1 /*
2  * Copyright (c) 2018, 2019, 2020 Stefan Sperling <stsp@openbsd.org>
3  * Copyright (c) 2020 Neels Hofmeyr <neels@hofmeyr.de>
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 
21 #include <errno.h>
22 #include <string.h>
23 #include <stdio.h>
24 #include <stdlib.h>
25 #include <time.h>
26 #include <limits.h>
27 #include <zlib.h>
28 
29 #include "got_compat.h"
30 
31 #include "got_error.h"
32 #include "got_object.h"
33 #include "got_cancel.h"
34 #include "got_blame.h"
35 #include "got_commit_graph.h"
36 #include "got_opentemp.h"
37 
38 #include "got_lib_inflate.h"
39 #include "got_lib_delta.h"
40 #include "got_lib_object.h"
41 #include "got_lib_diff.h"
42 
43 #ifndef MAX
44 #define	MAX(_a,_b) ((_a) > (_b) ? (_a) : (_b))
45 #endif
46 
47 struct got_blame_line {
48 	int annotated;
49 	struct got_object_id id;
50 };
51 
52 struct got_blame {
53 	struct diff_config *cfg;
54 	int nlines;	/* number of lines in file being blamed */
55 	int nannotated;	/* number of lines already annotated */
56 	struct got_blame_line *lines; /* one per line */
57 	int ncommits;
58 
59 	/*
60 	 * These change with every traversed commit. After diffing
61 	 * commits N:N-1, in preparation for diffing commits N-1:N-2,
62 	 * data for commit N is retained and flipped into data for N-1.
63 	 * 
64 	 */
65 	FILE *f1; /* older version from commit N-1. */
66 	FILE *f2; /* newer version from commit N. */
67 	unsigned char *map1;
68 	unsigned char *map2;
69 	off_t size1;
70 	off_t size2;
71 	int nlines1;
72 	int nlines2;
73 	off_t *line_offsets1;
74 	off_t *line_offsets2;
75 
76 	/*
77 	 * Map line numbers of an older version of the file to valid line
78 	 * numbers in the version of the file being blamed. This map is
79 	 * updated with each commit we traverse throughout the file's history.
80 	 * Lines mapped to -1 do not correspond to any line in the version
81 	 * being blamed.
82 	 */
83 	int *linemap1;
84 	int *linemap2;
85 
86 	struct diff_data *data1;
87 	struct diff_data *data2;
88 };
89 
90 static const struct got_error *
91 annotate_line(struct got_blame *blame, int lineno, struct got_object_id *id,
92     const struct got_error *(*cb)(void *, int, int, struct got_object_id *),
93     void *arg)
94 {
95 	const struct got_error *err = NULL;
96 	struct got_blame_line *line;
97 
98 	if (lineno < 0 || lineno >= blame->nlines)
99 		return NULL;
100 
101 	line = &blame->lines[lineno];
102 	if (line->annotated)
103 		return NULL;
104 
105 	memcpy(&line->id, id, sizeof(line->id));
106 	line->annotated = 1;
107 	blame->nannotated++;
108 	if (cb)
109 		err = cb(arg, blame->nlines, lineno + 1, id);
110 	return err;
111 }
112 
113 static const struct got_error *
114 blame_changes(struct got_blame *blame, struct diff_result *diff_result,
115     struct got_object_id *commit_id,
116     const struct got_error *(*cb)(void *, int, int, struct got_object_id *),
117     void *arg)
118 {
119 	const struct got_error *err = NULL;
120 	int i;
121 	int idx1 = 0, idx2 = 0;
122 
123 	for (i = 0; i < diff_result->chunks.len &&
124 	    blame->nannotated < blame->nlines; i++) {
125 		struct diff_chunk *c = diff_chunk_get(diff_result, i);
126 		unsigned int left_count, right_count;
127 		int j;
128 
129 		/*
130 		 * We do not need to worry about idx1/idx2 growing out
131 		 * of bounds because the diff implementation ensures
132 		 * that chunk ranges never exceed the number of lines
133 		 * in the left/right input files.
134 		 */
135 		left_count = diff_chunk_get_left_count(c);
136 		right_count = diff_chunk_get_right_count(c);
137 
138 		if (left_count == right_count) {
139 			for (j = 0; j < left_count; j++) {
140 				blame->linemap1[idx1++] =
141 				    blame->linemap2[idx2++];
142 			}
143 			continue;
144 		}
145 
146 		if (right_count == 0) {
147 			for (j = 0; j < left_count; j++) {
148 				blame->linemap1[idx1++] = -1;
149 			}
150 			continue;
151 		}
152 
153 		for (j = 0; j < right_count; j++) {
154 			int ln = blame->linemap2[idx2++];
155 			err = annotate_line(blame, ln, commit_id, cb, arg);
156 			if (err)
157 				return err;
158 			if (blame->nlines == blame->nannotated)
159 				break;
160 		}
161 	}
162 
163 	return NULL;
164 }
165 
166 static const struct got_error *
167 blame_prepare_file(FILE *f, unsigned char **p, off_t *size,
168     int *nlines, off_t **line_offsets, struct diff_data *diff_data,
169     const struct diff_config *cfg, struct got_blob_object *blob)
170 {
171 	const struct got_error *err = NULL;
172 	int diff_flags = 0, rc;
173 
174 	err = got_object_blob_dump_to_file(size, nlines, line_offsets,
175 	    f, blob);
176 	if (err)
177 		return err;
178 
179 #ifndef GOT_DIFF_NO_MMAP
180 	*p = mmap(NULL, *size, PROT_READ, MAP_PRIVATE, fileno(f), 0);
181 	if (*p == MAP_FAILED)
182 #endif
183 		*p = NULL; /* fall back on file I/O */
184 
185 	/* Allow blaming lines in binary files even though it's useless. */
186 	diff_flags |= DIFF_FLAG_FORCE_TEXT_DATA;
187 
188 	rc = diff_atomize_file(diff_data, cfg, f, *p, *size, diff_flags);
189 	if (rc)
190 		return got_error_set_errno(rc, "diff_atomize_file");
191 
192 	return NULL;
193 }
194 
195 static const struct got_error *
196 blame_commit(struct got_blame *blame, struct got_object_id *id,
197     const char *path, struct got_repository *repo,
198     const struct got_error *(*cb)(void *, int, int, struct got_object_id *),
199     void *arg)
200 {
201 	const struct got_error *err = NULL;
202 	struct got_commit_object *commit = NULL;
203 	struct got_object_qid *pid = NULL;
204 	struct got_object_id *pblob_id = NULL;
205 	struct got_blob_object *pblob = NULL;
206 	struct diff_result *diff_result = NULL;
207 
208 	err = got_object_open_as_commit(&commit, repo, id);
209 	if (err)
210 		return err;
211 
212 	pid = STAILQ_FIRST(got_object_commit_get_parent_ids(commit));
213 	if (pid == NULL) {
214 		got_object_commit_close(commit);
215 		return NULL;
216 	}
217 
218 	err = got_object_id_by_path(&pblob_id, repo, pid->id, path);
219 	if (err) {
220 		if (err->code == GOT_ERR_NO_TREE_ENTRY)
221 			err = NULL;
222 		goto done;
223 	}
224 
225 	err = got_object_open_as_blob(&pblob, repo, pblob_id, 8192);
226 	if (err)
227 		goto done;
228 
229 	blame->f1 = got_opentemp();
230 	if (blame->f1 == NULL) {
231 		err = got_error_from_errno("got_opentemp");
232 		goto done;
233 	}
234 
235 	err = blame_prepare_file(blame->f1, &blame->map1, &blame->size1,
236 	    &blame->nlines1, &blame->line_offsets1, blame->data1,
237 	    blame->cfg, pblob);
238 	if (err)
239 		goto done;
240 
241 	diff_result = diff_main(blame->cfg, blame->data1, blame->data2);
242 	if (diff_result == NULL) {
243 		err = got_error_set_errno(ENOMEM, "malloc");
244 		goto done;
245 	}
246 	if (diff_result->rc != DIFF_RC_OK) {
247 		err = got_error_set_errno(diff_result->rc, "diff");
248 		goto done;
249 	}
250 	if (diff_result->chunks.len > 0) {
251 		if (blame->nlines1 > 0) {
252 			blame->linemap1 = calloc(blame->nlines1,
253 			    sizeof(*blame->linemap1));
254 			if (blame->linemap1 == NULL) {
255 				err = got_error_from_errno("malloc");
256 				goto done;
257 			}
258 		}
259 		err = blame_changes(blame, diff_result, id, cb, arg);
260 		if (err)
261 			goto done;
262 	} else if (cb)
263 		err = cb(arg, blame->nlines, -1, id);
264 done:
265 	if (diff_result)
266 		diff_result_free(diff_result);
267 	if (commit)
268 		got_object_commit_close(commit);
269 	free(pblob_id);
270 	if (pblob)
271 		got_object_blob_close(pblob);
272 	return err;
273 }
274 
275 static const struct got_error *
276 blame_close(struct got_blame *blame)
277 {
278 	const struct got_error *err = NULL;
279 
280 	diff_data_free(blame->data1);
281 	free(blame->data1);
282 	diff_data_free(blame->data2);
283 	free(blame->data2);
284 	if (blame->map1) {
285 		if (munmap(blame->map1, blame->size1) == -1 && err == NULL)
286 			err = got_error_from_errno("munmap");
287 	}
288 	if (blame->map2) {
289 		if (munmap(blame->map2, blame->size2) == -1 && err == NULL)
290 			err = got_error_from_errno("munmap");
291 	}
292 	if (blame->f1 && fclose(blame->f1) == EOF && err == NULL)
293 		err = got_error_from_errno("fclose");
294 	if (blame->f2 && fclose(blame->f2) == EOF && err == NULL)
295 		err = got_error_from_errno("fclose");
296 	free(blame->lines);
297 	free(blame->line_offsets1);
298 	free(blame->line_offsets2);
299 	free(blame->linemap1);
300 	free(blame->linemap2);
301 	free(blame->cfg);
302 	free(blame);
303 	return err;
304 }
305 
306 static int
307 atomize_file(struct diff_data *d, FILE *f, off_t filesize, int nlines,
308     off_t *line_offsets)
309 {
310 	int i, rc = DIFF_RC_OK;
311 	int embedded_nul = 0;
312 
313 	ARRAYLIST_INIT(d->atoms, nlines);
314 
315 	for (i = 0; i < nlines; i++) {
316 		struct diff_atom *atom;
317 		off_t len, pos = line_offsets[i];
318 		unsigned int hash = 0;
319 		int j;
320 
321 		ARRAYLIST_ADD(atom, d->atoms);
322 		if (atom == NULL) {
323 			rc = errno;
324 			break;
325 		}
326 
327 		if (i < nlines - 1)
328 			len = line_offsets[i + 1] - pos;
329 		else
330 			len = filesize - pos;
331 
332 		if (fseeko(f, pos, SEEK_SET) == -1) {
333 			rc = errno;
334 			break;
335 		}
336 		for (j = 0; j < len; j++) {
337 			int c = fgetc(f);
338 			if (c == EOF) {
339 				if (feof(f))
340 					rc = EIO; /* unexpected EOF */
341 				else
342 					rc = errno;
343 				goto done;
344 			}
345 
346 			hash = diff_atom_hash_update(hash, (unsigned char)c);
347 
348 			if (c == '\0')
349 				embedded_nul = 1;
350 
351 		}
352 		*atom = (struct diff_atom){
353 			.root = d,
354 			.pos = pos,
355 			.at = NULL,	/* atom data is not memory-mapped */
356 			.len = len,
357 			.hash = hash,
358 		};
359 	}
360 
361 	/* File are considered binary if they contain embedded '\0' bytes. */
362 	if (embedded_nul)
363 		d->atomizer_flags |= DIFF_ATOMIZER_FOUND_BINARY_DATA;
364 done:
365 	if (rc)
366 		ARRAYLIST_FREE(d->atoms);
367 
368 	return rc;
369 }
370 
371 static int
372 atomize_file_mmap(struct diff_data *d, unsigned char *p,
373     off_t filesize, int nlines, off_t *line_offsets)
374 {
375 	int i, rc = DIFF_RC_OK;
376 	int embedded_nul = 0;
377 
378 	ARRAYLIST_INIT(d->atoms, nlines);
379 
380 	for (i = 0; i < nlines; i++) {
381 		struct diff_atom *atom;
382 		off_t len, pos = line_offsets[i];
383 		unsigned int hash = 0;
384 		int j;
385 
386 		ARRAYLIST_ADD(atom, d->atoms);
387 		if (atom == NULL) {
388 			rc = errno;
389 			break;
390 		}
391 
392 		if (i < nlines - 1)
393 			len = line_offsets[i + 1] - pos;
394 		else
395 			len = filesize - pos;
396 
397 		for (j = 0; j < len; j++)
398 			hash = diff_atom_hash_update(hash, p[pos + j]);
399 
400 		if (!embedded_nul && memchr(&p[pos], '\0', len) != NULL)
401 			embedded_nul = 1;
402 
403 		*atom = (struct diff_atom){
404 			.root = d,
405 			.pos = pos,
406 			.at = &p[pos],
407 			.len = len,
408 			.hash = hash,
409 		};
410 	}
411 
412 	/* File are considered binary if they contain embedded '\0' bytes. */
413 	if (embedded_nul)
414 		d->atomizer_flags |= DIFF_ATOMIZER_FOUND_BINARY_DATA;
415 
416 	if (rc)
417 		ARRAYLIST_FREE(d->atoms);
418 
419 	return rc;
420 }
421 
422 /* Implements diff_atomize_func_t */
423 static int
424 blame_atomize_file(void *arg, struct diff_data *d)
425 {
426 	struct got_blame *blame = arg;
427 
428 	if (d->f == blame->f1) {
429 		if (blame->map1)
430 			return atomize_file_mmap(d, blame->map1,
431 			    blame->size1, blame->nlines1,
432 			    blame->line_offsets1);
433 		else
434 			return atomize_file(d, blame->f1, blame->size1,
435 			    blame->nlines1, blame->line_offsets1);
436 	} else if (d->f == blame->f2) {
437 		if (d->atoms.len > 0) {
438 			/* Re-use data from previous commit. */
439 			return DIFF_RC_OK;
440 		}
441 		if (blame->map2)
442 			return atomize_file_mmap(d, blame->map2,
443 			    blame->size2, blame->nlines2,
444 			    blame->line_offsets2);
445 		else
446 			return atomize_file(d, blame->f2, blame->size2,
447 			    blame->nlines2, blame->line_offsets2);
448 	}
449 
450 	return DIFF_RC_OK;
451 }
452 
453 static const struct got_error *
454 close_file2_and_reuse_file1(struct got_blame *blame)
455 {
456 	struct diff_data *d;
457 
458 	free(blame->line_offsets2);
459 	blame->line_offsets2 = blame->line_offsets1;
460 	blame->line_offsets1 = NULL;
461 
462 	free(blame->linemap2);
463 	blame->linemap2 = blame->linemap1;
464 	blame->linemap1 = NULL;
465 
466 	if (blame->map2) {
467 		if (munmap(blame->map2, blame->size2) == -1)
468 			return got_error_from_errno("munmap");
469 		blame->map2 = blame->map1;
470 		blame->map1 = NULL;
471 
472 	}
473 	blame->size2 = blame->size1;
474 	blame->size1 = 0;
475 
476 	if (fclose(blame->f2) == EOF)
477 		return got_error_from_errno("fclose");
478 	blame->f2 = blame->f1;
479 	blame->f1 = NULL;
480 
481 	blame->nlines2 = blame->nlines1;
482 	blame->nlines1 = 0;
483 
484 	diff_data_free(blame->data2); /* does not free pointer itself */
485 	memset(blame->data2, 0, sizeof(*blame->data2));
486 	d = blame->data2;
487 	blame->data2 = blame->data1;
488 	blame->data1 = d;
489 
490 	return NULL;
491 }
492 
493 static const struct got_error *
494 blame_open(struct got_blame **blamep, const char *path,
495     struct got_object_id *start_commit_id, struct got_repository *repo,
496     const struct got_error *(*cb)(void *, int, int, struct got_object_id *),
497     void *arg, got_cancel_cb cancel_cb, void *cancel_arg)
498 {
499 	const struct got_error *err = NULL;
500 	struct got_object_id *obj_id = NULL;
501 	struct got_blob_object *blob = NULL;
502 	struct got_blame *blame = NULL;
503 	struct got_object_id *id = NULL;
504 	int lineno;
505 	struct got_commit_graph *graph = NULL;
506 
507 	*blamep = NULL;
508 
509 	err = got_object_id_by_path(&obj_id, repo, start_commit_id, path);
510 	if (err)
511 		goto done;
512 
513 	err = got_object_open_as_blob(&blob, repo, obj_id, 8192);
514 	if (err)
515 		goto done;
516 
517 	blame = calloc(1, sizeof(*blame));
518 	if (blame == NULL) {
519 		err = got_error_from_errno("calloc");
520 		goto done;
521 	}
522 
523 	blame->data1 = calloc(1, sizeof(*blame->data1));
524 	if (blame->data1 == NULL) {
525 		err = got_error_from_errno("calloc");
526 		goto done;
527 	}
528 	blame->data2 = calloc(1, sizeof(*blame->data2));
529 	if (blame->data2 == NULL) {
530 		err = got_error_from_errno("calloc");
531 		goto done;
532 	}
533 
534 	blame->f2 = got_opentemp();
535 	if (blame->f2 == NULL) {
536 		err = got_error_from_errno("got_opentemp");
537 		goto done;
538 	}
539 	err = got_diff_get_config(&blame->cfg, GOT_DIFF_ALGORITHM_PATIENCE,
540 	    blame_atomize_file, blame);
541 	if (err)
542 		goto done;
543 
544 	err = blame_prepare_file(blame->f2, &blame->map2, &blame->size2,
545 	    &blame->nlines2, &blame->line_offsets2, blame->data2,
546 	    blame->cfg, blob);
547 	blame->nlines = blame->nlines2;
548 	if (err || blame->nlines == 0)
549 		goto done;
550 
551 	got_object_blob_close(blob);
552 	blob = NULL;
553 
554 	/* Don't include \n at EOF in the blame line count. */
555 	if (blame->line_offsets2[blame->nlines - 1] == blame->size2)
556 		blame->nlines--;
557 
558 	blame->lines = calloc(blame->nlines, sizeof(*blame->lines));
559 	if (blame->lines == NULL) {
560 		err = got_error_from_errno("calloc");
561 		goto done;
562 	}
563 
564 	blame->linemap2 = calloc(blame->nlines2, sizeof(*blame->linemap2));
565 	if (blame->linemap2 == NULL) {
566 		err = got_error_from_errno("calloc");
567 		goto done;
568 	}
569 	for (lineno = 0; lineno < blame->nlines2; lineno++)
570 		blame->linemap2[lineno] = lineno;
571 
572 	err = got_commit_graph_open(&graph, path, 1);
573 	if (err)
574 		goto done;
575 
576 	err = got_commit_graph_iter_start(graph, start_commit_id, repo,
577 	    cancel_cb, cancel_arg);
578 	if (err)
579 		goto done;
580 	for (;;) {
581 		struct got_object_id *next_id;
582 		err = got_commit_graph_iter_next(&next_id, graph, repo,
583 		    cancel_cb, cancel_arg);
584 		if (err) {
585 			if (err->code == GOT_ERR_ITER_COMPLETED) {
586 				err = NULL;
587 				break;
588 			}
589 			goto done;
590 		}
591 		if (next_id) {
592 			id = next_id;
593 			err = blame_commit(blame, id, path, repo, cb, arg);
594 			if (err) {
595 				if (err->code == GOT_ERR_ITER_COMPLETED)
596 					err = NULL;
597 				goto done;
598 			}
599 			if (blame->nannotated == blame->nlines)
600 				break;
601 
602 			err = close_file2_and_reuse_file1(blame);
603 			if (err)
604 				goto done;
605 		}
606 	}
607 
608 	if (id && blame->nannotated < blame->nlines) {
609 		/* Annotate remaining non-annotated lines with last commit. */
610 		for (lineno = 0; lineno < blame->nlines; lineno++) {
611 			err = annotate_line(blame, lineno, id, cb, arg);
612 			if (err)
613 				goto done;
614 		}
615 	}
616 
617 done:
618 	if (graph)
619 		got_commit_graph_close(graph);
620 	free(obj_id);
621 	if (blob)
622 		got_object_blob_close(blob);
623 	if (err) {
624 		if (blame)
625 			blame_close(blame);
626 	} else
627 		*blamep = blame;
628 
629 	return err;
630 }
631 
632 const struct got_error *
633 got_blame(const char *path, struct got_object_id *commit_id,
634     struct got_repository *repo,
635     const struct got_error *(*cb)(void *, int, int, struct got_object_id *),
636     void *arg, got_cancel_cb cancel_cb, void* cancel_arg)
637 {
638 	const struct got_error *err = NULL, *close_err = NULL;
639 	struct got_blame *blame;
640 	char *abspath;
641 
642 	if (asprintf(&abspath, "%s%s", path[0] == '/' ? "" : "/", path) == -1)
643 		return got_error_from_errno2("asprintf", path);
644 
645 	err = blame_open(&blame, abspath, commit_id, repo, cb, arg,
646 	    cancel_cb, cancel_arg);
647 	free(abspath);
648 	if (blame)
649 		close_err = blame_close(blame);
650 	return err ? err : close_err;
651 }