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 #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 = SIMPLEQ_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(GOT_ERR_BAD_DELTA);
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(GOT_ERR_BAD_DELTA);
209 
210 	n = fwrite(*p, len, 1, outfile);
211 	if (n != 1)
212 		return got_ferror(outfile, GOT_ERR_IO);
213 
214 	*p += len;
215 	*remain -= len;
216 	return NULL;
217 }
218 
219 static const struct got_error *
220 parse_delta_sizes(uint64_t *base_size, uint64_t *result_size,
221     const uint8_t **p, size_t *remain)
222 {
223 	const struct got_error *err;
224 
225 	/* Read the two size fields at the beginning of the stream. */
226 	err = parse_size(base_size, p, remain);
227 	if (err)
228 		return err;
229 	err = next_delta_byte(p, remain);
230 	if (err)
231 		return err;
232 	err = parse_size(result_size, p, remain);
233 	if (err)
234 		return err;
235 
236 	return NULL;
237 }
238 
239 const struct got_error *
240 got_delta_get_sizes(uint64_t *base_size, uint64_t *result_size,
241     const uint8_t *delta_buf, size_t delta_len)
242 {
243 	size_t remain;
244 	const uint8_t *p;
245 
246 	if (delta_len < GOT_DELTA_STREAM_LENGTH_MIN)
247 		return got_error(GOT_ERR_BAD_DELTA);
248 
249 	p = delta_buf;
250 	remain = delta_len;
251 	return parse_delta_sizes(base_size, result_size, &p, &remain);
252 }
253 
254 const struct got_error *
255 got_delta_apply_in_mem(uint8_t *base_buf, size_t base_bufsz,
256     const uint8_t *delta_buf, size_t delta_len, uint8_t *outbuf,
257     size_t *outsize, size_t maxoutsize)
258 {
259 	const struct got_error *err = NULL;
260 	uint64_t base_size, result_size;
261 	size_t remain;
262 	const uint8_t *p;
263 
264 	*outsize= 0;
265 
266 	if (delta_len < GOT_DELTA_STREAM_LENGTH_MIN)
267 		return got_error(GOT_ERR_BAD_DELTA);
268 
269 	p = delta_buf;
270 	remain = delta_len;
271 	err = parse_delta_sizes(&base_size, &result_size, &p, &remain);
272 	if (err)
273 		return err;
274 
275 	/* Decode and execute copy instructions from the delta stream. */
276 	err = next_delta_byte(&p, &remain);
277 	while (err == NULL && remain > 0) {
278 		if (*p & GOT_DELTA_BASE_COPY) {
279 			off_t offset = 0;
280 			size_t len = 0;
281 			err = parse_opcode(&offset, &len, &p, &remain);
282 			if (err)
283 				break;
284 			if (SIZE_MAX - offset < len || offset + len < 0 ||
285 			    base_bufsz < offset + len ||
286 			    *outsize + len > maxoutsize)
287 				return got_error(GOT_ERR_BAD_DELTA);
288 			memcpy(outbuf + *outsize, base_buf + offset, len);
289 			if (err == NULL) {
290 				*outsize += len;
291 				if (remain > 0) {
292 					p++;
293 					remain--;
294 				}
295 			}
296 		} else {
297 			size_t len = (size_t)*p;
298 			if (len == 0) {
299 				err = got_error(GOT_ERR_BAD_DELTA);
300 				break;
301 			}
302 			err = next_delta_byte(&p, &remain);
303 			if (err)
304 				break;
305 			if (remain < len || SIZE_MAX - *outsize < len ||
306 			    *outsize + len > maxoutsize)
307 				return got_error(GOT_ERR_BAD_DELTA);
308 			memcpy(outbuf + *outsize, p, len);
309 			p += len;
310 			remain -= len;
311 			*outsize += len;
312 		}
313 	}
314 
315 	if (*outsize != result_size)
316 		err = got_error(GOT_ERR_BAD_DELTA);
317 	return err;
318 }
319 
320 const struct got_error *
321 got_delta_apply(FILE *base_file, const uint8_t *delta_buf,
322     size_t delta_len, FILE *outfile, size_t *outsize)
323 {
324 	const struct got_error *err = NULL;
325 	uint64_t base_size, result_size;
326 	size_t remain = 0;
327 	const uint8_t *p;
328 	FILE *memstream = NULL;
329 	char *memstream_buf = NULL;
330 	size_t memstream_size = 0;
331 
332 	*outsize = 0;
333 
334 	if (delta_len < GOT_DELTA_STREAM_LENGTH_MIN)
335 		return got_error(GOT_ERR_BAD_DELTA);
336 
337 	p = delta_buf;
338 	remain = delta_len;
339 	err = parse_delta_sizes(&base_size, &result_size, &p, &remain);
340 	if (err)
341 		return err;
342 
343 	if (result_size < GOT_DELTA_RESULT_SIZE_CACHED_MAX)
344 		memstream = open_memstream(&memstream_buf, &memstream_size);
345 
346 	/* Decode and execute copy instructions from the delta stream. */
347 	err = next_delta_byte(&p, &remain);
348 	while (err == NULL && remain > 0) {
349 		if (*p & GOT_DELTA_BASE_COPY) {
350 			off_t offset = 0;
351 			size_t len = 0;
352 			err = parse_opcode(&offset, &len, &p, &remain);
353 			if (err)
354 				break;
355 			err = copy_from_base(base_file, offset, len,
356 			    memstream ? memstream : outfile);
357 			if (err == NULL) {
358 				*outsize += len;
359 				if (remain > 0) {
360 					p++;
361 					remain--;
362 				}
363 			}
364 		} else {
365 			size_t len = (size_t)*p;
366 			if (len == 0) {
367 				err = got_error(GOT_ERR_BAD_DELTA);
368 				break;
369 			}
370 			err = next_delta_byte(&p, &remain);
371 			if (err)
372 				break;
373 			err = copy_from_delta(&p, &remain, len,
374 			    memstream ? memstream : outfile);
375 			if (err == NULL)
376 				*outsize += len;
377 		}
378 	}
379 
380 	if (*outsize != result_size)
381 		err = got_error(GOT_ERR_BAD_DELTA);
382 
383 	if (memstream != NULL) {
384 		if (fclose(memstream) != 0)
385 			err = got_error_from_errno("fclose");
386 		if (err == NULL) {
387 			size_t n;
388 			n = fwrite(memstream_buf, 1, memstream_size, outfile);
389 			if (n != memstream_size)
390 				err = got_ferror(outfile, GOT_ERR_IO);
391 		}
392 		free(memstream_buf);
393 	}
394 	if (err == NULL)
395 		rewind(outfile);
396 	return err;
397 }