reftable/block: create public interface for reading blocks
While users of the reftable library wouldn't generally require access to individual blocks in a reftable table, there are valid usecases where one may require low-level access to them. One such upcoming usecase in the Git codebase is to implement consistency checks for the reftable library where we want to verify each block individually. Create a public interface for reading blocks. The interface isn't yet complete and lacks e.g. a way to read individual records from a block. Such missing functionality will be backfilled in subsequent commits. Note that this change also requires us to expose `reftable_buf`, which is used by the `reftable_block_first_key()` function. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>maint
Patrick Steinhardt
Junio C Hamano
parent
ce76cec964
commit
655e18d6b4
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@ -18,13 +18,6 @@
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#define REFTABLE_UNUSED __attribute__((__unused__))
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struct reftable_buf {
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size_t alloc;
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size_t len;
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char *buf;
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};
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#define REFTABLE_BUF_INIT { 0 }
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/*
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* Initialize the buffer such that it is ready for use. This is equivalent to
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* using REFTABLE_BUF_INIT for stack-allocated variables.
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@ -11,6 +11,7 @@
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#include "basics.h"
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#include "record.h"
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#include "reftable-block.h"
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#include "reftable-blocksource.h"
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/*
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@ -62,53 +63,6 @@ int block_writer_finish(struct block_writer *w);
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/* clears out internally allocated block_writer members. */
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void block_writer_release(struct block_writer *bw);
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/*
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* A block part of a reftable. Contains records as well as some metadata
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* describing them.
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*/
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struct reftable_block {
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/* offset of the block header; nonzero for the first block in a
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* reftable. */
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uint32_t header_off;
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/* the memory block */
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struct reftable_block_data block_data;
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uint32_t hash_size;
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/* Uncompressed data for log entries. */
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struct z_stream_s *zstream;
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unsigned char *uncompressed_data;
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size_t uncompressed_cap;
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/*
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* Restart point data. Restart points are located after the block's
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* record data.
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*/
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uint16_t restart_count;
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uint32_t restart_off;
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/* size of the data in the file. For log blocks, this is the compressed
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* size. */
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uint32_t full_block_size;
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uint8_t block_type;
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};
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/*
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* Initialize a reftable block from the given block source.
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*/
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int reftable_block_init(struct reftable_block *b,
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struct reftable_block_source *source,
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uint32_t offset, uint32_t header_size,
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uint32_t table_block_size, uint32_t hash_size);
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void reftable_block_release(struct reftable_block *b);
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/* Returns the block type (eg. 'r' for refs) */
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uint8_t reftable_block_type(const struct reftable_block *b);
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/* Decodes the first key in the block */
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int reftable_block_first_key(const struct reftable_block *b, struct reftable_buf *key);
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/* Iterate over entries in a block */
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struct block_iter {
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/* offset within the block of the next entry to read. */
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@ -11,6 +11,14 @@
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#include <stddef.h>
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/* A buffer that contains arbitrary byte slices. */
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struct reftable_buf {
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size_t alloc;
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size_t len;
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char *buf;
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};
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#define REFTABLE_BUF_INIT { 0 }
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/*
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* Hash functions understood by the reftable library. Note that the values are
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* arbitrary and somewhat random such that we can easily detect cases where the
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@ -0,0 +1,69 @@
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/*
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* Copyright 2020 Google LLC
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*
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* Use of this source code is governed by a BSD-style
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* license that can be found in the LICENSE file or at
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* https://developers.google.com/open-source/licenses/bsd
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*/
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#ifndef REFTABLE_BLOCK_H
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#define REFTABLE_BLOCK_H
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#include <stdint.h>
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#include "reftable-basics.h"
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#include "reftable-blocksource.h"
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struct z_stream_s;
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/*
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* A block part of a reftable. Contains records as well as some metadata
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* describing them.
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*/
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struct reftable_block {
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/*
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* Offset of the block header; nonzero for the first block in a
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* reftable.
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*/
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uint32_t header_off;
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/* The memory block. */
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struct reftable_block_data block_data;
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uint32_t hash_size;
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/* Uncompressed data for log entries. */
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struct z_stream_s *zstream;
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unsigned char *uncompressed_data;
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size_t uncompressed_cap;
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/*
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* Restart point data. Restart points are located after the block's
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* record data.
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*/
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uint16_t restart_count;
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uint32_t restart_off;
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/*
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* Size of the data in the file. For log blocks, this is the compressed
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* size.
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*/
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uint32_t full_block_size;
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uint8_t block_type;
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};
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/* Initialize a reftable block from the given block source. */
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int reftable_block_init(struct reftable_block *b,
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struct reftable_block_source *source,
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uint32_t offset, uint32_t header_size,
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uint32_t table_block_size, uint32_t hash_size);
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/* Release resources allocated by the block. */
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void reftable_block_release(struct reftable_block *b);
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/* Returns the block type (eg. 'r' for refs). */
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uint8_t reftable_block_type(const struct reftable_block *b);
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/* Decodes the first key in the block. */
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int reftable_block_first_key(const struct reftable_block *b, struct reftable_buf *key);
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#endif /* REFTABLE_BLOCK_H */
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