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/*
* diff-delta code taken from git.git. See diff-delta.c for details.
*
*/
#ifndef INCLUDE_git_delta_h__
#define INCLUDE_git_delta_h__
#include "common.h"
#include "pack.h"
typedef struct git_delta_index git_delta_index;
/*
* git_delta_index_init: compute index data from given buffer
*
* This returns a pointer to a struct delta_index that should be passed to
* subsequent create_delta() calls, or to free_delta_index(). A NULL pointer
* is returned on failure. The given buffer must not be freed nor altered
* before free_delta_index() is called. The returned pointer must be freed
* using free_delta_index().
*/
extern int git_delta_index_init(
git_delta_index **out, const void *buf, size_t bufsize);
/*
* Free the index created by git_delta_index_init()
*/
extern void git_delta_index_free(git_delta_index *index);
/*
* Returns memory usage of delta index.
*/
extern size_t git_delta_index_size(git_delta_index *index);
/*
* create_delta: create a delta from given index for the given buffer
*
* This function may be called multiple times with different buffers using
* the same delta_index pointer. If max_delta_size is non-zero and the
* resulting delta is to be larger than max_delta_size then NULL is returned.
* On success, a non-NULL pointer to the buffer with the delta data is
* returned and *delta_size is updated with its size. The returned buffer
* must be freed by the caller.
*/
extern int git_delta_create_from_index(
void **out,
size_t *out_size,
const struct git_delta_index *index,
const void *buf,
size_t bufsize,
size_t max_delta_size);
/*
* diff_delta: create a delta from source buffer to target buffer
*
* If max_delta_size is non-zero and the resulting delta is to be larger
* than max_delta_size then GIT_EBUFS is returned. On success, a non-NULL
* pointer to the buffer with the delta data is returned and *delta_size is
* updated with its size. The returned buffer must be freed by the caller.
*/
GIT_INLINE(int) git_delta(
void **out, size_t *out_len,
const void *src_buf, size_t src_bufsize,
const void *trg_buf, size_t trg_bufsize,
size_t max_delta_size)
{
git_delta_index *index;
int error = 0;
*out = NULL;
*out_len = 0;
if ((error = git_delta_index_init(&index, src_buf, src_bufsize)) < 0)
return error;
if (index) {
error = git_delta_create_from_index(out, out_len,
index, trg_buf, trg_bufsize, max_delta_size);
git_delta_index_free(index);
}
return error;
}
/* the smallest possible delta size is 4 bytes */
#define GIT_DELTA_SIZE_MIN 4
/**
* Apply a git binary delta to recover the original content.
* The caller is responsible for freeing the returned buffer.
*
* @param out the output buffer
* @param out_len the length of the output buffer
* @param base the base to copy from during copy instructions.
* @param base_len number of bytes available at base.
* @param delta the delta to execute copy/insert instructions from.
* @param delta_len total number of bytes in the delta.
* @return 0 on success or an error code
*/
extern int git_delta_apply(
void **out,
size_t *out_len,
const unsigned char *base,
size_t base_len,
const unsigned char *delta,
size_t delta_len);
/**
* Read the header of a git binary delta.
*
* @param base_out pointer to store the base size field.
* @param result_out pointer to store the result size field.
* @param delta the delta to execute copy/insert instructions from.
* @param delta_len total number of bytes in the delta.
* @return 0 on success or an error code
*/
extern int git_delta_read_header(
size_t *base_out,
size_t *result_out,
const unsigned char *delta,
size_t delta_len);
/**
* Read the header of a git binary delta
*
* This variant reads just enough from the packfile stream to read the
* delta header.
*/
extern int git_delta_read_header_fromstream(
size_t *base_out,
size_t *result_out,
git_packfile_stream *stream);
#endif
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