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 <limits.h>
24 #include <zlib.h>
25 #include <time.h>
26 #include <zlib.h>
27 
28 #include "got_compat.h"
29 #include "got_error.h"
30 #include "got_repository.h"
31 #include "got_object.h"
32 #include "got_path.h"
33 
34 #include "got_lib_delta.h"
35 #include "got_lib_inflate.h"
36 #include "got_lib_object.h"
37 
38 #ifndef MIN
39 #define	MIN(_a,_b) ((_a) < (_b) ? (_a) : (_b))
40 #endif
41 
42 struct got_delta *
43 got_delta_open(off_t offset, size_t tslen, int type, size_t size,
44     off_t data_offset)
45 {
46 	struct got_delta *delta;
47 
48 	delta = malloc(sizeof(*delta));
49 	if (delta == NULL)
50 		return NULL;
51 
52 	delta->type = type;
53 	delta->offset = offset;
54 	delta->tslen = tslen;
55 	delta->size = size;
56 	delta->data_offset = data_offset;
57 	return delta;
58 }
59 
60 const struct got_error *
61 got_delta_chain_get_base_type(int *type, struct got_delta_chain *deltas)
62 {
63 	struct got_delta *delta;
64 
65 	/* The first delta in the chain should represent the base object. */
66 	delta = STAILQ_FIRST(&deltas->entries);
67 	if (delta->type == GOT_OBJ_TYPE_COMMIT ||
68 	    delta->type == GOT_OBJ_TYPE_TREE ||
69 	    delta->type == GOT_OBJ_TYPE_BLOB ||
70 	    delta->type == GOT_OBJ_TYPE_TAG) {
71 		*type = delta->type;
72 		return NULL;
73 	}
74 
75 	return got_error(GOT_ERR_BAD_DELTA_CHAIN);
76 }
77 
78 /* Fetch another (required) byte from the delta stream. */
79 static const struct got_error *
80 next_delta_byte(const uint8_t **p, size_t *remain)
81 {
82 	if (--(*remain) == 0)
83 		return got_error_msg(GOT_ERR_BAD_DELTA,
84 		    "delta data truncated");
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("fseeko");
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_msg(GOT_ERR_BAD_DELTA,
211 		    "copy from beyond end of delta data");
212 
213 	n = fwrite(*p, len, 1, outfile);
214 	if (n != 1)
215 		return got_ferror(outfile, GOT_ERR_IO);
216 
217 	*p += len;
218 	*remain -= len;
219 	return NULL;
220 }
221 
222 static const struct got_error *
223 parse_delta_sizes(uint64_t *base_size, uint64_t *result_size,
224     const uint8_t **p, size_t *remain)
225 {
226 	const struct got_error *err;
227 
228 	/* Read the two size fields at the beginning of the stream. */
229 	err = parse_size(base_size, p, remain);
230 	if (err)
231 		return err;
232 	err = next_delta_byte(p, remain);
233 	if (err)
234 		return err;
235 	err = parse_size(result_size, p, remain);
236 	if (err)
237 		return err;
238 
239 	return NULL;
240 }
241 
242 const struct got_error *
243 got_delta_get_sizes(uint64_t *base_size, uint64_t *result_size,
244     const uint8_t *delta_buf, size_t delta_len)
245 {
246 	size_t remain;
247 	const uint8_t *p;
248 
249 	if (delta_len < GOT_DELTA_STREAM_LENGTH_MIN)
250 		return got_error_msg(GOT_ERR_BAD_DELTA, "delta too small");
251 
252 	p = delta_buf;
253 	remain = delta_len;
254 	return parse_delta_sizes(base_size, result_size, &p, &remain);
255 }
256 
257 const struct got_error *
258 got_delta_apply_in_mem(uint8_t *base_buf, size_t base_bufsz,
259     const uint8_t *delta_buf, size_t delta_len, uint8_t *outbuf,
260     size_t *outsize, size_t maxoutsize)
261 {
262 	const struct got_error *err = NULL;
263 	uint64_t base_size, result_size;
264 	size_t remain;
265 	const uint8_t *p;
266 
267 	*outsize= 0;
268 
269 	if (delta_len < GOT_DELTA_STREAM_LENGTH_MIN)
270 		return got_error_msg(GOT_ERR_BAD_DELTA, "delta too small");
271 
272 	p = delta_buf;
273 	remain = delta_len;
274 	err = parse_delta_sizes(&base_size, &result_size, &p, &remain);
275 	if (err)
276 		return err;
277 
278 	/* Decode and execute copy instructions from the delta stream. */
279 	err = next_delta_byte(&p, &remain);
280 	while (err == NULL && remain > 0) {
281 		if (*p & GOT_DELTA_BASE_COPY) {
282 			off_t offset = 0;
283 			size_t len = 0;
284 			err = parse_opcode(&offset, &len, &p, &remain);
285 			if (err)
286 				break;
287 			if (SIZE_MAX - offset < len || offset + len < 0 ||
288 			    base_bufsz < offset + len ||
289 			    *outsize + len > maxoutsize)
290 				return got_error_msg(GOT_ERR_BAD_DELTA,
291 				    "bad delta copy length");
292 			memcpy(outbuf + *outsize, base_buf + offset, len);
293 			if (err == NULL) {
294 				*outsize += len;
295 				if (remain > 0) {
296 					p++;
297 					remain--;
298 				}
299 			}
300 		} else {
301 			size_t len = (size_t)*p;
302 			if (len == 0) {
303 				err = got_error_msg(GOT_ERR_BAD_DELTA,
304 				    "zero length delta");
305 				break;
306 			}
307 			err = next_delta_byte(&p, &remain);
308 			if (err)
309 				break;
310 			if (remain < len || SIZE_MAX - *outsize < len ||
311 			    *outsize + len > maxoutsize)
312 				return got_error_msg(GOT_ERR_BAD_DELTA,
313 				    "bad delta copy length");
314 			memcpy(outbuf + *outsize, p, len);
315 			p += len;
316 			remain -= len;
317 			*outsize += len;
318 		}
319 	}
320 
321 	if (*outsize != result_size)
322 		err = got_error_msg(GOT_ERR_BAD_DELTA,
323 		    "delta application result size mismatch");
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_msg(GOT_ERR_BAD_DELTA, "delta too small");
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_msg(GOT_ERR_BAD_DELTA,
375 				    "zero length delta");
376 				break;
377 			}
378 			err = next_delta_byte(&p, &remain);
379 			if (err)
380 				break;
381 			err = copy_from_delta(&p, &remain, len,
382 			    memstream ? memstream : outfile);
383 			if (err == NULL)
384 				*outsize += len;
385 		}
386 	}
387 
388 	if (*outsize != result_size)
389 		err = got_error_msg(GOT_ERR_BAD_DELTA,
390 		    "delta application result size mismatch");
391 
392 	if (memstream != NULL) {
393 		if (fclose(memstream) == EOF)
394 			err = got_error_from_errno("fclose");
395 		if (err == NULL) {
396 			size_t n;
397 			n = fwrite(memstream_buf, 1, memstream_size, outfile);
398 			if (n != memstream_size)
399 				err = got_ferror(outfile, GOT_ERR_IO);
400 		}
401 		free(memstream_buf);
402 	}
403 	if (err == NULL)
404 		rewind(outfile);
405 	return err;
406 }