git/delta.h at master · omgwtfun/git · GitHub

Repository navigation

History

100

101

102

103

104

#ifndef DELTA_H

#define DELTA_H

/* opaque object for delta index */

struct 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 delta_index *

create_delta_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 free_delta_index(struct 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 sizeof_delta_index(struct 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 *

create_delta(const struct 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.

static inline void *

diff_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 delta_index *index = create_delta_index(src_buf, src_bufsize);

if (index) {

void *delta = create_delta(index, trg_buf, trg_bufsize,

delta_size, max_delta_size);

free_delta_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 *patch_delta(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 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.

static inline unsigned long get_delta_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

git/delta.h at master · omgwtfun/git · GitHub

Repository navigation

Expand file tree

Breadcrumbs

delta.h

Latest commit

History

Breadcrumbs

delta.h

File metadata and controls