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-rw-r--r--reftable/reftable-blocksource.h49
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diff --git a/reftable/reftable-blocksource.h b/reftable/reftable-blocksource.h
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+/*
+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>
+
+/* block_source is a 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 {
+ uint8_t *data;
+ int 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 */
+ int (*read_block)(void *source, struct reftable_block *dest,
+ uint64_t off, uint32_t size);
+ /* mark the block as read; may return the data back to malloc */
+ void (*return_block)(void *source, struct reftable_block *blockp);
+
+ /* 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