1 /*
2  * Copyright (c) 2020 Neels Hofmeyr <neels@hofmeyr.de>
3  * Copyright (c) 2020 Stefan Sperling <stsp@openbsd.org>
4  *
5  * Permission to use, copy, modify, and distribute this software for any
6  * purpose with or without fee is hereby granted, provided that the above
7  * copyright notice and this permission notice appear in all copies.
8  *
9  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16  */
17 
18 #include <sys/mman.h>
19 #include <sys/stat.h>
20 #include <sys/queue.h>
21 
22 #include <errno.h>
23 #include <stdio.h>
24 #include <stdlib.h>
25 #include <string.h>
26 
27 #include "got_object.h"
28 #include "got_opentemp.h"
29 #include "got_error.h"
30 
31 #include "got_lib_diff.h"
32 
33 const struct diff_algo_config myers_then_patience;
34 const struct diff_algo_config myers_then_myers_divide;
35 const struct diff_algo_config patience;
36 const struct diff_algo_config myers_divide;
37 
38 const struct diff_algo_config myers_then_patience = (struct diff_algo_config){
39 	.impl = diff_algo_myers,
40 	.permitted_state_size = 1024 * 1024 * sizeof(int),
41 	.fallback_algo = &patience,
42 };
43 
44 const struct diff_algo_config myers_then_myers_divide =
45 	(struct diff_algo_config){
46 	.impl = diff_algo_myers,
47 	.permitted_state_size = 1024 * 1024 * sizeof(int),
48 	.fallback_algo = &myers_divide,
49 };
50 
51 const struct diff_algo_config patience = (struct diff_algo_config){
52 	.impl = diff_algo_patience,
53 	/* After subdivision, do Patience again: */
54 	.inner_algo = &patience,
55 	/* If subdivision failed, do Myers Divide et Impera: */
56 	.fallback_algo = &myers_then_myers_divide,
57 };
58 
59 const struct diff_algo_config myers_divide = (struct diff_algo_config){
60 	.impl = diff_algo_myers_divide,
61 	/* When division succeeded, start from the top: */
62 	.inner_algo = &myers_then_myers_divide,
63 	/* (fallback_algo = NULL implies diff_algo_none). */
64 };
65 
66 /* If the state for a forward-Myers is small enough, use Myers, otherwise first
67  * do a Myers-divide. */
68 const struct diff_config diff_config_myers_then_myers_divide = {
69 	.atomize_func = diff_atomize_text_by_line,
70 	.algo = &myers_then_myers_divide,
71 };
72 
73 /* If the state for a forward-Myers is small enough, use Myers, otherwise first
74  * do a Patience. */
75 const struct diff_config diff_config_myers_then_patience = {
76 	.atomize_func = diff_atomize_text_by_line,
77 	.algo = &myers_then_patience,
78 };
79 
80 /* Directly force Patience as a first divider of the source file. */
81 const struct diff_config diff_config_patience = {
82 	.atomize_func = diff_atomize_text_by_line,
83 	.algo = &patience,
84 };
85 
86 /* Directly force Patience as a first divider of the source file. */
87 const struct diff_config diff_config_no_algo = {
88 	.atomize_func = diff_atomize_text_by_line,
89 };
90 
91 const struct got_error *
92 got_diffreg_close(FILE *f1, char *p1, size_t size1,
93     FILE *f2, char *p2, size_t size2)
94 {
95 	const struct got_error *err = NULL;
96 
97 	if (p1 && munmap(p1, size1) == -1 && err == NULL)
98 		err = got_error_from_errno("munmap");
99 	if (p2 && munmap(p2, size2) == -1 && err == NULL)
100 		err = got_error_from_errno("munmap");
101 	if (f1 && fclose(f1) != 0 && err == NULL)
102 		err = got_error_from_errno("fclose");
103 	if (f2 && fclose(f2) != 0 && err == NULL)
104 		err = got_error_from_errno("fclose");
105 	return err;
106 }
107 
108 const struct diff_config *
109 got_diff_get_config(enum got_diff_algorithm algorithm)
110 {
111 	switch (algorithm) {
112 	case GOT_DIFF_ALGORITHM_PATIENCE:
113 		return &diff_config_patience;
114 	case GOT_DIFF_ALGORITHM_MYERS:
115 		return &diff_config_myers_then_myers_divide;
116 	}
117 	return NULL; /* should not happen */
118 }
119 
120 const struct got_error *
121 got_diff_prepare_file(FILE **f, char **p, int *f_created, size_t *size,
122     struct diff_data *diff_data, const struct diff_config *cfg,
123     int ignore_whitespace)
124 {
125 	const struct got_error *err = NULL;
126 	struct stat st;
127 	int diff_flags = 0, rc;
128 
129 	*size = 0;
130 
131 	diff_flags |= DIFF_FLAG_SHOW_PROTOTYPES;
132 	if (ignore_whitespace)
133 		diff_flags |= DIFF_FLAG_IGNORE_WHITESPACE;
134 
135 	if (f && *f) {
136 		if (fstat(fileno(*f), &st) == -1) {
137 			err = got_error_from_errno("fstat");
138 			goto done;
139 		}
140 	#ifndef GOT_DIFF_NO_MMAP
141 		*p = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE,
142 		    fileno(*f), 0);
143 		if (*p == MAP_FAILED)
144 	#endif
145 			*p = NULL; /* fall back on file I/O */
146 	} else {
147 		*f_created = 1;
148 		st.st_size = 0;
149 		*f = got_opentemp();
150 		if (*f == NULL) {
151 			err = got_error_from_errno("got_opentemp");
152 			goto done;
153 		}
154 	}
155 
156 	rc = diff_atomize_file(diff_data, cfg, *f, *p, st.st_size, diff_flags);
157 	if (rc) {
158 		err = got_error_set_errno(rc, "diff_atomize_file");
159 		goto done;
160 	}
161 done:
162 	if (err)
163 		diff_data_free(diff_data);
164 	else
165 		*size = st.st_size;
166 	return err;
167 }
168 
169 const struct got_error *
170 got_diffreg_prepared_files(struct got_diffreg_result **diffreg_result,
171     const struct diff_config *cfg,
172     struct diff_data *left, FILE *f1, char *p1, size_t size1,
173     struct diff_data *right, FILE *f2, char *p2, size_t size2)
174 {
175 	const struct got_error *err = NULL;
176 	struct diff_result *diff_result;
177 
178 	*diffreg_result = calloc(1, sizeof(**diffreg_result));
179 	if (*diffreg_result == NULL)
180 		return got_error_from_errno("calloc");
181 	
182 	diff_result = diff_main(cfg, left, right);
183 	if (diff_result == NULL) {
184 		err = got_error_set_errno(ENOMEM, "malloc");
185 		goto done;
186 	}
187 	if (diff_result->rc != DIFF_RC_OK) {
188 		err = got_error_set_errno(diff_result->rc, "diff");
189 		goto done;
190 	}
191 
192 	(*diffreg_result)->result = diff_result;
193 	(*diffreg_result)->f1 = f1;
194 	(*diffreg_result)->map1 = p1;
195 	(*diffreg_result)->size1 = size1;
196 	(*diffreg_result)->f2 = f2;
197 	(*diffreg_result)->map2 = p2;
198 	(*diffreg_result)->size2 = size2;
199 done:
200 	if (err) {
201 		if (diffreg_result) {
202 			free(*diffreg_result);
203 			*diffreg_result = NULL;
204 		}
205 	}
206 	
207 	return err;
208 }
209 
210 const struct got_error *
211 got_diffreg(struct got_diffreg_result **diffreg_result, FILE *f1, FILE *f2,
212     enum got_diff_algorithm algorithm, int ignore_whitespace)
213 {
214 	const struct got_error *err = NULL;
215 	const struct diff_config *cfg;
216 	char *p1 = NULL, *p2 = NULL;
217 	int f1_created = 0, f2_created = 0;
218 	size_t size1, size2;
219 	struct diff_data d_left, d_right;
220 	struct diff_data *left, *right;
221 	struct diff_result *diff_result;
222 
223 	if (diffreg_result) {
224 		*diffreg_result = calloc(1, sizeof(**diffreg_result));
225 		if (*diffreg_result == NULL)
226 			return got_error_from_errno("calloc");
227 		left = &(*diffreg_result)->left;
228 		right = &(*diffreg_result)->right;
229 	} else {
230 		memset(&d_left, 0, sizeof(d_left));
231 		memset(&d_right, 0, sizeof(d_right));
232 		left = &d_left;
233 		right = &d_right;
234 	}
235 	
236 	cfg = got_diff_get_config(algorithm);
237 	if (cfg == NULL) {
238 		err = got_error(GOT_ERR_NOT_IMPL);
239 		goto done;
240 	}
241 
242 	err = got_diff_prepare_file(&f1, &p1, &f1_created, &size1,
243 	    left, cfg, ignore_whitespace);
244 	if (err)
245 		goto done;
246 
247 	err = got_diff_prepare_file(&f2, &p2, &f2_created, &size2,
248 	    right, cfg, ignore_whitespace);
249 	if (err)
250 		goto done;
251 
252 	diff_result = diff_main(cfg, left, right);
253 	if (diff_result == NULL) {
254 		err = got_error_set_errno(ENOMEM, "malloc");
255 		goto done;
256 	}
257 	if (diff_result->rc != DIFF_RC_OK) {
258 		err = got_error_set_errno(diff_result->rc, "diff");
259 		goto done;
260 	}
261 
262 	if (diffreg_result) {
263 		(*diffreg_result)->result = diff_result;
264 		if (f1_created)
265 			(*diffreg_result)->f1 = f1;
266 		(*diffreg_result)->map1 = p1;
267 		(*diffreg_result)->size1 = size1;
268 		if (f2_created)
269 			(*diffreg_result)->f2 = f2;
270 		(*diffreg_result)->map2 = p2;
271 		(*diffreg_result)->size2 = size2;
272 	}
273 done:
274 	if (diffreg_result == NULL) {
275 		diff_data_free(left);
276 		diff_data_free(right);
277 	}
278 	if (err) {
279 		got_diffreg_close(f1_created ? f1 : NULL, p1, size1,
280 		    f2_created ? f2 : NULL, p2, size2);
281 		if (diffreg_result) {
282 			diff_data_free(left);
283 			diff_data_free(right);
284 			free(*diffreg_result);
285 			*diffreg_result = NULL;
286 		}
287 	}
288 	
289 	return err;
290 }
291 
292 const struct got_error *
293 got_diffreg_output(off_t **line_offsets, size_t *nlines,
294     struct got_diffreg_result *diff_result, FILE *f1, FILE *f2,
295     const char *path1, const char *path2,
296     enum got_diff_output_format output_format, int context_lines, FILE *outfile)
297 {
298 	struct diff_input_info info = {
299 		.left_path = path1,
300 		.right_path = path2,
301 	};
302 	int rc;
303 	struct diff_output_info *output_info;
304 
305 	switch (output_format) {
306 	case GOT_DIFF_OUTPUT_UNIDIFF:
307 		rc = diff_output_unidiff(
308 		    line_offsets ? &output_info : NULL, outfile, &info,
309 		    diff_result->result, context_lines);
310 		if (rc != DIFF_RC_OK)
311 			return got_error_set_errno(rc, "diff_output_unidiff");
312 		break;
313 	case GOT_DIFF_OUTPUT_EDSCRIPT:
314 		rc = diff_output_edscript(line_offsets ? &output_info : NULL,
315 		    outfile, &info, diff_result->result);
316 		if (rc != DIFF_RC_OK)
317 			return got_error_set_errno(rc, "diff_output_edscript");
318 		break;
319 
320 	}
321 
322 	if (line_offsets && *line_offsets) {
323 		if (output_info->line_offsets.len > 0) {
324 			off_t prev_offset = 0, *p, *o;
325 			int i, len;
326 			if (*nlines > 0) {
327 				prev_offset = (*line_offsets)[*nlines - 1];
328 				/*
329 				 * First line offset is always zero. Skip it
330 				 * when appending to a pre-populated array.
331 				 */
332 				o = &output_info->line_offsets.head[1];
333 				len = output_info->line_offsets.len - 1;
334 			} else {
335 				o = &output_info->line_offsets.head[0];
336 				len = output_info->line_offsets.len;
337 			}
338 			p = reallocarray(*line_offsets, *nlines + len,
339 			    sizeof(off_t));
340 			if (p == NULL)
341 				return got_error_from_errno("calloc");
342 			for (i = 0; i < len; i++)
343 				p[*nlines + i] = o[i] + prev_offset;
344 			*line_offsets = p;
345 			*nlines += len;
346 		}
347 		diff_output_info_free(output_info);
348 	}
349 
350 	return NULL;
351 }
352 
353 const struct got_error *
354 got_diffreg_result_free(struct got_diffreg_result *diffreg_result)
355 {
356 	const struct got_error *err;
357 
358 	diff_result_free(diffreg_result->result);
359 	diff_data_free(&diffreg_result->left);
360 	diff_data_free(&diffreg_result->right);
361 	err = got_diffreg_close(diffreg_result->f1, diffreg_result->map1,
362 	    diffreg_result->size1, diffreg_result->f2,
363 	    diffreg_result->map2, diffreg_result->size2);
364 	free(diffreg_result);
365 	return err;
366 }
367 
368 const struct got_error *
369 got_diffreg_result_free_left(struct got_diffreg_result *diffreg_result)
370 {
371 	diff_data_free(&diffreg_result->left);
372 	memset(&diffreg_result->left, 0, sizeof(diffreg_result->left));
373 	return got_diffreg_close(diffreg_result->f1, diffreg_result->map1,
374 	    diffreg_result->size1, NULL, NULL, 0);
375 }
376 
377 const struct got_error *
378 got_diffreg_result_free_right(struct got_diffreg_result *diffreg_result)
379 {
380 	diff_data_free(&diffreg_result->right);
381 	memset(&diffreg_result->right, 0, sizeof(diffreg_result->right));
382 	return got_diffreg_close(NULL, NULL, 0, diffreg_result->f2,
383 	    diffreg_result->map2, diffreg_result->size2);
384 }
385 
386 void
387 got_diff_dump_change(FILE *outfile, struct diff_chunk *change,
388     FILE *f1, FILE *f2)
389 {
390 }