summaryrefslogtreecommitdiff
path: root/shallow.c
blob: e483780d4916a817e5256ec325e6cbcf31eb9328 (plain)
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
#include "cache.h"
#include "commit.h"
#include "tag.h"
#include "pkt-line.h"
#include "remote.h"
#include "refs.h"
#include "sha1-array.h"
#include "diff.h"
#include "revision.h"
#include "commit-slab.h"

static int is_shallow = -1;
static struct stat shallow_stat;
static char *alternate_shallow_file;

void set_alternate_shallow_file(const char *path, int override)
{
	if (is_shallow != -1)
		die("BUG: is_repository_shallow must not be called before set_alternate_shallow_file");
	if (alternate_shallow_file && !override)
		return;
	free(alternate_shallow_file);
	alternate_shallow_file = path ? xstrdup(path) : NULL;
}

int register_shallow(const unsigned char *sha1)
{
	struct commit_graft *graft =
		xmalloc(sizeof(struct commit_graft));
	struct commit *commit = lookup_commit(sha1);

	hashcpy(graft->sha1, sha1);
	graft->nr_parent = -1;
	if (commit && commit->object.parsed)
		commit->parents = NULL;
	return register_commit_graft(graft, 0);
}

int is_repository_shallow(void)
{
	FILE *fp;
	char buf[1024];
	const char *path = alternate_shallow_file;

	if (is_shallow >= 0)
		return is_shallow;

	if (!path)
		path = git_path("shallow");
	/*
	 * fetch-pack sets '--shallow-file ""' as an indicator that no
	 * shallow file should be used. We could just open it and it
	 * will likely fail. But let's do an explicit check instead.
	 */
	if (!*path ||
	    stat(path, &shallow_stat) ||
	    (fp = fopen(path, "r")) == NULL) {
		is_shallow = 0;
		return is_shallow;
	}
	is_shallow = 1;

	while (fgets(buf, sizeof(buf), fp)) {
		unsigned char sha1[20];
		if (get_sha1_hex(buf, sha1))
			die("bad shallow line: %s", buf);
		register_shallow(sha1);
	}
	fclose(fp);
	return is_shallow;
}

struct commit_list *get_shallow_commits(struct object_array *heads, int depth,
		int shallow_flag, int not_shallow_flag)
{
	int i = 0, cur_depth = 0;
	struct commit_list *result = NULL;
	struct object_array stack = OBJECT_ARRAY_INIT;
	struct commit *commit = NULL;
	struct commit_graft *graft;

	while (commit || i < heads->nr || stack.nr) {
		struct commit_list *p;
		if (!commit) {
			if (i < heads->nr) {
				commit = (struct commit *)
					deref_tag(heads->objects[i++].item, NULL, 0);
				if (!commit || commit->object.type != OBJ_COMMIT) {
					commit = NULL;
					continue;
				}
				if (!commit->util)
					commit->util = xmalloc(sizeof(int));
				*(int *)commit->util = 0;
				cur_depth = 0;
			} else {
				commit = (struct commit *)
					stack.objects[--stack.nr].item;
				cur_depth = *(int *)commit->util;
			}
		}
		if (parse_commit(commit))
			die("invalid commit");
		cur_depth++;
		if ((depth != INFINITE_DEPTH && cur_depth >= depth) ||
		    (is_repository_shallow() && !commit->parents &&
		     (graft = lookup_commit_graft(commit->object.sha1)) != NULL &&
		     graft->nr_parent < 0)) {
			commit_list_insert(commit, &result);
			commit->object.flags |= shallow_flag;
			commit = NULL;
			continue;
		}
		commit->object.flags |= not_shallow_flag;
		for (p = commit->parents, commit = NULL; p; p = p->next) {
			if (!p->item->util) {
				int *pointer = xmalloc(sizeof(int));
				p->item->util = pointer;
				*pointer =  cur_depth;
			} else {
				int *pointer = p->item->util;
				if (cur_depth >= *pointer)
					continue;
				*pointer = cur_depth;
			}
			if (p->next)
				add_object_array(&p->item->object,
						NULL, &stack);
			else {
				commit = p->item;
				cur_depth = *(int *)commit->util;
			}
		}
	}

	return result;
}

void check_shallow_file_for_update(void)
{
	struct stat st;

	if (!is_shallow)
		return;
	else if (is_shallow == -1)
		die("BUG: shallow must be initialized by now");

	if (stat(git_path("shallow"), &st))
		die("shallow file was removed during fetch");
	else if (st.st_mtime != shallow_stat.st_mtime
#ifdef USE_NSEC
		 || ST_MTIME_NSEC(st) != ST_MTIME_NSEC(shallow_stat)
#endif
		   )
		die("shallow file was changed during fetch");
}

#define SEEN_ONLY 1
#define VERBOSE   2

struct write_shallow_data {
	struct strbuf *out;
	int use_pack_protocol;
	int count;
	unsigned flags;
};

static int write_one_shallow(const struct commit_graft *graft, void *cb_data)
{
	struct write_shallow_data *data = cb_data;
	const char *hex = sha1_to_hex(graft->sha1);
	if (graft->nr_parent != -1)
		return 0;
	if (data->flags & SEEN_ONLY) {
		struct commit *c = lookup_commit(graft->sha1);
		if (!c || !(c->object.flags & SEEN)) {
			if (data->flags & VERBOSE)
				printf("Removing %s from .git/shallow\n",
				       sha1_to_hex(c->object.sha1));
			return 0;
		}
	}
	data->count++;
	if (data->use_pack_protocol)
		packet_buf_write(data->out, "shallow %s", hex);
	else {
		strbuf_addstr(data->out, hex);
		strbuf_addch(data->out, '\n');
	}
	return 0;
}

static int write_shallow_commits_1(struct strbuf *out, int use_pack_protocol,
				   const struct sha1_array *extra,
				   unsigned flags)
{
	struct write_shallow_data data;
	int i;
	data.out = out;
	data.use_pack_protocol = use_pack_protocol;
	data.count = 0;
	data.flags = flags;
	for_each_commit_graft(write_one_shallow, &data);
	if (!extra)
		return data.count;
	for (i = 0; i < extra->nr; i++) {
		strbuf_addstr(out, sha1_to_hex(extra->sha1[i]));
		strbuf_addch(out, '\n');
		data.count++;
	}
	return data.count;
}

int write_shallow_commits(struct strbuf *out, int use_pack_protocol,
			  const struct sha1_array *extra)
{
	return write_shallow_commits_1(out, use_pack_protocol, extra, 0);
}

char *setup_temporary_shallow(const struct sha1_array *extra)
{
	struct strbuf sb = STRBUF_INIT;
	int fd;

	if (write_shallow_commits(&sb, 0, extra)) {
		struct strbuf path = STRBUF_INIT;
		strbuf_addstr(&path, git_path("shallow_XXXXXX"));
		fd = xmkstemp(path.buf);
		if (write_in_full(fd, sb.buf, sb.len) != sb.len)
			die_errno("failed to write to %s",
				  path.buf);
		close(fd);
		strbuf_release(&sb);
		return strbuf_detach(&path, NULL);
	}
	/*
	 * is_repository_shallow() sees empty string as "no shallow
	 * file".
	 */
	return xstrdup("");
}

void setup_alternate_shallow(struct lock_file *shallow_lock,
			     const char **alternate_shallow_file,
			     const struct sha1_array *extra)
{
	struct strbuf sb = STRBUF_INIT;
	int fd;

	check_shallow_file_for_update();
	fd = hold_lock_file_for_update(shallow_lock, git_path("shallow"),
				       LOCK_DIE_ON_ERROR);
	if (write_shallow_commits(&sb, 0, extra)) {
		if (write_in_full(fd, sb.buf, sb.len) != sb.len)
			die_errno("failed to write to %s",
				  shallow_lock->filename);
		*alternate_shallow_file = shallow_lock->filename;
	} else
		/*
		 * is_repository_shallow() sees empty string as "no
		 * shallow file".
		 */
		*alternate_shallow_file = "";
	strbuf_release(&sb);
}

static int advertise_shallow_grafts_cb(const struct commit_graft *graft, void *cb)
{
	int fd = *(int *)cb;
	if (graft->nr_parent == -1)
		packet_write(fd, "shallow %s\n", sha1_to_hex(graft->sha1));
	return 0;
}

void advertise_shallow_grafts(int fd)
{
	if (!is_repository_shallow())
		return;
	for_each_commit_graft(advertise_shallow_grafts_cb, &fd);
}

/*
 * mark_reachable_objects() should have been run prior to this and all
 * reachable commits marked as "SEEN".
 */
void prune_shallow(int show_only)
{
	static struct lock_file shallow_lock;
	struct strbuf sb = STRBUF_INIT;
	int fd;

	if (show_only) {
		write_shallow_commits_1(&sb, 0, NULL, SEEN_ONLY | VERBOSE);
		strbuf_release(&sb);
		return;
	}
	check_shallow_file_for_update();
	fd = hold_lock_file_for_update(&shallow_lock, git_path("shallow"),
				       LOCK_DIE_ON_ERROR);
	if (write_shallow_commits_1(&sb, 0, NULL, SEEN_ONLY)) {
		if (write_in_full(fd, sb.buf, sb.len) != sb.len)
			die_errno("failed to write to %s",
				  shallow_lock.filename);
		commit_lock_file(&shallow_lock);
	} else {
		unlink(git_path("shallow"));
		rollback_lock_file(&shallow_lock);
	}
	strbuf_release(&sb);
}

#define TRACE_KEY "GIT_TRACE_SHALLOW"

/*
 * Step 1, split sender shallow commits into "ours" and "theirs"
 * Step 2, clean "ours" based on .git/shallow
 */
void prepare_shallow_info(struct shallow_info *info, struct sha1_array *sa)
{
	int i;
	trace_printf_key(TRACE_KEY, "shallow: prepare_shallow_info\n");
	memset(info, 0, sizeof(*info));
	info->shallow = sa;
	if (!sa)
		return;
	info->ours = xmalloc(sizeof(*info->ours) * sa->nr);
	info->theirs = xmalloc(sizeof(*info->theirs) * sa->nr);
	for (i = 0; i < sa->nr; i++) {
		if (has_sha1_file(sa->sha1[i])) {
			struct commit_graft *graft;
			graft = lookup_commit_graft(sa->sha1[i]);
			if (graft && graft->nr_parent < 0)
				continue;
			info->ours[info->nr_ours++] = i;
		} else
			info->theirs[info->nr_theirs++] = i;
	}
}

void clear_shallow_info(struct shallow_info *info)
{
	free(info->ours);
	free(info->theirs);
}

/* Step 4, remove non-existent ones in "theirs" after getting the pack */

void remove_nonexistent_theirs_shallow(struct shallow_info *info)
{
	unsigned char (*sha1)[20] = info->shallow->sha1;
	int i, dst;
	trace_printf_key(TRACE_KEY, "shallow: remove_nonexistent_theirs_shallow\n");
	for (i = dst = 0; i < info->nr_theirs; i++) {
		if (i != dst)
			info->theirs[dst] = info->theirs[i];
		if (has_sha1_file(sha1[info->theirs[i]]))
			dst++;
	}
	info->nr_theirs = dst;
}

define_commit_slab(ref_bitmap, uint32_t *);

struct paint_info {
	struct ref_bitmap ref_bitmap;
	unsigned nr_bits;
	char **slab;
	char *free, *end;
	unsigned slab_count;
};

static uint32_t *paint_alloc(struct paint_info *info)
{
	unsigned nr = (info->nr_bits + 31) / 32;
	unsigned size = nr * sizeof(uint32_t);
	void *p;
	if (!info->slab_count || info->free + size > info->end) {
		info->slab_count++;
		info->slab = xrealloc(info->slab,
				      info->slab_count * sizeof(*info->slab));
		info->free = xmalloc(COMMIT_SLAB_SIZE);
		info->slab[info->slab_count - 1] = info->free;
		info->end = info->free + COMMIT_SLAB_SIZE;
	}
	p = info->free;
	info->free += size;
	return p;
}

/*
 * Given a commit SHA-1, walk down to parents until either SEEN,
 * UNINTERESTING or BOTTOM is hit. Set the id-th bit in ref_bitmap for
 * all walked commits.
 */
static void paint_down(struct paint_info *info, const unsigned char *sha1,
		       int id)
{
	unsigned int i, nr;
	struct commit_list *head = NULL;
	int bitmap_nr = (info->nr_bits + 31) / 32;
	int bitmap_size = bitmap_nr * sizeof(uint32_t);
	uint32_t *tmp = xmalloc(bitmap_size); /* to be freed before return */
	uint32_t *bitmap = paint_alloc(info);
	struct commit *c = lookup_commit_reference_gently(sha1, 1);
	if (!c)
		return;
	memset(bitmap, 0, bitmap_size);
	bitmap[id / 32] |= (1 << (id % 32));
	commit_list_insert(c, &head);
	while (head) {
		struct commit_list *p;
		struct commit *c = head->item;
		uint32_t **refs = ref_bitmap_at(&info->ref_bitmap, c);

		p = head;
		head = head->next;
		free(p);

		/* XXX check "UNINTERESTING" from pack bitmaps if available */
		if (c->object.flags & (SEEN | UNINTERESTING))
			continue;
		else
			c->object.flags |= SEEN;

		if (*refs == NULL)
			*refs = bitmap;
		else {
			memcpy(tmp, *refs, bitmap_size);
			for (i = 0; i < bitmap_nr; i++)
				tmp[i] |= bitmap[i];
			if (memcmp(tmp, *refs, bitmap_size)) {
				*refs = paint_alloc(info);
				memcpy(*refs, tmp, bitmap_size);
			}
		}

		if (c->object.flags & BOTTOM)
			continue;

		if (parse_commit(c))
			die("unable to parse commit %s",
			    sha1_to_hex(c->object.sha1));

		for (p = c->parents; p; p = p->next) {
			uint32_t **p_refs = ref_bitmap_at(&info->ref_bitmap,
							  p->item);
			if (p->item->object.flags & SEEN)
				continue;
			if (*p_refs == NULL || *p_refs == *refs)
				*p_refs = *refs;
			commit_list_insert(p->item, &head);
		}
	}

	nr = get_max_object_index();
	for (i = 0; i < nr; i++) {
		struct object *o = get_indexed_object(i);
		if (o && o->type == OBJ_COMMIT)
			o->flags &= ~SEEN;
	}

	free(tmp);
}

static int mark_uninteresting(const char *refname,
			      const unsigned char *sha1,
			      int flags, void *cb_data)
{
	struct commit *commit = lookup_commit_reference_gently(sha1, 1);
	if (!commit)
		return 0;
	commit->object.flags |= UNINTERESTING;
	mark_parents_uninteresting(commit);
	return 0;
}

static void post_assign_shallow(struct shallow_info *info,
				struct ref_bitmap *ref_bitmap,
				int *ref_status);
/*
 * Step 6(+7), associate shallow commits with new refs
 *
 * info->ref must be initialized before calling this function.
 *
 * If used is not NULL, it's an array of info->shallow->nr
 * bitmaps. The n-th bit set in the m-th bitmap if ref[n] needs the
 * m-th shallow commit from info->shallow.
 *
 * If used is NULL, "ours" and "theirs" are updated. And if ref_status
 * is not NULL it's an array of ref->nr ints. ref_status[i] is true if
 * the ref needs some shallow commits from either info->ours or
 * info->theirs.
 */
void assign_shallow_commits_to_refs(struct shallow_info *info,
				    uint32_t **used, int *ref_status)
{
	unsigned char (*sha1)[20] = info->shallow->sha1;
	struct sha1_array *ref = info->ref;
	unsigned int i, nr;
	int *shallow, nr_shallow = 0;
	struct paint_info pi;

	trace_printf_key(TRACE_KEY, "shallow: assign_shallow_commits_to_refs\n");
	shallow = xmalloc(sizeof(*shallow) * (info->nr_ours + info->nr_theirs));
	for (i = 0; i < info->nr_ours; i++)
		shallow[nr_shallow++] = info->ours[i];
	for (i = 0; i < info->nr_theirs; i++)
		shallow[nr_shallow++] = info->theirs[i];

	/*
	 * Prepare the commit graph to track what refs can reach what
	 * (new) shallow commits.
	 */
	nr = get_max_object_index();
	for (i = 0; i < nr; i++) {
		struct object *o = get_indexed_object(i);
		if (!o || o->type != OBJ_COMMIT)
			continue;

		o->flags &= ~(UNINTERESTING | BOTTOM | SEEN);
	}

	memset(&pi, 0, sizeof(pi));
	init_ref_bitmap(&pi.ref_bitmap);
	pi.nr_bits = ref->nr;

	/*
	 * "--not --all" to cut short the traversal if new refs
	 * connect to old refs. If not (e.g. force ref updates) it'll
	 * have to go down to the current shallow commits.
	 */
	head_ref(mark_uninteresting, NULL);
	for_each_ref(mark_uninteresting, NULL);

	/* Mark potential bottoms so we won't go out of bound */
	for (i = 0; i < nr_shallow; i++) {
		struct commit *c = lookup_commit(sha1[shallow[i]]);
		c->object.flags |= BOTTOM;
	}

	for (i = 0; i < ref->nr; i++)
		paint_down(&pi, ref->sha1[i], i);

	if (used) {
		int bitmap_size = ((pi.nr_bits + 31) / 32) * sizeof(uint32_t);
		memset(used, 0, sizeof(*used) * info->shallow->nr);
		for (i = 0; i < nr_shallow; i++) {
			const struct commit *c = lookup_commit(sha1[shallow[i]]);
			uint32_t **map = ref_bitmap_at(&pi.ref_bitmap, c);
			if (*map)
				used[shallow[i]] = xmemdupz(*map, bitmap_size);
		}
		/*
		 * unreachable shallow commits are not removed from
		 * "ours" and "theirs". The user is supposed to run
		 * step 7 on every ref separately and not trust "ours"
		 * and "theirs" any more.
		 */
	} else
		post_assign_shallow(info, &pi.ref_bitmap, ref_status);

	clear_ref_bitmap(&pi.ref_bitmap);
	for (i = 0; i < pi.slab_count; i++)
		free(pi.slab[i]);
	free(pi.slab);
	free(shallow);
}

struct commit_array {
	struct commit **commits;
	int nr, alloc;
};

static int add_ref(const char *refname,
		   const unsigned char *sha1, int flags, void *cb_data)
{
	struct commit_array *ca = cb_data;
	ALLOC_GROW(ca->commits, ca->nr + 1, ca->alloc);
	ca->commits[ca->nr] = lookup_commit_reference_gently(sha1, 1);
	if (ca->commits[ca->nr])
		ca->nr++;
	return 0;
}

static void update_refstatus(int *ref_status, int nr, uint32_t *bitmap)
{
	int i;
	if (!ref_status)
		return;
	for (i = 0; i < nr; i++)
		if (bitmap[i / 32] & (1 << (i % 32)))
			ref_status[i]++;
}

/*
 * Step 7, reachability test on "ours" at commit level
 */
static void post_assign_shallow(struct shallow_info *info,
				struct ref_bitmap *ref_bitmap,
				int *ref_status)
{
	unsigned char (*sha1)[20] = info->shallow->sha1;
	struct commit *c;
	uint32_t **bitmap;
	int dst, i, j;
	int bitmap_nr = (info->ref->nr + 31) / 32;
	struct commit_array ca;

	trace_printf_key(TRACE_KEY, "shallow: post_assign_shallow\n");
	if (ref_status)
		memset(ref_status, 0, sizeof(*ref_status) * info->ref->nr);

	/* Remove unreachable shallow commits from "theirs" */
	for (i = dst = 0; i < info->nr_theirs; i++) {
		if (i != dst)
			info->theirs[dst] = info->theirs[i];
		c = lookup_commit(sha1[info->theirs[i]]);
		bitmap = ref_bitmap_at(ref_bitmap, c);
		if (!*bitmap)
			continue;
		for (j = 0; j < bitmap_nr; j++)
			if (bitmap[0][j]) {
				update_refstatus(ref_status, info->ref->nr, *bitmap);
				dst++;
				break;
			}
	}
	info->nr_theirs = dst;

	memset(&ca, 0, sizeof(ca));
	head_ref(add_ref, &ca);
	for_each_ref(add_ref, &ca);

	/* Remove unreachable shallow commits from "ours" */
	for (i = dst = 0; i < info->nr_ours; i++) {
		if (i != dst)
			info->ours[dst] = info->ours[i];
		c = lookup_commit(sha1[info->ours[i]]);
		bitmap = ref_bitmap_at(ref_bitmap, c);
		if (!*bitmap)
			continue;
		for (j = 0; j < bitmap_nr; j++)
			if (bitmap[0][j] &&
			    /* Step 7, reachability test at commit level */
			    !in_merge_bases_many(c, ca.nr, ca.commits)) {
				update_refstatus(ref_status, info->ref->nr, *bitmap);
				dst++;
				break;
			}
	}
	info->nr_ours = dst;

	free(ca.commits);
}

/* (Delayed) step 7, reachability test at commit level */
int delayed_reachability_test(struct shallow_info *si, int c)
{
	if (si->need_reachability_test[c]) {
		struct commit *commit = lookup_commit(si->shallow->sha1[c]);

		if (!si->commits) {
			struct commit_array ca;
			memset(&ca, 0, sizeof(ca));
			head_ref(add_ref, &ca);
			for_each_ref(add_ref, &ca);
			si->commits = ca.commits;
			si->nr_commits = ca.nr;
		}

		si->reachable[c] = in_merge_bases_many(commit,
						       si->nr_commits,
						       si->commits);
		si->need_reachability_test[c] = 0;
	}
	return si->reachable[c];
}