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 <sha1.h>
24 #include <sha2.h>
25 #include <stdio.h>
26 #include <stdlib.h>
27 #include <string.h>
28 
29 #include "got_object.h"
30 #include "got_opentemp.h"
31 #include "got_error.h"
32 #include "got_diff.h"
33 
34 #include "got_lib_diff.h"
35 
36 const struct diff_algo_config myers_then_patience;
37 const struct diff_algo_config myers_then_myers_divide;
38 const struct diff_algo_config patience;
39 const struct diff_algo_config myers_divide;
40 
41 const struct diff_algo_config myers_then_patience = {
42 	.impl = diff_algo_myers,
43 	.permitted_state_size = 1024 * 1024 * sizeof(int),
44 	.fallback_algo = &patience,
45 };
46 
47 const struct diff_algo_config myers_then_myers_divide = {
48 	.impl = diff_algo_myers,
49 	.permitted_state_size = 1024 * 1024 * sizeof(int),
50 	.fallback_algo = &myers_divide,
51 };
52 
53 const struct diff_algo_config patience = {
54 	.impl = diff_algo_patience,
55 	/* After subdivision, do Patience again: */
56 	.inner_algo = &patience,
57 	/* If subdivision failed, do Myers Divide et Impera: */
58 	.fallback_algo = &myers_then_myers_divide,
59 };
60 
61 const struct diff_algo_config myers_divide = {
62 	.impl = diff_algo_myers_divide,
63 	/* When division succeeded, start from the top: */
64 	.inner_algo = &myers_then_myers_divide,
65 	/* (fallback_algo = NULL implies diff_algo_none). */
66 };
67 
68 /* If the state for a forward-Myers is small enough, use Myers, otherwise first
69  * do a Myers-divide. */
70 const struct diff_config diff_config_myers_then_myers_divide = {
71 	.atomize_func = diff_atomize_text_by_line,
72 	.algo = &myers_then_myers_divide,
73 };
74 
75 /* If the state for a forward-Myers is small enough, use Myers, otherwise first
76  * do a Patience. */
77 const struct diff_config diff_config_myers_then_patience = {
78 	.atomize_func = diff_atomize_text_by_line,
79 	.algo = &myers_then_patience,
80 };
81 
82 /* Directly force Patience as a first divider of the source file. */
83 const struct diff_config diff_config_patience = {
84 	.atomize_func = diff_atomize_text_by_line,
85 	.algo = &patience,
86 };
87 
88 /* Directly force Patience as a first divider of the source file. */
89 const struct diff_config diff_config_no_algo = {
90 	.atomize_func = diff_atomize_text_by_line,
91 };
92 
93 const struct got_error *
94 got_diffreg_close(char *p1, size_t size1, char *p2, size_t size2)
95 {
96 	const struct got_error *err = NULL;
97 
98 	if (p1 && munmap(p1, size1) == -1 && err == NULL)
99 		err = got_error_from_errno("munmap");
100 	if (p2 && munmap(p2, size2) == -1 && err == NULL)
101 		err = got_error_from_errno("munmap");
102 	return err;
103 }
104 
105 const struct got_error *
106 got_diff_get_config(struct diff_config **cfg,
107     enum got_diff_algorithm algorithm,
108     diff_atomize_func_t atomize_func, void *atomize_func_data)
109 {
110 	*cfg = calloc(1, sizeof(**cfg));
111 	if (*cfg == NULL)
112 		return got_error_from_errno("calloc");
113 
114 	switch (algorithm) {
115 	case GOT_DIFF_ALGORITHM_PATIENCE:
116 		(*cfg)->algo = &patience;
117 		break;
118 	case GOT_DIFF_ALGORITHM_MYERS:
119 		(*cfg)->algo = &myers_then_myers_divide;
120 		break;
121 	default:
122 		return got_error_msg(GOT_ERR_NOT_IMPL, "bad diff algorithm");
123 	}
124 
125 	if (atomize_func) {
126 		(*cfg)->atomize_func = atomize_func;
127 		(*cfg)->atomize_func_data = atomize_func_data;
128 	} else
129 		(*cfg)->atomize_func = diff_atomize_text_by_line;
130 
131 	(*cfg)->max_recursion_depth = 0; /* use default recursion depth */
132 
133 	return NULL;
134 }
135 
136 const struct got_error *
137 got_diff_prepare_file(FILE *f, char **p, size_t *size,
138     struct diff_data *diff_data, const struct diff_config *cfg,
139     int ignore_whitespace, int force_text_diff)
140 {
141 	const struct got_error *err = NULL;
142 	struct stat st;
143 	int diff_flags = 0, rc;
144 
145 	*size = 0;
146 
147 	diff_flags |= DIFF_FLAG_SHOW_PROTOTYPES;
148 	if (ignore_whitespace)
149 		diff_flags |= DIFF_FLAG_IGNORE_WHITESPACE;
150 	if (force_text_diff)
151 		diff_flags |= DIFF_FLAG_FORCE_TEXT_DATA;
152 
153 	if (fstat(fileno(f), &st) == -1) {
154 		err = got_error_from_errno("fstat");
155 		goto done;
156 	}
157 #ifndef GOT_DIFF_NO_MMAP
158 	*p = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE,
159 	    fileno(f), 0);
160 	if (*p == MAP_FAILED)
161 #endif
162 		*p = NULL; /* fall back on file I/O */
163 
164 	rc = diff_atomize_file(diff_data, cfg, f, *p, st.st_size, diff_flags);
165 	if (rc) {
166 		err = got_error_set_errno(rc, "diff_atomize_file");
167 		goto done;
168 	}
169 done:
170 	if (err)
171 		diff_data_free(diff_data);
172 	else
173 		*size = st.st_size;
174 	return err;
175 }
176 
177 const struct got_error *
178 got_diffreg(struct got_diffreg_result **diffreg_result, FILE *f1, FILE *f2,
179     enum got_diff_algorithm algorithm, int ignore_whitespace,
180     int force_text_diff)
181 {
182 	const struct got_error *err = NULL;
183 	struct diff_config *cfg = NULL;
184 	char *p1 = NULL, *p2 = NULL;
185 	size_t size1, size2;
186 	struct diff_data d_left, d_right;
187 	struct diff_data *left, *right;
188 	struct diff_result *diff_result;
189 
190 	if (diffreg_result) {
191 		*diffreg_result = calloc(1, sizeof(**diffreg_result));
192 		if (*diffreg_result == NULL)
193 			return got_error_from_errno("calloc");
194 		left = &(*diffreg_result)->left;
195 		right = &(*diffreg_result)->right;
196 	} else {
197 		memset(&d_left, 0, sizeof(d_left));
198 		memset(&d_right, 0, sizeof(d_right));
199 		left = &d_left;
200 		right = &d_right;
201 	}
202 
203 	err = got_diff_get_config(&cfg, algorithm, NULL, NULL);
204 	if (err)
205 		goto done;
206 
207 	err = got_diff_prepare_file(f1, &p1, &size1, left, cfg,
208 	    ignore_whitespace, force_text_diff);
209 	if (err)
210 		goto done;
211 
212 	err = got_diff_prepare_file(f2, &p2, &size2, right, cfg,
213 	    ignore_whitespace, force_text_diff);
214 	if (err)
215 		goto done;
216 
217 	diff_result = diff_main(cfg, left, right);
218 	if (diff_result == NULL) {
219 		err = got_error_set_errno(ENOMEM, "malloc");
220 		goto done;
221 	}
222 	if (diff_result->rc != DIFF_RC_OK) {
223 		err = got_error_set_errno(diff_result->rc, "diff");
224 		goto done;
225 	}
226 
227 	if (diffreg_result) {
228 		(*diffreg_result)->result = diff_result;
229 		(*diffreg_result)->map1 = p1;
230 		(*diffreg_result)->size1 = size1;
231 		(*diffreg_result)->map2 = p2;
232 		(*diffreg_result)->size2 = size2;
233 	}
234 done:
235 	free(cfg);
236 	if (diffreg_result == NULL) {
237 		diff_data_free(left);
238 		diff_data_free(right);
239 	}
240 	if (err) {
241 		got_diffreg_close(p1, size1, p2, size2);
242 		if (diffreg_result) {
243 			diff_data_free(left);
244 			diff_data_free(right);
245 			free(*diffreg_result);
246 			*diffreg_result = NULL;
247 		}
248 	}
249 
250 	return err;
251 }
252 
253 const struct got_error *
254 got_diffreg_output(struct got_diff_line **lines, size_t *nlines,
255     struct got_diffreg_result *diff_result, int f1_exists, int f2_exists,
256     const char *path1, const char *path2,
257     enum got_diff_output_format output_format, int context_lines, FILE *outfile)
258 {
259 	struct diff_input_info info = {
260 		.left_path = path1,
261 		.right_path = path2,
262 		.flags = 0,
263 	};
264 	int rc;
265 	struct diff_output_info *output_info;
266 
267 	if (!f1_exists)
268 		info.flags |= DIFF_INPUT_LEFT_NONEXISTENT;
269 	if (!f2_exists)
270 		info.flags |= DIFF_INPUT_RIGHT_NONEXISTENT;
271 
272 	switch (output_format) {
273 	case GOT_DIFF_OUTPUT_UNIDIFF:
274 		rc = diff_output_unidiff(
275 		    lines ? &output_info : NULL, outfile, &info,
276 		    diff_result->result, context_lines);
277 		if (rc != DIFF_RC_OK)
278 			return got_error_set_errno(rc, "diff_output_unidiff");
279 		break;
280 	case GOT_DIFF_OUTPUT_PLAIN:
281 		rc = diff_output_plain(lines ? &output_info : NULL,
282 		    outfile, &info, diff_result->result, 1);
283 		if (rc != DIFF_RC_OK)
284 			return got_error_set_errno(rc, "diff_output_edscript");
285 		break;
286 
287 	}
288 
289 	if (lines && *lines) {
290 		if (output_info->line_offsets.len > 0) {
291 			struct got_diff_line *p;
292 			off_t prev_offset = 0, *o;
293 			uint8_t *o2;
294 			int i, len;
295 			if (*nlines > 0) {
296 				prev_offset = (*lines)[*nlines - 1].offset;
297 				/*
298 				 * First line offset is always zero. Skip it
299 				 * when appending to a pre-populated array.
300 				 */
301 				o = &output_info->line_offsets.head[1];
302 				o2 = &output_info->line_types.head[1];
303 				len = output_info->line_offsets.len - 1;
304 			} else {
305 				o = &output_info->line_offsets.head[0];
306 				o2 = &output_info->line_types.head[0];
307 				len = output_info->line_offsets.len;
308 			}
309 			p = reallocarray(*lines, *nlines + len, sizeof(**lines));
310 			if (p == NULL)
311 				return got_error_from_errno("calloc");
312 			for (i = 0; i < len; i++) {
313 				p[*nlines + i].offset = o[i] + prev_offset;
314 				p[*nlines + i].type = o2[i];
315 			}
316 			*lines = p;
317 			*nlines += len;
318 		}
319 		diff_output_info_free(output_info);
320 	}
321 
322 	return NULL;
323 }
324 
325 const struct got_error *
326 got_diffreg_result_free(struct got_diffreg_result *diffreg_result)
327 {
328 	const struct got_error *err;
329 
330 	diff_result_free(diffreg_result->result);
331 	diff_data_free(&diffreg_result->left);
332 	diff_data_free(&diffreg_result->right);
333 	err = got_diffreg_close(diffreg_result->map1, diffreg_result->size1,
334 	    diffreg_result->map2, diffreg_result->size2);
335 	free(diffreg_result);
336 	return err;
337 }
338 
339 const struct got_error *
340 got_diffreg_result_free_left(struct got_diffreg_result *diffreg_result)
341 {
342 	diff_data_free(&diffreg_result->left);
343 	memset(&diffreg_result->left, 0, sizeof(diffreg_result->left));
344 	return got_diffreg_close(diffreg_result->map1, diffreg_result->size1,
345 	    NULL, 0);
346 }
347 
348 const struct got_error *
349 got_diffreg_result_free_right(struct got_diffreg_result *diffreg_result)
350 {
351 	diff_data_free(&diffreg_result->right);
352 	memset(&diffreg_result->right, 0, sizeof(diffreg_result->right));
353 	return got_diffreg_close(NULL, 0, diffreg_result->map2,
354 	    diffreg_result->size2);
355 }