reftable-blocksource.h · leroysheep/rag-system

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1	/*
2	* Copyright 2020 Google LLC
3	*
4	* Use of this source code is governed by a BSD-style
5	* license that can be found in the LICENSE file or at
6	* https://developers.google.com/open-source/licenses/bsd
7	*/
8
9	#ifndef REFTABLE_BLOCKSOURCE_H
10	#define REFTABLE_BLOCKSOURCE_H
11
12	#include "reftable-system.h"
13
14	/*
15	* Generic wrapper for a seekable readable file.
16	*/
17	struct reftable_block_source {
18	struct reftable_block_source_vtable *ops;
19	void *arg;
20	};
21
22	/* a contiguous segment of bytes. It keeps track of its generating block_source
23	* so it can return itself into the pool. */
24	struct reftable_block_data {
25	uint8_t *data;
26	size_t len;
27	struct reftable_block_source source;
28	};
29
30	/* block_source_vtable are the operations that make up block_source */
31	struct reftable_block_source_vtable {
32	/* Returns the size of a block source. */
33	uint64_t (size)(void source);
34
35	/*
36	* Reads a segment from the block source. It is an error to read beyond
37	* the end of the block.
38	*/
39	ssize_t (read_data)(void source, struct reftable_block_data *dest,
40	uint64_t off, uint32_t size);
41
42	/* Mark the block as read; may release the data. */
43	void (release_data)(void source, struct reftable_block_data *data);
44
45	/* Release all resources associated with the block source. */
46	void (close)(void source);
47	};
48
49	/* opens a file on the file system as a block_source */
50	int reftable_block_source_from_file(struct reftable_block_source *block_src,
51	const char *name);
52
53	#endif