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34c17b840d
We're including a couple of standard headers like <stdint.h> in a bunch
of locations, which makes it hard for a project to plug in their own
logic for making required functionality available. For us this is for
example via "compat/posix.h", which already includes all of the system
headers relevant to us.
Introduce a new "reftable-system.h" header that allows projects to
provide their own headers. This new header is supposed to contain all
the project-specific bits to provide the POSIX-like environment, and some
additional supporting code. With this change, we thus have the following
split in our system-specific code:
- "reftable/reftable-system.h" is the project-specific header that
provides a POSIX-like environment. Every project is expected to
provide their own implementation.
- "reftable/system.h" contains the project-independent definition of
the interfaces that a project needs to implement. This file should
not be touched by a project.
- "reftable/system.c" contains the project-specific implementation of
the interfaces defined in "system.h". Again, every project is
expected to provide their own implementation.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
54 lines
1.4 KiB
C
54 lines
1.4 KiB
C
/*
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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_BLOCKSOURCE_H
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#define REFTABLE_BLOCKSOURCE_H
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#include "reftable-system.h"
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/*
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* Generic wrapper for a seekable readable file.
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*/
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struct reftable_block_source {
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struct reftable_block_source_vtable *ops;
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void *arg;
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};
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/* a contiguous segment of bytes. It keeps track of its generating block_source
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* so it can return itself into the pool. */
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struct reftable_block_data {
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uint8_t *data;
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size_t len;
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struct reftable_block_source source;
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};
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/* block_source_vtable are the operations that make up block_source */
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struct reftable_block_source_vtable {
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/* Returns the size of a block source. */
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uint64_t (*size)(void *source);
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/*
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* Reads a segment from the block source. It is an error to read beyond
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* the end of the block.
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*/
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ssize_t (*read_data)(void *source, struct reftable_block_data *dest,
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uint64_t off, uint32_t size);
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/* Mark the block as read; may release the data. */
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void (*release_data)(void *source, struct reftable_block_data *data);
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/* Release all resources associated with the block source. */
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void (*close)(void *source);
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};
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/* opens a file on the file system as a block_source */
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int reftable_block_source_from_file(struct reftable_block_source *block_src,
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const char *name);
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#endif
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