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/queue.h>
19 #include <sys/mman.h>
20 #include <sys/stat.h>
21 
22 #include <errno.h>
23 #include <sha1.h>
24 #include <string.h>
25 #include <stdio.h>
26 #include <stdlib.h>
27 #include <time.h>
28 #include <limits.h>
29 #include <util.h>
30 #include <zlib.h>
31 
32 #include "got_error.h"
33 #include "got_object.h"
34 #include "got_cancel.h"
35 #include "got_blame.h"
36 #include "got_commit_graph.h"
37 #include "got_opentemp.h"
38 
39 #include "got_lib_inflate.h"
40 #include "got_lib_delta.h"
41 #include "got_lib_object.h"
42 #include "got_lib_diff.h"
43 
44 #ifndef MAX
45 #define	MAX(_a,_b) ((_a) > (_b) ? (_a) : (_b))
46 #endif
47 
48 struct got_blame_line {
49 	int annotated;
50 	struct got_object_id id;
51 };
52 
53 struct got_blame {
54 	struct diff_config *cfg;
55 	int nlines;	/* number of lines in file being blamed */
56 	int nannotated;	/* number of lines already annotated */
57 	struct got_blame_line *lines; /* one per line */
58 	int ncommits;
59 
60 	/*
61 	 * These change with every traversed commit. After diffing
62 	 * commits N:N-1, in preparation for diffing commits N-1:N-2,
63 	 * data for commit N is retained and flipped into data for N-1.
64 	 * 
65 	 */
66 	FILE *f1; /* older version from commit N-1. */
67 	FILE *f2; /* newer version from commit N. */
68 	unsigned char *map1;
69 	unsigned char *map2;
70 	off_t size1;
71 	off_t size2;
72 	int nlines1;
73 	int nlines2;
74 	off_t *line_offsets1;
75 	off_t *line_offsets2;
76 
77 	/*
78 	 * Map line numbers of an older version of the file to valid line
79 	 * numbers in the version of the file being blamed. This map is
80 	 * updated with each commit we traverse throughout the file's history.
81 	 * Lines mapped to -1 do not correspond to any line in the version
82 	 * being blamed.
83 	 */
84 	int *linemap1;
85 	int *linemap2;
86 
87 	struct diff_data *data1;
88 	struct diff_data *data2;
89 };
90 
91 static const struct got_error *
92 annotate_line(struct got_blame *blame, int lineno,
93     struct got_commit_object *commit, struct got_object_id *id,
94     got_blame_cb cb, void *arg)
95 {
96 	const struct got_error *err = NULL;
97 	struct got_blame_line *line;
98 
99 	if (lineno < 0 || lineno >= blame->nlines)
100 		return NULL;
101 
102 	line = &blame->lines[lineno];
103 	if (line->annotated)
104 		return NULL;
105 
106 	memcpy(&line->id, id, sizeof(line->id));
107 	line->annotated = 1;
108 	blame->nannotated++;
109 	if (cb)
110 		err = cb(arg, blame->nlines, lineno + 1, commit, id);
111 	return err;
112 }
113 
114 static const struct got_error *
115 blame_changes(struct got_blame *blame, struct diff_result *diff_result,
116     struct got_commit_object *commit, struct got_object_id *commit_id,
117     got_blame_cb cb, 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, commit_id,
156 			    cb, arg);
157 			if (err)
158 				return err;
159 			if (blame->nlines == blame->nannotated)
160 				break;
161 		}
162 	}
163 
164 	return NULL;
165 }
166 
167 static const struct got_error *
168 blame_prepare_file(FILE *f, unsigned char **p, off_t *size,
169     int *nlines, off_t **line_offsets, struct diff_data *diff_data,
170     const struct diff_config *cfg, struct got_blob_object *blob)
171 {
172 	const struct got_error *err = NULL;
173 	int diff_flags = 0, rc;
174 
175 	err = got_object_blob_dump_to_file(size, nlines, line_offsets,
176 	    f, blob);
177 	if (err)
178 		return err;
179 
180 #ifndef GOT_DIFF_NO_MMAP
181 	*p = mmap(NULL, *size, PROT_READ, MAP_PRIVATE, fileno(f), 0);
182 	if (*p == MAP_FAILED)
183 #endif
184 		*p = NULL; /* fall back on file I/O */
185 
186 	/* Allow blaming lines in binary files even though it's useless. */
187 	diff_flags |= DIFF_FLAG_FORCE_TEXT_DATA;
188 
189 	rc = diff_atomize_file(diff_data, cfg, f, *p, *size, diff_flags);
190 	if (rc)
191 		return got_error_set_errno(rc, "diff_atomize_file");
192 
193 	return NULL;
194 }
195 
196 static const struct got_error *
197 blame_commit(struct got_blame *blame, struct got_object_id *id,
198     const char *path, struct got_repository *repo,
199     got_blame_cb cb, void *arg)
200 {
201 	const struct got_error *err = NULL;
202 	struct got_commit_object *commit = NULL, *pcommit = 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 	int fd = -1;
208 
209 	err = got_object_open_as_commit(&commit, repo, id);
210 	if (err)
211 		return err;
212 
213 	pid = STAILQ_FIRST(got_object_commit_get_parent_ids(commit));
214 	if (pid == NULL) {
215 		got_object_commit_close(commit);
216 		return NULL;
217 	}
218 
219 	fd = got_opentempfd();
220 	if (fd == -1) {
221 		err = got_error_from_errno("got_opentempfd");
222 		goto done;
223 	}
224 
225 	err = got_object_open_as_commit(&pcommit, repo, &pid->id);
226 	if (err)
227 		goto done;
228 
229 	err = got_object_id_by_path(&pblob_id, repo, pcommit, path);
230 	if (err) {
231 		if (err->code == GOT_ERR_NO_TREE_ENTRY)
232 			err = NULL;
233 		goto done;
234 	}
235 
236 	err = got_object_open_as_blob(&pblob, repo, pblob_id, 8192, fd);
237 	if (err)
238 		goto done;
239 
240 	blame->f1 = got_opentemp();
241 	if (blame->f1 == NULL) {
242 		err = got_error_from_errno("got_opentemp");
243 		goto done;
244 	}
245 
246 	err = blame_prepare_file(blame->f1, &blame->map1, &blame->size1,
247 	    &blame->nlines1, &blame->line_offsets1, blame->data1,
248 	    blame->cfg, pblob);
249 	if (err)
250 		goto done;
251 
252 	diff_result = diff_main(blame->cfg, blame->data1, blame->data2);
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 	if (diff_result->chunks.len > 0) {
262 		if (blame->nlines1 > 0) {
263 			blame->linemap1 = calloc(blame->nlines1,
264 			    sizeof(*blame->linemap1));
265 			if (blame->linemap1 == NULL) {
266 				err = got_error_from_errno("malloc");
267 				goto done;
268 			}
269 		}
270 		err = blame_changes(blame, diff_result, commit, id, cb, arg);
271 		if (err)
272 			goto done;
273 	} else if (cb)
274 		err = cb(arg, blame->nlines, -1, commit, id);
275 done:
276 	if (diff_result)
277 		diff_result_free(diff_result);
278 	if (commit)
279 		got_object_commit_close(commit);
280 	if (pcommit)
281 		got_object_commit_close(pcommit);
282 	free(pblob_id);
283 	if (fd != -1 && close(fd) == -1 && err == NULL)
284 		err = got_error_from_errno("close");
285 	if (pblob)
286 		got_object_blob_close(pblob);
287 	return err;
288 }
289 
290 static const struct got_error *
291 blame_close(struct got_blame *blame)
292 {
293 	const struct got_error *err = NULL;
294 
295 	diff_data_free(blame->data1);
296 	free(blame->data1);
297 	diff_data_free(blame->data2);
298 	free(blame->data2);
299 	if (blame->map1) {
300 		if (munmap(blame->map1, blame->size1) == -1 && err == NULL)
301 			err = got_error_from_errno("munmap");
302 	}
303 	if (blame->map2) {
304 		if (munmap(blame->map2, blame->size2) == -1 && err == NULL)
305 			err = got_error_from_errno("munmap");
306 	}
307 	if (blame->f1 && fclose(blame->f1) == EOF && err == NULL)
308 		err = got_error_from_errno("fclose");
309 	if (blame->f2 && fclose(blame->f2) == EOF && err == NULL)
310 		err = got_error_from_errno("fclose");
311 	free(blame->lines);
312 	free(blame->line_offsets1);
313 	free(blame->line_offsets2);
314 	free(blame->linemap1);
315 	free(blame->linemap2);
316 	free(blame->cfg);
317 	free(blame);
318 	return err;
319 }
320 
321 static int
322 atomize_file(struct diff_data *d, FILE *f, off_t filesize, int nlines,
323     off_t *line_offsets)
324 {
325 	int i, rc = DIFF_RC_OK;
326 	int embedded_nul = 0;
327 
328 	ARRAYLIST_INIT(d->atoms, nlines);
329 
330 	for (i = 0; i < nlines; i++) {
331 		struct diff_atom *atom;
332 		off_t len, pos = line_offsets[i];
333 		unsigned int hash = 0;
334 		int j;
335 
336 		ARRAYLIST_ADD(atom, d->atoms);
337 		if (atom == NULL) {
338 			rc = errno;
339 			break;
340 		}
341 
342 		if (i < nlines - 1)
343 			len = line_offsets[i + 1] - pos;
344 		else
345 			len = filesize - pos;
346 
347 		if (fseeko(f, pos, SEEK_SET) == -1) {
348 			rc = errno;
349 			break;
350 		}
351 		for (j = 0; j < len; j++) {
352 			int c = fgetc(f);
353 			if (c == EOF) {
354 				if (feof(f))
355 					rc = EIO; /* unexpected EOF */
356 				else
357 					rc = errno;
358 				goto done;
359 			}
360 
361 			hash = diff_atom_hash_update(hash, (unsigned char)c);
362 
363 			if (c == '\0')
364 				embedded_nul = 1;
365 
366 		}
367 		*atom = (struct diff_atom){
368 			.root = d,
369 			.pos = pos,
370 			.at = NULL,	/* atom data is not memory-mapped */
371 			.len = len,
372 			.hash = hash,
373 		};
374 	}
375 
376 	/* File are considered binary if they contain embedded '\0' bytes. */
377 	if (embedded_nul)
378 		d->atomizer_flags |= DIFF_ATOMIZER_FOUND_BINARY_DATA;
379 done:
380 	if (rc)
381 		ARRAYLIST_FREE(d->atoms);
382 
383 	return rc;
384 }
385 
386 static int
387 atomize_file_mmap(struct diff_data *d, unsigned char *p,
388     off_t filesize, int nlines, off_t *line_offsets)
389 {
390 	int i, rc = DIFF_RC_OK;
391 	int embedded_nul = 0;
392 
393 	ARRAYLIST_INIT(d->atoms, nlines);
394 
395 	for (i = 0; i < nlines; i++) {
396 		struct diff_atom *atom;
397 		off_t len, pos = line_offsets[i];
398 		unsigned int hash = 0;
399 		int j;
400 
401 		ARRAYLIST_ADD(atom, d->atoms);
402 		if (atom == NULL) {
403 			rc = errno;
404 			break;
405 		}
406 
407 		if (i < nlines - 1)
408 			len = line_offsets[i + 1] - pos;
409 		else
410 			len = filesize - pos;
411 
412 		for (j = 0; j < len; j++)
413 			hash = diff_atom_hash_update(hash, p[pos + j]);
414 
415 		if (!embedded_nul && memchr(&p[pos], '\0', len) != NULL)
416 			embedded_nul = 1;
417 
418 		*atom = (struct diff_atom){
419 			.root = d,
420 			.pos = pos,
421 			.at = &p[pos],
422 			.len = len,
423 			.hash = hash,
424 		};
425 	}
426 
427 	/* File are considered binary if they contain embedded '\0' bytes. */
428 	if (embedded_nul)
429 		d->atomizer_flags |= DIFF_ATOMIZER_FOUND_BINARY_DATA;
430 
431 	if (rc)
432 		ARRAYLIST_FREE(d->atoms);
433 
434 	return rc;
435 }
436 
437 /* Implements diff_atomize_func_t */
438 static int
439 blame_atomize_file(void *arg, struct diff_data *d)
440 {
441 	struct got_blame *blame = arg;
442 
443 	if (d->f == blame->f1) {
444 		if (blame->map1)
445 			return atomize_file_mmap(d, blame->map1,
446 			    blame->size1, blame->nlines1,
447 			    blame->line_offsets1);
448 		else
449 			return atomize_file(d, blame->f1, blame->size1,
450 			    blame->nlines1, blame->line_offsets1);
451 	} else if (d->f == blame->f2) {
452 		if (d->atoms.len > 0) {
453 			/* Re-use data from previous commit. */
454 			return DIFF_RC_OK;
455 		}
456 		if (blame->map2)
457 			return atomize_file_mmap(d, blame->map2,
458 			    blame->size2, blame->nlines2,
459 			    blame->line_offsets2);
460 		else
461 			return atomize_file(d, blame->f2, blame->size2,
462 			    blame->nlines2, blame->line_offsets2);
463 	}
464 
465 	return DIFF_RC_OK;
466 }
467 
468 static const struct got_error *
469 close_file2_and_reuse_file1(struct got_blame *blame)
470 {
471 	struct diff_data *d;
472 
473 	free(blame->line_offsets2);
474 	blame->line_offsets2 = blame->line_offsets1;
475 	blame->line_offsets1 = NULL;
476 
477 	free(blame->linemap2);
478 	blame->linemap2 = blame->linemap1;
479 	blame->linemap1 = NULL;
480 
481 	if (blame->map2) {
482 		if (munmap(blame->map2, blame->size2) == -1)
483 			return got_error_from_errno("munmap");
484 		blame->map2 = blame->map1;
485 		blame->map1 = NULL;
486 
487 	}
488 	blame->size2 = blame->size1;
489 	blame->size1 = 0;
490 
491 	if (fclose(blame->f2) == EOF)
492 		return got_error_from_errno("fclose");
493 	blame->f2 = blame->f1;
494 	blame->f1 = NULL;
495 
496 	blame->nlines2 = blame->nlines1;
497 	blame->nlines1 = 0;
498 
499 	diff_data_free(blame->data2); /* does not free pointer itself */
500 	memset(blame->data2, 0, sizeof(*blame->data2));
501 	d = blame->data2;
502 	blame->data2 = blame->data1;
503 	blame->data1 = d;
504 
505 	return NULL;
506 }
507 
508 static const struct got_error *
509 blame_open(struct got_blame **blamep, const char *path,
510     struct got_object_id *start_commit_id, struct got_repository *repo,
511     got_blame_cb cb, void *arg, got_cancel_cb cancel_cb, void *cancel_arg,
512     int fd)
513 {
514 	const struct got_error *err = NULL;
515 	struct got_commit_object *start_commit = NULL, *last_commit = NULL;
516 	struct got_object_id *obj_id = NULL;
517 	struct got_blob_object *blob = NULL;
518 	struct got_blame *blame = NULL;
519 	struct got_object_id *id = NULL;
520 	int lineno;
521 	struct got_commit_graph *graph = NULL;
522 
523 	*blamep = NULL;
524 
525 	err = got_object_open_as_commit(&start_commit, repo, start_commit_id);
526 	if (err)
527 		goto done;
528 
529 	err = got_object_id_by_path(&obj_id, repo, start_commit, path);
530 	if (err)
531 		goto done;
532 
533 	err = got_object_open_as_blob(&blob, repo, obj_id, 8192, fd);
534 	if (err)
535 		goto done;
536 
537 	blame = calloc(1, sizeof(*blame));
538 	if (blame == NULL) {
539 		err = got_error_from_errno("calloc");
540 		goto done;
541 	}
542 
543 	blame->data1 = calloc(1, sizeof(*blame->data1));
544 	if (blame->data1 == NULL) {
545 		err = got_error_from_errno("calloc");
546 		goto done;
547 	}
548 	blame->data2 = calloc(1, sizeof(*blame->data2));
549 	if (blame->data2 == NULL) {
550 		err = got_error_from_errno("calloc");
551 		goto done;
552 	}
553 
554 	blame->f2 = got_opentemp();
555 	if (blame->f2 == NULL) {
556 		err = got_error_from_errno("got_opentemp");
557 		goto done;
558 	}
559 	err = got_diff_get_config(&blame->cfg, GOT_DIFF_ALGORITHM_PATIENCE,
560 	    blame_atomize_file, blame);
561 	if (err)
562 		goto done;
563 
564 	err = blame_prepare_file(blame->f2, &blame->map2, &blame->size2,
565 	    &blame->nlines2, &blame->line_offsets2, blame->data2,
566 	    blame->cfg, blob);
567 	blame->nlines = blame->nlines2;
568 	if (err || blame->nlines == 0)
569 		goto done;
570 
571 	got_object_blob_close(blob);
572 	blob = NULL;
573 
574 	/* Don't include \n at EOF in the blame line count. */
575 	if (blame->line_offsets2[blame->nlines - 1] == blame->size2)
576 		blame->nlines--;
577 
578 	blame->lines = calloc(blame->nlines, sizeof(*blame->lines));
579 	if (blame->lines == NULL) {
580 		err = got_error_from_errno("calloc");
581 		goto done;
582 	}
583 
584 	blame->linemap2 = calloc(blame->nlines2, sizeof(*blame->linemap2));
585 	if (blame->linemap2 == NULL) {
586 		err = got_error_from_errno("calloc");
587 		goto done;
588 	}
589 	for (lineno = 0; lineno < blame->nlines2; lineno++)
590 		blame->linemap2[lineno] = lineno;
591 
592 	err = got_commit_graph_open(&graph, path, 1);
593 	if (err)
594 		goto done;
595 
596 	err = got_commit_graph_iter_start(graph, start_commit_id, repo,
597 	    cancel_cb, cancel_arg);
598 	if (err)
599 		goto done;
600 	for (;;) {
601 		struct got_object_id *next_id;
602 		err = got_commit_graph_iter_next(&next_id, graph, repo,
603 		    cancel_cb, cancel_arg);
604 		if (err) {
605 			if (err->code == GOT_ERR_ITER_COMPLETED) {
606 				err = NULL;
607 				break;
608 			}
609 			goto done;
610 		}
611 		if (next_id) {
612 			id = next_id;
613 			err = blame_commit(blame, id, path, repo, cb, arg);
614 			if (err) {
615 				if (err->code == GOT_ERR_ITER_COMPLETED)
616 					err = NULL;
617 				goto done;
618 			}
619 			if (blame->nannotated == blame->nlines)
620 				break;
621 
622 			err = close_file2_and_reuse_file1(blame);
623 			if (err)
624 				goto done;
625 		}
626 	}
627 
628 	if (id && blame->nannotated < blame->nlines) {
629 		/* Annotate remaining non-annotated lines with last commit. */
630 		err = got_object_open_as_commit(&last_commit, repo, id);
631 		if (err)
632 			goto done;
633 		for (lineno = 0; lineno < blame->nlines; lineno++) {
634 			err = annotate_line(blame, lineno, last_commit, id,
635 			    cb, arg);
636 			if (err)
637 				goto done;
638 		}
639 	}
640 
641 done:
642 	if (graph)
643 		got_commit_graph_close(graph);
644 	free(obj_id);
645 	if (blob)
646 		got_object_blob_close(blob);
647 	if (start_commit)
648 		got_object_commit_close(start_commit);
649 	if (last_commit)
650 		got_object_commit_close(last_commit);
651 	if (err) {
652 		if (blame)
653 			blame_close(blame);
654 	} else
655 		*blamep = blame;
656 
657 	return err;
658 }
659 
660 const struct got_error *
661 got_blame(const char *path, struct got_object_id *commit_id,
662     struct got_repository *repo, got_blame_cb cb, void *arg,
663     got_cancel_cb cancel_cb, void* cancel_arg, int fd)
664 {
665 	const struct got_error *err = NULL, *close_err = NULL;
666 	struct got_blame *blame;
667 	char *abspath;
668 
669 	if (asprintf(&abspath, "%s%s", path[0] == '/' ? "" : "/", path) == -1)
670 		return got_error_from_errno2("asprintf", path);
671 
672 	err = blame_open(&blame, abspath, commit_id, repo, cb, arg,
673 	    cancel_cb, cancel_arg, fd);
674 	free(abspath);
675 	if (blame)
676 		close_err = blame_close(blame);
677 	return err ? err : close_err;
678 }