thodg/libgit2/include/git2/buffer.h

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• Hash : f0e693b1
  Author :
  Date : 2021-09-07T17:53:49
  

  str: introduce `git_str` for internal, `git_buf` is external libgit2 has two distinct requirements that were previously solved by `git_buf`. We require: 1. A general purpose string class that provides a number of utility APIs for manipulating data (eg, concatenating, truncating, etc). 2. A structure that we can use to return strings to callers that they can take ownership of. By using a single class (`git_buf`) for both of these purposes, we have confused the API to the point that refactorings are difficult and reasoning about correctness is also difficult. Move the utility class `git_buf` to be called `git_str`: this represents its general purpose, as an internal string buffer class. The name also is an homage to Junio Hamano ("gitstr"). The public API remains `git_buf`, and has a much smaller footprint. It is generally only used as an "out" param with strict requirements that follow the documentation. (Exceptions exist for some legacy APIs to avoid breaking callers unnecessarily.) Utility functions exist to convert a user-specified `git_buf` to a `git_str` so that we can call internal functions, then converting it back again.

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• include/git2/buffer.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_buf_h__
  #define INCLUDE_git_buf_h__
  
  #include "common.h"
  
  /**
   * @file git2/buffer.h
   * @brief Buffer export structure
   *
   * @ingroup Git
   * @{
   */
  GIT_BEGIN_DECL
  
  /**
   * A data buffer for exporting data from libgit2
   *
   * Sometimes libgit2 wants to return an allocated data buffer to the
   * caller and have the caller take responsibility for freeing that memory.
   * To make ownership clear in these cases, libgit2 uses  `git_buf` to
   * return this data.  Callers should use `git_buf_dispose()` to release
   * the memory when they are done.
   *
   * A `git_buf` contains a pointer to a NUL-terminated C string, and
   * the length of the string (not including the NUL terminator).
   */
  typedef struct {
  	/**
  	 * The buffer contents.  `ptr` points to the start of the buffer
  	 * being returned.  The buffer's length (in bytes) is specified
  	 * by the `size` member of the structure, and contains a NUL
  	 * terminator at position `(size + 1)`.
  	 */
  	char *ptr;
  
  	/**
  	 * This field is reserved and unused.
  	 */
  	size_t reserved;
  
  	/**
  	 * The length (in bytes) of the buffer pointed to by `ptr`,
  	 * not including a NUL terminator.
  	 */
  	size_t size;
  } git_buf;
  
  /**
   * Use to initialize a `git_buf` before passing it to a function that
   * will populate it.
   */
  #define GIT_BUF_INIT { NULL, 0, 0 }
  
  /**
   * Free the memory referred to by the git_buf.
   *
   * Note that this does not free the `git_buf` itself, just the memory
   * pointed to by `buffer->ptr`.
   *
   * @param buffer The buffer to deallocate
   */
  GIT_EXTERN(void) git_buf_dispose(git_buf *buffer);
  
  GIT_END_DECL
  
  /** @} */
  
  #endif
  

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