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_start, left_count;
128 		unsigned int right_start, right_count;
129 		int j;
130 
131 		/*
132 		 * We do not need to worry about idx1/idx2 growing out
133 		 * of bounds because the diff implementation ensures
134 		 * that chunk ranges never exceed the number of lines
135 		 * in the left/right input files.
136 		 */
137 		left_start = diff_chunk_get_left_start(c, diff_result, 0);
138 		left_count = diff_chunk_get_left_count(c);
139 		right_start = diff_chunk_get_right_start(c, diff_result, 0);
140 		right_count = diff_chunk_get_right_count(c);
141 
142 		if (left_count == right_count) {
143 			for (j = 0; j < left_count; j++) {
144 				blame->linemap1[idx1++] =
145 				    blame->linemap2[idx2++];
146 			}
147 			continue;
148 		}
149 
150 		if (right_count == 0) {
151 			for (j = 0; j < left_count; j++) {
152 				blame->linemap1[idx1++] = -1;
153 			}
154 			continue;
155 		}
156 
157 		for (j = 0; j < right_count; j++) {
158 			int ln = blame->linemap2[idx2++];
159 			err = annotate_line(blame, ln, commit_id, cb, arg);
160 			if (err)
161 				return err;
162 			if (blame->nlines == blame->nannotated)
163 				break;
164 		}
165 	}
166 
167 	return NULL;
168 }
169 
170 static const struct got_error *
171 blame_prepare_file(FILE *f, unsigned char **p, off_t *size,
172     int *nlines, off_t **line_offsets, struct diff_data *diff_data,
173     const struct diff_config *cfg, struct got_blob_object *blob)
174 {
175 	const struct got_error *err = NULL;
176 	int diff_flags = 0, rc;
177 
178 	err = got_object_blob_dump_to_file(size, nlines, line_offsets,
179 	    f, blob);
180 	if (err)
181 		return err;
182 
183 #ifndef GOT_DIFF_NO_MMAP
184 	*p = mmap(NULL, *size, PROT_READ, MAP_PRIVATE, fileno(f), 0);
185 	if (*p == MAP_FAILED)
186 #endif
187 		*p = NULL; /* fall back on file I/O */
188 
189 	/* Allow blaming lines in binary files even though it's useless. */
190 	diff_flags |= DIFF_FLAG_FORCE_TEXT_DATA;
191 
192 	rc = diff_atomize_file(diff_data, cfg, f, *p, *size, diff_flags);
193 	if (rc)
194 		return got_error_set_errno(rc, "diff_atomize_file");
195 
196 	return NULL;
197 }
198 
199 static const struct got_error *
200 blame_commit(struct got_blame *blame, struct got_object_id *id,
201     const char *path, struct got_repository *repo,
202     const struct got_error *(*cb)(void *, int, int, struct got_object_id *),
203     void *arg)
204 {
205 	const struct got_error *err = NULL;
206 	struct got_commit_object *commit = NULL;
207 	struct got_object_qid *pid = NULL;
208 	struct got_object_id *pblob_id = NULL;
209 	struct got_blob_object *pblob = NULL;
210 	struct diff_result *diff_result = NULL;
211 
212 	err = got_object_open_as_commit(&commit, repo, id);
213 	if (err)
214 		return err;
215 
216 	pid = STAILQ_FIRST(got_object_commit_get_parent_ids(commit));
217 	if (pid == NULL) {
218 		got_object_commit_close(commit);
219 		return NULL;
220 	}
221 
222 	err = got_object_id_by_path(&pblob_id, repo, pid->id, path);
223 	if (err) {
224 		if (err->code == GOT_ERR_NO_TREE_ENTRY)
225 			err = NULL;
226 		goto done;
227 	}
228 
229 	err = got_object_open_as_blob(&pblob, repo, pblob_id, 8192);
230 	if (err)
231 		goto done;
232 
233 	blame->f1 = got_opentemp();
234 	if (blame->f1 == NULL) {
235 		err = got_error_from_errno("got_opentemp");
236 		goto done;
237 	}
238 
239 	err = blame_prepare_file(blame->f1, &blame->map1, &blame->size1,
240 	    &blame->nlines1, &blame->line_offsets1, blame->data1,
241 	    blame->cfg, pblob);
242 	if (err)
243 		goto done;
244 
245 	diff_result = diff_main(blame->cfg, blame->data1, blame->data2);
246 	if (diff_result == NULL) {
247 		err = got_error_set_errno(ENOMEM, "malloc");
248 		goto done;
249 	}
250 	if (diff_result->rc != DIFF_RC_OK) {
251 		err = got_error_set_errno(diff_result->rc, "diff");
252 		goto done;
253 	}
254 	if (diff_result->chunks.len > 0) {
255 		if (blame->nlines1 > 0) {
256 			blame->linemap1 = calloc(blame->nlines1,
257 			    sizeof(*blame->linemap1));
258 			if (blame->linemap1 == NULL) {
259 				err = got_error_from_errno("malloc");
260 				goto done;
261 			}
262 		}
263 		err = blame_changes(blame, diff_result, id, cb, arg);
264 		if (err)
265 			goto done;
266 	} else if (cb)
267 		err = cb(arg, blame->nlines, -1, id);
268 done:
269 	if (diff_result)
270 		diff_result_free(diff_result);
271 	if (commit)
272 		got_object_commit_close(commit);
273 	free(pblob_id);
274 	if (pblob)
275 		got_object_blob_close(pblob);
276 	return err;
277 }
278 
279 static const struct got_error *
280 blame_close(struct got_blame *blame)
281 {
282 	const struct got_error *err = NULL;
283 
284 	diff_data_free(blame->data1);
285 	free(blame->data1);
286 	diff_data_free(blame->data2);
287 	free(blame->data2);
288 	if (blame->map1) {
289 		if (munmap(blame->map1, blame->size1) == -1 && err == NULL)
290 			err = got_error_from_errno("munmap");
291 	}
292 	if (blame->map2) {
293 		if (munmap(blame->map2, blame->size2) == -1 && err == NULL)
294 			err = got_error_from_errno("munmap");
295 	}
296 	if (blame->f1 && fclose(blame->f1) == EOF && err == NULL)
297 		err = got_error_from_errno("fclose");
298 	if (blame->f2 && fclose(blame->f2) == EOF && err == NULL)
299 		err = got_error_from_errno("fclose");
300 	free(blame->lines);
301 	free(blame->line_offsets1);
302 	free(blame->line_offsets2);
303 	free(blame->linemap1);
304 	free(blame->linemap2);
305 	free(blame->cfg);
306 	free(blame);
307 	return err;
308 }
309 
310 static int
311 atomize_file(struct diff_data *d, FILE *f, off_t filesize, int nlines,
312     off_t *line_offsets)
313 {
314 	int i, rc = DIFF_RC_OK;
315 	int embedded_nul = 0;
316 
317 	ARRAYLIST_INIT(d->atoms, nlines);
318 
319 	for (i = 0; i < nlines; i++) {
320 		struct diff_atom *atom;
321 		off_t len, pos = line_offsets[i];
322 		unsigned int hash = 0;
323 		int j;
324 
325 		ARRAYLIST_ADD(atom, d->atoms);
326 		if (atom == NULL) {
327 			rc = errno;
328 			break;
329 		}
330 
331 		if (i < nlines - 1)
332 			len = line_offsets[i + 1] - pos;
333 		else
334 			len = filesize - pos;
335 
336 		if (fseeko(f, pos, SEEK_SET) == -1) {
337 			rc = errno;
338 			break;
339 		}
340 		for (j = 0; j < len; j++) {
341 			int c = fgetc(f);
342 			if (c == EOF) {
343 				if (feof(f))
344 					rc = EIO; /* unexpected EOF */
345 				else
346 					rc = errno;
347 				goto done;
348 			}
349 
350 			hash = diff_atom_hash_update(hash, (unsigned char)c);
351 
352 			if (c == '\0')
353 				embedded_nul = 1;
354 
355 		}
356 		*atom = (struct diff_atom){
357 			.root = d,
358 			.pos = pos,
359 			.at = NULL,	/* atom data is not memory-mapped */
360 			.len = len,
361 			.hash = hash,
362 		};
363 	}
364 
365 	/* File are considered binary if they contain embedded '\0' bytes. */
366 	if (embedded_nul)
367 		d->atomizer_flags |= DIFF_ATOMIZER_FOUND_BINARY_DATA;
368 done:
369 	if (rc)
370 		ARRAYLIST_FREE(d->atoms);
371 
372 	return rc;
373 }
374 
375 static int
376 atomize_file_mmap(struct diff_data *d, unsigned char *p,
377     off_t filesize, int nlines, off_t *line_offsets)
378 {
379 	int i, rc = DIFF_RC_OK;
380 	int embedded_nul = 0;
381 
382 	ARRAYLIST_INIT(d->atoms, nlines);
383 
384 	for (i = 0; i < nlines; i++) {
385 		struct diff_atom *atom;
386 		off_t len, pos = line_offsets[i];
387 		unsigned int hash = 0;
388 		int j;
389 
390 		ARRAYLIST_ADD(atom, d->atoms);
391 		if (atom == NULL) {
392 			rc = errno;
393 			break;
394 		}
395 
396 		if (i < nlines - 1)
397 			len = line_offsets[i + 1] - pos;
398 		else
399 			len = filesize - pos;
400 
401 		for (j = 0; j < len; j++)
402 			hash = diff_atom_hash_update(hash, p[pos + j]);
403 
404 		if (!embedded_nul && memchr(&p[pos], '\0', len) != NULL)
405 			embedded_nul = 1;
406 
407 		*atom = (struct diff_atom){
408 			.root = d,
409 			.pos = pos,
410 			.at = &p[pos],
411 			.len = len,
412 			.hash = hash,
413 		};
414 	}
415 
416 	/* File are considered binary if they contain embedded '\0' bytes. */
417 	if (embedded_nul)
418 		d->atomizer_flags |= DIFF_ATOMIZER_FOUND_BINARY_DATA;
419 
420 	if (rc)
421 		ARRAYLIST_FREE(d->atoms);
422 
423 	return rc;
424 }
425 
426 /* Implements diff_atomize_func_t */
427 static int
428 blame_atomize_file(void *arg, struct diff_data *d)
429 {
430 	struct got_blame *blame = arg;
431 
432 	if (d->f == blame->f1) {
433 		if (blame->map1)
434 			return atomize_file_mmap(d, blame->map1,
435 			    blame->size1, blame->nlines1,
436 			    blame->line_offsets1);
437 		else
438 			return atomize_file(d, blame->f1, blame->size1,
439 			    blame->nlines1, blame->line_offsets1);
440 	} else if (d->f == blame->f2) {
441 		if (d->atoms.len > 0) {
442 			/* Re-use data from previous commit. */
443 			return DIFF_RC_OK;
444 		}
445 		if (blame->map2)
446 			return atomize_file_mmap(d, blame->map2,
447 			    blame->size2, blame->nlines2,
448 			    blame->line_offsets2);
449 		else
450 			return atomize_file(d, blame->f2, blame->size2,
451 			    blame->nlines2, blame->line_offsets2);
452 	}
453 
454 	return DIFF_RC_OK;
455 }
456 
457 static const struct got_error *
458 close_file2_and_reuse_file1(struct got_blame *blame)
459 {
460 	struct diff_data *d;
461 
462 	free(blame->line_offsets2);
463 	blame->line_offsets2 = blame->line_offsets1;
464 	blame->line_offsets1 = NULL;
465 
466 	free(blame->linemap2);
467 	blame->linemap2 = blame->linemap1;
468 	blame->linemap1 = NULL;
469 
470 	if (blame->map2) {
471 		if (munmap(blame->map2, blame->size2) == -1)
472 			return got_error_from_errno("munmap");
473 		blame->map2 = blame->map1;
474 		blame->map1 = NULL;
475 
476 	}
477 	blame->size2 = blame->size1;
478 	blame->size1 = 0;
479 
480 	if (fclose(blame->f2) == EOF)
481 		return got_error_from_errno("fclose");
482 	blame->f2 = blame->f1;
483 	blame->f1 = NULL;
484 
485 	blame->nlines2 = blame->nlines1;
486 	blame->nlines1 = 0;
487 
488 	diff_data_free(blame->data2); /* does not free pointer itself */
489 	memset(blame->data2, 0, sizeof(*blame->data2));
490 	d = blame->data2;
491 	blame->data2 = blame->data1;
492 	blame->data1 = d;
493 
494 	return NULL;
495 }
496 
497 static const struct got_error *
498 blame_open(struct got_blame **blamep, const char *path,
499     struct got_object_id *start_commit_id, struct got_repository *repo,
500     const struct got_error *(*cb)(void *, int, int, struct got_object_id *),
501     void *arg, got_cancel_cb cancel_cb, void *cancel_arg)
502 {
503 	const struct got_error *err = NULL;
504 	struct got_object_id *obj_id = NULL;
505 	struct got_blob_object *blob = NULL;
506 	struct got_blame *blame = NULL;
507 	struct got_object_id *id = NULL;
508 	int lineno;
509 	struct got_commit_graph *graph = NULL;
510 
511 	*blamep = NULL;
512 
513 	err = got_object_id_by_path(&obj_id, repo, start_commit_id, path);
514 	if (err)
515 		goto done;
516 
517 	err = got_object_open_as_blob(&blob, repo, obj_id, 8192);
518 	if (err)
519 		goto done;
520 
521 	blame = calloc(1, sizeof(*blame));
522 	if (blame == NULL) {
523 		err = got_error_from_errno("calloc");
524 		goto done;
525 	}
526 
527 	blame->data1 = calloc(1, sizeof(*blame->data1));
528 	if (blame->data1 == NULL) {
529 		err = got_error_from_errno("calloc");
530 		goto done;
531 	}
532 	blame->data2 = calloc(1, sizeof(*blame->data2));
533 	if (blame->data2 == NULL) {
534 		err = got_error_from_errno("calloc");
535 		goto done;
536 	}
537 
538 	blame->f2 = got_opentemp();
539 	if (blame->f2 == NULL) {
540 		err = got_error_from_errno("got_opentemp");
541 		goto done;
542 	}
543 	err = got_diff_get_config(&blame->cfg, GOT_DIFF_ALGORITHM_PATIENCE,
544 	    blame_atomize_file, blame);
545 	if (err)
546 		goto done;
547 
548 	err = blame_prepare_file(blame->f2, &blame->map2, &blame->size2,
549 	    &blame->nlines2, &blame->line_offsets2, blame->data2,
550 	    blame->cfg, blob);
551 	blame->nlines = blame->nlines2;
552 	if (err || blame->nlines == 0)
553 		goto done;
554 
555 	got_object_blob_close(blob);
556 	blob = NULL;
557 
558 	/* Don't include \n at EOF in the blame line count. */
559 	if (blame->line_offsets2[blame->nlines - 1] == blame->size2)
560 		blame->nlines--;
561 
562 	blame->lines = calloc(blame->nlines, sizeof(*blame->lines));
563 	if (blame->lines == NULL) {
564 		err = got_error_from_errno("calloc");
565 		goto done;
566 	}
567 
568 	blame->linemap2 = calloc(blame->nlines2, sizeof(*blame->linemap2));
569 	if (blame->linemap2 == NULL) {
570 		err = got_error_from_errno("calloc");
571 		goto done;
572 	}
573 	for (lineno = 0; lineno < blame->nlines2; lineno++)
574 		blame->linemap2[lineno] = lineno;
575 
576 	err = got_commit_graph_open(&graph, path, 1);
577 	if (err)
578 		goto done;
579 
580 	err = got_commit_graph_iter_start(graph, start_commit_id, repo,
581 	    cancel_cb, cancel_arg);
582 	if (err)
583 		goto done;
584 	for (;;) {
585 		struct got_object_id *next_id;
586 		err = got_commit_graph_iter_next(&next_id, graph, repo,
587 		    cancel_cb, cancel_arg);
588 		if (err) {
589 			if (err->code == GOT_ERR_ITER_COMPLETED) {
590 				err = NULL;
591 				break;
592 			}
593 			goto done;
594 		}
595 		if (next_id) {
596 			id = next_id;
597 			err = blame_commit(blame, id, path, repo, cb, arg);
598 			if (err) {
599 				if (err->code == GOT_ERR_ITER_COMPLETED)
600 					err = NULL;
601 				goto done;
602 			}
603 			if (blame->nannotated == blame->nlines)
604 				break;
605 
606 			err = close_file2_and_reuse_file1(blame);
607 			if (err)
608 				goto done;
609 		}
610 	}
611 
612 	if (id && blame->nannotated < blame->nlines) {
613 		/* Annotate remaining non-annotated lines with last commit. */
614 		for (lineno = 0; lineno < blame->nlines; lineno++) {
615 			err = annotate_line(blame, lineno, id, cb, arg);
616 			if (err)
617 				goto done;
618 		}
619 	}
620 
621 done:
622 	if (graph)
623 		got_commit_graph_close(graph);
624 	free(obj_id);
625 	if (blob)
626 		got_object_blob_close(blob);
627 	if (err) {
628 		if (blame)
629 			blame_close(blame);
630 	} else
631 		*blamep = blame;
632 
633 	return err;
634 }
635 
636 const struct got_error *
637 got_blame(const char *path, struct got_object_id *commit_id,
638     struct got_repository *repo,
639     const struct got_error *(*cb)(void *, int, int, struct got_object_id *),
640     void *arg, got_cancel_cb cancel_cb, void* cancel_arg)
641 {
642 	const struct got_error *err = NULL, *close_err = NULL;
643 	struct got_blame *blame;
644 	char *abspath;
645 
646 	if (asprintf(&abspath, "%s%s", path[0] == '/' ? "" : "/", path) == -1)
647 		return got_error_from_errno2("asprintf", path);
648 
649 	err = blame_open(&blame, abspath, commit_id, repo, cb, arg,
650 	    cancel_cb, cancel_arg);
651 	free(abspath);
652 	if (blame)
653 		close_err = blame_close(blame);
654 	return err ? err : close_err;
655 }