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 
18 #include <stdio.h>
19 #include <stdlib.h>
20 #include <stdint.h>
21 #include <string.h>
22 #include <limits.h>
23 #include <zlib.h>
24 #include <time.h>
25 #include <zlib.h>
26 
27 #include "got_error.h"
28 #include "got_repository.h"
29 #include "got_object.h"
30 #include "got_path.h"
31 
32 #include "got_lib_delta.h"
33 #include "got_lib_inflate.h"
34 #include "got_lib_object.h"
35 
36 #ifndef MIN
37 #define	MIN(_a,_b) ((_a) < (_b) ? (_a) : (_b))
38 #endif
39 
40 struct got_delta *
41 got_delta_open(off_t offset, size_t tslen, int type, size_t size,
42     off_t data_offset)
43 {
44 	struct got_delta *delta;
45 
46 	delta = malloc(sizeof(*delta));
47 	if (delta == NULL)
48 		return NULL;
49 
50 	delta->type = type;
51 	delta->offset = offset;
52 	delta->tslen = tslen;
53 	delta->size = size;
54 	delta->data_offset = data_offset;
55 	return delta;
56 }
57 
58 const struct got_error *
59 got_delta_chain_get_base_type(int *type, struct got_delta_chain *deltas)
60 {
61 	struct got_delta *delta;
62 
63 	/* The first delta in the chain should represent the base object. */
64 	delta = STAILQ_FIRST(&deltas->entries);
65 	if (delta->type == GOT_OBJ_TYPE_COMMIT ||
66 	    delta->type == GOT_OBJ_TYPE_TREE ||
67 	    delta->type == GOT_OBJ_TYPE_BLOB ||
68 	    delta->type == GOT_OBJ_TYPE_TAG) {
69 		*type = delta->type;
70 		return NULL;
71 	}
72 
73 	return got_error(GOT_ERR_BAD_DELTA_CHAIN);
74 }
75 
76 /* Fetch another (required) byte from the delta stream. */
77 static const struct got_error *
78 next_delta_byte(const uint8_t **p, size_t *remain)
79 {
80 	if (--(*remain) == 0)
81 		return got_error_msg(GOT_ERR_BAD_DELTA,
82 		    "delta data truncated");
83 	(*p)++;
84 	return NULL;
85 }
86 
87 static const struct got_error *
88 parse_size(uint64_t *size, const uint8_t **p, size_t *remain)
89 {
90 	const struct got_error *err = NULL;
91 	int i = 0;
92 
93 	*size = 0;
94 	do {
95 		/* We do not support size values which don't fit in 64 bit. */
96 		if (i > 9)
97 			return got_error(GOT_ERR_NO_SPACE);
98 
99 		if (i == 0)
100 			*size = ((**p) & GOT_DELTA_SIZE_VAL_MASK);
101 		else {
102 			size_t shift = GOT_DELTA_SIZE_SHIFT * i;
103 			*size |= (((**p) & GOT_DELTA_SIZE_VAL_MASK) << shift);
104 		}
105 
106 		if (((**p) & GOT_DELTA_SIZE_MORE) == 0)
107 			break;
108 		i++;
109 		err = next_delta_byte(p, remain);
110 	} while (err == NULL);
111 
112 	return err;
113 }
114 
115 static const struct got_error *
116 parse_opcode(off_t *offset, size_t *len, const uint8_t **p, size_t *remain)
117 {
118 	const struct got_error *err = NULL;
119 	off_t o = 0;
120 	size_t l = 0;
121 	uint8_t opcode = **p;
122 
123 	if (opcode & GOT_DELTA_COPY_OFF1) {
124 		err = next_delta_byte(p, remain);
125 		if (err)
126 			return err;
127 		o = (off_t)(**p);
128 	}
129 	if (opcode & GOT_DELTA_COPY_OFF2) {
130 		err = next_delta_byte(p, remain);
131 		if (err)
132 			return err;
133 		o |= ((off_t)(**p)) << 8;
134 	}
135 	if (opcode & GOT_DELTA_COPY_OFF3) {
136 		err = next_delta_byte(p, remain);
137 		if (err)
138 			return err;
139 		o |= ((off_t)(**p)) << 16;
140 	}
141 	if (opcode & GOT_DELTA_COPY_OFF4) {
142 		err = next_delta_byte(p, remain);
143 		if (err)
144 			return err;
145 		o |= ((off_t)(**p)) << 24;
146 	}
147 
148 	if (opcode & GOT_DELTA_COPY_LEN1) {
149 		err = next_delta_byte(p, remain);
150 		if (err)
151 			return err;
152 		l = (off_t)(**p);
153 	}
154 	if (opcode & GOT_DELTA_COPY_LEN2) {
155 		err = next_delta_byte(p, remain);
156 		if (err)
157 			return err;
158 		l |= ((off_t)(**p)) << 8;
159 	}
160 	if (opcode & GOT_DELTA_COPY_LEN3) {
161 		err = next_delta_byte(p, remain);
162 		if (err)
163 			return err;
164 		l |= ((off_t)(**p)) << 16;
165 	}
166 
167 	if (o == 0)
168 		o = GOT_DELTA_COPY_DEFAULT_OFF;
169 	if (l == 0)
170 		l = GOT_DELTA_COPY_DEFAULT_LEN;
171 
172 	*offset = o;
173 	*len = l;
174 	return NULL;
175 }
176 
177 static const struct got_error *
178 copy_from_base(FILE *base_file, off_t offset, size_t size, FILE *outfile)
179 {
180 	if (fseeko(base_file, offset, SEEK_SET) != 0)
181 		return got_error_from_errno("fseeko");
182 
183 	while (size > 0) {
184 		uint8_t data[2048];
185 		size_t len = MIN(size, sizeof(data));
186 		size_t n;
187 
188 		n = fread(data, len, 1, base_file);
189 		if (n != 1)
190 			return got_ferror(base_file, GOT_ERR_IO);
191 
192 		n = fwrite(data, len, 1, outfile);
193 		if (n != 1)
194 			return got_ferror(outfile, GOT_ERR_IO);
195 
196 		size -= len;
197 	}
198 
199 	return NULL;
200 }
201 
202 static const struct got_error *
203 copy_from_delta(const uint8_t **p, size_t *remain, size_t len, FILE *outfile)
204 {
205 	size_t n;
206 
207 	if (*remain < len)
208 		return got_error_msg(GOT_ERR_BAD_DELTA,
209 		    "copy from beyond end of delta data");
210 
211 	n = fwrite(*p, len, 1, outfile);
212 	if (n != 1)
213 		return got_ferror(outfile, GOT_ERR_IO);
214 
215 	*p += len;
216 	*remain -= len;
217 	return NULL;
218 }
219 
220 static const struct got_error *
221 parse_delta_sizes(uint64_t *base_size, uint64_t *result_size,
222     const uint8_t **p, size_t *remain)
223 {
224 	const struct got_error *err;
225 
226 	/* Read the two size fields at the beginning of the stream. */
227 	err = parse_size(base_size, p, remain);
228 	if (err)
229 		return err;
230 	err = next_delta_byte(p, remain);
231 	if (err)
232 		return err;
233 	err = parse_size(result_size, p, remain);
234 	if (err)
235 		return err;
236 
237 	return NULL;
238 }
239 
240 const struct got_error *
241 got_delta_get_sizes(uint64_t *base_size, uint64_t *result_size,
242     const uint8_t *delta_buf, size_t delta_len)
243 {
244 	size_t remain;
245 	const uint8_t *p;
246 
247 	if (delta_len < GOT_DELTA_STREAM_LENGTH_MIN)
248 		return got_error_msg(GOT_ERR_BAD_DELTA, "delta too small");
249 
250 	p = delta_buf;
251 	remain = delta_len;
252 	return parse_delta_sizes(base_size, result_size, &p, &remain);
253 }
254 
255 const struct got_error *
256 got_delta_apply_in_mem(uint8_t *base_buf, size_t base_bufsz,
257     const uint8_t *delta_buf, size_t delta_len, uint8_t *outbuf,
258     size_t *outsize, size_t maxoutsize)
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_msg(GOT_ERR_BAD_DELTA, "delta too small");
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 			if (SIZE_MAX - offset < len || offset + len < 0 ||
286 			    base_bufsz < offset + len ||
287 			    *outsize + len > maxoutsize)
288 				return got_error_msg(GOT_ERR_BAD_DELTA,
289 				    "bad delta copy length");
290 			memcpy(outbuf + *outsize, base_buf + offset, len);
291 			if (err == NULL) {
292 				*outsize += len;
293 				if (remain > 0) {
294 					p++;
295 					remain--;
296 				}
297 			}
298 		} else {
299 			size_t len = (size_t)*p;
300 			if (len == 0) {
301 				err = got_error_msg(GOT_ERR_BAD_DELTA,
302 				    "zero length delta");
303 				break;
304 			}
305 			err = next_delta_byte(&p, &remain);
306 			if (err)
307 				break;
308 			if (remain < len || SIZE_MAX - *outsize < len ||
309 			    *outsize + len > maxoutsize)
310 				return got_error_msg(GOT_ERR_BAD_DELTA,
311 				    "bad delta copy length");
312 			memcpy(outbuf + *outsize, p, len);
313 			p += len;
314 			remain -= len;
315 			*outsize += len;
316 		}
317 	}
318 
319 	if (*outsize != result_size)
320 		err = got_error_msg(GOT_ERR_BAD_DELTA,
321 		    "delta application result size mismatch");
322 	return err;
323 }
324 
325 const struct got_error *
326 got_delta_apply(FILE *base_file, const uint8_t *delta_buf,
327     size_t delta_len, FILE *outfile, size_t *outsize)
328 {
329 	const struct got_error *err = NULL;
330 	uint64_t base_size, result_size;
331 	size_t remain = 0;
332 	const uint8_t *p;
333 	FILE *memstream = NULL;
334 	char *memstream_buf = NULL;
335 	size_t memstream_size = 0;
336 
337 	*outsize = 0;
338 
339 	if (delta_len < GOT_DELTA_STREAM_LENGTH_MIN)
340 		return got_error_msg(GOT_ERR_BAD_DELTA, "delta too small");
341 
342 	p = delta_buf;
343 	remain = delta_len;
344 	err = parse_delta_sizes(&base_size, &result_size, &p, &remain);
345 	if (err)
346 		return err;
347 
348 	if (result_size < GOT_DELTA_RESULT_SIZE_CACHED_MAX)
349 		memstream = open_memstream(&memstream_buf, &memstream_size);
350 
351 	/* Decode and execute copy instructions from the delta stream. */
352 	err = next_delta_byte(&p, &remain);
353 	while (err == NULL && remain > 0) {
354 		if (*p & GOT_DELTA_BASE_COPY) {
355 			off_t offset = 0;
356 			size_t len = 0;
357 			err = parse_opcode(&offset, &len, &p, &remain);
358 			if (err)
359 				break;
360 			err = copy_from_base(base_file, offset, len,
361 			    memstream ? memstream : outfile);
362 			if (err == NULL) {
363 				*outsize += len;
364 				if (remain > 0) {
365 					p++;
366 					remain--;
367 				}
368 			}
369 		} else {
370 			size_t len = (size_t)*p;
371 			if (len == 0) {
372 				err = got_error_msg(GOT_ERR_BAD_DELTA,
373 				    "zero length delta");
374 				break;
375 			}
376 			err = next_delta_byte(&p, &remain);
377 			if (err)
378 				break;
379 			err = copy_from_delta(&p, &remain, len,
380 			    memstream ? memstream : outfile);
381 			if (err == NULL)
382 				*outsize += len;
383 		}
384 	}
385 
386 	if (*outsize != result_size)
387 		err = got_error_msg(GOT_ERR_BAD_DELTA,
388 		    "delta application result size mismatch");
389 
390 	if (memstream != NULL) {
391 		if (fclose(memstream) == EOF)
392 			err = got_error_from_errno("fclose");
393 		if (err == NULL) {
394 			size_t n;
395 			n = fwrite(memstream_buf, 1, memstream_size, outfile);
396 			if (n != memstream_size)
397 				err = got_ferror(outfile, GOT_ERR_IO);
398 		}
399 		free(memstream_buf);
400 	}
401 	if (err == NULL)
402 		rewind(outfile);
403 	return err;
404 }