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 "got_delta_lib.h"
30 #include "got_path_lib.h"
31 #include "got_zbuf_lib.h"
32 
33 #ifndef MIN
34 #define	MIN(_a,_b) ((_a) < (_b) ? (_a) : (_b))
35 #endif
36 
37 struct got_delta *
38 got_delta_open(const char *path_packfile, off_t offset, size_t tslen,
39     int type, size_t size, off_t data_offset)
40 {
41 	struct got_delta *delta;
42 
43 	delta = calloc(1, sizeof(*delta));
44 	if (delta == NULL)
45 		return NULL;
46 
47 	delta->type = type;
48 	delta->offset = offset;
49 	delta->tslen = tslen;
50 	delta->size = size;
51 	delta->data_offset = data_offset;
52 	return delta;
53 }
54 
55 void
56 got_delta_close(struct got_delta *delta)
57 {
58 	free(delta);
59 }
60 
61 const struct got_error *
62 got_delta_chain_get_base_type(int *type, struct got_delta_chain *deltas)
63 {
64 	struct got_delta *delta;
65 
66 	/* The first delta in the chain should represent the base object. */
67 	delta = SIMPLEQ_FIRST(&deltas->entries);
68 	if (delta->type == GOT_OBJ_TYPE_COMMIT ||
69 	    delta->type == GOT_OBJ_TYPE_TREE ||
70 	    delta->type == GOT_OBJ_TYPE_BLOB ||
71 	    delta->type == GOT_OBJ_TYPE_TAG) {
72 		*type = delta->type;
73 		return NULL;
74 	}
75 
76 	return got_error(GOT_ERR_BAD_DELTA_CHAIN);
77 }
78 
79 /* Fetch another (required) byte from the delta stream. */
80 static const struct got_error *
81 next_delta_byte(const uint8_t **p, size_t *remain)
82 {
83 	if (--(*remain) == 0)
84 		return got_error(GOT_ERR_BAD_DELTA);
85 	(*p)++;
86 	return NULL;
87 }
88 
89 static const struct got_error *
90 parse_size(uint64_t *size, const uint8_t **p, size_t *remain)
91 {
92 	const struct got_error *err = NULL;
93 	int i = 0;
94 
95 	*size = 0;
96 	do {
97 		/* We do not support size values which don't fit in 64 bit. */
98 		if (i > 9)
99 			return got_error(GOT_ERR_NO_SPACE);
100 
101 		if (i == 0)
102 			*size = ((**p) & GOT_DELTA_SIZE_VAL_MASK);
103 		else {
104 			size_t shift = GOT_DELTA_SIZE_SHIFT * i;
105 			*size |= (((**p) & GOT_DELTA_SIZE_VAL_MASK) << shift);
106 		}
107 
108 		if (((**p) & GOT_DELTA_SIZE_MORE) == 0)
109 			break;
110 		i++;
111 		err = next_delta_byte(p, remain);
112 	} while (err == NULL);
113 
114 	return err;
115 }
116 
117 static const struct got_error *
118 parse_opcode(off_t *offset, size_t *len, const uint8_t **p, size_t *remain)
119 {
120 	const struct got_error *err = NULL;
121 	off_t o = 0;
122 	size_t l = 0;
123 	uint8_t opcode = **p;
124 
125 	if (opcode & GOT_DELTA_COPY_OFF1) {
126 		err = next_delta_byte(p, remain);
127 		if (err)
128 			return err;
129 		o = (off_t)(**p);
130 	}
131 	if (opcode & GOT_DELTA_COPY_OFF2) {
132 		err = next_delta_byte(p, remain);
133 		if (err)
134 			return err;
135 		o |= ((off_t)(**p)) << 8;
136 	}
137 	if (opcode & GOT_DELTA_COPY_OFF3) {
138 		err = next_delta_byte(p, remain);
139 		if (err)
140 			return err;
141 		o |= ((off_t)(**p)) << 16;
142 	}
143 	if (opcode & GOT_DELTA_COPY_OFF4) {
144 		err = next_delta_byte(p, remain);
145 		if (err)
146 			return err;
147 		o |= ((off_t)(**p)) << 24;
148 	}
149 
150 	if (opcode & GOT_DELTA_COPY_LEN1) {
151 		err = next_delta_byte(p, remain);
152 		if (err)
153 			return err;
154 		l = (off_t)(**p);
155 	}
156 	if (opcode & GOT_DELTA_COPY_LEN2) {
157 		err = next_delta_byte(p, remain);
158 		if (err)
159 			return err;
160 		l |= ((off_t)(**p)) << 8;
161 	}
162 	if (opcode & GOT_DELTA_COPY_LEN3) {
163 		err = next_delta_byte(p, remain);
164 		if (err)
165 			return err;
166 		l |= ((off_t)(**p)) << 16;
167 	}
168 
169 	if (o == 0)
170 		o = GOT_DELTA_COPY_DEFAULT_OFF;
171 	if (l == 0)
172 		l = GOT_DELTA_COPY_DEFAULT_LEN;
173 
174 	*offset = o;
175 	*len = l;
176 	return NULL;
177 }
178 
179 static const struct got_error *
180 copy_from_base(FILE *base_file, off_t offset, size_t size, FILE *outfile)
181 {
182 	if (fseeko(base_file, offset, SEEK_SET) != 0)
183 		return got_error_from_errno();
184 
185 	while (size > 0) {
186 		uint8_t data[2048];
187 		size_t len = MIN(size, sizeof(data));
188 		size_t n;
189 
190 		n = fread(data, len, 1, base_file);
191 		if (n != 1)
192 			return got_ferror(base_file, GOT_ERR_IO);
193 
194 		n = fwrite(data, len, 1, outfile);
195 		if (n != 1)
196 			return got_ferror(outfile, GOT_ERR_IO);
197 
198 		size -= len;
199 	}
200 
201 	return NULL;
202 }
203 
204 static const struct got_error *
205 copy_from_delta(const uint8_t **p, size_t *remain, size_t len, FILE *outfile)
206 {
207 	size_t n;
208 
209 	if (*remain < len)
210 		return got_error(GOT_ERR_BAD_DELTA);
211 
212 	n = fwrite(*p, len, 1, outfile);
213 	if (n != 1)
214 		return got_ferror(outfile, GOT_ERR_IO);
215 
216 	*p += len;
217 	*remain -= len;
218 	return NULL;
219 }
220 
221 static const struct got_error *
222 parse_delta_sizes(uint64_t *base_size, uint64_t *result_size,
223     const uint8_t **p, size_t *remain)
224 {
225 	const struct got_error *err;
226 
227 	/* Read the two size fields at the beginning of the stream. */
228 	err = parse_size(base_size, p, remain);
229 	if (err)
230 		return err;
231 	err = next_delta_byte(p, remain);
232 	if (err)
233 		return err;
234 	err = parse_size(result_size, p, remain);
235 	if (err)
236 		return err;
237 
238 	return NULL;
239 }
240 
241 const struct got_error *
242 got_delta_get_sizes(uint64_t *base_size, uint64_t *result_size,
243     const uint8_t *delta_buf, size_t delta_len)
244 {
245 	size_t remain;
246 	const uint8_t *p;
247 
248 	if (delta_len < GOT_DELTA_STREAM_LENGTH_MIN)
249 		return got_error(GOT_ERR_BAD_DELTA);
250 
251 	p = delta_buf;
252 	remain = delta_len;
253 	return parse_delta_sizes(base_size, result_size, &p, &remain);
254 }
255 
256 const struct got_error *
257 got_delta_apply_in_mem(uint8_t *base_buf, const uint8_t *delta_buf,
258     size_t delta_len, uint8_t *outbuf, size_t *outsize)
259 {
260 	const struct got_error *err = NULL;
261 	uint64_t base_size, result_size;
262 	size_t remain;
263 	const uint8_t *p;
264 
265 	*outsize= 0;
266 
267 	if (delta_len < GOT_DELTA_STREAM_LENGTH_MIN)
268 		return got_error(GOT_ERR_BAD_DELTA);
269 
270 	p = delta_buf;
271 	remain = delta_len;
272 	err = parse_delta_sizes(&base_size, &result_size, &p, &remain);
273 	if (err)
274 		return err;
275 
276 	/* Decode and execute copy instructions from the delta stream. */
277 	err = next_delta_byte(&p, &remain);
278 	while (err == NULL && remain > 0) {
279 		if (*p & GOT_DELTA_BASE_COPY) {
280 			off_t offset = 0;
281 			size_t len = 0;
282 			err = parse_opcode(&offset, &len, &p, &remain);
283 			if (err)
284 				break;
285 			memcpy(outbuf + *outsize, base_buf + offset, len);
286 			if (err == NULL) {
287 				*outsize += len;
288 				if (remain > 0) {
289 					p++;
290 					remain--;
291 				}
292 			}
293 		} else {
294 			size_t len = (size_t)*p;
295 			if (len == 0) {
296 				err = got_error(GOT_ERR_BAD_DELTA);
297 				break;
298 			}
299 			err = next_delta_byte(&p, &remain);
300 			if (err)
301 				break;
302 			if (remain < len)
303 				return got_error(GOT_ERR_BAD_DELTA);
304 			memcpy(outbuf + *outsize, p, len);
305 			p += len;
306 			remain -= len;
307 			*outsize += len;
308 		}
309 	}
310 
311 	if (*outsize != result_size)
312 		err = got_error(GOT_ERR_BAD_DELTA);
313 	return err;
314 }
315 
316 const struct got_error *
317 got_delta_apply(FILE *base_file, const uint8_t *delta_buf,
318     size_t delta_len, FILE *outfile, size_t *outsize)
319 {
320 	const struct got_error *err = NULL;
321 	uint64_t base_size, result_size;
322 	size_t remain = 0;
323 	const uint8_t *p;
324 	FILE *memstream = NULL;
325 	char *memstream_buf = NULL;
326 	size_t memstream_size = 0;
327 
328 	*outsize = 0;
329 
330 	if (delta_len < GOT_DELTA_STREAM_LENGTH_MIN)
331 		return got_error(GOT_ERR_BAD_DELTA);
332 
333 	p = delta_buf;
334 	remain = delta_len;
335 	err = parse_delta_sizes(&base_size, &result_size, &p, &remain);
336 	if (err)
337 		return err;
338 
339 	if (result_size < GOT_DELTA_RESULT_SIZE_CACHED_MAX)
340 		memstream = open_memstream(&memstream_buf, &memstream_size);
341 
342 	/* Decode and execute copy instructions from the delta stream. */
343 	err = next_delta_byte(&p, &remain);
344 	while (err == NULL && remain > 0) {
345 		if (*p & GOT_DELTA_BASE_COPY) {
346 			off_t offset = 0;
347 			size_t len = 0;
348 			err = parse_opcode(&offset, &len, &p, &remain);
349 			if (err)
350 				break;
351 			err = copy_from_base(base_file, offset, len,
352 			    memstream ? memstream : outfile);
353 			if (err == NULL) {
354 				*outsize += len;
355 				if (remain > 0) {
356 					p++;
357 					remain--;
358 				}
359 			}
360 		} else {
361 			size_t len = (size_t)*p;
362 			if (len == 0) {
363 				err = got_error(GOT_ERR_BAD_DELTA);
364 				break;
365 			}
366 			err = next_delta_byte(&p, &remain);
367 			if (err)
368 				break;
369 			err = copy_from_delta(&p, &remain, len,
370 			    memstream ? memstream : outfile);
371 			if (err == NULL)
372 				*outsize += len;
373 		}
374 	}
375 
376 	if (*outsize != result_size)
377 		err = got_error(GOT_ERR_BAD_DELTA);
378 
379 	if (memstream != NULL) {
380 		fclose(memstream);
381 		if (err == NULL) {
382 			size_t n;
383 			n = fwrite(memstream_buf, 1, memstream_size, outfile);
384 			if (n != memstream_size)
385 				err = got_ferror(outfile, GOT_ERR_IO);
386 		}
387 		free(memstream_buf);
388 	}
389 	if (err == NULL)
390 		rewind(outfile);
391 	return err;
392 }