Project: Git
Code Location: git://github.com/git/git.gitmaster
Browse
/
Outline
Download File
tree-diff.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
/*
 * Helper functions for tree diff generation
 */
#include "cache.h"
#include "diff.h"
#include "diffcore.h"
#include "tree.h"

/*
 * internal mode marker, saying a tree entry != entry of tp[imin]
 * (see ll_diff_tree_paths for what it means there)
 *
 * we will update/use/emit entry for diff only with it unset.
 */
#define S_IFXMIN_NEQ	S_DIFFTREE_IFXMIN_NEQ


static struct combine_diff_path *ll_diff_tree_paths(
	struct combine_diff_path *p, const unsigned char *sha1,
	const unsigned char **parents_sha1, int nparent,
	struct strbuf *base, struct diff_options *opt);
static int ll_diff_tree_sha1(const unsigned char *old, const unsigned char *new,
			     struct strbuf *base, struct diff_options *opt);

/*
 * Compare two tree entries, taking into account only path/S_ISDIR(mode),
 * but not their sha1's.
 *
 * NOTE files and directories *always* compare differently, even when having
 *      the same name - thanks to base_name_compare().
 *
 * NOTE empty (=invalid) descriptor(s) take part in comparison as +infty,
 *      so that they sort *after* valid tree entries.
 *
 *      Due to this convention, if trees are scanned in sorted order, all
 *      non-empty descriptors will be processed first.
 */
static int tree_entry_pathcmp(struct tree_desc *t1, struct tree_desc *t2)
{
	struct name_entry *e1, *e2;
	int cmp;

	/* empty descriptors sort after valid tree entries */
	if (!t1->size)
		return t2->size ? 1 : 0;
	else if (!t2->size)
		return -1;

	e1 = &t1->entry;
	e2 = &t2->entry;
	cmp = base_name_compare(e1->path, tree_entry_len(e1), e1->mode,
				e2->path, tree_entry_len(e2), e2->mode);
	return cmp;
}


/*
 * convert path -> opt->diff_*() callbacks
 *
 * emits diff to first parent only, and tells diff tree-walker that we are done
 * with p and it can be freed.
 */
static int emit_diff_first_parent_only(struct diff_options *opt, struct combine_diff_path *p)
{
	struct combine_diff_parent *p0 = &p->parent[0];
	if (p->mode && p0->mode) {
		opt->change(opt, p0->mode, p->mode, p0->sha1, p->sha1,
			1, 1, p->path, 0, 0);
	}
	else {
		const unsigned char *sha1;
		unsigned int mode;
		int addremove;

		if (p->mode) {
			addremove = '+';
			sha1 = p->sha1;
			mode = p->mode;
		} else {
			addremove = '-';
			sha1 = p0->sha1;
			mode = p0->mode;
		}

		opt->add_remove(opt, addremove, mode, sha1, 1, p->path, 0);
	}

	return 0;	/* we are done with p */
}


/*
 * Make a new combine_diff_path from path/mode/sha1
 * and append it to paths list tail.
 *
 * Memory for created elements could be reused:
 *
 *	- if last->next == NULL, the memory is allocated;
 *
 *	- if last->next != NULL, it is assumed that p=last->next was returned
 *	  earlier by this function, and p->next was *not* modified.
 *	  The memory is then reused from p.
 *
 * so for clients,
 *
 * - if you do need to keep the element
 *
 *	p = path_appendnew(p, ...);
 *	process(p);
 *	p->next = NULL;
 *
 * - if you don't need to keep the element after processing
 *
 *	pprev = p;
 *	p = path_appendnew(p, ...);
 *	process(p);
 *	p = pprev;
 *	; don't forget to free tail->next in the end
 *
 * p->parent[] remains uninitialized.
 */
static struct combine_diff_path *path_appendnew(struct combine_diff_path *last,
	int nparent, const struct strbuf *base, const char *path, int pathlen,
	unsigned mode, const unsigned char *sha1)
{
	struct combine_diff_path *p;
	int len = base->len + pathlen;
	int alloclen = combine_diff_path_size(nparent, len);

	/* if last->next is !NULL - it is a pre-allocated memory, we can reuse */
	p = last->next;
	if (p && (alloclen > (intptr_t)p->next)) {
		free(p);
		p = NULL;
	}

	if (!p) {
		p = xmalloc(alloclen);

		/*
		 * until we go to it next round, .next holds how many bytes we
		 * allocated (for faster realloc - we don't need copying old data).
		 */
		p->next = (struct combine_diff_path *)(intptr_t)alloclen;
	}

	last->next = p;

	p->path = (char *)&(p->parent[nparent]);
	memcpy(p->path, base->buf, base->len);
	memcpy(p->path + base->len, path, pathlen);
	p->path[len] = 0;
	p->mode = mode;
	hashcpy(p->sha1, sha1 ? sha1 : null_sha1);

	return p;
}

/*
 * new path should be added to combine diff
 *
 * 3 cases on how/when it should be called and behaves:
 *
 *	 t, !tp		-> path added, all parents lack it
 *	!t,  tp		-> path removed from all parents
 *	 t,  tp		-> path modified/added
 *			   (M for tp[i]=tp[imin], A otherwise)
 */
static struct combine_diff_path *emit_path(struct combine_diff_path *p,
	struct strbuf *base, struct diff_options *opt, int nparent,
	struct tree_desc *t, struct tree_desc *tp,
	int imin)
{
	unsigned mode;
	const char *path;
	const unsigned char *sha1;
	int pathlen;
	int old_baselen = base->len;
	int i, isdir, recurse = 0, emitthis = 1;

	/* at least something has to be valid */
	assert(t || tp);

	if (t) {
		/* path present in resulting tree */
		sha1 = tree_entry_extract(t, &path, &mode);
		pathlen = tree_entry_len(&t->entry);
		isdir = S_ISDIR(mode);
	} else {
		/*
		 * a path was removed - take path from imin parent. Also take
		 * mode from that parent, to decide on recursion(1).
		 *
		 * 1) all modes for tp[i]=tp[imin] should be the same wrt
		 *    S_ISDIR, thanks to base_name_compare().
		 */
		tree_entry_extract(&tp[imin], &path, &mode);
		pathlen = tree_entry_len(&tp[imin].entry);

		isdir = S_ISDIR(mode);
		sha1 = NULL;
		mode = 0;
	}

	if (DIFF_OPT_TST(opt, RECURSIVE) && isdir) {
		recurse = 1;
		emitthis = DIFF_OPT_TST(opt, TREE_IN_RECURSIVE);
	}

	if (emitthis) {
		int keep;
		struct combine_diff_path *pprev = p;
		p = path_appendnew(p, nparent, base, path, pathlen, mode, sha1);

		for (i = 0; i < nparent; ++i) {
			/*
			 * tp[i] is valid, if present and if tp[i]==tp[imin] -
			 * otherwise, we should ignore it.
			 */
			int tpi_valid = tp && !(tp[i].entry.mode & S_IFXMIN_NEQ);

			const unsigned char *sha1_i;
			unsigned mode_i;

			p->parent[i].status =
				!t ? DIFF_STATUS_DELETED :
					tpi_valid ?
						DIFF_STATUS_MODIFIED :
						DIFF_STATUS_ADDED;

			if (tpi_valid) {
				sha1_i = tp[i].entry.sha1;
				mode_i = tp[i].entry.mode;
			}
			else {
				sha1_i = NULL;
				mode_i = 0;
			}

			p->parent[i].mode = mode_i;
			hashcpy(p->parent[i].sha1, sha1_i ? sha1_i : null_sha1);
		}

		keep = 1;
		if (opt->pathchange)
			keep = opt->pathchange(opt, p);

		/*
		 * If a path was filtered or consumed - we don't need to add it
		 * to the list and can reuse its memory, leaving it as
		 * pre-allocated element on the tail.
		 *
		 * On the other hand, if path needs to be kept, we need to
		 * correct its .next to NULL, as it was pre-initialized to how
		 * much memory was allocated.
		 *
		 * see path_appendnew() for details.
		 */
		if (!keep)
			p = pprev;
		else
			p->next = NULL;
	}

	if (recurse) {
		const unsigned char **parents_sha1;

		parents_sha1 = xalloca(nparent * sizeof(parents_sha1[0]));
		for (i = 0; i < nparent; ++i) {
			/* same rule as in emitthis */
			int tpi_valid = tp && !(tp[i].entry.mode & S_IFXMIN_NEQ);

			parents_sha1[i] = tpi_valid ? tp[i].entry.sha1
						    : NULL;
		}

		strbuf_add(base, path, pathlen);
		strbuf_addch(base, '/');
		p = ll_diff_tree_paths(p, sha1, parents_sha1, nparent, base, opt);
		xalloca_free(parents_sha1);
	}

	strbuf_setlen(base, old_baselen);
	return p;
}

static void skip_uninteresting(struct tree_desc *t, struct strbuf *base,
			       struct diff_options *opt)
{
	enum interesting match;

	while (t->size) {
		match = tree_entry_interesting(&t->entry, base, 0, &opt->pathspec);
		if (match) {
			if (match == all_entries_not_interesting)
				t->size = 0;
			break;
		}
		update_tree_entry(t);
	}
}


/*
 * generate paths for combined diff D(sha1,parents_sha1[])
 *
 * Resulting paths are appended to combine_diff_path linked list, and also, are
 * emitted on the go via opt->pathchange() callback, so it is possible to
 * process the result as batch or incrementally.
 *
 * The paths are generated scanning new tree and all parents trees
 * simultaneously, similarly to what diff_tree() was doing for 2 trees.
 * The theory behind such scan is as follows:
 *
 *
 * D(T,P1...Pn) calculation scheme
 * -------------------------------
 *
 * D(T,P1...Pn) = D(T,P1) ^ ... ^ D(T,Pn)	(regarding resulting paths set)
 *
 *	D(T,Pj)		- diff between T..Pj
 *	D(T,P1...Pn)	- combined diff from T to parents P1,...,Pn
 *
 *
 * We start from all trees, which are sorted, and compare their entries in
 * lock-step:
 *
 *	 T     P1       Pn
 *	 -     -        -
 *	|t|   |p1|     |pn|
 *	|-|   |--| ... |--|      imin = argmin(p1...pn)
 *	| |   |  |     |  |
 *	|-|   |--|     |--|
 *	|.|   |. |     |. |
 *	 .     .        .
 *	 .     .        .
 *
 * at any time there could be 3 cases:
 *
 *	1)  t < p[imin];
 *	2)  t > p[imin];
 *	3)  t = p[imin].
 *
 * Schematic deduction of what every case means, and what to do, follows:
 *
 * 1)  t < p[imin]  ->  ∀j t ∉ Pj  ->  "+t" ∈ D(T,Pj)  ->  D += "+t";  t↓
 *
 * 2)  t > p[imin]
 *
 *     2.1) ∃j: pj > p[imin]  ->  "-p[imin]" ∉ D(T,Pj)  ->  D += ø;  ∀ pi=p[imin]  pi↓
 *     2.2) ∀i  pi = p[imin]  ->  pi ∉ T  ->  "-pi" ∈ D(T,Pi)  ->  D += "-p[imin]";  ∀i pi↓
 *
 * 3)  t = p[imin]
 *
 *     3.1) ∃j: pj > p[imin]  ->  "+t" ∈ D(T,Pj)  ->  only pi=p[imin] remains to investigate
 *     3.2) pi = p[imin]  ->  investigate δ(t,pi)
 *      |
 *      |
 *      v
 *
 *     3.1+3.2) looking at δ(t,pi) ∀i: pi=p[imin] - if all != ø  ->
 *
 *                       ⎧δ(t,pi)  - if pi=p[imin]
 *              ->  D += ⎨
 *                       ⎩"+t"     - if pi>p[imin]
 *
 *
 *     in any case t↓  ∀ pi=p[imin]  pi↓
 *
 *
 * ~~~~~~~~
 *
 * NOTE
 *
 *	Usual diff D(A,B) is by definition the same as combined diff D(A,[B]),
 *	so this diff paths generator can, and is used, for plain diffs
 *	generation too.
 *
 *	Please keep attention to the common D(A,[B]) case when working on the
 *	code, in order not to slow it down.
 *
 * NOTE
 *	nparent must be > 0.
 */


/* ∀ pi=p[imin]  pi↓ */
static inline void update_tp_entries(struct tree_desc *tp, int nparent)
{
	int i;
	for (i = 0; i < nparent; ++i)
		if (!(tp[i].entry.mode & S_IFXMIN_NEQ))
			update_tree_entry(&tp[i]);
}

static struct combine_diff_path *ll_diff_tree_paths(
	struct combine_diff_path *p, const unsigned char *sha1,
	const unsigned char **parents_sha1, int nparent,
	struct strbuf *base, struct diff_options *opt)
{
	struct tree_desc t, *tp;
	void *ttree, **tptree;
	int i;

	tp     = xalloca(nparent * sizeof(tp[0]));
	tptree = xalloca(nparent * sizeof(tptree[0]));

	/*
	 * load parents first, as they are probably already cached.
	 *
	 * ( log_tree_diff() parses commit->parent before calling here via
	 *   diff_tree_sha1(parent, commit) )
	 */
	for (i = 0; i < nparent; ++i)
		tptree[i] = fill_tree_descriptor(&tp[i], parents_sha1[i]);
	ttree = fill_tree_descriptor(&t, sha1);

	/* Enable recursion indefinitely */
	opt->pathspec.recursive = DIFF_OPT_TST(opt, RECURSIVE);

	for (;;) {
		int imin, cmp;

		if (diff_can_quit_early(opt))
			break;

		if (opt->pathspec.nr) {
			skip_uninteresting(&t, base, opt);
			for (i = 0; i < nparent; i++)
				skip_uninteresting(&tp[i], base, opt);
		}

		/* comparing is finished when all trees are done */
		if (!t.size) {
			int done = 1;
			for (i = 0; i < nparent; ++i)
				if (tp[i].size) {
					done = 0;
					break;
				}
			if (done)
				break;
		}

		/*
		 * lookup imin = argmin(p1...pn),
		 * mark entries whether they =p[imin] along the way
		 */
		imin = 0;
		tp[0].entry.mode &= ~S_IFXMIN_NEQ;

		for (i = 1; i < nparent; ++i) {
			cmp = tree_entry_pathcmp(&tp[i], &tp[imin]);
			if (cmp < 0) {
				imin = i;
				tp[i].entry.mode &= ~S_IFXMIN_NEQ;
			}
			else if (cmp == 0) {
				tp[i].entry.mode &= ~S_IFXMIN_NEQ;
			}
			else {
				tp[i].entry.mode |= S_IFXMIN_NEQ;
			}
		}

		/* fixup markings for entries before imin */
		for (i = 0; i < imin; ++i)
			tp[i].entry.mode |= S_IFXMIN_NEQ;	/* pi > p[imin] */



		/* compare t vs p[imin] */
		cmp = tree_entry_pathcmp(&t, &tp[imin]);

		/* t = p[imin] */
		if (cmp == 0) {
			/* are either pi > p[imin] or diff(t,pi) != ø ? */
			if (!DIFF_OPT_TST(opt, FIND_COPIES_HARDER)) {
				for (i = 0; i < nparent; ++i) {
					/* p[i] > p[imin] */
					if (tp[i].entry.mode & S_IFXMIN_NEQ)
						continue;

					/* diff(t,pi) != ø */
					if (hashcmp(t.entry.sha1, tp[i].entry.sha1) ||
					    (t.entry.mode != tp[i].entry.mode))
						continue;

					goto skip_emit_t_tp;
				}
			}

			/* D += {δ(t,pi) if pi=p[imin];  "+a" if pi > p[imin]} */
			p = emit_path(p, base, opt, nparent,
					&t, tp, imin);

		skip_emit_t_tp:
			/* t↓,  ∀ pi=p[imin]  pi↓ */
			update_tree_entry(&t);
			update_tp_entries(tp, nparent);
		}

		/* t < p[imin] */
		else if (cmp < 0) {
			/* D += "+t" */
			p = emit_path(p, base, opt, nparent,
					&t, /*tp=*/NULL, -1);

			/* t↓ */
			update_tree_entry(&t);
		}

		/* t > p[imin] */
		else {
			/* ∀i pi=p[imin] -> D += "-p[imin]" */
			if (!DIFF_OPT_TST(opt, FIND_COPIES_HARDER)) {
				for (i = 0; i < nparent; ++i)
					if (tp[i].entry.mode & S_IFXMIN_NEQ)
						goto skip_emit_tp;
			}

			p = emit_path(p, base, opt, nparent,
					/*t=*/NULL, tp, imin);

		skip_emit_tp:
			/* ∀ pi=p[imin]  pi↓ */
			update_tp_entries(tp, nparent);
		}
	}

	free(ttree);
	for (i = nparent-1; i >= 0; i--)
		free(tptree[i]);
	xalloca_free(tptree);
	xalloca_free(tp);

	return p;
}

struct combine_diff_path *diff_tree_paths(
	struct combine_diff_path *p, const unsigned char *sha1,
	const unsigned char **parents_sha1, int nparent,
	struct strbuf *base, struct diff_options *opt)
{
	p = ll_diff_tree_paths(p, sha1, parents_sha1, nparent, base, opt);

	/*
	 * free pre-allocated last element, if any
	 * (see path_appendnew() for details about why)
	 */
	if (p->next) {
		free(p->next);
		p->next = NULL;
	}

	return p;
}

/*
 * Does it look like the resulting diff might be due to a rename?
 *  - single entry
 *  - not a valid previous file
 */
static inline int diff_might_be_rename(void)
{
	return diff_queued_diff.nr == 1 &&
		!DIFF_FILE_VALID(diff_queued_diff.queue[0]->one);
}

static void try_to_follow_renames(const unsigned char *old, const unsigned char *new, struct strbuf *base, struct diff_options *opt)
{
	struct diff_options diff_opts;
	struct diff_queue_struct *q = &diff_queued_diff;
	struct diff_filepair *choice;
	int i;

	/*
	 * follow-rename code is very specific, we need exactly one
	 * path. Magic that matches more than one path is not
	 * supported.
	 */
	GUARD_PATHSPEC(&opt->pathspec, PATHSPEC_FROMTOP | PATHSPEC_LITERAL);
#if 0
	/*
	 * We should reject wildcards as well. Unfortunately we
	 * haven't got a reliable way to detect that 'foo\*bar' in
	 * fact has no wildcards. nowildcard_len is merely a hint for
	 * optimization. Let it slip for now until wildmatch is taught
	 * about dry-run mode and returns wildcard info.
	 */
	if (opt->pathspec.has_wildcard)
		die("BUG:%s:%d: wildcards are not supported",
		    __FILE__, __LINE__);
#endif

	/* Remove the file creation entry from the diff queue, and remember it */
	choice = q->queue[0];
	q->nr = 0;

	diff_setup(&diff_opts);
	DIFF_OPT_SET(&diff_opts, RECURSIVE);
	DIFF_OPT_SET(&diff_opts, FIND_COPIES_HARDER);
	diff_opts.output_format = DIFF_FORMAT_NO_OUTPUT;
	diff_opts.single_follow = opt->pathspec.items[0].match;
	diff_opts.break_opt = opt->break_opt;
	diff_opts.rename_score = opt->rename_score;
	diff_setup_done(&diff_opts);
	ll_diff_tree_sha1(old, new, base, &diff_opts);
	diffcore_std(&diff_opts);
	free_pathspec(&diff_opts.pathspec);

	/* Go through the new set of filepairing, and see if we find a more interesting one */
	opt->found_follow = 0;
	for (i = 0; i < q->nr; i++) {
		struct diff_filepair *p = q->queue[i];

		/*
		 * Found a source? Not only do we use that for the new
		 * diff_queued_diff, we will also use that as the path in
		 * the future!
		 */
		if ((p->status == 'R' || p->status == 'C') &&
		    !strcmp(p->two->path, opt->pathspec.items[0].match)) {
			const char *path[2];

			/* Switch the file-pairs around */
			q->queue[i] = choice;
			choice = p;

			/* Update the path we use from now on.. */
			path[0] = p->one->path;
			path[1] = NULL;
			free_pathspec(&opt->pathspec);
			parse_pathspec(&opt->pathspec,
				       PATHSPEC_ALL_MAGIC & ~PATHSPEC_LITERAL,
				       PATHSPEC_LITERAL_PATH, "", path);

			/*
			 * The caller expects us to return a set of vanilla
			 * filepairs to let a later call to diffcore_std()
			 * it makes to sort the renames out (among other
			 * things), but we already have found renames
			 * ourselves; signal diffcore_std() not to muck with
			 * rename information.
			 */
			opt->found_follow = 1;
			break;
		}
	}

	/*
	 * Then, discard all the non-relevant file pairs...
	 */
	for (i = 0; i < q->nr; i++) {
		struct diff_filepair *p = q->queue[i];
		diff_free_filepair(p);
	}

	/*
	 * .. and re-instate the one we want (which might be either the
	 * original one, or the rename/copy we found)
	 */
	q->queue[0] = choice;
	q->nr = 1;
}

static int ll_diff_tree_sha1(const unsigned char *old, const unsigned char *new,
			     struct strbuf *base, struct diff_options *opt)
{
	struct combine_diff_path phead, *p;
	pathchange_fn_t pathchange_old = opt->pathchange;

	phead.next = NULL;
	opt->pathchange = emit_diff_first_parent_only;
	diff_tree_paths(&phead, new, &old, 1, base, opt);

	for (p = phead.next; p;) {
		struct combine_diff_path *pprev = p;
		p = p->next;
		free(pprev);
	}

	opt->pathchange = pathchange_old;
	return 0;
}

int diff_tree_sha1(const unsigned char *old, const unsigned char *new, const char *base_str, struct diff_options *opt)
{
	struct strbuf base;
	int retval;

	strbuf_init(&base, PATH_MAX);
	strbuf_addstr(&base, base_str);

	retval = ll_diff_tree_sha1(old, new, &base, opt);
	if (!*base_str && DIFF_OPT_TST(opt, FOLLOW_RENAMES) && diff_might_be_rename())
		try_to_follow_renames(old, new, &base, opt);

	strbuf_release(&base);

	return retval;
}

int diff_root_tree_sha1(const unsigned char *new, const char *base, struct diff_options *opt)
{
	return diff_tree_sha1(NULL, new, base, opt);
}