1 /*
2  * Copyright (c) 2018 Stefan Sperling <stsp@openbsd.org>
3  *
4  * Permission to use, copy, modify, and distribute this software for any
5  * purpose with or without fee is hereby granted, provided that the above
6  * copyright notice and this permission notice appear in all copies.
7  *
8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15  */
16 
17 #include <sys/queue.h>
18 
19 #include <stdio.h>
20 #include <stdlib.h>
21 #include <string.h>
22 #include <zlib.h>
23 #include <sha1.h>
24 
25 #include "got_error.h"
26 #include "got_repository.h"
27 #include "got_object.h"
28 
29 #include "delta.h"
30 #include "zb.h"
31 
32 #ifndef MIN
33 #define	MIN(_a,_b) ((_a) < (_b) ? (_a) : (_b))
34 #endif
35 
36 struct got_delta *
37 got_delta_open(const char *path_packfile, int type, off_t offset,
38     size_t size)
39 {
40 	struct got_delta *delta;
41 
42 	delta = calloc(1, sizeof(*delta));
43 	if (delta == NULL)
44 		return NULL;
45 
46 	delta->path_packfile = strdup(path_packfile);
47 	if (delta->path_packfile == NULL) {
48 		free(delta);
49 		return NULL;
50 	}
51 	delta->type = type;
52 	delta->offset = offset;
53 	delta->size = size;
54 	return delta;
55 }
56 
57 void
58 got_delta_close(struct got_delta *delta)
59 {
60 	free(delta->path_packfile);
61 	free(delta);
62 
63 }
64 
65 const struct got_error *
66 got_delta_chain_get_base_type(int *type, struct got_delta_chain *deltas)
67 {
68 	struct got_delta *delta;
69 
70 	/* The first delta in the chain should represent the base object. */
71 	delta = SIMPLEQ_FIRST(&deltas->entries);
72 	if (delta->type == GOT_OBJ_TYPE_COMMIT ||
73 	    delta->type == GOT_OBJ_TYPE_TREE ||
74 	    delta->type == GOT_OBJ_TYPE_BLOB ||
75 	    delta->type == GOT_OBJ_TYPE_TAG) {
76 		*type = delta->type;
77 		return NULL;
78 	}
79 
80 	return got_error(GOT_ERR_BAD_DELTA_CHAIN);
81 }
82 
83 /* Fetch another (required) byte from the delta stream. */
84 static const struct got_error *
85 next_delta_byte(const uint8_t **p, size_t *remain)
86 {
87 	if (--(*remain) == 0)
88 		return got_error(GOT_ERR_BAD_DELTA);
89 	(*p)++;
90 	return NULL;
91 }
92 
93 static const struct got_error *
94 parse_size(uint64_t *size, const uint8_t **p, size_t *remain)
95 {
96 	const struct got_error *err = NULL;
97 	int i = 0;
98 
99 	*size = 0;
100 	do {
101 		/* We do not support size values which don't fit in 64 bit. */
102 		if (i > 9)
103 			return got_error(GOT_ERR_NO_SPACE);
104 
105 		if (i == 0)
106 			*size = ((**p) & GOT_DELTA_SIZE_VAL_MASK);
107 		else {
108 			size_t shift = GOT_DELTA_SIZE_SHIFT * i;
109 			*size |= (((**p) & GOT_DELTA_SIZE_VAL_MASK) << shift);
110 		}
111 
112 		if (((**p) & GOT_DELTA_SIZE_MORE) == 0)
113 			break;
114 		i++;
115 		err = next_delta_byte(p, remain);
116 	} while (err == NULL);
117 
118 	return err;
119 }
120 
121 static const struct got_error *
122 parse_opcode(off_t *offset, size_t *len, const uint8_t **p, size_t *remain)
123 {
124 	const struct got_error *err = NULL;
125 	off_t o = 0;
126 	size_t l = 0;
127 	uint8_t opcode = **p;
128 
129 	if (opcode & GOT_DELTA_COPY_OFF1) {
130 		err = next_delta_byte(p, remain);
131 		if (err)
132 			return err;
133 		o = (off_t)(**p);
134 	}
135 	if (opcode & GOT_DELTA_COPY_OFF2) {
136 		err = next_delta_byte(p, remain);
137 		if (err)
138 			return err;
139 		o |= ((off_t)(**p)) << 8;
140 	}
141 	if (opcode & GOT_DELTA_COPY_OFF3) {
142 		err = next_delta_byte(p, remain);
143 		if (err)
144 			return err;
145 		o |= ((off_t)(**p)) << 16;
146 	}
147 	if (opcode & GOT_DELTA_COPY_OFF4) {
148 		err = next_delta_byte(p, remain);
149 		if (err)
150 			return err;
151 		o |= ((off_t)(**p)) << 24;
152 	}
153 
154 	if (opcode & GOT_DELTA_COPY_LEN1) {
155 		err = next_delta_byte(p, remain);
156 		if (err)
157 			return err;
158 		l = (off_t)(**p);
159 	}
160 	if (opcode & GOT_DELTA_COPY_LEN2) {
161 		err = next_delta_byte(p, remain);
162 		if (err)
163 			return err;
164 		l |= ((off_t)(**p)) << 8;
165 	}
166 	if (opcode & GOT_DELTA_COPY_LEN3) {
167 		err = next_delta_byte(p, remain);
168 		if (err)
169 			return err;
170 		l |= ((off_t)(**p)) << 16;
171 	}
172 
173 	if (o == 0)
174 		o = GOT_DELTA_COPY_DEFAULT_OFF;
175 	if (l == 0)
176 		l = GOT_DELTA_COPY_DEFAULT_LEN;
177 
178 	*offset = o;
179 	*len = l;
180 	return NULL;
181 }
182 
183 static const struct got_error *
184 copy_from_base(FILE *base_file, off_t offset, size_t size, FILE *outfile)
185 {
186 	if (fseeko(base_file, offset, SEEK_SET) != 0)
187 		return got_error_from_errno();
188 
189 	while (size > 0) {
190 		uint8_t data[2048];
191 		size_t len = MIN(size, sizeof(data));
192 		size_t n;
193 
194 		n = fread(data, len, 1, base_file);
195 		if (n != 1)
196 			return got_ferror(base_file, GOT_ERR_IO);
197 
198 		n = fwrite(data, len, 1, outfile);
199 		if (n != 1)
200 			return got_ferror(outfile, GOT_ERR_IO);
201 
202 		size -= len;
203 	}
204 
205 	return NULL;
206 }
207 
208 static const struct got_error *
209 copy_from_delta(const uint8_t **p, size_t *remain, size_t len, FILE *outfile)
210 {
211 	size_t n;
212 
213 	if (*remain < len)
214 		return got_error(GOT_ERR_BAD_DELTA);
215 
216 	n = fwrite(*p, len, 1, outfile);
217 	if (n != 1)
218 		return got_ferror(outfile, GOT_ERR_IO);
219 
220 	*p += len;
221 	*remain -= len;
222 	return NULL;
223 }
224 
225 const struct got_error *
226 got_delta_apply(FILE *base_compressed, const uint8_t *delta_buf,
227     size_t delta_len, FILE *outfile)
228 {
229 	const struct got_error *err = NULL;
230 	FILE *base_file = NULL;
231 	uint64_t base_size, result_size;
232 	size_t remain, outsize = 0;
233 	const uint8_t *p;
234 
235 	if (delta_len < GOT_DELTA_STREAM_LENGTH_MIN)
236 		return got_error(GOT_ERR_BAD_DELTA);
237 
238 	p = delta_buf;
239 	remain = delta_len;
240 
241 	/* Read the two size fields at the beginning of the stream. */
242 	err = parse_size(&base_size, &p, &remain);
243 	if (err)
244 		return err;
245 	err = next_delta_byte(&p, &remain);
246 	if (err)
247 		return err;
248 	err = parse_size(&result_size, &p, &remain);
249 	if (err)
250 		return err;
251 
252 	/* Decode and execute copy instructions from the delta stream. */
253 	err = next_delta_byte(&p, &remain);
254 	while (err == NULL) {
255 		if (*p & GOT_DELTA_BASE_COPY) {
256 			off_t offset = 0;
257 			size_t len = 0;
258 			err = parse_opcode(&offset, &len, &p, &remain);
259 			if (err)
260 				break;
261 			if (base_file == NULL) {
262 				size_t inflated_size;
263 				err = got_inflate_to_tempfile(&base_file,
264 				    &inflated_size, base_compressed);
265 				if (err)
266 					break;
267 				if (inflated_size != base_size) {
268 					err = got_error(GOT_ERR_BAD_DELTA);
269 					break;
270 				}
271 			}
272 			err = copy_from_base(base_file, offset, len, outfile);
273 			if (err == NULL)
274 				outsize += len;
275 		} else {
276 			size_t len = (size_t)*p;
277 			if (len == 0) {
278 				err = got_error(GOT_ERR_BAD_DELTA);
279 				break;
280 			}
281 			err = next_delta_byte(&p, &remain);
282 			if (err)
283 				return err;
284 			err = copy_from_delta(&p, &remain, len, outfile);
285 			if (err == NULL)
286 				outsize += len;
287 		}
288 
289 		if (err == NULL) {
290 			if (remain == 0)
291 				break;
292 			/* Fetch the next instruction. */
293 			p++;
294 			remain--;
295 		}
296 	}
297 
298 	if (outsize != result_size)
299 		err = got_error(GOT_ERR_BAD_DELTA);
300 
301 	if (base_file)
302 		fclose(base_file);
303 	if (err == NULL)
304 		rewind(outfile);
305 	return err;
306 }