1 /*
2  * Copyright (c) 2020 Ori Bernstein
3  * Copyright (c) 2021 Stefan Sperling <stsp@openbsd.org>
4  *
5  * Permission to use, copy, modify, and distribute this software for any
6  * purpose with or without fee is hereby granted, provided that the above
7  * copyright notice and this permission notice appear in all copies.
8  *
9  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16  */
17 
18 struct got_delta_block {
19 	off_t		len;
20 	off_t		offset;
21 	uint32_t	hash;
22 };
23 
24 struct got_delta_table {
25 	struct got_delta_block	*blocks;
26 	int			nblocks;
27 	int			nalloc;
28 
29 	/*
30 	 * Index for blocks.  offs[n] is zero when the slot is free,
31 	 * otherwise it points to blocks[offs[n] - 1].
32 	 */
33 	uint32_t		*offs;
34 	int			 len;
35 	int			 size;
36 };
37 
38 struct got_delta_instruction {
39 	int	copy;
40 	off_t	offset;
41 	off_t	len;
42 };
43 
44 enum {
45 	GOT_DELTIFY_MINCHUNK	= 32,
46 	GOT_DELTIFY_MAXCHUNK	= 8192,
47 	GOT_DELTIFY_SPLITMASK	= (1 << 8) - 1,
48 };
49 
50 const struct got_error *got_deltify_init(struct got_delta_table **dt, FILE *f,
51     off_t fileoffset, off_t filesize, uint32_t seed);
52 const struct got_error *got_deltify_init_mem(struct got_delta_table **dt,
53     uint8_t *data, off_t fileoffset, off_t filesize, uint32_t seed);
54 const struct got_error *got_deltify(struct got_delta_instruction **deltas,
55     int *ndeltas, FILE *f, off_t fileoffset, off_t filesize, uint32_t seed,
56     struct got_delta_table *dt, FILE *basefile, off_t basefile_offset0,
57     off_t basefile_size);
58 const struct got_error *got_deltify_file_mem(
59     struct got_delta_instruction **deltas, int *ndeltas,
60     FILE *f, off_t fileoffset, off_t filesize, uint32_t seed,
61     struct got_delta_table *dt, uint8_t *basedata, off_t basefile_offset0,
62     off_t basefile_size);
63 const struct got_error *got_deltify_mem_file(
64     struct got_delta_instruction **deltas, int *ndeltas,
65     uint8_t *data, off_t fileoffset, off_t filesize, uint32_t seed,
66     struct got_delta_table *dt, FILE *basefile, off_t basefile_offset0,
67     off_t basefile_size);
68 const struct got_error *got_deltify_mem_mem(
69     struct got_delta_instruction **deltas, int *ndeltas,
70     uint8_t *data, off_t fileoffset, off_t filesize, uint32_t seed,
71     struct got_delta_table *dt, uint8_t *basedata, off_t basefile_offset0,
72     off_t basefile_size);
73 void got_deltify_free(struct got_delta_table *dt);