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 <stdint.h>
22 #include <string.h>
23 #include <zlib.h>
24 #include <sha1.h>
25 #include <time.h>
26 
27 #include "got_error.h"
28 #include "got_repository.h"
29 #include "got_object.h"
30 
31 #include "got_lib_delta.h"
32 #include "got_lib_path.h"
33 #include "got_lib_inflate.h"
34 
35 #ifndef MIN
36 #define	MIN(_a,_b) ((_a) < (_b) ? (_a) : (_b))
37 #endif
38 
39 struct got_delta *
40 got_delta_open(off_t offset, size_t tslen, int type, size_t size,
41     off_t data_offset, uint8_t *delta_buf, size_t delta_len)
42 {
43 	struct got_delta *delta;
44 
45 	delta = malloc(sizeof(*delta));
46 	if (delta == NULL)
47 		return NULL;
48 
49 	delta->type = type;
50 	delta->offset = offset;
51 	delta->tslen = tslen;
52 	delta->size = size;
53 	delta->data_offset = data_offset;
54 	delta->delta_buf = delta_buf;
55 	delta->delta_len = delta_len;
56 	return delta;
57 }
58 
59 void
60 got_delta_close(struct got_delta *delta)
61 {
62 	free(delta->delta_buf);
63 	free(delta);
64 }
65 
66 const struct got_error *
67 got_delta_chain_get_base_type(int *type, struct got_delta_chain *deltas)
68 {
69 	struct got_delta *delta;
70 
71 	/* The first delta in the chain should represent the base object. */
72 	delta = SIMPLEQ_FIRST(&deltas->entries);
73 	if (delta->type == GOT_OBJ_TYPE_COMMIT ||
74 	    delta->type == GOT_OBJ_TYPE_TREE ||
75 	    delta->type == GOT_OBJ_TYPE_BLOB ||
76 	    delta->type == GOT_OBJ_TYPE_TAG) {
77 		*type = delta->type;
78 		return NULL;
79 	}
80 
81 	return got_error(GOT_ERR_BAD_DELTA_CHAIN);
82 }
83 
84 /* Fetch another (required) byte from the delta stream. */
85 static const struct got_error *
86 next_delta_byte(const uint8_t **p, size_t *remain)
87 {
88 	if (--(*remain) == 0)
89 		return got_error(GOT_ERR_BAD_DELTA);
90 	(*p)++;
91 	return NULL;
92 }
93 
94 static const struct got_error *
95 parse_size(uint64_t *size, const uint8_t **p, size_t *remain)
96 {
97 	const struct got_error *err = NULL;
98 	int i = 0;
99 
100 	*size = 0;
101 	do {
102 		/* We do not support size values which don't fit in 64 bit. */
103 		if (i > 9)
104 			return got_error(GOT_ERR_NO_SPACE);
105 
106 		if (i == 0)
107 			*size = ((**p) & GOT_DELTA_SIZE_VAL_MASK);
108 		else {
109 			size_t shift = GOT_DELTA_SIZE_SHIFT * i;
110 			*size |= (((**p) & GOT_DELTA_SIZE_VAL_MASK) << shift);
111 		}
112 
113 		if (((**p) & GOT_DELTA_SIZE_MORE) == 0)
114 			break;
115 		i++;
116 		err = next_delta_byte(p, remain);
117 	} while (err == NULL);
118 
119 	return err;
120 }
121 
122 static const struct got_error *
123 parse_opcode(off_t *offset, size_t *len, const uint8_t **p, size_t *remain)
124 {
125 	const struct got_error *err = NULL;
126 	off_t o = 0;
127 	size_t l = 0;
128 	uint8_t opcode = **p;
129 
130 	if (opcode & GOT_DELTA_COPY_OFF1) {
131 		err = next_delta_byte(p, remain);
132 		if (err)
133 			return err;
134 		o = (off_t)(**p);
135 	}
136 	if (opcode & GOT_DELTA_COPY_OFF2) {
137 		err = next_delta_byte(p, remain);
138 		if (err)
139 			return err;
140 		o |= ((off_t)(**p)) << 8;
141 	}
142 	if (opcode & GOT_DELTA_COPY_OFF3) {
143 		err = next_delta_byte(p, remain);
144 		if (err)
145 			return err;
146 		o |= ((off_t)(**p)) << 16;
147 	}
148 	if (opcode & GOT_DELTA_COPY_OFF4) {
149 		err = next_delta_byte(p, remain);
150 		if (err)
151 			return err;
152 		o |= ((off_t)(**p)) << 24;
153 	}
154 
155 	if (opcode & GOT_DELTA_COPY_LEN1) {
156 		err = next_delta_byte(p, remain);
157 		if (err)
158 			return err;
159 		l = (off_t)(**p);
160 	}
161 	if (opcode & GOT_DELTA_COPY_LEN2) {
162 		err = next_delta_byte(p, remain);
163 		if (err)
164 			return err;
165 		l |= ((off_t)(**p)) << 8;
166 	}
167 	if (opcode & GOT_DELTA_COPY_LEN3) {
168 		err = next_delta_byte(p, remain);
169 		if (err)
170 			return err;
171 		l |= ((off_t)(**p)) << 16;
172 	}
173 
174 	if (o == 0)
175 		o = GOT_DELTA_COPY_DEFAULT_OFF;
176 	if (l == 0)
177 		l = GOT_DELTA_COPY_DEFAULT_LEN;
178 
179 	*offset = o;
180 	*len = l;
181 	return NULL;
182 }
183 
184 static const struct got_error *
185 copy_from_base(FILE *base_file, off_t offset, size_t size, FILE *outfile)
186 {
187 	if (fseeko(base_file, offset, SEEK_SET) != 0)
188 		return got_error_from_errno();
189 
190 	while (size > 0) {
191 		uint8_t data[2048];
192 		size_t len = MIN(size, sizeof(data));
193 		size_t n;
194 
195 		n = fread(data, len, 1, base_file);
196 		if (n != 1)
197 			return got_ferror(base_file, GOT_ERR_IO);
198 
199 		n = fwrite(data, len, 1, outfile);
200 		if (n != 1)
201 			return got_ferror(outfile, GOT_ERR_IO);
202 
203 		size -= len;
204 	}
205 
206 	return NULL;
207 }
208 
209 static const struct got_error *
210 copy_from_delta(const uint8_t **p, size_t *remain, size_t len, FILE *outfile)
211 {
212 	size_t n;
213 
214 	if (*remain < len)
215 		return got_error(GOT_ERR_BAD_DELTA);
216 
217 	n = fwrite(*p, len, 1, outfile);
218 	if (n != 1)
219 		return got_ferror(outfile, GOT_ERR_IO);
220 
221 	*p += len;
222 	*remain -= len;
223 	return NULL;
224 }
225 
226 static const struct got_error *
227 parse_delta_sizes(uint64_t *base_size, uint64_t *result_size,
228     const uint8_t **p, size_t *remain)
229 {
230 	const struct got_error *err;
231 
232 	/* Read the two size fields at the beginning of the stream. */
233 	err = parse_size(base_size, p, remain);
234 	if (err)
235 		return err;
236 	err = next_delta_byte(p, remain);
237 	if (err)
238 		return err;
239 	err = parse_size(result_size, p, remain);
240 	if (err)
241 		return err;
242 
243 	return NULL;
244 }
245 
246 const struct got_error *
247 got_delta_get_sizes(uint64_t *base_size, uint64_t *result_size,
248     const uint8_t *delta_buf, size_t delta_len)
249 {
250 	size_t remain;
251 	const uint8_t *p;
252 
253 	if (delta_len < GOT_DELTA_STREAM_LENGTH_MIN)
254 		return got_error(GOT_ERR_BAD_DELTA);
255 
256 	p = delta_buf;
257 	remain = delta_len;
258 	return parse_delta_sizes(base_size, result_size, &p, &remain);
259 }
260 
261 const struct got_error *
262 got_delta_apply_in_mem(uint8_t *base_buf, size_t base_bufsz,
263     const uint8_t *delta_buf, size_t delta_len, uint8_t *outbuf,
264     size_t *outsize, size_t maxoutsize)
265 {
266 	const struct got_error *err = NULL;
267 	uint64_t base_size, result_size;
268 	size_t remain;
269 	const uint8_t *p;
270 
271 	*outsize= 0;
272 
273 	if (delta_len < GOT_DELTA_STREAM_LENGTH_MIN)
274 		return got_error(GOT_ERR_BAD_DELTA);
275 
276 	p = delta_buf;
277 	remain = delta_len;
278 	err = parse_delta_sizes(&base_size, &result_size, &p, &remain);
279 	if (err)
280 		return err;
281 
282 	/* Decode and execute copy instructions from the delta stream. */
283 	err = next_delta_byte(&p, &remain);
284 	while (err == NULL && remain > 0) {
285 		if (*p & GOT_DELTA_BASE_COPY) {
286 			off_t offset = 0;
287 			size_t len = 0;
288 			err = parse_opcode(&offset, &len, &p, &remain);
289 			if (err)
290 				break;
291 			if (SIZE_MAX - offset < len || offset + len < 0 ||
292 			    base_bufsz < offset + len ||
293 			    *outsize + len > maxoutsize)
294 				return got_error(GOT_ERR_BAD_DELTA);
295 			memcpy(outbuf + *outsize, base_buf + offset, len);
296 			if (err == NULL) {
297 				*outsize += len;
298 				if (remain > 0) {
299 					p++;
300 					remain--;
301 				}
302 			}
303 		} else {
304 			size_t len = (size_t)*p;
305 			if (len == 0) {
306 				err = got_error(GOT_ERR_BAD_DELTA);
307 				break;
308 			}
309 			err = next_delta_byte(&p, &remain);
310 			if (err)
311 				break;
312 			if (remain < len || SIZE_MAX - *outsize < len ||
313 			    *outsize + len > maxoutsize)
314 				return got_error(GOT_ERR_BAD_DELTA);
315 			memcpy(outbuf + *outsize, p, len);
316 			p += len;
317 			remain -= len;
318 			*outsize += len;
319 		}
320 	}
321 
322 	if (*outsize != result_size)
323 		err = got_error(GOT_ERR_BAD_DELTA);
324 	return err;
325 }
326 
327 const struct got_error *
328 got_delta_apply(FILE *base_file, const uint8_t *delta_buf,
329     size_t delta_len, FILE *outfile, size_t *outsize)
330 {
331 	const struct got_error *err = NULL;
332 	uint64_t base_size, result_size;
333 	size_t remain = 0;
334 	const uint8_t *p;
335 	FILE *memstream = NULL;
336 	char *memstream_buf = NULL;
337 	size_t memstream_size = 0;
338 
339 	*outsize = 0;
340 
341 	if (delta_len < GOT_DELTA_STREAM_LENGTH_MIN)
342 		return got_error(GOT_ERR_BAD_DELTA);
343 
344 	p = delta_buf;
345 	remain = delta_len;
346 	err = parse_delta_sizes(&base_size, &result_size, &p, &remain);
347 	if (err)
348 		return err;
349 
350 	if (result_size < GOT_DELTA_RESULT_SIZE_CACHED_MAX)
351 		memstream = open_memstream(&memstream_buf, &memstream_size);
352 
353 	/* Decode and execute copy instructions from the delta stream. */
354 	err = next_delta_byte(&p, &remain);
355 	while (err == NULL && remain > 0) {
356 		if (*p & GOT_DELTA_BASE_COPY) {
357 			off_t offset = 0;
358 			size_t len = 0;
359 			err = parse_opcode(&offset, &len, &p, &remain);
360 			if (err)
361 				break;
362 			err = copy_from_base(base_file, offset, len,
363 			    memstream ? memstream : outfile);
364 			if (err == NULL) {
365 				*outsize += len;
366 				if (remain > 0) {
367 					p++;
368 					remain--;
369 				}
370 			}
371 		} else {
372 			size_t len = (size_t)*p;
373 			if (len == 0) {
374 				err = got_error(GOT_ERR_BAD_DELTA);
375 				break;
376 			}
377 			err = next_delta_byte(&p, &remain);
378 			if (err)
379 				break;
380 			err = copy_from_delta(&p, &remain, len,
381 			    memstream ? memstream : outfile);
382 			if (err == NULL)
383 				*outsize += len;
384 		}
385 	}
386 
387 	if (*outsize != result_size)
388 		err = got_error(GOT_ERR_BAD_DELTA);
389 
390 	if (memstream != NULL) {
391 		fclose(memstream);
392 		if (err == NULL) {
393 			size_t n;
394 			n = fwrite(memstream_buf, 1, memstream_size, outfile);
395 			if (n != memstream_size)
396 				err = got_ferror(outfile, GOT_ERR_IO);
397 		}
398 		free(memstream_buf);
399 	}
400 	if (err == NULL)
401 		rewind(outfile);
402 	return err;
403 }