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