/*

 * 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.

 * This can be awkward if the caller does not have easy access to the same

 * allocation functions that libgit2 is using.  In those cases, libgit2

 * will fill in a `git_buf` and the caller can use `git_buf_free()` to

 * release it when they are done.

 *

 * A `git_buf` may also be used for the caller to pass in a reference to

 * a block of memory they hold.  In this case, libgit2 will not resize or

 * free the memory, but will read from it as needed.

 *

 * A `git_buf` is a public structure with three fields:

 *

 * - `ptr` points to the start of the allocated memory.  If it is NULL,

 *   then the `git_buf` is considered empty and libgit2 will feel free

 *   to overwrite it with new data.

 *

 * - `size` holds the size (in bytes) of the data that is actually used.

 *

 * - `asize` holds the known total amount of allocated memory if the `ptr`

 *    was allocated by libgit2.  It may be larger than `size`.  If `ptr`

 *    was not allocated by libgit2 and should not be resized and/or freed,

 *    then `asize` will be set to zero.

 *

 * Some APIs may occasionally do something slightly unusual with a buffer,

 * such as setting `ptr` to a value that was passed in by the user.  In

 * those cases, the behavior will be clearly documented by the API.

 */

typedef struct {

	char   *ptr;

	size_t asize, size;

} git_buf;

/**

 * Static initializer for git_buf from static buffer

 */

#define GIT_BUF_INIT_CONST(STR,LEN) { (char *)(STR), 0, (size_t)(LEN) }

/**

 * 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`.  This will not free the memory if it looks

 * like it was not allocated internally, but it will clear the buffer back

 * to the empty state.

 *

 * @param buffer The buffer to deallocate

 */

GIT_EXTERN(void) git_buf_free(git_buf *buffer);

/**

 * Resize the buffer allocation to make more space.

 *

 * This will attempt to grow the buffer to accommodate the target size.

 *

 * If the buffer refers to memory that was not allocated by libgit2 (i.e.

 * the `asize` field is zero), then `ptr` will be replaced with a newly

 * allocated block of data.  Be careful so that memory allocated by the

 * caller is not lost.  As a special variant, if you pass `target_size` as

 * 0 and the memory is not allocated by libgit2, this will allocate a new

 * buffer of size `size` and copy the external data into it.

 *

 * Currently, this will never shrink a buffer, only expand it.

 *

 * If the allocation fails, this will return an error and the buffer will be

 * marked as invalid for future operations, invaliding the contents.

 *

 * @param buffer The buffer to be resized; may or may not be allocated yet

 * @param target_size The desired available size

 * @return 0 on success, -1 on allocation failure

 */

GIT_EXTERN(int) git_buf_grow(git_buf *buffer, size_t target_size);

/**

 * Set buffer to a copy of some raw data.

 *

 * @param buffer The buffer to set

 * @param data The data to copy into the buffer

 * @param datalen The length of the data to copy into the buffer

 * @return 0 on success, -1 on allocation failure

 */

GIT_EXTERN(int) git_buf_set(

	git_buf *buffer, const void *data, size_t datalen);

/**

* Check quickly if buffer looks like it contains binary data

*

* @param buf Buffer to check

* @return 1 if buffer looks like non-text data

*/

GIT_EXTERN(int) git_buf_is_binary(const git_buf *buf);

/**

* Check quickly if buffer contains a NUL byte

*

* @param buf Buffer to check

* @return 1 if buffer contains a NUL byte

*/

GIT_EXTERN(int) git_buf_contains_nul(const git_buf *buf);

GIT_END_DECL

/** @} */

#endif