173 lines
5.5 KiB
C
173 lines
5.5 KiB
C
/*
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* Copyright (C) the libgit2 contributors. All rights reserved.
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*
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* This file is part of libgit2, distributed under the GNU GPL v2 with
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* a Linking Exception. For full terms see the included COPYING file.
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*/
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#ifndef INCLUDE_sys_git_odb_backend_h__
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#define INCLUDE_sys_git_odb_backend_h__
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#include "git2/common.h"
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#include "git2/types.h"
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#include "git2/oid.h"
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#include "git2/odb.h"
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/**
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* @file git2/sys/backend.h
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* @brief Git custom backend implementors functions
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* @defgroup git_backend Git custom backend APIs
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* @ingroup Git
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* @{
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*/
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GIT_BEGIN_DECL
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/**
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* An instance for a custom backend
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*/
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struct git_odb_backend {
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unsigned int version;
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git_odb *odb;
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/* read and read_prefix each return to libgit2 a buffer which
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* will be freed later. The buffer should be allocated using
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* the function git_odb_backend_data_alloc to ensure that libgit2
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* can safely free it later. */
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int GIT_CALLBACK(read)(
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void **, size_t *, git_object_t *, git_odb_backend *, const git_oid *);
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/* To find a unique object given a prefix of its oid. The oid given
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* must be so that the remaining (GIT_OID_SHA1_HEXSIZE - len)*4 bits are 0s.
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*/
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int GIT_CALLBACK(read_prefix)(
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git_oid *, void **, size_t *, git_object_t *,
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git_odb_backend *, const git_oid *, size_t);
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int GIT_CALLBACK(read_header)(
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size_t *, git_object_t *, git_odb_backend *, const git_oid *);
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/**
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* Write an object into the backend. The id of the object has
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* already been calculated and is passed in.
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*/
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int GIT_CALLBACK(write)(
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git_odb_backend *, const git_oid *, const void *, size_t, git_object_t);
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int GIT_CALLBACK(writestream)(
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git_odb_stream **, git_odb_backend *, git_object_size_t, git_object_t);
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int GIT_CALLBACK(readstream)(
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git_odb_stream **, size_t *, git_object_t *,
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git_odb_backend *, const git_oid *);
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int GIT_CALLBACK(exists)(
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git_odb_backend *, const git_oid *);
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int GIT_CALLBACK(exists_prefix)(
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git_oid *, git_odb_backend *, const git_oid *, size_t);
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/**
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* If the backend implements a refreshing mechanism, it should be exposed
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* through this endpoint. Each call to `git_odb_refresh()` will invoke it.
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*
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* The odb layer will automatically call this when needed on failed
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* lookups (ie. `exists()`, `read()`, `read_header()`).
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*/
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int GIT_CALLBACK(refresh)(git_odb_backend *);
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int GIT_CALLBACK(foreach)(
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git_odb_backend *, git_odb_foreach_cb cb, void *payload);
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int GIT_CALLBACK(writepack)(
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git_odb_writepack **, git_odb_backend *, git_odb *odb,
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git_indexer_progress_cb progress_cb, void *progress_payload);
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/**
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* If the backend supports pack files, this will create a
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* `multi-pack-index` file which will contain an index of all objects
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* across all the `.pack` files.
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*/
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int GIT_CALLBACK(writemidx)(git_odb_backend *);
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/**
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* "Freshens" an already existing object, updating its last-used
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* time. This occurs when `git_odb_write` was called, but the
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* object already existed (and will not be re-written). The
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* underlying implementation may want to update last-used timestamps.
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*
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* If callers implement this, they should return `0` if the object
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* exists and was freshened, and non-zero otherwise.
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*/
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int GIT_CALLBACK(freshen)(git_odb_backend *, const git_oid *);
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/**
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* Frees any resources held by the odb (including the `git_odb_backend`
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* itself). An odb backend implementation must provide this function.
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*/
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void GIT_CALLBACK(free)(git_odb_backend *);
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};
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#define GIT_ODB_BACKEND_VERSION 1
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#define GIT_ODB_BACKEND_INIT {GIT_ODB_BACKEND_VERSION}
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/**
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* Initializes a `git_odb_backend` with default values. Equivalent to
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* creating an instance with GIT_ODB_BACKEND_INIT.
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*
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* @param backend the `git_odb_backend` struct to initialize.
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* @param version Version the struct; pass `GIT_ODB_BACKEND_VERSION`
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* @return Zero on success; -1 on failure.
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*/
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GIT_EXTERN(int) git_odb_init_backend(
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git_odb_backend *backend,
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unsigned int version);
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/**
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* Allocate data for an ODB object. Custom ODB backends may use this
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* to provide data back to the ODB from their read function. This
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* memory should not be freed once it is returned to libgit2. If a
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* custom ODB uses this function but encounters an error and does not
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* return this data to libgit2, then they should use the corresponding
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* git_odb_backend_data_free function.
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*
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* @param backend the ODB backend that is allocating this memory
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* @param len the number of bytes to allocate
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* @return the allocated buffer on success or NULL if out of memory
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*/
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GIT_EXTERN(void *) git_odb_backend_data_alloc(git_odb_backend *backend, size_t len);
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/**
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* Frees custom allocated ODB data. This should only be called when
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* memory allocated using git_odb_backend_data_alloc is not returned
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* to libgit2 because the backend encountered an error in the read
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* function after allocation and did not return this data to libgit2.
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*
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* @param backend the ODB backend that is freeing this memory
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* @param data the buffer to free
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*/
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GIT_EXTERN(void) git_odb_backend_data_free(git_odb_backend *backend, void *data);
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/*
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* Users can avoid deprecated functions by defining `GIT_DEPRECATE_HARD`.
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*/
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#ifndef GIT_DEPRECATE_HARD
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/**
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* Allocate memory for an ODB object from a custom backend. This is
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* an alias of `git_odb_backend_data_alloc` and is preserved for
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* backward compatibility.
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*
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* This function is deprecated, but there is no plan to remove this
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* function at this time.
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*
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* @deprecated git_odb_backend_data_alloc
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* @see git_odb_backend_data_alloc
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*/
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GIT_EXTERN(void *) git_odb_backend_malloc(git_odb_backend *backend, size_t len);
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#endif
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GIT_END_DECL
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#endif
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