thodg/libgit2/include/git2/odb_backend.h

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• Hash : 4047950f
  Author :
  Date : 2013-08-29T14:19:34
  

  odb: Prevent stream_finalize_write() from overwriting Now that #1785 is merged, git_odb_stream_finalize_write() calculates the object id before invoking the odb backend. This commit gives a chance to the backend to check if it already knows this object.

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• include/git2/odb_backend.h

• /*
   * 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_git_odb_backend_h__
  #define INCLUDE_git_odb_backend_h__
  
  #include "git2/common.h"
  #include "git2/types.h"
  
  /**
   * @file git2/backend.h
   * @brief Git custom backend functions
   * @defgroup git_odb Git object database routines
   * @ingroup Git
   * @{
   */
  GIT_BEGIN_DECL
  
  /*
   * Constructors for in-box ODB backends.
   */
  
  /**
   * Create a backend for the packfiles.
   *
   * @param out location to store the odb backend pointer
   * @param objects_dir the Git repository's objects directory
   *
   * @return 0 or an error code
   */
  GIT_EXTERN(int) git_odb_backend_pack(git_odb_backend **out, const char *objects_dir);
  
  /**
   * Create a backend for loose objects
   *
   * @param out location to store the odb backend pointer
   * @param objects_dir the Git repository's objects directory
   * @param compression_level zlib compression level to use
   * @param do_fsync whether to do an fsync() after writing (currently ignored)
   *
   * @return 0 or an error code
   */
  GIT_EXTERN(int) git_odb_backend_loose(git_odb_backend **out, const char *objects_dir, int compression_level, int do_fsync);
  
  /**
   * Create a backend out of a single packfile
   *
   * This can be useful for inspecting the contents of a single
   * packfile.
   *
   * @param out location to store the odb backend pointer
   * @param index_file path to the packfile's .idx file
   *
   * @return 0 or an error code
   */
  GIT_EXTERN(int) git_odb_backend_one_pack(git_odb_backend **out, const char *index_file);
  
  /** Streaming mode */
  typedef enum {
  	GIT_STREAM_RDONLY = (1 << 1),
  	GIT_STREAM_WRONLY = (1 << 2),
  	GIT_STREAM_RW = (GIT_STREAM_RDONLY | GIT_STREAM_WRONLY),
  } git_odb_stream_t;
  
  /**
   * A stream to read/write from a backend.
   *
   * This represents a stream of data being written to or read from a
   * backend. When writing, the frontend functions take care of
   * calculating the object's id and all `finalize_write` needs to do is
   * store the object with the id it is passed.
   */
  struct git_odb_stream {
  	git_odb_backend *backend;
  	unsigned int mode;
  	void *hash_ctx;
  
  	/**
  	 * Write at most `len` bytes into `buffer` and advance the
  	 * stream.
  	 */
  	int (*read)(git_odb_stream *stream, char *buffer, size_t len);
  
  	/**
  	 * Write `len` bytes from `buffer` into the stream.
  	 */
  	int (*write)(git_odb_stream *stream, const char *buffer, size_t len);
  
  	/**
  	 * Store the contents of the stream as an object with the id
  	 * specified in `oid`.
  	 *
  	 * This method will *not* be invoked by libgit2 if the object pointed at
  	 * by `oid` already exists in any backend. Libgit2 will however take care
  	 * of properly disposing the stream through a call to `free()`.
  	 */
  	int (*finalize_write)(git_odb_stream *stream, const git_oid *oid);
  
  	/**
  	 * Free the stream's memory.
  	 */
  	void (*free)(git_odb_stream *stream);
  };
  
  /** A stream to write a pack file to the ODB */
  struct git_odb_writepack {
  	git_odb_backend *backend;
  
  	int (*add)(git_odb_writepack *writepack, const void *data, size_t size, git_transfer_progress *stats);
  	int (*commit)(git_odb_writepack *writepack, git_transfer_progress *stats);
  	void (*free)(git_odb_writepack *writepack);
  };
  
  GIT_END_DECL
  
  #endif
  

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