/*
* 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
