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, struct got_object_id *id,
93     const struct got_error *(*cb)(void *, int, int, struct got_object_id *),
94     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, 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_object_id *commit_id,
117     const struct got_error *(*cb)(void *, int, int, struct got_object_id *),
118     void *arg)
119 {
120 	const struct got_error *err = NULL;
121 	int i;
122 	int idx1 = 0, idx2 = 0;
123 
124 	for (i = 0; i < diff_result->chunks.len &&
125 	    blame->nannotated < blame->nlines; i++) {
126 		struct diff_chunk *c = diff_chunk_get(diff_result, i);
127 		unsigned int left_count, right_count;
128 		int j;
129 
130 		/*
131 		 * We do not need to worry about idx1/idx2 growing out
132 		 * of bounds because the diff implementation ensures
133 		 * that chunk ranges never exceed the number of lines
134 		 * in the left/right input files.
135 		 */
136 		left_count = diff_chunk_get_left_count(c);
137 		right_count = diff_chunk_get_right_count(c);
138 
139 		if (left_count == right_count) {
140 			for (j = 0; j < left_count; j++) {
141 				blame->linemap1[idx1++] =
142 				    blame->linemap2[idx2++];
143 			}
144 			continue;
145 		}
146 
147 		if (right_count == 0) {
148 			for (j = 0; j < left_count; j++) {
149 				blame->linemap1[idx1++] = -1;
150 			}
151 			continue;
152 		}
153 
154 		for (j = 0; j < right_count; j++) {
155 			int ln = blame->linemap2[idx2++];
156 			err = annotate_line(blame, ln, commit_id, 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     const struct got_error *(*cb)(void *, int, int, struct got_object_id *),
200     void *arg)
201 {
202 	const struct got_error *err = NULL;
203 	struct got_commit_object *commit = NULL, *pcommit = NULL;
204 	struct got_object_qid *pid = NULL;
205 	struct got_object_id *pblob_id = NULL;
206 	struct got_blob_object *pblob = NULL;
207 	struct diff_result *diff_result = NULL;
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 	err = got_object_open_as_commit(&pcommit, repo, pid->id);
220 	if (err)
221 		goto done;
222 
223 	err = got_object_id_by_path(&pblob_id, repo, pcommit, path);
224 	if (err) {
225 		if (err->code == GOT_ERR_NO_TREE_ENTRY)
226 			err = NULL;
227 		goto done;
228 	}
229 
230 	err = got_object_open_as_blob(&pblob, repo, pblob_id, 8192);
231 	if (err)
232 		goto done;
233 
234 	blame->f1 = got_opentemp();
235 	if (blame->f1 == NULL) {
236 		err = got_error_from_errno("got_opentemp");
237 		goto done;
238 	}
239 
240 	err = blame_prepare_file(blame->f1, &blame->map1, &blame->size1,
241 	    &blame->nlines1, &blame->line_offsets1, blame->data1,
242 	    blame->cfg, pblob);
243 	if (err)
244 		goto done;
245 
246 	diff_result = diff_main(blame->cfg, blame->data1, blame->data2);
247 	if (diff_result == NULL) {
248 		err = got_error_set_errno(ENOMEM, "malloc");
249 		goto done;
250 	}
251 	if (diff_result->rc != DIFF_RC_OK) {
252 		err = got_error_set_errno(diff_result->rc, "diff");
253 		goto done;
254 	}
255 	if (diff_result->chunks.len > 0) {
256 		if (blame->nlines1 > 0) {
257 			blame->linemap1 = calloc(blame->nlines1,
258 			    sizeof(*blame->linemap1));
259 			if (blame->linemap1 == NULL) {
260 				err = got_error_from_errno("malloc");
261 				goto done;
262 			}
263 		}
264 		err = blame_changes(blame, diff_result, id, cb, arg);
265 		if (err)
266 			goto done;
267 	} else if (cb)
268 		err = cb(arg, blame->nlines, -1, id);
269 done:
270 	if (diff_result)
271 		diff_result_free(diff_result);
272 	if (commit)
273 		got_object_commit_close(commit);
274 	if (pcommit)
275 		got_object_commit_close(pcommit);
276 	free(pblob_id);
277 	if (pblob)
278 		got_object_blob_close(pblob);
279 	return err;
280 }
281 
282 static const struct got_error *
283 blame_close(struct got_blame *blame)
284 {
285 	const struct got_error *err = NULL;
286 
287 	diff_data_free(blame->data1);
288 	free(blame->data1);
289 	diff_data_free(blame->data2);
290 	free(blame->data2);
291 	if (blame->map1) {
292 		if (munmap(blame->map1, blame->size1) == -1 && err == NULL)
293 			err = got_error_from_errno("munmap");
294 	}
295 	if (blame->map2) {
296 		if (munmap(blame->map2, blame->size2) == -1 && err == NULL)
297 			err = got_error_from_errno("munmap");
298 	}
299 	if (blame->f1 && fclose(blame->f1) == EOF && err == NULL)
300 		err = got_error_from_errno("fclose");
301 	if (blame->f2 && fclose(blame->f2) == EOF && err == NULL)
302 		err = got_error_from_errno("fclose");
303 	free(blame->lines);
304 	free(blame->line_offsets1);
305 	free(blame->line_offsets2);
306 	free(blame->linemap1);
307 	free(blame->linemap2);
308 	free(blame->cfg);
309 	free(blame);
310 	return err;
311 }
312 
313 static int
314 atomize_file(struct diff_data *d, FILE *f, off_t filesize, int nlines,
315     off_t *line_offsets)
316 {
317 	int i, rc = DIFF_RC_OK;
318 	int embedded_nul = 0;
319 
320 	ARRAYLIST_INIT(d->atoms, nlines);
321 
322 	for (i = 0; i < nlines; i++) {
323 		struct diff_atom *atom;
324 		off_t len, pos = line_offsets[i];
325 		unsigned int hash = 0;
326 		int j;
327 
328 		ARRAYLIST_ADD(atom, d->atoms);
329 		if (atom == NULL) {
330 			rc = errno;
331 			break;
332 		}
333 
334 		if (i < nlines - 1)
335 			len = line_offsets[i + 1] - pos;
336 		else
337 			len = filesize - pos;
338 
339 		if (fseeko(f, pos, SEEK_SET) == -1) {
340 			rc = errno;
341 			break;
342 		}
343 		for (j = 0; j < len; j++) {
344 			int c = fgetc(f);
345 			if (c == EOF) {
346 				if (feof(f))
347 					rc = EIO; /* unexpected EOF */
348 				else
349 					rc = errno;
350 				goto done;
351 			}
352 
353 			hash = diff_atom_hash_update(hash, (unsigned char)c);
354 
355 			if (c == '\0')
356 				embedded_nul = 1;
357 
358 		}
359 		*atom = (struct diff_atom){
360 			.root = d,
361 			.pos = pos,
362 			.at = NULL,	/* atom data is not memory-mapped */
363 			.len = len,
364 			.hash = hash,
365 		};
366 	}
367 
368 	/* File are considered binary if they contain embedded '\0' bytes. */
369 	if (embedded_nul)
370 		d->atomizer_flags |= DIFF_ATOMIZER_FOUND_BINARY_DATA;
371 done:
372 	if (rc)
373 		ARRAYLIST_FREE(d->atoms);
374 
375 	return rc;
376 }
377 
378 static int
379 atomize_file_mmap(struct diff_data *d, unsigned char *p,
380     off_t filesize, int nlines, off_t *line_offsets)
381 {
382 	int i, rc = DIFF_RC_OK;
383 	int embedded_nul = 0;
384 
385 	ARRAYLIST_INIT(d->atoms, nlines);
386 
387 	for (i = 0; i < nlines; i++) {
388 		struct diff_atom *atom;
389 		off_t len, pos = line_offsets[i];
390 		unsigned int hash = 0;
391 		int j;
392 
393 		ARRAYLIST_ADD(atom, d->atoms);
394 		if (atom == NULL) {
395 			rc = errno;
396 			break;
397 		}
398 
399 		if (i < nlines - 1)
400 			len = line_offsets[i + 1] - pos;
401 		else
402 			len = filesize - pos;
403 
404 		for (j = 0; j < len; j++)
405 			hash = diff_atom_hash_update(hash, p[pos + j]);
406 
407 		if (!embedded_nul && memchr(&p[pos], '\0', len) != NULL)
408 			embedded_nul = 1;
409 
410 		*atom = (struct diff_atom){
411 			.root = d,
412 			.pos = pos,
413 			.at = &p[pos],
414 			.len = len,
415 			.hash = hash,
416 		};
417 	}
418 
419 	/* File are considered binary if they contain embedded '\0' bytes. */
420 	if (embedded_nul)
421 		d->atomizer_flags |= DIFF_ATOMIZER_FOUND_BINARY_DATA;
422 
423 	if (rc)
424 		ARRAYLIST_FREE(d->atoms);
425 
426 	return rc;
427 }
428 
429 /* Implements diff_atomize_func_t */
430 static int
431 blame_atomize_file(void *arg, struct diff_data *d)
432 {
433 	struct got_blame *blame = arg;
434 
435 	if (d->f == blame->f1) {
436 		if (blame->map1)
437 			return atomize_file_mmap(d, blame->map1,
438 			    blame->size1, blame->nlines1,
439 			    blame->line_offsets1);
440 		else
441 			return atomize_file(d, blame->f1, blame->size1,
442 			    blame->nlines1, blame->line_offsets1);
443 	} else if (d->f == blame->f2) {
444 		if (d->atoms.len > 0) {
445 			/* Re-use data from previous commit. */
446 			return DIFF_RC_OK;
447 		}
448 		if (blame->map2)
449 			return atomize_file_mmap(d, blame->map2,
450 			    blame->size2, blame->nlines2,
451 			    blame->line_offsets2);
452 		else
453 			return atomize_file(d, blame->f2, blame->size2,
454 			    blame->nlines2, blame->line_offsets2);
455 	}
456 
457 	return DIFF_RC_OK;
458 }
459 
460 static const struct got_error *
461 close_file2_and_reuse_file1(struct got_blame *blame)
462 {
463 	struct diff_data *d;
464 
465 	free(blame->line_offsets2);
466 	blame->line_offsets2 = blame->line_offsets1;
467 	blame->line_offsets1 = NULL;
468 
469 	free(blame->linemap2);
470 	blame->linemap2 = blame->linemap1;
471 	blame->linemap1 = NULL;
472 
473 	if (blame->map2) {
474 		if (munmap(blame->map2, blame->size2) == -1)
475 			return got_error_from_errno("munmap");
476 		blame->map2 = blame->map1;
477 		blame->map1 = NULL;
478 
479 	}
480 	blame->size2 = blame->size1;
481 	blame->size1 = 0;
482 
483 	if (fclose(blame->f2) == EOF)
484 		return got_error_from_errno("fclose");
485 	blame->f2 = blame->f1;
486 	blame->f1 = NULL;
487 
488 	blame->nlines2 = blame->nlines1;
489 	blame->nlines1 = 0;
490 
491 	diff_data_free(blame->data2); /* does not free pointer itself */
492 	memset(blame->data2, 0, sizeof(*blame->data2));
493 	d = blame->data2;
494 	blame->data2 = blame->data1;
495 	blame->data1 = d;
496 
497 	return NULL;
498 }
499 
500 static const struct got_error *
501 blame_open(struct got_blame **blamep, const char *path,
502     struct got_object_id *start_commit_id, struct got_repository *repo,
503     const struct got_error *(*cb)(void *, int, int, struct got_object_id *),
504     void *arg, got_cancel_cb cancel_cb, void *cancel_arg)
505 {
506 	const struct got_error *err = NULL;
507 	struct got_commit_object *start_commit = NULL;
508 	struct got_object_id *obj_id = NULL;
509 	struct got_blob_object *blob = NULL;
510 	struct got_blame *blame = NULL;
511 	struct got_object_id *id = NULL;
512 	int lineno;
513 	struct got_commit_graph *graph = NULL;
514 
515 	*blamep = NULL;
516 
517 	err = got_object_open_as_commit(&start_commit, repo, start_commit_id);
518 	if (err)
519 		goto done;
520 
521 	err = got_object_id_by_path(&obj_id, repo, start_commit, path);
522 	if (err)
523 		goto done;
524 
525 	err = got_object_open_as_blob(&blob, repo, obj_id, 8192);
526 	if (err)
527 		goto done;
528 
529 	blame = calloc(1, sizeof(*blame));
530 	if (blame == NULL) {
531 		err = got_error_from_errno("calloc");
532 		goto done;
533 	}
534 
535 	blame->data1 = calloc(1, sizeof(*blame->data1));
536 	if (blame->data1 == NULL) {
537 		err = got_error_from_errno("calloc");
538 		goto done;
539 	}
540 	blame->data2 = calloc(1, sizeof(*blame->data2));
541 	if (blame->data2 == NULL) {
542 		err = got_error_from_errno("calloc");
543 		goto done;
544 	}
545 
546 	blame->f2 = got_opentemp();
547 	if (blame->f2 == NULL) {
548 		err = got_error_from_errno("got_opentemp");
549 		goto done;
550 	}
551 	err = got_diff_get_config(&blame->cfg, GOT_DIFF_ALGORITHM_PATIENCE,
552 	    blame_atomize_file, blame);
553 	if (err)
554 		goto done;
555 
556 	err = blame_prepare_file(blame->f2, &blame->map2, &blame->size2,
557 	    &blame->nlines2, &blame->line_offsets2, blame->data2,
558 	    blame->cfg, blob);
559 	blame->nlines = blame->nlines2;
560 	if (err || blame->nlines == 0)
561 		goto done;
562 
563 	got_object_blob_close(blob);
564 	blob = NULL;
565 
566 	/* Don't include \n at EOF in the blame line count. */
567 	if (blame->line_offsets2[blame->nlines - 1] == blame->size2)
568 		blame->nlines--;
569 
570 	blame->lines = calloc(blame->nlines, sizeof(*blame->lines));
571 	if (blame->lines == NULL) {
572 		err = got_error_from_errno("calloc");
573 		goto done;
574 	}
575 
576 	blame->linemap2 = calloc(blame->nlines2, sizeof(*blame->linemap2));
577 	if (blame->linemap2 == NULL) {
578 		err = got_error_from_errno("calloc");
579 		goto done;
580 	}
581 	for (lineno = 0; lineno < blame->nlines2; lineno++)
582 		blame->linemap2[lineno] = lineno;
583 
584 	err = got_commit_graph_open(&graph, path, 1);
585 	if (err)
586 		goto done;
587 
588 	err = got_commit_graph_iter_start(graph, start_commit_id, repo,
589 	    cancel_cb, cancel_arg);
590 	if (err)
591 		goto done;
592 	for (;;) {
593 		struct got_object_id *next_id;
594 		err = got_commit_graph_iter_next(&next_id, graph, repo,
595 		    cancel_cb, cancel_arg);
596 		if (err) {
597 			if (err->code == GOT_ERR_ITER_COMPLETED) {
598 				err = NULL;
599 				break;
600 			}
601 			goto done;
602 		}
603 		if (next_id) {
604 			id = next_id;
605 			err = blame_commit(blame, id, path, repo, cb, arg);
606 			if (err) {
607 				if (err->code == GOT_ERR_ITER_COMPLETED)
608 					err = NULL;
609 				goto done;
610 			}
611 			if (blame->nannotated == blame->nlines)
612 				break;
613 
614 			err = close_file2_and_reuse_file1(blame);
615 			if (err)
616 				goto done;
617 		}
618 	}
619 
620 	if (id && blame->nannotated < blame->nlines) {
621 		/* Annotate remaining non-annotated lines with last commit. */
622 		for (lineno = 0; lineno < blame->nlines; lineno++) {
623 			err = annotate_line(blame, lineno, id, cb, arg);
624 			if (err)
625 				goto done;
626 		}
627 	}
628 
629 done:
630 	if (graph)
631 		got_commit_graph_close(graph);
632 	free(obj_id);
633 	if (blob)
634 		got_object_blob_close(blob);
635 	if (start_commit)
636 		got_object_commit_close(start_commit);
637 	if (err) {
638 		if (blame)
639 			blame_close(blame);
640 	} else
641 		*blamep = blame;
642 
643 	return err;
644 }
645 
646 const struct got_error *
647 got_blame(const char *path, struct got_object_id *commit_id,
648     struct got_repository *repo,
649     const struct got_error *(*cb)(void *, int, int, struct got_object_id *),
650     void *arg, got_cancel_cb cancel_cb, void* cancel_arg)
651 {
652 	const struct got_error *err = NULL, *close_err = NULL;
653 	struct got_blame *blame;
654 	char *abspath;
655 
656 	if (asprintf(&abspath, "%s%s", path[0] == '/' ? "" : "/", path) == -1)
657 		return got_error_from_errno2("asprintf", path);
658 
659 	err = blame_open(&blame, abspath, commit_id, repo, cb, arg,
660 	    cancel_cb, cancel_arg);
661 	free(abspath);
662 	if (blame)
663 		close_err = blame_close(blame);
664 	return err ? err : close_err;
665 }