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_error.h"
29 #include "got_repository.h"
30 #include "got_object.h"
31 #include "got_path.h"
32 
33 #include "got_lib_delta.h"
34 #include "got_lib_inflate.h"
35 #include "got_lib_object.h"
36 
37 #ifndef MIN
38 #define	MIN(_a,_b) ((_a) < (_b) ? (_a) : (_b))
39 #endif
40 
41 struct got_delta *
42 got_delta_open(off_t offset, size_t tslen, int type, size_t size,
43     off_t data_offset)
44 {
45 	struct got_delta *delta;
46 
47 	delta = malloc(sizeof(*delta));
48 	if (delta == NULL)
49 		return NULL;
50 
51 	delta->type = type;
52 	delta->offset = offset;
53 	delta->tslen = tslen;
54 	delta->size = size;
55 	delta->data_offset = data_offset;
56 	return delta;
57 }
58 
59 const struct got_error *
60 got_delta_chain_get_base_type(int *type, struct got_delta_chain *deltas)
61 {
62 	struct got_delta *delta;
63 
64 	/* The first delta in the chain should represent the base object. */
65 	delta = STAILQ_FIRST(&deltas->entries);
66 	if (delta->type == GOT_OBJ_TYPE_COMMIT ||
67 	    delta->type == GOT_OBJ_TYPE_TREE ||
68 	    delta->type == GOT_OBJ_TYPE_BLOB ||
69 	    delta->type == GOT_OBJ_TYPE_TAG) {
70 		*type = delta->type;
71 		return NULL;
72 	}
73 
74 	return got_error(GOT_ERR_BAD_DELTA_CHAIN);
75 }
76 
77 /* Fetch another (required) byte from the delta stream. */
78 static const struct got_error *
79 next_delta_byte(const uint8_t **p, size_t *remain)
80 {
81 	if (--(*remain) == 0)
82 		return got_error_msg(GOT_ERR_BAD_DELTA,
83 		    "delta data truncated");
84 	(*p)++;
85 	return NULL;
86 }
87 
88 static const struct got_error *
89 parse_size(uint64_t *size, const uint8_t **p, size_t *remain)
90 {
91 	const struct got_error *err = NULL;
92 	int i = 0;
93 
94 	*size = 0;
95 	do {
96 		/* We do not support size values which don't fit in 64 bit. */
97 		if (i > 9)
98 			return got_error(GOT_ERR_NO_SPACE);
99 
100 		if (i == 0)
101 			*size = ((**p) & GOT_DELTA_SIZE_VAL_MASK);
102 		else {
103 			size_t shift = GOT_DELTA_SIZE_SHIFT * i;
104 			*size |= (((**p) & GOT_DELTA_SIZE_VAL_MASK) << shift);
105 		}
106 
107 		if (((**p) & GOT_DELTA_SIZE_MORE) == 0)
108 			break;
109 		i++;
110 		err = next_delta_byte(p, remain);
111 	} while (err == NULL);
112 
113 	return err;
114 }
115 
116 static const struct got_error *
117 parse_opcode(off_t *offset, size_t *len, const uint8_t **p, size_t *remain)
118 {
119 	const struct got_error *err = NULL;
120 	off_t o = 0;
121 	size_t l = 0;
122 	uint8_t opcode = **p;
123 
124 	if (opcode & GOT_DELTA_COPY_OFF1) {
125 		err = next_delta_byte(p, remain);
126 		if (err)
127 			return err;
128 		o = (off_t)(**p);
129 	}
130 	if (opcode & GOT_DELTA_COPY_OFF2) {
131 		err = next_delta_byte(p, remain);
132 		if (err)
133 			return err;
134 		o |= ((off_t)(**p)) << 8;
135 	}
136 	if (opcode & GOT_DELTA_COPY_OFF3) {
137 		err = next_delta_byte(p, remain);
138 		if (err)
139 			return err;
140 		o |= ((off_t)(**p)) << 16;
141 	}
142 	if (opcode & GOT_DELTA_COPY_OFF4) {
143 		err = next_delta_byte(p, remain);
144 		if (err)
145 			return err;
146 		o |= ((off_t)(**p)) << 24;
147 	}
148 
149 	if (opcode & GOT_DELTA_COPY_LEN1) {
150 		err = next_delta_byte(p, remain);
151 		if (err)
152 			return err;
153 		l = (off_t)(**p);
154 	}
155 	if (opcode & GOT_DELTA_COPY_LEN2) {
156 		err = next_delta_byte(p, remain);
157 		if (err)
158 			return err;
159 		l |= ((off_t)(**p)) << 8;
160 	}
161 	if (opcode & GOT_DELTA_COPY_LEN3) {
162 		err = next_delta_byte(p, remain);
163 		if (err)
164 			return err;
165 		l |= ((off_t)(**p)) << 16;
166 	}
167 
168 	if (o == 0)
169 		o = GOT_DELTA_COPY_DEFAULT_OFF;
170 	if (l == 0)
171 		l = GOT_DELTA_COPY_DEFAULT_LEN;
172 
173 	*offset = o;
174 	*len = l;
175 	return NULL;
176 }
177 
178 static const struct got_error *
179 copy_from_base(FILE *base_file, off_t offset, size_t size, FILE *outfile)
180 {
181 	if (fseeko(base_file, offset, SEEK_SET) != 0)
182 		return got_error_from_errno("fseeko");
183 
184 	while (size > 0) {
185 		uint8_t data[2048];
186 		size_t len = MIN(size, sizeof(data));
187 		size_t n;
188 
189 		n = fread(data, len, 1, base_file);
190 		if (n != 1)
191 			return got_ferror(base_file, GOT_ERR_IO);
192 
193 		n = fwrite(data, len, 1, outfile);
194 		if (n != 1)
195 			return got_ferror(outfile, GOT_ERR_IO);
196 
197 		size -= len;
198 	}
199 
200 	return NULL;
201 }
202 
203 static const struct got_error *
204 copy_from_delta(const uint8_t **p, size_t *remain, size_t len, FILE *outfile)
205 {
206 	size_t n;
207 
208 	if (*remain < len)
209 		return got_error_msg(GOT_ERR_BAD_DELTA,
210 		    "copy from beyond end of delta data");
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_msg(GOT_ERR_BAD_DELTA, "delta too small");
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, size_t base_bufsz,
258     const uint8_t *delta_buf, size_t delta_len, uint8_t *outbuf,
259     size_t *outsize, size_t maxoutsize)
260 {
261 	const struct got_error *err = NULL;
262 	uint64_t base_size, result_size;
263 	size_t remain;
264 	const uint8_t *p;
265 
266 	*outsize= 0;
267 
268 	if (delta_len < GOT_DELTA_STREAM_LENGTH_MIN)
269 		return got_error_msg(GOT_ERR_BAD_DELTA, "delta too small");
270 
271 	p = delta_buf;
272 	remain = delta_len;
273 	err = parse_delta_sizes(&base_size, &result_size, &p, &remain);
274 	if (err)
275 		return err;
276 
277 	/* Decode and execute copy instructions from the delta stream. */
278 	err = next_delta_byte(&p, &remain);
279 	while (err == NULL && remain > 0) {
280 		if (*p & GOT_DELTA_BASE_COPY) {
281 			off_t offset = 0;
282 			size_t len = 0;
283 			err = parse_opcode(&offset, &len, &p, &remain);
284 			if (err)
285 				break;
286 			if (SIZE_MAX - offset < len || offset + len < 0 ||
287 			    base_bufsz < offset + len ||
288 			    *outsize + len > maxoutsize)
289 				return got_error_msg(GOT_ERR_BAD_DELTA,
290 				    "bad delta copy length");
291 			memcpy(outbuf + *outsize, base_buf + offset, len);
292 			if (err == NULL) {
293 				*outsize += len;
294 				if (remain > 0) {
295 					p++;
296 					remain--;
297 				}
298 			}
299 		} else {
300 			size_t len = (size_t)*p;
301 			if (len == 0) {
302 				err = got_error_msg(GOT_ERR_BAD_DELTA,
303 				    "zero length delta");
304 				break;
305 			}
306 			err = next_delta_byte(&p, &remain);
307 			if (err)
308 				break;
309 			if (remain < len || SIZE_MAX - *outsize < len ||
310 			    *outsize + len > maxoutsize)
311 				return got_error_msg(GOT_ERR_BAD_DELTA,
312 				    "bad delta copy length");
313 			memcpy(outbuf + *outsize, p, len);
314 			p += len;
315 			remain -= len;
316 			*outsize += len;
317 		}
318 	}
319 
320 	if (*outsize != result_size)
321 		err = got_error_msg(GOT_ERR_BAD_DELTA,
322 		    "delta application result size mismatch");
323 	return err;
324 }
325 
326 const struct got_error *
327 got_delta_apply(FILE *base_file, const uint8_t *delta_buf,
328     size_t delta_len, FILE *outfile, size_t *outsize)
329 {
330 	const struct got_error *err = NULL;
331 	uint64_t base_size, result_size;
332 	size_t remain = 0;
333 	const uint8_t *p;
334 	FILE *memstream = NULL;
335 	char *memstream_buf = NULL;
336 	size_t memstream_size = 0;
337 
338 	*outsize = 0;
339 
340 	if (delta_len < GOT_DELTA_STREAM_LENGTH_MIN)
341 		return got_error_msg(GOT_ERR_BAD_DELTA, "delta too small");
342 
343 	p = delta_buf;
344 	remain = delta_len;
345 	err = parse_delta_sizes(&base_size, &result_size, &p, &remain);
346 	if (err)
347 		return err;
348 
349 	if (result_size < GOT_DELTA_RESULT_SIZE_CACHED_MAX)
350 		memstream = open_memstream(&memstream_buf, &memstream_size);
351 
352 	/* Decode and execute copy instructions from the delta stream. */
353 	err = next_delta_byte(&p, &remain);
354 	while (err == NULL && remain > 0) {
355 		if (*p & GOT_DELTA_BASE_COPY) {
356 			off_t offset = 0;
357 			size_t len = 0;
358 			err = parse_opcode(&offset, &len, &p, &remain);
359 			if (err)
360 				break;
361 			err = copy_from_base(base_file, offset, len,
362 			    memstream ? memstream : outfile);
363 			if (err == NULL) {
364 				*outsize += len;
365 				if (remain > 0) {
366 					p++;
367 					remain--;
368 				}
369 			}
370 		} else {
371 			size_t len = (size_t)*p;
372 			if (len == 0) {
373 				err = got_error_msg(GOT_ERR_BAD_DELTA,
374 				    "zero length 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_msg(GOT_ERR_BAD_DELTA,
389 		    "delta application result size mismatch");
390 
391 	if (memstream != NULL) {
392 		if (fclose(memstream) == EOF)
393 			err = got_error_from_errno("fclose");
394 		if (err == NULL) {
395 			size_t n;
396 			n = fwrite(memstream_buf, 1, memstream_size, outfile);
397 			if (n != memstream_size)
398 				err = got_ferror(outfile, GOT_ERR_IO);
399 		}
400 		free(memstream_buf);
401 	}
402 	if (err == NULL)
403 		rewind(outfile);
404 	return err;
405 }