/*
* 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"
/* opaque object for delta index */
struct git_delta_index;
/*
* create_delta_index: 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 struct git_delta_index *
git_delta_create_index(const void *buf, unsigned long bufsize);
/*
* free_delta_index: free the index created by create_delta_index()
*
* Given pointer must be what create_delta_index() returned, or NULL.
*/
extern void git_delta_free_index(struct git_delta_index *index);
/*
* sizeof_delta_index: returns memory usage of delta index
*
* Given pointer must be what create_delta_index() returned, or NULL.
*/
extern unsigned long git_delta_sizeof_index(struct 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 void *git_delta_create(
const struct git_delta_index *index,
const void *buf,
unsigned long bufsize,
unsigned long *delta_size,
unsigned long 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 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.
*/
GIT_INLINE(void *) git_delta(
const void *src_buf, unsigned long src_bufsize,
const void *trg_buf, unsigned long trg_bufsize,
unsigned long *delta_size,
unsigned long max_delta_size)
{
struct git_delta_index *index = git_delta_create_index(src_buf, src_bufsize);
if (index) {
void *delta = git_delta_create(
index, trg_buf, trg_bufsize, delta_size, max_delta_size);
git_delta_free_index(index);
return delta;
}
return NULL;
}
/*
* patch_delta: recreate target buffer given source buffer and delta data
*
* On success, a non-NULL pointer to the target buffer is returned and
* *trg_bufsize is updated with its size. On failure a NULL pointer is
* returned. The returned buffer must be freed by the caller.
*/
extern void *git_delta_patch(
const void *src_buf, unsigned long src_size,
const void *delta_buf, unsigned long delta_size,
unsigned long *dst_size);
/* the smallest possible delta size is 4 bytes */
#define GIT_DELTA_SIZE_MIN 4
/*
* This must be called twice on the delta data buffer, first to get the
* expected source buffer size, and again to get the target buffer size.
*/
GIT_INLINE(unsigned long) git_delta_get_hdr_size(
const unsigned char **datap, const unsigned char *top)
{
const unsigned char *data = *datap;
unsigned long cmd, size = 0;
int i = 0;
do {
cmd = *data++;
size |= (cmd & 0x7f) << i;
i += 7;
} while (cmd & 0x80 && data < top);
*datap = data;
return size;
}
#endif
