commit_graph.c 33.4 KB
Newer Older
1 2 3 4 5 6 7 8 9
/*
 * Copyright (C) the libgit2 contributors. All rights reserved.
 *
 * This file is part of libgit2, distributed under the GNU GPL v2 with
 * a Linking Exception. For full terms see the included COPYING file.
 */

#include "commit_graph.h"

10
#include "array.h"
11
#include "buf.h"
12
#include "filebuf.h"
13 14
#include "futils.h"
#include "hash.h"
15 16
#include "oidarray.h"
#include "oidmap.h"
17
#include "pack.h"
18 19
#include "repository.h"
#include "revwalk.h"
20 21

#define GIT_COMMIT_GRAPH_MISSING_PARENT 0x70000000
22 23
#define GIT_COMMIT_GRAPH_GENERATION_NUMBER_MAX 0x3FFFFFFF
#define GIT_COMMIT_GRAPH_GENERATION_NUMBER_INFINITY 0xFFFFFFFF
24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47

#define COMMIT_GRAPH_SIGNATURE 0x43475048 /* "CGPH" */
#define COMMIT_GRAPH_VERSION 1
#define COMMIT_GRAPH_OBJECT_ID_VERSION 1
struct git_commit_graph_header {
	uint32_t signature;
	uint8_t version;
	uint8_t object_id_version;
	uint8_t chunks;
	uint8_t base_graph_files;
};

#define COMMIT_GRAPH_OID_FANOUT_ID 0x4f494446	      /* "OIDF" */
#define COMMIT_GRAPH_OID_LOOKUP_ID 0x4f49444c	      /* "OIDL" */
#define COMMIT_GRAPH_COMMIT_DATA_ID 0x43444154	      /* "CDAT" */
#define COMMIT_GRAPH_EXTRA_EDGE_LIST_ID 0x45444745    /* "EDGE" */
#define COMMIT_GRAPH_BLOOM_FILTER_INDEX_ID 0x42494458 /* "BIDX" */
#define COMMIT_GRAPH_BLOOM_FILTER_DATA_ID 0x42444154  /* "BDAT" */

struct git_commit_graph_chunk {
	off64_t offset;
	size_t length;
};

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
typedef git_array_t(size_t) parent_index_array_t;

struct packed_commit {
	size_t index;
	git_oid sha1;
	git_oid tree_oid;
	uint32_t generation;
	git_time_t commit_time;
	git_array_oid_t parents;
	parent_index_array_t parent_indices;
};

static void packed_commit_free(struct packed_commit *p)
{
	if (!p)
		return;

	git_array_clear(p->parents);
	git_array_clear(p->parent_indices);
	git__free(p);
}

static struct packed_commit *packed_commit_new(git_commit *commit)
{
	unsigned int i, parentcount = git_commit_parentcount(commit);
lhchavez committed
73
	struct packed_commit *p = git__calloc(1, sizeof(struct packed_commit));
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
	if (!p)
		goto cleanup;

	git_array_init_to_size(p->parents, parentcount);
	if (parentcount && !p->parents.ptr)
		goto cleanup;

	if (git_oid_cpy(&p->sha1, git_commit_id(commit)) < 0)
		goto cleanup;
	if (git_oid_cpy(&p->tree_oid, git_commit_tree_id(commit)) < 0)
		goto cleanup;
	p->commit_time = git_commit_time(commit);

	for (i = 0; i < parentcount; ++i) {
		git_oid *parent_id = git_array_alloc(p->parents);
		if (!parent_id)
			goto cleanup;
		if (git_oid_cpy(parent_id, git_commit_parent_id(commit, i)) < 0)
			goto cleanup;
	}

	return p;

cleanup:
	packed_commit_free(p);
	return NULL;
}

typedef int (*commit_graph_write_cb)(const char *buf, size_t size, void *cb_data);

104 105 106 107 108 109 110
static int commit_graph_error(const char *message)
{
	git_error_set(GIT_ERROR_ODB, "invalid commit-graph file - %s", message);
	return -1;
}

static int commit_graph_parse_oid_fanout(
111
		git_commit_graph_file *file,
112 113 114 115 116 117 118 119 120 121 122
		const unsigned char *data,
		struct git_commit_graph_chunk *chunk_oid_fanout)
{
	uint32_t i, nr;
	if (chunk_oid_fanout->offset == 0)
		return commit_graph_error("missing OID Fanout chunk");
	if (chunk_oid_fanout->length == 0)
		return commit_graph_error("empty OID Fanout chunk");
	if (chunk_oid_fanout->length != 256 * 4)
		return commit_graph_error("OID Fanout chunk has wrong length");

123
	file->oid_fanout = (const uint32_t *)(data + chunk_oid_fanout->offset);
124 125
	nr = 0;
	for (i = 0; i < 256; ++i) {
126
		uint32_t n = ntohl(file->oid_fanout[i]);
127 128 129 130
		if (n < nr)
			return commit_graph_error("index is non-monotonic");
		nr = n;
	}
131
	file->num_commits = nr;
132 133 134 135
	return 0;
}

static int commit_graph_parse_oid_lookup(
136
		git_commit_graph_file *file,
137 138 139 140
		const unsigned char *data,
		struct git_commit_graph_chunk *chunk_oid_lookup)
{
	uint32_t i;
141
	unsigned char *oid, *prev_oid, zero_oid[GIT_OID_SHA1_SIZE] = {0};
142 143 144 145 146

	if (chunk_oid_lookup->offset == 0)
		return commit_graph_error("missing OID Lookup chunk");
	if (chunk_oid_lookup->length == 0)
		return commit_graph_error("empty OID Lookup chunk");
147
	if (chunk_oid_lookup->length != file->num_commits * GIT_OID_SHA1_SIZE)
148 149
		return commit_graph_error("OID Lookup chunk has wrong length");

150 151
	file->oid_lookup = oid = (unsigned char *)(data + chunk_oid_lookup->offset);
	prev_oid = zero_oid;
152
	for (i = 0; i < file->num_commits; ++i, oid += GIT_OID_SHA1_SIZE) {
Edward Thomson committed
153
		if (git_oid_raw_cmp(prev_oid, oid, GIT_OID_SHA1_SIZE) >= 0)
154 155 156 157 158 159 160 161
			return commit_graph_error("OID Lookup index is non-monotonic");
		prev_oid = oid;
	}

	return 0;
}

static int commit_graph_parse_commit_data(
162
		git_commit_graph_file *file,
163 164 165 166 167 168 169
		const unsigned char *data,
		struct git_commit_graph_chunk *chunk_commit_data)
{
	if (chunk_commit_data->offset == 0)
		return commit_graph_error("missing Commit Data chunk");
	if (chunk_commit_data->length == 0)
		return commit_graph_error("empty Commit Data chunk");
170
	if (chunk_commit_data->length != file->num_commits * (GIT_OID_SHA1_SIZE + 16))
171 172
		return commit_graph_error("Commit Data chunk has wrong length");

173
	file->commit_data = data + chunk_commit_data->offset;
174 175 176 177 178

	return 0;
}

static int commit_graph_parse_extra_edge_list(
179
		git_commit_graph_file *file,
180 181 182 183 184 185 186 187
		const unsigned char *data,
		struct git_commit_graph_chunk *chunk_extra_edge_list)
{
	if (chunk_extra_edge_list->length == 0)
		return 0;
	if (chunk_extra_edge_list->length % 4 != 0)
		return commit_graph_error("malformed Extra Edge List chunk");

188 189
	file->extra_edge_list = data + chunk_extra_edge_list->offset;
	file->num_extra_edge_list = chunk_extra_edge_list->length / 4;
190 191 192 193

	return 0;
}

194 195 196 197
int git_commit_graph_file_parse(
		git_commit_graph_file *file,
		const unsigned char *data,
		size_t size)
198 199 200 201 202 203
{
	struct git_commit_graph_header *hdr;
	const unsigned char *chunk_hdr;
	struct git_commit_graph_chunk *last_chunk;
	uint32_t i;
	off64_t last_chunk_offset, chunk_offset, trailer_offset;
204 205
	unsigned char checksum[GIT_HASH_SHA1_SIZE];
	size_t checksum_size;
206 207 208 209 210
	int error;
	struct git_commit_graph_chunk chunk_oid_fanout = {0}, chunk_oid_lookup = {0},
				      chunk_commit_data = {0}, chunk_extra_edge_list = {0},
				      chunk_unsupported = {0};

211
	GIT_ASSERT_ARG(file);
212

213
	if (size < sizeof(struct git_commit_graph_header) + GIT_OID_SHA1_SIZE)
214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229
		return commit_graph_error("commit-graph is too short");

	hdr = ((struct git_commit_graph_header *)data);

	if (hdr->signature != htonl(COMMIT_GRAPH_SIGNATURE) || hdr->version != COMMIT_GRAPH_VERSION
	    || hdr->object_id_version != COMMIT_GRAPH_OBJECT_ID_VERSION) {
		return commit_graph_error("unsupported commit-graph version");
	}
	if (hdr->chunks == 0)
		return commit_graph_error("no chunks in commit-graph");

	/*
	 * The very first chunk's offset should be after the header, all the chunk
	 * headers, and a special zero chunk.
	 */
	last_chunk_offset = sizeof(struct git_commit_graph_header) + (1 + hdr->chunks) * 12;
230
	trailer_offset = size - GIT_OID_SHA1_SIZE;
231 232
	checksum_size = GIT_HASH_SHA1_SIZE;

233 234
	if (trailer_offset < last_chunk_offset)
		return commit_graph_error("wrong commit-graph size");
235
	memcpy(file->checksum, (data + trailer_offset), checksum_size);
236

237
	if (git_hash_buf(checksum, data, (size_t)trailer_offset, GIT_HASH_ALGORITHM_SHA1) < 0)
238
		return commit_graph_error("could not calculate signature");
239
	if (memcmp(checksum, file->checksum, checksum_size) != 0)
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
		return commit_graph_error("index signature mismatch");

	chunk_hdr = data + sizeof(struct git_commit_graph_header);
	last_chunk = NULL;
	for (i = 0; i < hdr->chunks; ++i, chunk_hdr += 12) {
		chunk_offset = ((off64_t)ntohl(*((uint32_t *)(chunk_hdr + 4)))) << 32
				| ((off64_t)ntohl(*((uint32_t *)(chunk_hdr + 8))));
		if (chunk_offset < last_chunk_offset)
			return commit_graph_error("chunks are non-monotonic");
		if (chunk_offset >= trailer_offset)
			return commit_graph_error("chunks extend beyond the trailer");
		if (last_chunk != NULL)
			last_chunk->length = (size_t)(chunk_offset - last_chunk_offset);
		last_chunk_offset = chunk_offset;

		switch (ntohl(*((uint32_t *)(chunk_hdr + 0)))) {
		case COMMIT_GRAPH_OID_FANOUT_ID:
			chunk_oid_fanout.offset = last_chunk_offset;
			last_chunk = &chunk_oid_fanout;
			break;

		case COMMIT_GRAPH_OID_LOOKUP_ID:
			chunk_oid_lookup.offset = last_chunk_offset;
			last_chunk = &chunk_oid_lookup;
			break;

		case COMMIT_GRAPH_COMMIT_DATA_ID:
			chunk_commit_data.offset = last_chunk_offset;
			last_chunk = &chunk_commit_data;
			break;

		case COMMIT_GRAPH_EXTRA_EDGE_LIST_ID:
			chunk_extra_edge_list.offset = last_chunk_offset;
			last_chunk = &chunk_extra_edge_list;
			break;

		case COMMIT_GRAPH_BLOOM_FILTER_INDEX_ID:
		case COMMIT_GRAPH_BLOOM_FILTER_DATA_ID:
			chunk_unsupported.offset = last_chunk_offset;
			last_chunk = &chunk_unsupported;
			break;

		default:
			return commit_graph_error("unrecognized chunk ID");
		}
	}
	last_chunk->length = (size_t)(trailer_offset - last_chunk_offset);

288
	error = commit_graph_parse_oid_fanout(file, data, &chunk_oid_fanout);
289 290
	if (error < 0)
		return error;
291
	error = commit_graph_parse_oid_lookup(file, data, &chunk_oid_lookup);
292 293
	if (error < 0)
		return error;
294
	error = commit_graph_parse_commit_data(file, data, &chunk_commit_data);
295 296
	if (error < 0)
		return error;
297
	error = commit_graph_parse_extra_edge_list(file, data, &chunk_extra_edge_list);
298 299 300 301 302 303
	if (error < 0)
		return error;

	return 0;
}

304
int git_commit_graph_new(git_commit_graph **cgraph_out, const char *objects_dir, bool open_file)
305
{
306 307 308 309 310 311 312 313 314
	git_commit_graph *cgraph = NULL;
	int error = 0;

	GIT_ASSERT_ARG(cgraph_out);
	GIT_ASSERT_ARG(objects_dir);

	cgraph = git__calloc(1, sizeof(git_commit_graph));
	GIT_ERROR_CHECK_ALLOC(cgraph);

315
	error = git_str_joinpath(&cgraph->filename, objects_dir, "info/commit-graph");
316 317 318 319
	if (error < 0)
		goto error;

	if (open_file) {
320
		error = git_commit_graph_file_open(&cgraph->file, git_str_cstr(&cgraph->filename));
321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341
		if (error < 0)
			goto error;
		cgraph->checked = 1;
	}

	*cgraph_out = cgraph;
	return 0;

error:
	git_commit_graph_free(cgraph);
	return error;
}

int git_commit_graph_open(git_commit_graph **cgraph_out, const char *objects_dir)
{
	return git_commit_graph_new(cgraph_out, objects_dir, true);
}

int git_commit_graph_file_open(git_commit_graph_file **file_out, const char *path)
{
	git_commit_graph_file *file;
342 343 344 345 346 347 348 349 350 351 352 353
	git_file fd = -1;
	size_t cgraph_size;
	struct stat st;
	int error;

	/* TODO: properly open the file without access time using O_NOATIME */
	fd = git_futils_open_ro(path);
	if (fd < 0)
		return fd;

	if (p_fstat(fd, &st) < 0) {
		p_close(fd);
354 355
		git_error_set(GIT_ERROR_ODB, "commit-graph file not found - '%s'", path);
		return GIT_ENOTFOUND;
356 357 358 359 360
	}

	if (!S_ISREG(st.st_mode) || !git__is_sizet(st.st_size)) {
		p_close(fd);
		git_error_set(GIT_ERROR_ODB, "invalid pack index '%s'", path);
361
		return GIT_ENOTFOUND;
362 363 364
	}
	cgraph_size = (size_t)st.st_size;

365 366
	file = git__calloc(1, sizeof(git_commit_graph_file));
	GIT_ERROR_CHECK_ALLOC(file);
367

368
	error = git_futils_mmap_ro(&file->graph_map, fd, 0, cgraph_size);
369 370
	p_close(fd);
	if (error < 0) {
371
		git_commit_graph_file_free(file);
372 373 374
		return error;
	}

375 376
	if ((error = git_commit_graph_file_parse(file, file->graph_map.data, cgraph_size)) < 0) {
		git_commit_graph_file_free(file);
377 378 379
		return error;
	}

380
	*file_out = file;
381 382 383
	return 0;
}

384 385 386 387 388 389 390 391 392 393
int git_commit_graph_get_file(git_commit_graph_file **file_out, git_commit_graph *cgraph)
{
	if (!cgraph->checked) {
		int error = 0;
		git_commit_graph_file *result = NULL;

		/* We only check once, no matter the result. */
		cgraph->checked = 1;

		/* Best effort */
394
		error = git_commit_graph_file_open(&result, git_str_cstr(&cgraph->filename));
395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413

		if (error < 0)
			return error;

		cgraph->file = result;
	}
	if (!cgraph->file)
		return GIT_ENOTFOUND;

	*file_out = cgraph->file;
	return 0;
}

void git_commit_graph_refresh(git_commit_graph *cgraph)
{
	if (!cgraph->checked)
		return;

	if (cgraph->file
414
	    && git_commit_graph_file_needs_refresh(cgraph->file, git_str_cstr(&cgraph->filename))) {
415 416 417 418 419 420 421 422 423
		/* We just free the commit graph. The next time it is requested, it will be
		 * re-loaded. */
		git_commit_graph_file_free(cgraph->file);
		cgraph->file = NULL;
	}
	/* Force a lazy re-check next time it is needed. */
	cgraph->checked = 0;
}

424 425
static int git_commit_graph_entry_get_byindex(
		git_commit_graph_entry *e,
426
		const git_commit_graph_file *file,
427 428 429 430 431
		size_t pos)
{
	const unsigned char *commit_data;

	GIT_ASSERT_ARG(e);
432
	GIT_ASSERT_ARG(file);
433

434
	if (pos >= file->num_commits) {
435 436 437 438
		git_error_set(GIT_ERROR_INVALID, "commit index %zu does not exist", pos);
		return GIT_ENOTFOUND;
	}

439
	commit_data = file->commit_data + pos * (GIT_OID_SHA1_SIZE + 4 * sizeof(uint32_t));
440
	git_oid__fromraw(&e->tree_oid, commit_data, GIT_OID_SHA1);
441
	e->parent_indices[0] = ntohl(*((uint32_t *)(commit_data + GIT_OID_SHA1_SIZE)));
lhchavez committed
442
	e->parent_indices[1] = ntohl(
443
			*((uint32_t *)(commit_data + GIT_OID_SHA1_SIZE + sizeof(uint32_t))));
444 445
	e->parent_count = (e->parent_indices[0] != GIT_COMMIT_GRAPH_MISSING_PARENT)
			+ (e->parent_indices[1] != GIT_COMMIT_GRAPH_MISSING_PARENT);
446 447
	e->generation = ntohl(*((uint32_t *)(commit_data + GIT_OID_SHA1_SIZE + 2 * sizeof(uint32_t))));
	e->commit_time = ntohl(*((uint32_t *)(commit_data + GIT_OID_SHA1_SIZE + 3 * sizeof(uint32_t))));
448

449
	e->commit_time |= (e->generation & UINT64_C(0x3)) << UINT64_C(32);
450 451 452 453 454
	e->generation >>= 2u;
	if (e->parent_indices[1] & 0x80000000u) {
		uint32_t extra_edge_list_pos = e->parent_indices[1] & 0x7fffffff;

		/* Make sure we're not being sent out of bounds */
455
		if (extra_edge_list_pos >= file->num_extra_edge_list) {
456 457 458 459 460 461 462
			git_error_set(GIT_ERROR_INVALID,
				      "commit %u does not exist",
				      extra_edge_list_pos);
			return GIT_ENOTFOUND;
		}

		e->extra_parents_index = extra_edge_list_pos;
463
		while (extra_edge_list_pos < file->num_extra_edge_list
464
		       && (ntohl(*(
465
					   (uint32_t *)(file->extra_edge_list
466 467 468 469 470 471 472
							+ extra_edge_list_pos * sizeof(uint32_t))))
			   & 0x80000000u)
				       == 0) {
			extra_edge_list_pos++;
			e->parent_count++;
		}
	}
473

474
	git_oid__fromraw(&e->sha1, &file->oid_lookup[pos * GIT_OID_SHA1_SIZE], GIT_OID_SHA1);
475 476 477
	return 0;
}

478
bool git_commit_graph_file_needs_refresh(const git_commit_graph_file *file, const char *path)
479 480 481 482
{
	git_file fd = -1;
	struct stat st;
	ssize_t bytes_read;
483 484
	unsigned char checksum[GIT_HASH_SHA1_SIZE];
	size_t checksum_size = GIT_HASH_SHA1_SIZE;
485 486 487 488 489 490 491 492 493 494 495 496

	/* TODO: properly open the file without access time using O_NOATIME */
	fd = git_futils_open_ro(path);
	if (fd < 0)
		return true;

	if (p_fstat(fd, &st) < 0) {
		p_close(fd);
		return true;
	}

	if (!S_ISREG(st.st_mode) || !git__is_sizet(st.st_size)
497
	    || (size_t)st.st_size != file->graph_map.len) {
498 499 500 501
		p_close(fd);
		return true;
	}

502
	bytes_read = p_pread(fd, checksum, checksum_size, st.st_size - checksum_size);
503
	p_close(fd);
504
	if (bytes_read != (ssize_t)checksum_size)
505 506
		return true;

507
	return (memcmp(checksum, file->checksum, checksum_size) != 0);
508 509
}

510 511
int git_commit_graph_entry_find(
		git_commit_graph_entry *e,
512
		const git_commit_graph_file *file,
513 514 515 516 517
		const git_oid *short_oid,
		size_t len)
{
	int pos, found = 0;
	uint32_t hi, lo;
518
	const unsigned char *current = NULL;
519 520

	GIT_ASSERT_ARG(e);
521
	GIT_ASSERT_ARG(file);
522 523
	GIT_ASSERT_ARG(short_oid);

524 525
	hi = ntohl(file->oid_fanout[(int)short_oid->id[0]]);
	lo = ((short_oid->id[0] == 0x0) ? 0 : ntohl(file->oid_fanout[(int)short_oid->id[0] - 1]));
526

527
	pos = git_pack__lookup_sha1(file->oid_lookup, GIT_OID_SHA1_SIZE, lo, hi, short_oid->id);
528 529 530 531

	if (pos >= 0) {
		/* An object matching exactly the oid was found */
		found = 1;
532
		current = file->oid_lookup + (pos * GIT_OID_SHA1_SIZE);
533 534 535 536
	} else {
		/* No object was found */
		/* pos refers to the object with the "closest" oid to short_oid */
		pos = -1 - pos;
537
		if (pos < (int)file->num_commits) {
538
			current = file->oid_lookup + (pos * GIT_OID_SHA1_SIZE);
539

540
			if (!git_oid_raw_ncmp(short_oid->id, current, len))
541 542 543 544
				found = 1;
		}
	}

545
	if (found && len != GIT_OID_SHA1_HEXSIZE && pos + 1 < (int)file->num_commits) {
546
		/* Check for ambiguousity */
547
		const unsigned char *next = current + GIT_OID_SHA1_SIZE;
548

549
		if (!git_oid_raw_ncmp(short_oid->id, next, len))
550 551 552 553 554
			found = 2;
	}

	if (!found)
		return git_odb__error_notfound(
555
				"failed to find offset for commit-graph index entry", short_oid, len);
556 557
	if (found > 1)
		return git_odb__error_ambiguous(
558
				"found multiple offsets for commit-graph index entry");
559

560
	return git_commit_graph_entry_get_byindex(e, file, pos);
561 562 563 564
}

int git_commit_graph_entry_parent(
		git_commit_graph_entry *parent,
565
		const git_commit_graph_file *file,
566 567 568 569
		const git_commit_graph_entry *entry,
		size_t n)
{
	GIT_ASSERT_ARG(parent);
570
	GIT_ASSERT_ARG(file);
571 572 573 574 575 576 577

	if (n >= entry->parent_count) {
		git_error_set(GIT_ERROR_INVALID, "parent index %zu does not exist", n);
		return GIT_ENOTFOUND;
	}

	if (n == 0 || (n == 1 && entry->parent_count == 2))
578
		return git_commit_graph_entry_get_byindex(parent, file, entry->parent_indices[n]);
579 580 581

	return git_commit_graph_entry_get_byindex(
			parent,
582
			file,
583
			ntohl(
584
					*(uint32_t *)(file->extra_edge_list
585 586 587 588 589
						      + (entry->extra_parents_index + n - 1)
								      * sizeof(uint32_t)))
					& 0x7fffffff);
}

590
int git_commit_graph_file_close(git_commit_graph_file *file)
591
{
592
	GIT_ASSERT_ARG(file);
593

594 595
	if (file->graph_map.data)
		git_futils_mmap_free(&file->graph_map);
596 597 598 599

	return 0;
}

600
void git_commit_graph_free(git_commit_graph *cgraph)
601 602 603 604
{
	if (!cgraph)
		return;

605
	git_str_dispose(&cgraph->filename);
606
	git_commit_graph_file_free(cgraph->file);
607 608
	git__free(cgraph);
}
609 610 611 612 613 614 615 616 617

void git_commit_graph_file_free(git_commit_graph_file *file)
{
	if (!file)
		return;

	git_commit_graph_file_close(file);
	git__free(file);
}
618 619 620 621 622 623 624 625 626 627 628 629 630

static int packed_commit__cmp(const void *a_, const void *b_)
{
	const struct packed_commit *a = a_;
	const struct packed_commit *b = b_;
	return git_oid_cmp(&a->sha1, &b->sha1);
}

int git_commit_graph_writer_new(git_commit_graph_writer **out, const char *objects_info_dir)
{
	git_commit_graph_writer *w = git__calloc(1, sizeof(git_commit_graph_writer));
	GIT_ERROR_CHECK_ALLOC(w);

631
	if (git_str_sets(&w->objects_info_dir, objects_info_dir) < 0) {
632 633 634 635 636
		git__free(w);
		return -1;
	}

	if (git_vector_init(&w->commits, 0, packed_commit__cmp) < 0) {
637
		git_str_dispose(&w->objects_info_dir);
638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656
		git__free(w);
		return -1;
	}

	*out = w;
	return 0;
}

void git_commit_graph_writer_free(git_commit_graph_writer *w)
{
	struct packed_commit *packed_commit;
	size_t i;

	if (!w)
		return;

	git_vector_foreach (&w->commits, i, packed_commit)
		packed_commit_free(packed_commit);
	git_vector_free(&w->commits);
657
	git_str_dispose(&w->objects_info_dir);
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
	git__free(w);
}

struct object_entry_cb_state {
	git_repository *repo;
	git_odb *db;
	git_vector *commits;
};

static int object_entry__cb(const git_oid *id, void *data)
{
	struct object_entry_cb_state *state = (struct object_entry_cb_state *)data;
	git_commit *commit = NULL;
	struct packed_commit *packed_commit = NULL;
	size_t header_len;
	git_object_t header_type;
	int error = 0;

	error = git_odb_read_header(&header_len, &header_type, state->db, id);
	if (error < 0)
		return error;

	if (header_type != GIT_OBJECT_COMMIT)
		return 0;

	error = git_commit_lookup(&commit, state->repo, id);
	if (error < 0)
		return error;

	packed_commit = packed_commit_new(commit);
	git_commit_free(commit);
	GIT_ERROR_CHECK_ALLOC(packed_commit);

	error = git_vector_insert(state->commits, packed_commit);
	if (error < 0) {
		packed_commit_free(packed_commit);
		return error;
	}

	return 0;
}

int git_commit_graph_writer_add_index_file(
		git_commit_graph_writer *w,
		git_repository *repo,
		const char *idx_path)
{
	int error;
	struct git_pack_file *p = NULL;
lhchavez committed
707 708 709
	struct object_entry_cb_state state = {0};
	state.repo = repo;
	state.commits = &w->commits;
710 711 712 713 714 715 716 717 718 719 720 721 722 723

	error = git_repository_odb(&state.db, repo);
	if (error < 0)
		goto cleanup;

	error = git_mwindow_get_pack(&p, idx_path);
	if (error < 0)
		goto cleanup;

	error = git_pack_foreach_entry(p, object_entry__cb, &state);
	if (error < 0)
		goto cleanup;

cleanup:
724 725
	if (p)
		git_mwindow_put_pack(p);
726 727 728 729 730 731 732 733 734 735
	git_odb_free(state.db);
	return error;
}

int git_commit_graph_writer_add_revwalk(git_commit_graph_writer *w, git_revwalk *walk)
{
	int error;
	git_oid id;
	git_repository *repo = git_revwalk_repository(walk);
	git_commit *commit;
736
	struct packed_commit *packed_commit;
737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760

	while ((git_revwalk_next(&id, walk)) == 0) {
		error = git_commit_lookup(&commit, repo, &id);
		if (error < 0)
			return error;

		packed_commit = packed_commit_new(commit);
		git_commit_free(commit);
		GIT_ERROR_CHECK_ALLOC(packed_commit);

		error = git_vector_insert(&w->commits, packed_commit);
		if (error < 0) {
			packed_commit_free(packed_commit);
			return error;
		}
	}

	return 0;
}

enum generation_number_commit_state {
	GENERATION_NUMBER_COMMIT_STATE_UNVISITED = 0,
	GENERATION_NUMBER_COMMIT_STATE_ADDED = 1,
	GENERATION_NUMBER_COMMIT_STATE_EXPANDED = 2,
761
	GENERATION_NUMBER_COMMIT_STATE_VISITED = 3
762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840
};

static int compute_generation_numbers(git_vector *commits)
{
	git_array_t(size_t) index_stack = GIT_ARRAY_INIT;
	size_t i, j;
	size_t *parent_idx;
	enum generation_number_commit_state *commit_states = NULL;
	struct packed_commit *child_packed_commit;
	git_oidmap *packed_commit_map = NULL;
	int error = 0;

	/* First populate the parent indices fields */
	error = git_oidmap_new(&packed_commit_map);
	if (error < 0)
		goto cleanup;
	git_vector_foreach (commits, i, child_packed_commit) {
		child_packed_commit->index = i;
		error = git_oidmap_set(
				packed_commit_map, &child_packed_commit->sha1, child_packed_commit);
		if (error < 0)
			goto cleanup;
	}

	git_vector_foreach (commits, i, child_packed_commit) {
		size_t parent_i, *parent_idx_ptr;
		struct packed_commit *parent_packed_commit;
		git_oid *parent_id;
		git_array_init_to_size(
				child_packed_commit->parent_indices,
				git_array_size(child_packed_commit->parents));
		if (git_array_size(child_packed_commit->parents)
		    && !child_packed_commit->parent_indices.ptr) {
			error = -1;
			goto cleanup;
		}
		git_array_foreach (child_packed_commit->parents, parent_i, parent_id) {
			parent_packed_commit = git_oidmap_get(packed_commit_map, parent_id);
			if (!parent_packed_commit) {
				git_error_set(GIT_ERROR_ODB,
					      "parent commit %s not found in commit graph",
					      git_oid_tostr_s(parent_id));
				error = GIT_ENOTFOUND;
				goto cleanup;
			}
			parent_idx_ptr = git_array_alloc(child_packed_commit->parent_indices);
			if (!parent_idx_ptr) {
				error = -1;
				goto cleanup;
			}
			*parent_idx_ptr = parent_packed_commit->index;
		}
	}

	/*
	 * We copy all the commits to the stack and then during visitation,
	 * each node can be added up to two times to the stack.
	 */
	git_array_init_to_size(index_stack, 3 * git_vector_length(commits));
	if (!index_stack.ptr) {
		error = -1;
		goto cleanup;
	}

	commit_states = (enum generation_number_commit_state *)git__calloc(
			git_vector_length(commits), sizeof(enum generation_number_commit_state));
	if (!commit_states) {
		error = -1;
		goto cleanup;
	}

	/*
	 * Perform a Post-Order traversal so that all parent nodes are fully
	 * visited before the child node.
	 */
	git_vector_foreach (commits, i, child_packed_commit)
		*(size_t *)git_array_alloc(index_stack) = i;

	while (git_array_size(index_stack)) {
841 842
		size_t *index_ptr = git_array_pop(index_stack);
		i = *index_ptr;
843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923
		child_packed_commit = git_vector_get(commits, i);

		if (commit_states[i] == GENERATION_NUMBER_COMMIT_STATE_VISITED) {
			/* This commit has already been fully visited. */
			continue;
		}
		if (commit_states[i] == GENERATION_NUMBER_COMMIT_STATE_EXPANDED) {
			/* All of the commits parents have been visited. */
			child_packed_commit->generation = 0;
			git_array_foreach (child_packed_commit->parent_indices, j, parent_idx) {
				struct packed_commit *parent = git_vector_get(commits, *parent_idx);
				if (child_packed_commit->generation < parent->generation)
					child_packed_commit->generation = parent->generation;
			}
			if (child_packed_commit->generation
			    < GIT_COMMIT_GRAPH_GENERATION_NUMBER_MAX) {
				++child_packed_commit->generation;
			}
			commit_states[i] = GENERATION_NUMBER_COMMIT_STATE_VISITED;
			continue;
		}

		/*
		 * This is the first time we see this commit. We need
		 * to visit all its parents before we can fully visit
		 * it.
		 */
		if (git_array_size(child_packed_commit->parent_indices) == 0) {
			/*
			 * Special case: if the commit has no parents, there's
			 * no need to add it to the stack just to immediately
			 * remove it.
			 */
			commit_states[i] = GENERATION_NUMBER_COMMIT_STATE_VISITED;
			child_packed_commit->generation = 1;
			continue;
		}

		/*
		 * Add this current commit again so that it is visited
		 * again once all its children have been visited.
		 */
		*(size_t *)git_array_alloc(index_stack) = i;
		git_array_foreach (child_packed_commit->parent_indices, j, parent_idx) {
			if (commit_states[*parent_idx]
			    != GENERATION_NUMBER_COMMIT_STATE_UNVISITED) {
				/* This commit has already been considered. */
				continue;
			}

			commit_states[*parent_idx] = GENERATION_NUMBER_COMMIT_STATE_ADDED;
			*(size_t *)git_array_alloc(index_stack) = *parent_idx;
		}
		commit_states[i] = GENERATION_NUMBER_COMMIT_STATE_EXPANDED;
	}

cleanup:
	git_oidmap_free(packed_commit_map);
	git__free(commit_states);
	git_array_clear(index_stack);

	return error;
}

static int write_offset(off64_t offset, commit_graph_write_cb write_cb, void *cb_data)
{
	int error;
	uint32_t word;

	word = htonl((uint32_t)((offset >> 32) & 0xffffffffu));
	error = write_cb((const char *)&word, sizeof(word), cb_data);
	if (error < 0)
		return error;
	word = htonl((uint32_t)((offset >> 0) & 0xffffffffu));
	error = write_cb((const char *)&word, sizeof(word), cb_data);
	if (error < 0)
		return error;

	return 0;
}

924 925 926 927 928
static int write_chunk_header(
		int chunk_id,
		off64_t offset,
		commit_graph_write_cb write_cb,
		void *cb_data)
929 930 931 932 933 934 935 936 937 938
{
	uint32_t word = htonl(chunk_id);
	int error = write_cb((const char *)&word, sizeof(word), cb_data);
	if (error < 0)
		return error;
	return write_offset(offset, write_cb, cb_data);
}

static int commit_graph_write_buf(const char *buf, size_t size, void *data)
{
939 940
	git_str *b = (git_str *)data;
	return git_str_put(b, buf, size);
941 942 943 944 945 946 947 948 949 950
}

struct commit_graph_write_hash_context {
	commit_graph_write_cb write_cb;
	void *cb_data;
	git_hash_ctx *ctx;
};

static int commit_graph_write_hash(const char *buf, size_t size, void *data)
{
lhchavez committed
951
	struct commit_graph_write_hash_context *ctx = data;
952 953 954 955 956 957 958 959 960 961 962 963 964 965
	int error;

	error = git_hash_update(ctx->ctx, buf, size);
	if (error < 0)
		return error;

	return ctx->write_cb(buf, size, ctx->cb_data);
}

static void packed_commit_free_dup(void *packed_commit)
{
	packed_commit_free(packed_commit);
}

966 967 968 969
static int commit_graph_write(
		git_commit_graph_writer *w,
		commit_graph_write_cb write_cb,
		void *cb_data)
970 971 972 973
{
	int error = 0;
	size_t i;
	struct packed_commit *packed_commit;
lhchavez committed
974
	struct git_commit_graph_header hdr = {0};
975 976 977 978
	uint32_t oid_fanout_count;
	uint32_t extra_edge_list_count;
	uint32_t oid_fanout[256];
	off64_t offset;
979 980
	git_str oid_lookup = GIT_STR_INIT, commit_data = GIT_STR_INIT,
		extra_edge_list = GIT_STR_INIT;
981 982
	unsigned char checksum[GIT_HASH_SHA1_SIZE];
	size_t checksum_size;
983
	git_hash_ctx ctx;
lhchavez committed
984 985 986 987 988 989 990 991 992 993
	struct commit_graph_write_hash_context hash_cb_data = {0};

	hdr.signature = htonl(COMMIT_GRAPH_SIGNATURE);
	hdr.version = COMMIT_GRAPH_VERSION;
	hdr.object_id_version = COMMIT_GRAPH_OBJECT_ID_VERSION;
	hdr.chunks = 0;
	hdr.base_graph_files = 0;
	hash_cb_data.write_cb = write_cb;
	hash_cb_data.cb_data = cb_data;
	hash_cb_data.ctx = &ctx;
994

995
	checksum_size = GIT_HASH_SHA1_SIZE;
996
	error = git_hash_ctx_init(&ctx, GIT_HASH_ALGORITHM_SHA1);
997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011
	if (error < 0)
		return error;
	cb_data = &hash_cb_data;
	write_cb = commit_graph_write_hash;

	/* Sort the commits. */
	git_vector_sort(&w->commits);
	git_vector_uniq(&w->commits, packed_commit_free_dup);
	error = compute_generation_numbers(&w->commits);
	if (error < 0)
		goto cleanup;

	/* Fill the OID Fanout table. */
	oid_fanout_count = 0;
	for (i = 0; i < 256; i++) {
1012 1013 1014
		while (oid_fanout_count < git_vector_length(&w->commits) &&
		       (packed_commit = (struct packed_commit *)git_vector_get(&w->commits, oid_fanout_count)) &&
		       packed_commit->sha1.id[0] <= i)
1015 1016 1017 1018 1019 1020
			++oid_fanout_count;
		oid_fanout[i] = htonl(oid_fanout_count);
	}

	/* Fill the OID Lookup table. */
	git_vector_foreach (&w->commits, i, packed_commit) {
1021
		error = git_str_put(&oid_lookup,
1022
			(const char *)&packed_commit->sha1.id,
1023
			GIT_OID_SHA1_SIZE);
1024

1025 1026 1027 1028 1029 1030 1031 1032 1033 1034
		if (error < 0)
			goto cleanup;
	}

	/* Fill the Commit Data and Extra Edge List tables. */
	extra_edge_list_count = 0;
	git_vector_foreach (&w->commits, i, packed_commit) {
		uint64_t commit_time;
		uint32_t generation;
		uint32_t word;
1035
		size_t *packed_index;
1036 1037
		unsigned int parentcount = (unsigned int)git_array_size(packed_commit->parents);

1038
		error = git_str_put(&commit_data,
1039
			(const char *)&packed_commit->tree_oid.id,
1040
			GIT_OID_SHA1_SIZE);
1041

1042 1043 1044
		if (error < 0)
			goto cleanup;

1045
		if (parentcount == 0) {
1046
			word = htonl(GIT_COMMIT_GRAPH_MISSING_PARENT);
1047 1048 1049 1050
		} else {
			packed_index = git_array_get(packed_commit->parent_indices, 0);
			word = htonl((uint32_t)*packed_index);
		}
1051
		error = git_str_put(&commit_data, (const char *)&word, sizeof(word));
1052 1053 1054
		if (error < 0)
			goto cleanup;

1055
		if (parentcount < 2) {
1056
			word = htonl(GIT_COMMIT_GRAPH_MISSING_PARENT);
1057 1058 1059 1060
		} else if (parentcount == 2) {
			packed_index = git_array_get(packed_commit->parent_indices, 1);
			word = htonl((uint32_t)*packed_index);
		} else {
1061
			word = htonl(0x80000000u | extra_edge_list_count);
1062
		}
1063
		error = git_str_put(&commit_data, (const char *)&word, sizeof(word));
1064 1065 1066 1067 1068 1069
		if (error < 0)
			goto cleanup;

		if (parentcount > 2) {
			unsigned int parent_i;
			for (parent_i = 1; parent_i < parentcount; ++parent_i) {
1070
				packed_index = git_array_get(
1071 1072 1073
					packed_commit->parent_indices, parent_i);
				word = htonl((uint32_t)(*packed_index | (parent_i + 1 == parentcount ? 0x80000000u : 0)));

1074
				error = git_str_put(&extra_edge_list,
lhchavez committed
1075 1076
						(const char *)&word,
						sizeof(word));
1077 1078 1079 1080 1081 1082 1083 1084 1085 1086
				if (error < 0)
					goto cleanup;
			}
			extra_edge_list_count += parentcount - 1;
		}

		generation = packed_commit->generation;
		commit_time = (uint64_t)packed_commit->commit_time;
		if (generation > GIT_COMMIT_GRAPH_GENERATION_NUMBER_MAX)
			generation = GIT_COMMIT_GRAPH_GENERATION_NUMBER_MAX;
1087
		word = ntohl((uint32_t)((generation << 2) | (((uint32_t)(commit_time >> 32)) & 0x3) ));
1088
		error = git_str_put(&commit_data, (const char *)&word, sizeof(word));
1089 1090
		if (error < 0)
			goto cleanup;
1091
		word = ntohl((uint32_t)(commit_time & 0xfffffffful));
1092
		error = git_str_put(&commit_data, (const char *)&word, sizeof(word));
1093 1094 1095 1096 1097 1098
		if (error < 0)
			goto cleanup;
	}

	/* Write the header. */
	hdr.chunks = 3;
1099
	if (git_str_len(&extra_edge_list) > 0)
1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113
		hdr.chunks++;
	error = write_cb((const char *)&hdr, sizeof(hdr), cb_data);
	if (error < 0)
		goto cleanup;

	/* Write the chunk headers. */
	offset = sizeof(hdr) + (hdr.chunks + 1) * 12;
	error = write_chunk_header(COMMIT_GRAPH_OID_FANOUT_ID, offset, write_cb, cb_data);
	if (error < 0)
		goto cleanup;
	offset += sizeof(oid_fanout);
	error = write_chunk_header(COMMIT_GRAPH_OID_LOOKUP_ID, offset, write_cb, cb_data);
	if (error < 0)
		goto cleanup;
1114
	offset += git_str_len(&oid_lookup);
1115 1116 1117
	error = write_chunk_header(COMMIT_GRAPH_COMMIT_DATA_ID, offset, write_cb, cb_data);
	if (error < 0)
		goto cleanup;
1118 1119
	offset += git_str_len(&commit_data);
	if (git_str_len(&extra_edge_list) > 0) {
1120 1121 1122 1123
		error = write_chunk_header(
				COMMIT_GRAPH_EXTRA_EDGE_LIST_ID, offset, write_cb, cb_data);
		if (error < 0)
			goto cleanup;
1124
		offset += git_str_len(&extra_edge_list);
1125 1126 1127 1128 1129 1130 1131 1132 1133
	}
	error = write_chunk_header(0, offset, write_cb, cb_data);
	if (error < 0)
		goto cleanup;

	/* Write all the chunks. */
	error = write_cb((const char *)oid_fanout, sizeof(oid_fanout), cb_data);
	if (error < 0)
		goto cleanup;
1134
	error = write_cb(git_str_cstr(&oid_lookup), git_str_len(&oid_lookup), cb_data);
1135 1136
	if (error < 0)
		goto cleanup;
1137
	error = write_cb(git_str_cstr(&commit_data), git_str_len(&commit_data), cb_data);
1138 1139
	if (error < 0)
		goto cleanup;
1140
	error = write_cb(git_str_cstr(&extra_edge_list), git_str_len(&extra_edge_list), cb_data);
1141 1142 1143 1144
	if (error < 0)
		goto cleanup;

	/* Finalize the checksum and write the trailer. */
1145
	error = git_hash_final(checksum, &ctx);
1146 1147
	if (error < 0)
		goto cleanup;
1148
	error = write_cb((char *)checksum, checksum_size, cb_data);
1149 1150 1151 1152
	if (error < 0)
		goto cleanup;

cleanup:
1153 1154 1155
	git_str_dispose(&oid_lookup);
	git_str_dispose(&commit_data);
	git_str_dispose(&extra_edge_list);
1156 1157 1158 1159 1160 1161 1162 1163 1164 1165
	git_hash_ctx_cleanup(&ctx);
	return error;
}

static int commit_graph_write_filebuf(const char *buf, size_t size, void *data)
{
	git_filebuf *f = (git_filebuf *)data;
	return git_filebuf_write(f, buf, size);
}

1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177
int git_commit_graph_writer_options_init(
	git_commit_graph_writer_options *opts,
	unsigned int version)
{
	GIT_INIT_STRUCTURE_FROM_TEMPLATE(
			opts,
			version,
			git_commit_graph_writer_options,
			GIT_COMMIT_GRAPH_WRITER_OPTIONS_INIT);
	return 0;
}

1178 1179 1180 1181 1182 1183
int git_commit_graph_writer_commit(
		git_commit_graph_writer *w,
		git_commit_graph_writer_options *opts)
{
	int error;
	int filebuf_flags = GIT_FILEBUF_DO_NOT_BUFFER;
1184
	git_str commit_graph_path = GIT_STR_INIT;
1185 1186
	git_filebuf output = GIT_FILEBUF_INIT;

1187
	/* TODO: support options and fill in defaults. */
1188 1189
	GIT_UNUSED(opts);

1190 1191
	error = git_str_joinpath(
			&commit_graph_path, git_str_cstr(&w->objects_info_dir), "commit-graph");
1192 1193 1194 1195 1196
	if (error < 0)
		return error;

	if (git_repository__fsync_gitdir)
		filebuf_flags |= GIT_FILEBUF_FSYNC;
1197 1198
	error = git_filebuf_open(&output, git_str_cstr(&commit_graph_path), filebuf_flags, 0644);
	git_str_dispose(&commit_graph_path);
1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211
	if (error < 0)
		return error;

	error = commit_graph_write(w, commit_graph_write_filebuf, &output);
	if (error < 0) {
		git_filebuf_cleanup(&output);
		return error;
	}

	return git_filebuf_commit(&output);
}

int git_commit_graph_writer_dump(
1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222
	git_buf *cgraph,
	git_commit_graph_writer *w,
	git_commit_graph_writer_options *opts)
{
	GIT_BUF_WRAP_PRIVATE(cgraph, git_commit_graph__writer_dump, w, opts);
}

int git_commit_graph__writer_dump(
	git_str *cgraph,
	git_commit_graph_writer *w,
	git_commit_graph_writer_options *opts)
1223
{
lhchavez committed
1224
	/* TODO: support options. */
1225 1226 1227
	GIT_UNUSED(opts);
	return commit_graph_write(w, commit_graph_write_buf, cgraph);
}