1 3b0f3d61 2020-01-22 neels /* Generic infrastructure to implement various diff algorithms (implementation). */
  2 3b0f3d61 2020-01-22 neels /*
  3 3b0f3d61 2020-01-22 neels  * Copyright (c) 2020 Neels Hofmeyr <neels@hofmeyr.de>
  4 3b0f3d61 2020-01-22 neels  *
  5 3b0f3d61 2020-01-22 neels  * Permission to use, copy, modify, and distribute this software for any
  6 3b0f3d61 2020-01-22 neels  * purpose with or without fee is hereby granted, provided that the above
  7 3b0f3d61 2020-01-22 neels  * copyright notice and this permission notice appear in all copies.
  8 3b0f3d61 2020-01-22 neels  *
  9 3b0f3d61 2020-01-22 neels  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 10 3b0f3d61 2020-01-22 neels  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 11 3b0f3d61 2020-01-22 neels  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 12 3b0f3d61 2020-01-22 neels  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 13 3b0f3d61 2020-01-22 neels  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 14 3b0f3d61 2020-01-22 neels  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 15 3b0f3d61 2020-01-22 neels  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 16 3b0f3d61 2020-01-22 neels  */
 17 3b0f3d61 2020-01-22 neels 
 18 3b0f3d61 2020-01-22 neels 
 19 3b0f3d61 2020-01-22 neels #include <sys/queue.h>
 20 e10a628a 2020-09-16 stsp #include <errno.h>
 21 3b0f3d61 2020-01-22 neels #include <stdint.h>
 22 3b0f3d61 2020-01-22 neels #include <stdlib.h>
 23 3b0f3d61 2020-01-22 neels #include <stdbool.h>
 24 3b0f3d61 2020-01-22 neels #include <stdio.h>
 25 3b0f3d61 2020-01-22 neels #include <string.h>
 26 3b0f3d61 2020-01-22 neels #include <limits.h>
 27 c6eecea3 2020-07-26 stsp #include <unistd.h>
 28 3b0f3d61 2020-01-22 neels 
 29 3b0f3d61 2020-01-22 neels #include <assert.h>
 30 3b0f3d61 2020-01-22 neels 
 31 e10a628a 2020-09-16 stsp #include <diff/arraylist.h>
 32 3b0f3d61 2020-01-22 neels #include <diff/diff_main.h>
 33 3b0f3d61 2020-01-22 neels 
 34 3b0f3d61 2020-01-22 neels #include "debug.h"
 35 c6eecea3 2020-07-26 stsp 
 36 b3fb4686 2020-09-20 neels static int
 37 b3fb4686 2020-09-20 neels read_at(int fd, int at_pos, unsigned char *buf, size_t len)
 38 c6eecea3 2020-07-26 stsp {
 39 b3fb4686 2020-09-20 neels 	int r;
 40 b3fb4686 2020-09-20 neels 	if (lseek(fd, at_pos, SEEK_SET) == -1)
 41 b3fb4686 2020-09-20 neels 		return errno;
 42 b3fb4686 2020-09-20 neels 	r = read(fd, buf, len);
 43 b3fb4686 2020-09-20 neels 	if (r == -1)
 44 b3fb4686 2020-09-20 neels 		return errno;
 45 b3fb4686 2020-09-20 neels 	if (r != len)
 46 b3fb4686 2020-09-20 neels 		return EIO;
 47 b3fb4686 2020-09-20 neels 	return 0;
 48 b3fb4686 2020-09-20 neels }
 49 b3fb4686 2020-09-20 neels 
 50 b3fb4686 2020-09-20 neels static int
 51 b3fb4686 2020-09-20 neels buf_cmp(const unsigned char *left, size_t left_len,
 52 b3fb4686 2020-09-20 neels 	const unsigned char *right, size_t right_len)
 53 b3fb4686 2020-09-20 neels {
 54 b3fb4686 2020-09-20 neels 	int cmp = memcmp(left, right, MIN(left_len, right_len));
 55 b3fb4686 2020-09-20 neels 	if (cmp)
 56 b3fb4686 2020-09-20 neels 		return cmp;
 57 b3fb4686 2020-09-20 neels 	if (left_len == right_len)
 58 b3fb4686 2020-09-20 neels 		return 0;
 59 b3fb4686 2020-09-20 neels 	return (left_len > right_len) ? 1 : -1;
 60 b3fb4686 2020-09-20 neels }
 61 b3fb4686 2020-09-20 neels 
 62 b3fb4686 2020-09-20 neels int
 63 b3fb4686 2020-09-20 neels diff_atom_cmp(int *cmp,
 64 b3fb4686 2020-09-20 neels 	      const struct diff_atom *left,
 65 b3fb4686 2020-09-20 neels 	      const struct diff_atom *right)
 66 b3fb4686 2020-09-20 neels {
 67 c6eecea3 2020-07-26 stsp 	off_t remain_left, remain_right;
 68 c6eecea3 2020-07-26 stsp 
 69 b3fb4686 2020-09-20 neels 	if (!left->len && !right->len) {
 70 b3fb4686 2020-09-20 neels 		*cmp = 0;
 71 b3fb4686 2020-09-20 neels 		return 0;
 72 b3fb4686 2020-09-20 neels 	}
 73 b3fb4686 2020-09-20 neels 	if (!right->len) {
 74 b3fb4686 2020-09-20 neels 		*cmp = 1;
 75 b3fb4686 2020-09-20 neels 		return 0;
 76 b3fb4686 2020-09-20 neels 	}
 77 b3fb4686 2020-09-20 neels 	if (!left->len) {
 78 b3fb4686 2020-09-20 neels 		*cmp = -1;
 79 b3fb4686 2020-09-20 neels 		return 0;
 80 b3fb4686 2020-09-20 neels 	}
 81 c6eecea3 2020-07-26 stsp 
 82 b3fb4686 2020-09-20 neels 	if (left->at != NULL && right->at != NULL) {
 83 b3fb4686 2020-09-20 neels 		*cmp = buf_cmp(left->at, left->len, right->at, right->len);
 84 b3fb4686 2020-09-20 neels 		return 0;
 85 b3fb4686 2020-09-20 neels 	}
 86 c6eecea3 2020-07-26 stsp 
 87 c6eecea3 2020-07-26 stsp 	remain_left = left->len;
 88 c6eecea3 2020-07-26 stsp 	remain_right = right->len;
 89 c6eecea3 2020-07-26 stsp 	while (remain_left > 0 || remain_right > 0) {
 90 c6eecea3 2020-07-26 stsp 		const size_t chunksz = 8192;
 91 c6eecea3 2020-07-26 stsp 		unsigned char buf_left[chunksz], buf_right[chunksz];
 92 c6eecea3 2020-07-26 stsp 		const uint8_t *p_left, *p_right;
 93 c6eecea3 2020-07-26 stsp 		off_t n_left, n_right;
 94 c6eecea3 2020-07-26 stsp 		ssize_t r;
 95 c6eecea3 2020-07-26 stsp 
 96 b3fb4686 2020-09-20 neels 		if (!remain_right) {
 97 b3fb4686 2020-09-20 neels 			*cmp = 1;
 98 b3fb4686 2020-09-20 neels 			return 0;
 99 b3fb4686 2020-09-20 neels 		}
100 b3fb4686 2020-09-20 neels 		if (!remain_left) {
101 b3fb4686 2020-09-20 neels 			*cmp = -1;
102 b3fb4686 2020-09-20 neels 			return 0;
103 b3fb4686 2020-09-20 neels 		}
104 b3fb4686 2020-09-20 neels 
105 c6eecea3 2020-07-26 stsp 		n_left = MIN(chunksz, remain_left);
106 c6eecea3 2020-07-26 stsp 		n_right = MIN(chunksz, remain_right);
107 c6eecea3 2020-07-26 stsp 
108 c6eecea3 2020-07-26 stsp 		if (left->at == NULL) {
109 b3fb4686 2020-09-20 neels 			r = read_at(left->d->root->fd,
110 b3fb4686 2020-09-20 neels 				    left->pos + (left->len - remain_left),
111 b3fb4686 2020-09-20 neels 				    buf_left, n_left);
112 b3fb4686 2020-09-20 neels 			if (r) {
113 b3fb4686 2020-09-20 neels 				*cmp = 0;
114 b3fb4686 2020-09-20 neels 				return r;
115 b3fb4686 2020-09-20 neels 			}
116 c6eecea3 2020-07-26 stsp 			p_left = buf_left;
117 c6eecea3 2020-07-26 stsp 		} else {
118 c6eecea3 2020-07-26 stsp 			p_left = left->at + (left->len - remain_left);
119 c6eecea3 2020-07-26 stsp 		}
120 c6eecea3 2020-07-26 stsp 
121 c6eecea3 2020-07-26 stsp 		if (right->at == NULL) {
122 b3fb4686 2020-09-20 neels 			r = read_at(right->d->root->fd,
123 b3fb4686 2020-09-20 neels 				    right->pos + (right->len - remain_right),
124 b3fb4686 2020-09-20 neels 				    buf_right, n_right);
125 b3fb4686 2020-09-20 neels 			if (r) {
126 b3fb4686 2020-09-20 neels 				*cmp = 0;
127 b3fb4686 2020-09-20 neels 				return r;
128 b3fb4686 2020-09-20 neels 			}
129 c6eecea3 2020-07-26 stsp 			p_right = buf_right;
130 c6eecea3 2020-07-26 stsp 		} else {
131 c6eecea3 2020-07-26 stsp 			p_right = right->at + (right->len - remain_right);
132 c6eecea3 2020-07-26 stsp 		}
133 b3fb4686 2020-09-20 neels 
134 b3fb4686 2020-09-20 neels 		r = buf_cmp(p_left, n_left, p_right, n_right);
135 b3fb4686 2020-09-20 neels 		if (r) {
136 b3fb4686 2020-09-20 neels 			*cmp = r;
137 b3fb4686 2020-09-20 neels 			return 0;
138 c6eecea3 2020-07-26 stsp 		}
139 c6eecea3 2020-07-26 stsp 
140 c6eecea3 2020-07-26 stsp 		remain_left -= n_left;
141 c6eecea3 2020-07-26 stsp 		remain_right -= n_right;
142 c6eecea3 2020-07-26 stsp 	}
143 3b0f3d61 2020-01-22 neels 
144 b3fb4686 2020-09-20 neels 	*cmp = 0;
145 b3fb4686 2020-09-20 neels 	return 0;
146 b3fb4686 2020-09-20 neels }
147 b3fb4686 2020-09-20 neels 
148 b3fb4686 2020-09-20 neels int
149 b3fb4686 2020-09-20 neels diff_atom_same(bool *same,
150 b3fb4686 2020-09-20 neels 	       const struct diff_atom *left,
151 b3fb4686 2020-09-20 neels 	       const struct diff_atom *right)
152 b3fb4686 2020-09-20 neels {
153 b3fb4686 2020-09-20 neels 	int cmp;
154 b3fb4686 2020-09-20 neels 	int r = diff_atom_cmp(&cmp, left, right);
155 b3fb4686 2020-09-20 neels 	if (r) {
156 b3fb4686 2020-09-20 neels 		*same = true;
157 b3fb4686 2020-09-20 neels 		return r;
158 b3fb4686 2020-09-20 neels 	}
159 b3fb4686 2020-09-20 neels 	*same = (cmp == 0);
160 b3fb4686 2020-09-20 neels 	return 0;
161 c6eecea3 2020-07-26 stsp }
162 c6eecea3 2020-07-26 stsp 
163 0d27172a 2020-05-06 neels /* Even if a left or right side is empty, diff output may need to know the
164 0d27172a 2020-05-06 neels  * position in that file.
165 0d27172a 2020-05-06 neels  * So left_start or right_start must never be NULL -- pass left_count or
166 0d27172a 2020-05-06 neels  * right_count as zero to indicate staying at that position without consuming
167 0d27172a 2020-05-06 neels  * any lines. */
168 61a7b578 2020-05-06 neels struct diff_chunk *
169 61a7b578 2020-05-06 neels diff_state_add_chunk(struct diff_state *state, bool solved,
170 61a7b578 2020-05-06 neels 		     struct diff_atom *left_start, unsigned int left_count,
171 61a7b578 2020-05-06 neels 		     struct diff_atom *right_start, unsigned int right_count)
172 3b0f3d61 2020-01-22 neels {
173 8546b045 2020-09-20 neels 	diff_chunk_arraylist_t *result = NULL;
174 8546b045 2020-09-20 neels 	struct diff_chunk *new_chunk;
175 8546b045 2020-09-20 neels 	struct diff_chunk chunk = {
176 3b0f3d61 2020-01-22 neels 		.solved = solved,
177 3b0f3d61 2020-01-22 neels 		.left_start = left_start,
178 3b0f3d61 2020-01-22 neels 		.left_count = left_count,
179 3b0f3d61 2020-01-22 neels 		.right_start = right_start,
180 3b0f3d61 2020-01-22 neels 		.right_count = right_count,
181 3b0f3d61 2020-01-22 neels 	};
182 8546b045 2020-09-20 neels 	enum diff_chunk_type last_t;
183 8546b045 2020-09-20 neels 	enum diff_chunk_type prev_last_t;
184 8546b045 2020-09-20 neels 	enum diff_chunk_type new_t;
185 3b0f3d61 2020-01-22 neels 
186 8546b045 2020-09-20 neels 	if (!solved || state->temp_result.len) {
187 8546b045 2020-09-20 neels 		/* Append to temp_result */
188 8546b045 2020-09-20 neels 		result = &state->temp_result;
189 8546b045 2020-09-20 neels 	} else if (!state->result->chunks.len) {
190 8546b045 2020-09-20 neels 		/* Append to final result */
191 8546b045 2020-09-20 neels 		result = &state->result->chunks;
192 8546b045 2020-09-20 neels 	}
193 8546b045 2020-09-20 neels 	if (result) {
194 8546b045 2020-09-20 neels 		ARRAYLIST_ADD(new_chunk, *result);
195 8546b045 2020-09-20 neels 		if (!new_chunk)
196 8546b045 2020-09-20 neels 			return NULL;
197 8546b045 2020-09-20 neels 		*new_chunk = chunk;
198 8546b045 2020-09-20 neels 		goto chunk_added;
199 8546b045 2020-09-20 neels 	}
200 8546b045 2020-09-20 neels 
201 8546b045 2020-09-20 neels 	/* Append to solved chunks; make sure that adjacent chunks of same type are combined, and that a minus chunk
202 8546b045 2020-09-20 neels 	 * never directly follows a plus chunk. */
203 8546b045 2020-09-20 neels 	result = &state->result->chunks;
204 8546b045 2020-09-20 neels 
205 8546b045 2020-09-20 neels 	prev_last_t = result->len > 1 ?
206 8546b045 2020-09-20 neels 		diff_chunk_type(&result->head[result->len - 2]) : CHUNK_EMPTY;
207 8546b045 2020-09-20 neels 	last_t = diff_chunk_type(&result->head[result->len - 1]);
208 8546b045 2020-09-20 neels 	new_t = diff_chunk_type(&chunk);
209 8546b045 2020-09-20 neels 
210 8546b045 2020-09-20 neels 	if (new_t == last_t) {
211 8546b045 2020-09-20 neels 		new_chunk = &result->head[result->len - 1];
212 8546b045 2020-09-20 neels 		new_chunk->left_count += chunk.left_count;
213 8546b045 2020-09-20 neels 		new_chunk->right_count += chunk.right_count;
214 8546b045 2020-09-20 neels 	} else if (last_t == CHUNK_PLUS && new_t == CHUNK_MINUS) {
215 8546b045 2020-09-20 neels 		/* If a minus-chunk follows a plus-chunk, place it above the plus-chunk.
216 8546b045 2020-09-20 neels 		 * Is the one before that also a minus? combine. */
217 8546b045 2020-09-20 neels 		if (prev_last_t == CHUNK_MINUS) {
218 8546b045 2020-09-20 neels 			new_chunk = &result->head[result->len - 2];
219 8546b045 2020-09-20 neels 			new_chunk->left_count += chunk.left_count;
220 8546b045 2020-09-20 neels 			new_chunk->right_count += chunk.right_count;
221 8546b045 2020-09-20 neels 		} else {
222 8546b045 2020-09-20 neels 			ARRAYLIST_INSERT(new_chunk, *result, result->len - 2);
223 8546b045 2020-09-20 neels 			if (!new_chunk)
224 8546b045 2020-09-20 neels 				return NULL;
225 8546b045 2020-09-20 neels 			*new_chunk = chunk;
226 8546b045 2020-09-20 neels 		}
227 8546b045 2020-09-20 neels 	} else {
228 8546b045 2020-09-20 neels 		ARRAYLIST_ADD(new_chunk, *result);
229 8546b045 2020-09-20 neels 		if (!new_chunk)
230 8546b045 2020-09-20 neels 			return NULL;
231 8546b045 2020-09-20 neels 		*new_chunk = chunk;
232 8546b045 2020-09-20 neels 		goto chunk_added;
233 8546b045 2020-09-20 neels 	}
234 8546b045 2020-09-20 neels 
235 8546b045 2020-09-20 neels chunk_added:
236 8546b045 2020-09-20 neels 	debug("Add %s chunk:\n", new_chunk->solved ? "solved" : "UNSOLVED");
237 8546b045 2020-09-20 neels 	debug("L\n");
238 8546b045 2020-09-20 neels 	debug_dump_atoms(&state->left, new_chunk->left_start, new_chunk->left_count);
239 3b0f3d61 2020-01-22 neels 	debug("R\n");
240 8546b045 2020-09-20 neels 	debug_dump_atoms(&state->right, new_chunk->right_start, new_chunk->right_count);
241 8546b045 2020-09-20 neels 	return new_chunk;
242 3b0f3d61 2020-01-22 neels }
243 3b0f3d61 2020-01-22 neels 
244 61a7b578 2020-05-06 neels void
245 c6eecea3 2020-07-26 stsp diff_data_init_root(struct diff_data *d, int fd, const uint8_t *data,
246 c6eecea3 2020-07-26 stsp     unsigned long long len)
247 3b0f3d61 2020-01-22 neels {
248 3b0f3d61 2020-01-22 neels 	*d = (struct diff_data){
249 c6eecea3 2020-07-26 stsp 		.fd = fd,
250 c6eecea3 2020-07-26 stsp 		.pos = 0,
251 3b0f3d61 2020-01-22 neels 		.data = data,
252 3b0f3d61 2020-01-22 neels 		.len = len,
253 3b0f3d61 2020-01-22 neels 		.root = d,
254 3b0f3d61 2020-01-22 neels 	};
255 3b0f3d61 2020-01-22 neels }
256 3b0f3d61 2020-01-22 neels 
257 61a7b578 2020-05-06 neels void
258 61a7b578 2020-05-06 neels diff_data_init_subsection(struct diff_data *d, struct diff_data *parent,
259 61a7b578 2020-05-06 neels 			  struct diff_atom *from_atom, unsigned int atoms_count)
260 3b0f3d61 2020-01-22 neels {
261 3b0f3d61 2020-01-22 neels 	struct diff_atom *last_atom = from_atom + atoms_count - 1;
262 3b0f3d61 2020-01-22 neels 	*d = (struct diff_data){
263 c6eecea3 2020-07-26 stsp 		.fd = -1,
264 c6eecea3 2020-07-26 stsp 		.pos = from_atom->pos,
265 3b0f3d61 2020-01-22 neels 		.data = from_atom->at,
266 c6eecea3 2020-07-26 stsp 		.len = (last_atom->pos + last_atom->len) - from_atom->pos,
267 3b0f3d61 2020-01-22 neels 		.root = parent->root,
268 3b0f3d61 2020-01-22 neels 		.atoms.head = from_atom,
269 3b0f3d61 2020-01-22 neels 		.atoms.len = atoms_count,
270 3b0f3d61 2020-01-22 neels 	};
271 3b0f3d61 2020-01-22 neels 
272 3b0f3d61 2020-01-22 neels 	debug("subsection:\n");
273 3b0f3d61 2020-01-22 neels 	debug_dump(d);
274 3b0f3d61 2020-01-22 neels }
275 3b0f3d61 2020-01-22 neels 
276 61a7b578 2020-05-06 neels void
277 61a7b578 2020-05-06 neels diff_data_free(struct diff_data *diff_data)
278 3b0f3d61 2020-01-22 neels {
279 3b0f3d61 2020-01-22 neels 	if (!diff_data)
280 3b0f3d61 2020-01-22 neels 		return;
281 3b0f3d61 2020-01-22 neels 	if (diff_data->atoms.allocated)
282 3b0f3d61 2020-01-22 neels 		ARRAYLIST_FREE(diff_data->atoms);
283 3b0f3d61 2020-01-22 neels }
284 3b0f3d61 2020-01-22 neels 
285 3e6cba3a 2020-08-13 stsp int
286 0d27172a 2020-05-06 neels diff_algo_none(const struct diff_algo_config *algo_config,
287 0d27172a 2020-05-06 neels 	       struct diff_state *state)
288 3b0f3d61 2020-01-22 neels {
289 3b0f3d61 2020-01-22 neels 	debug("\n** %s\n", __func__);
290 3b0f3d61 2020-01-22 neels 	debug("left:\n");
291 3b0f3d61 2020-01-22 neels 	debug_dump(&state->left);
292 3b0f3d61 2020-01-22 neels 	debug("right:\n");
293 3b0f3d61 2020-01-22 neels 	debug_dump(&state->right);
294 0d27172a 2020-05-06 neels 	debug_dump_myers_graph(&state->left, &state->right, NULL, NULL, 0, NULL,
295 0d27172a 2020-05-06 neels 			       0);
296 3b0f3d61 2020-01-22 neels 
297 3b0f3d61 2020-01-22 neels 	/* Add a chunk of equal lines, if any */
298 3b0f3d61 2020-01-22 neels 	unsigned int equal_atoms = 0;
299 0d27172a 2020-05-06 neels 	while (equal_atoms < state->left.atoms.len
300 b3fb4686 2020-09-20 neels 	       && equal_atoms < state->right.atoms.len) {
301 b3fb4686 2020-09-20 neels 		int r;
302 b3fb4686 2020-09-20 neels 		bool same;
303 b3fb4686 2020-09-20 neels 		r = diff_atom_same(&same, &state->left.atoms.head[equal_atoms],
304 b3fb4686 2020-09-20 neels 				   &state->right.atoms.head[equal_atoms]);
305 b3fb4686 2020-09-20 neels 		if (r)
306 b3fb4686 2020-09-20 neels 			return r;
307 b3fb4686 2020-09-20 neels 		if (!same)
308 b3fb4686 2020-09-20 neels 			break;
309 3b0f3d61 2020-01-22 neels 		equal_atoms++;
310 b3fb4686 2020-09-20 neels 	}
311 3b0f3d61 2020-01-22 neels 	if (equal_atoms) {
312 3b0f3d61 2020-01-22 neels 		if (!diff_state_add_chunk(state, true,
313 0d27172a 2020-05-06 neels 					  &state->left.atoms.head[0],
314 0d27172a 2020-05-06 neels 					  equal_atoms,
315 0d27172a 2020-05-06 neels 					  &state->right.atoms.head[0],
316 0d27172a 2020-05-06 neels 					  equal_atoms))
317 3e6cba3a 2020-08-13 stsp 			return ENOMEM;
318 3b0f3d61 2020-01-22 neels 	}
319 3b0f3d61 2020-01-22 neels 
320 3b0f3d61 2020-01-22 neels 	/* Add a "minus" chunk with all lines from the left. */
321 3b0f3d61 2020-01-22 neels 	if (equal_atoms < state->left.atoms.len) {
322 3b0f3d61 2020-01-22 neels 		if (!diff_state_add_chunk(state, true,
323 3b0f3d61 2020-01-22 neels 					  &state->left.atoms.head[equal_atoms],
324 3b0f3d61 2020-01-22 neels 					  state->left.atoms.len - equal_atoms,
325 3b0f3d61 2020-01-22 neels 					  NULL, 0))
326 3e6cba3a 2020-08-13 stsp 		    return ENOMEM;
327 3b0f3d61 2020-01-22 neels 	}
328 3b0f3d61 2020-01-22 neels 
329 3b0f3d61 2020-01-22 neels 	/* Add a "plus" chunk with all lines from the right. */
330 3b0f3d61 2020-01-22 neels 	if (equal_atoms < state->right.atoms.len) {
331 3b0f3d61 2020-01-22 neels 		if (!diff_state_add_chunk(state, true,
332 3b0f3d61 2020-01-22 neels 					  NULL, 0,
333 3b0f3d61 2020-01-22 neels 					  &state->right.atoms.head[equal_atoms],
334 3b0f3d61 2020-01-22 neels 					  state->right.atoms.len - equal_atoms))
335 3e6cba3a 2020-08-13 stsp 		return ENOMEM;
336 3b0f3d61 2020-01-22 neels 	}
337 3b0f3d61 2020-01-22 neels 	return DIFF_RC_OK;
338 3b0f3d61 2020-01-22 neels }
339 3b0f3d61 2020-01-22 neels 
340 3e6cba3a 2020-08-13 stsp int
341 0d27172a 2020-05-06 neels diff_run_algo(const struct diff_algo_config *algo_config,
342 0d27172a 2020-05-06 neels 	      struct diff_state *state)
343 3b0f3d61 2020-01-22 neels {
344 3e6cba3a 2020-08-13 stsp 	int rc;
345 3b0f3d61 2020-01-22 neels 	ARRAYLIST_FREE(state->temp_result);
346 3b0f3d61 2020-01-22 neels 
347 0d27172a 2020-05-06 neels 	if (!algo_config || !algo_config->impl
348 0d27172a 2020-05-06 neels 	    || !state->recursion_depth_left) {
349 3b0f3d61 2020-01-22 neels 		debug("MAX RECURSION REACHED, just dumping diff chunks\n");
350 3b0f3d61 2020-01-22 neels 		return diff_algo_none(algo_config, state);
351 3b0f3d61 2020-01-22 neels 	}
352 3b0f3d61 2020-01-22 neels 
353 3b0f3d61 2020-01-22 neels 	ARRAYLIST_INIT(state->temp_result, DIFF_RESULT_ALLOC_BLOCKSIZE);
354 3b0f3d61 2020-01-22 neels 	rc = algo_config->impl(algo_config, state);
355 3b0f3d61 2020-01-22 neels 	switch (rc) {
356 3b0f3d61 2020-01-22 neels 	case DIFF_RC_USE_DIFF_ALGO_FALLBACK:
357 0d27172a 2020-05-06 neels 		debug("Got DIFF_RC_USE_DIFF_ALGO_FALLBACK (%p)\n",
358 0d27172a 2020-05-06 neels 		      algo_config->fallback_algo);
359 3b0f3d61 2020-01-22 neels 		rc = diff_run_algo(algo_config->fallback_algo, state);
360 3b0f3d61 2020-01-22 neels 		goto return_rc;
361 3b0f3d61 2020-01-22 neels 
362 3b0f3d61 2020-01-22 neels 	case DIFF_RC_OK:
363 3b0f3d61 2020-01-22 neels 		/* continue below */
364 3b0f3d61 2020-01-22 neels 		break;
365 3b0f3d61 2020-01-22 neels 
366 3b0f3d61 2020-01-22 neels 	default:
367 3b0f3d61 2020-01-22 neels 		/* some error happened */
368 3b0f3d61 2020-01-22 neels 		goto return_rc;
369 3b0f3d61 2020-01-22 neels 	}
370 3b0f3d61 2020-01-22 neels 
371 0d27172a 2020-05-06 neels 	/* Pick up any diff chunks that are still unsolved and feed to
372 0d27172a 2020-05-06 neels 	 * inner_algo.  inner_algo will solve unsolved chunks and append to
373 0d27172a 2020-05-06 neels 	 * result, and subsequent solved chunks on this level are then appended
374 0d27172a 2020-05-06 neels 	 * to result afterwards. */
375 3b0f3d61 2020-01-22 neels 	int i;
376 3b0f3d61 2020-01-22 neels 	for (i = 0; i < state->temp_result.len; i++) {
377 3b0f3d61 2020-01-22 neels 		struct diff_chunk *c = &state->temp_result.head[i];
378 3b0f3d61 2020-01-22 neels 		if (c->solved) {
379 3b0f3d61 2020-01-22 neels 			struct diff_chunk *final_c;
380 3b0f3d61 2020-01-22 neels 			ARRAYLIST_ADD(final_c, state->result->chunks);
381 3b0f3d61 2020-01-22 neels 			if (!final_c) {
382 3e6cba3a 2020-08-13 stsp 				rc = ENOMEM;
383 3b0f3d61 2020-01-22 neels 				goto return_rc;
384 3b0f3d61 2020-01-22 neels 			}
385 3b0f3d61 2020-01-22 neels 			*final_c = *c;
386 3b0f3d61 2020-01-22 neels 			continue;
387 3b0f3d61 2020-01-22 neels 		}
388 3b0f3d61 2020-01-22 neels 
389 3b0f3d61 2020-01-22 neels 		/* c is an unsolved chunk, feed to inner_algo */
390 3b0f3d61 2020-01-22 neels 		struct diff_state inner_state = {
391 3b0f3d61 2020-01-22 neels 			.result = state->result,
392 3b0f3d61 2020-01-22 neels 			.recursion_depth_left = state->recursion_depth_left - 1,
393 3b0f3d61 2020-01-22 neels 		};
394 0d27172a 2020-05-06 neels 		diff_data_init_subsection(&inner_state.left, &state->left,
395 0d27172a 2020-05-06 neels 					  c->left_start, c->left_count);
396 0d27172a 2020-05-06 neels 		diff_data_init_subsection(&inner_state.right, &state->right,
397 0d27172a 2020-05-06 neels 					  c->right_start, c->right_count);
398 3b0f3d61 2020-01-22 neels 
399 3b0f3d61 2020-01-22 neels 		rc = diff_run_algo(algo_config->inner_algo, &inner_state);
400 3b0f3d61 2020-01-22 neels 
401 3b0f3d61 2020-01-22 neels 		if (rc != DIFF_RC_OK)
402 3b0f3d61 2020-01-22 neels 			goto return_rc;
403 3b0f3d61 2020-01-22 neels 	}
404 3b0f3d61 2020-01-22 neels 
405 3b0f3d61 2020-01-22 neels 	rc = DIFF_RC_OK;
406 3b0f3d61 2020-01-22 neels return_rc:
407 3b0f3d61 2020-01-22 neels 	ARRAYLIST_FREE(state->temp_result);
408 3b0f3d61 2020-01-22 neels 	return rc;
409 3b0f3d61 2020-01-22 neels }
410 3b0f3d61 2020-01-22 neels 
411 61a7b578 2020-05-06 neels struct diff_result *
412 61a7b578 2020-05-06 neels diff_main(const struct diff_config *config,
413 c6eecea3 2020-07-26 stsp 	  int left_fd, const uint8_t *left_data, off_t left_len,
414 c6eecea3 2020-07-26 stsp 	  int right_fd, const uint8_t *right_data, off_t right_len)
415 3b0f3d61 2020-01-22 neels {
416 3b0f3d61 2020-01-22 neels 	struct diff_result *result = malloc(sizeof(struct diff_result));
417 3b0f3d61 2020-01-22 neels 	if (!result)
418 3b0f3d61 2020-01-22 neels 		return NULL;
419 3b0f3d61 2020-01-22 neels 
420 3b0f3d61 2020-01-22 neels 	*result = (struct diff_result){};
421 c6eecea3 2020-07-26 stsp 	diff_data_init_root(&result->left, left_fd, left_data, left_len);
422 c6eecea3 2020-07-26 stsp 	diff_data_init_root(&result->right, right_fd, right_data, right_len);
423 3b0f3d61 2020-01-22 neels 
424 3b0f3d61 2020-01-22 neels 	if (!config->atomize_func) {
425 3e6cba3a 2020-08-13 stsp 		result->rc = EINVAL;
426 3b0f3d61 2020-01-22 neels 		return result;
427 3b0f3d61 2020-01-22 neels 	}
428 3b0f3d61 2020-01-22 neels 
429 0d27172a 2020-05-06 neels 	result->rc = config->atomize_func(config->atomize_func_data,
430 0d27172a 2020-05-06 neels 					  &result->left, &result->right);
431 3b0f3d61 2020-01-22 neels 	if (result->rc != DIFF_RC_OK)
432 3b0f3d61 2020-01-22 neels 		return result;
433 3b0f3d61 2020-01-22 neels 
434 3b0f3d61 2020-01-22 neels 	struct diff_state state = {
435 3b0f3d61 2020-01-22 neels 		.result = result,
436 3b0f3d61 2020-01-22 neels 		.recursion_depth_left = config->max_recursion_depth ? : 1024,
437 3b0f3d61 2020-01-22 neels 	};
438 0d27172a 2020-05-06 neels 	diff_data_init_subsection(&state.left, &result->left,
439 0d27172a 2020-05-06 neels 				  result->left.atoms.head,
440 0d27172a 2020-05-06 neels 				  result->left.atoms.len);
441 0d27172a 2020-05-06 neels 	diff_data_init_subsection(&state.right, &result->right,
442 0d27172a 2020-05-06 neels 				  result->right.atoms.head,
443 0d27172a 2020-05-06 neels 				  result->right.atoms.len);
444 3b0f3d61 2020-01-22 neels 
445 3b0f3d61 2020-01-22 neels 	result->rc = diff_run_algo(config->algo, &state);
446 3b0f3d61 2020-01-22 neels 
447 3b0f3d61 2020-01-22 neels 	return result;
448 3b0f3d61 2020-01-22 neels }
449 3b0f3d61 2020-01-22 neels 
450 61a7b578 2020-05-06 neels void
451 61a7b578 2020-05-06 neels diff_result_free(struct diff_result *result)
452 3b0f3d61 2020-01-22 neels {
453 3b0f3d61 2020-01-22 neels 	if (!result)
454 3b0f3d61 2020-01-22 neels 		return;
455 3b0f3d61 2020-01-22 neels 	diff_data_free(&result->left);
456 3b0f3d61 2020-01-22 neels 	diff_data_free(&result->right);
457 3b0f3d61 2020-01-22 neels 	ARRAYLIST_FREE(result->chunks);
458 3b0f3d61 2020-01-22 neels 	free(result);
459 3b0f3d61 2020-01-22 neels }