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