/*
 * 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.
 */
module libgit2_d.buffer;


/**
 * @file git2/buffer.h
 * @brief Buffer export structure
 *
 * @ingroup Git
 * @{
 */
extern (C):
nothrow @nogc:
public:

/**
 * 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_dispose()` 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.
 *
 * 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.
 */
struct git_buf
{
	/**
	 * The buffer contents.
	 *
	 * `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.
	 */
	char* ptr_;

	/**
	 * `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.
	 */
	size_t asize;

	/**
	 * `size` holds the size (in bytes) of the data that is actually used.
	 */
	size_t size;
}

/**
 * Static initializer for git_buf from static buffer
 */
pragma(inline, true)
pure nothrow @safe @nogc
.git_buf GIT_BUF_INIT_CONST(char* STR, size_t LEN)

	do
	{
		.git_buf OUTPUT =
		{
			ptr_: STR,
			asize: 0,
			size: LEN,
		};

		return OUTPUT;
	}

/**
 * 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.
 *
 * Params:
 *      buffer = The buffer to deallocate
 */
//GIT_EXTERN
void git_buf_dispose(.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.
 *
 * Params:
 *      buffer = The buffer to be resized; may or may not be allocated yet
 *      target_size = The desired available size
 *
 * Returns: 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.
 *
 * Params:
 *      buffer = The buffer to set
 *      data = The data to copy into the buffer
 *      datalen = The length of the data to copy into the buffer
 *
 * Returns: 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
 *
 * Params:
 *      buf = Buffer to check
 *
 * Returns: 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
 *
 * Params:
 *      buf = Buffer to check
 *
 * Returns: 1 if buffer contains a NUL byte
 */
//GIT_EXTERN
int git_buf_contains_nul(const (.git_buf)* buf);

/** @} */