code is governed by a BSD-style
+ * license that can be found in the LICENSE file or at
+ * https://developers.google.com/open-source/licenses/bsd
+ */
+
+#ifndef REFTABLE_BLOCKSOURCE_H
+#define REFTABLE_BLOCKSOURCE_H
+
+#include <stdint.h>
+
+/*
+ * Generic wrapper for a seekable readable file.
+ */
+struct reftable_block_source {
+	struct reftable_block_source_vtable *ops;
+	void *arg;
+};
+
+/* a contiguous segment of bytes. It keeps track of its generating block_source
+ * so it can return itself into the pool. */
+struct reftable_block_data {
+	uint8_t *data;
+	size_t len;
+	struct reftable_block_source source;
+};
+
+/* block_source_vtable are the operations that make up block_source */
+struct reftable_block_source_vtable {
+	/* Returns the size of a block source. */
+	uint64_t (*size)(void *source);
+
+	/*
+	 * Reads a segment from the block source. It is an error to read beyond
+	 * the end of the block.
+	 */
+	ssize_t (*read_data)(void *source, struct reftable_block_data *dest,
+			uint64_t off, uint32_t size);
+
+	/* Mark the block as read; may release the data. */
+	void (*release_data)(void *source, struct reftable_block_data *data);
+
+	/* Release all resources associated with the block source. */
+	void (*close)(void *source);
+};
+
+/* opens a file on the file system as a block_source */
+int reftable_block_source_from_file(struct reftable_block_source *block_src,
+				    const char *name);
+
+#endif