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/*
* Copyright (C) the libgit2 contributors. All rights reserved.
*
* This file is part of libgit2, distributed under the GNU GPL v2 with
* a Linking Exception. For full terms see the included COPYING file.
*/
#ifndef INCLUDE_sys_git_odb_backend_h__
#define INCLUDE_sys_git_odb_backend_h__
#include "git2/common.h"
#include "git2/types.h"
#include "git2/oid.h"
#include "git2/odb.h"
/**
* @file git2/sys/backend.h
* @brief Git custom backend implementors functions
* @defgroup git_backend Git custom backend APIs
* @ingroup Git
* @{
*/
GIT_BEGIN_DECL
/**
* An instance for a custom backend
*/
struct git_odb_backend {
unsigned int version;
git_odb *odb;
/* read and read_prefix each return to libgit2 a buffer which
* will be freed later. The buffer should be allocated using
* the function git_odb_backend_malloc to ensure that it can
* be safely freed later. */
int (* read)(
void **, size_t *, git_otype *, git_odb_backend *, const git_oid *);
/* To find a unique object given a prefix of its oid. The oid given
* must be so that the remaining (GIT_OID_HEXSZ - len)*4 bits are 0s.
*/
int (* read_prefix)(
git_oid *, void **, size_t *, git_otype *,
git_odb_backend *, const git_oid *, size_t);
int (* read_header)(
size_t *, git_otype *, git_odb_backend *, const git_oid *);
/**
* Write an object into the backend. The id of the object has
* already been calculated and is passed in.
*/
int (* write)(
git_odb_backend *, const git_oid *, const void *, size_t, git_otype);
int (* writestream)(
git_odb_stream **, git_odb_backend *, git_off_t, git_otype);
int (* readstream)(
git_odb_stream **, git_odb_backend *, const git_oid *);
int (* exists)(
git_odb_backend *, const git_oid *);
int (* exists_prefix)(
git_oid *, git_odb_backend *, const git_oid *, size_t);
/**
* If the backend implements a refreshing mechanism, it should be exposed
* through this endpoint. Each call to `git_odb_refresh()` will invoke it.
*
* However, the backend implementation should try to stay up-to-date as much
* as possible by itself as libgit2 will not automatically invoke
* `git_odb_refresh()`. For instance, a potential strategy for the backend
* implementation to achieve this could be to internally invoke this
* endpoint on failed lookups (ie. `exists()`, `read()`, `read_header()`).
*/
int (* refresh)(git_odb_backend *);
int (* foreach)(
git_odb_backend *, git_odb_foreach_cb cb, void *payload);
int (* writepack)(
git_odb_writepack **, git_odb_backend *, git_odb *odb,
git_transfer_progress_cb progress_cb, void *progress_payload);
void (* free)(git_odb_backend *);
};
#define GIT_ODB_BACKEND_VERSION 1
#define GIT_ODB_BACKEND_INIT {GIT_ODB_BACKEND_VERSION}
/**
* Initializes a `git_odb_backend` with default values. Equivalent to
* creating an instance with GIT_ODB_BACKEND_INIT.
*
* @param opts the `git_odb_backend` struct to initialize.
* @param version Version the struct; pass `GIT_ODB_BACKEND_VERSION`
* @return Zero on success; -1 on failure.
*/
GIT_EXTERN(int) git_odb_init_backend(
git_odb_backend *backend,
unsigned int version);
GIT_EXTERN(void *) git_odb_backend_malloc(git_odb_backend *backend, size_t len);
GIT_END_DECL
#endif
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