git@vger.kernel.org list mirror (unofficial, one of many)
 help / color / Atom feed
143999738e352088c774e513fb25611812615e3a blob 28734 bytes (raw)

   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
 708
 709
 710
 711
 712
 713
 714
 715
 716
 717
 718
 719
 720
 721
 722
 723
 724
 725
 726
 727
 728
 729
 730
 731
 732
 733
 734
 735
 736
 737
 738
 739
 740
 741
 742
 743
 744
 745
 746
 747
 748
 749
 750
 751
 752
 753
 754
 755
 756
 757
 758
 759
 760
 761
 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
 841
 842
 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
 924
 925
 926
 927
 928
 929
 930
 931
 932
 933
 934
 935
 936
 937
 938
 939
 940
 941
 942
 943
 944
 945
 946
 947
 948
 949
 950
 951
 952
 953
 954
 955
 956
 957
 958
 959
 960
 961
 962
 963
 964
 965
 966
 967
 968
 969
 970
 971
 972
 973
 974
 975
 976
 977
 978
 979
 980
 981
 982
 983
 984
 985
 986
 987
 988
 989
 990
 991
 992
 993
 994
 995
 996
 997
 998
 999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
 
/*
 * "git fast-export" builtin command
 *
 * Copyright (C) 2007 Johannes E. Schindelin
 */
#include "builtin.h"
#include "cache.h"
#include "config.h"
#include "refs.h"
#include "refspec.h"
#include "commit.h"
#include "object.h"
#include "tag.h"
#include "diff.h"
#include "diffcore.h"
#include "log-tree.h"
#include "revision.h"
#include "decorate.h"
#include "string-list.h"
#include "utf8.h"
#include "parse-options.h"
#include "quote.h"
#include "remote.h"
#include "blob.h"

static const char *fast_export_usage[] = {
	N_("git fast-export [rev-list-opts]"),
	NULL
};

static int progress;
static enum { ABORT, VERBATIM, WARN, WARN_STRIP, STRIP } signed_tag_mode = ABORT;
static enum { ERROR, DROP, REWRITE } tag_of_filtered_mode = ERROR;
static int fake_missing_tagger;
static int use_done_feature;
static int no_data;
static int full_tree;
static struct string_list extra_refs = STRING_LIST_INIT_NODUP;
static struct refspec refspecs = REFSPEC_INIT_FETCH;
static int anonymize;

static int parse_opt_signed_tag_mode(const struct option *opt,
				     const char *arg, int unset)
{
	if (unset || !strcmp(arg, "abort"))
		signed_tag_mode = ABORT;
	else if (!strcmp(arg, "verbatim") || !strcmp(arg, "ignore"))
		signed_tag_mode = VERBATIM;
	else if (!strcmp(arg, "warn"))
		signed_tag_mode = WARN;
	else if (!strcmp(arg, "warn-strip"))
		signed_tag_mode = WARN_STRIP;
	else if (!strcmp(arg, "strip"))
		signed_tag_mode = STRIP;
	else
		return error("Unknown signed-tags mode: %s", arg);
	return 0;
}

static int parse_opt_tag_of_filtered_mode(const struct option *opt,
					  const char *arg, int unset)
{
	if (unset || !strcmp(arg, "abort"))
		tag_of_filtered_mode = ERROR;
	else if (!strcmp(arg, "drop"))
		tag_of_filtered_mode = DROP;
	else if (!strcmp(arg, "rewrite"))
		tag_of_filtered_mode = REWRITE;
	else
		return error("Unknown tag-of-filtered mode: %s", arg);
	return 0;
}

static struct decoration idnums;
static uint32_t last_idnum;

static int has_unshown_parent(struct commit *commit)
{
	struct commit_list *parent;

	for (parent = commit->parents; parent; parent = parent->next)
		if (!(parent->item->object.flags & SHOWN) &&
		    !(parent->item->object.flags & UNINTERESTING))
			return 1;
	return 0;
}

struct anonymized_entry {
	struct hashmap_entry hash;
	const char *orig;
	size_t orig_len;
	const char *anon;
	size_t anon_len;
};

static int anonymized_entry_cmp(const void *unused_cmp_data,
				const void *va, const void *vb,
				const void *unused_keydata)
{
	const struct anonymized_entry *a = va, *b = vb;
	return a->orig_len != b->orig_len ||
		memcmp(a->orig, b->orig, a->orig_len);
}

/*
 * Basically keep a cache of X->Y so that we can repeatedly replace
 * the same anonymized string with another. The actual generation
 * is farmed out to the generate function.
 */
static const void *anonymize_mem(struct hashmap *map,
				 void *(*generate)(const void *, size_t *),
				 const void *orig, size_t *len)
{
	struct anonymized_entry key, *ret;

	if (!map->cmpfn)
		hashmap_init(map, anonymized_entry_cmp, NULL, 0);

	hashmap_entry_init(&key, memhash(orig, *len));
	key.orig = orig;
	key.orig_len = *len;
	ret = hashmap_get(map, &key, NULL);

	if (!ret) {
		ret = xmalloc(sizeof(*ret));
		hashmap_entry_init(&ret->hash, key.hash.hash);
		ret->orig = xstrdup(orig);
		ret->orig_len = *len;
		ret->anon = generate(orig, len);
		ret->anon_len = *len;
		hashmap_put(map, ret);
	}

	*len = ret->anon_len;
	return ret->anon;
}

/*
 * We anonymize each component of a path individually,
 * so that paths a/b and a/c will share a common root.
 * The paths are cached via anonymize_mem so that repeated
 * lookups for "a" will yield the same value.
 */
static void anonymize_path(struct strbuf *out, const char *path,
			   struct hashmap *map,
			   void *(*generate)(const void *, size_t *))
{
	while (*path) {
		const char *end_of_component = strchrnul(path, '/');
		size_t len = end_of_component - path;
		const char *c = anonymize_mem(map, generate, path, &len);
		strbuf_add(out, c, len);
		path = end_of_component;
		if (*path)
			strbuf_addch(out, *path++);
	}
}

/* Since intptr_t is C99, we do not use it here */
static inline uint32_t *mark_to_ptr(uint32_t mark)
{
	return ((uint32_t *)NULL) + mark;
}

static inline uint32_t ptr_to_mark(void * mark)
{
	return (uint32_t *)mark - (uint32_t *)NULL;
}

static inline void mark_object(struct object *object, uint32_t mark)
{
	add_decoration(&idnums, object, mark_to_ptr(mark));
}

static inline void mark_next_object(struct object *object)
{
	mark_object(object, ++last_idnum);
}

static int get_object_mark(struct object *object)
{
	void *decoration = lookup_decoration(&idnums, object);
	if (!decoration)
		return 0;
	return ptr_to_mark(decoration);
}

static void show_progress(void)
{
	static int counter = 0;
	if (!progress)
		return;
	if ((++counter % progress) == 0)
		printf("progress %d objects\n", counter);
}

/*
 * Ideally we would want some transformation of the blob data here
 * that is unreversible, but would still be the same size and have
 * the same data relationship to other blobs (so that we get the same
 * delta and packing behavior as the original). But the first and last
 * requirements there are probably mutually exclusive, so let's take
 * the easy way out for now, and just generate arbitrary content.
 *
 * There's no need to cache this result with anonymize_mem, since
 * we already handle blob content caching with marks.
 */
static char *anonymize_blob(unsigned long *size)
{
	static int counter;
	struct strbuf out = STRBUF_INIT;
	strbuf_addf(&out, "anonymous blob %d", counter++);
	*size = out.len;
	return strbuf_detach(&out, NULL);
}

static void export_blob(const struct object_id *oid)
{
	unsigned long size;
	enum object_type type;
	char *buf;
	struct object *object;
	int eaten;

	if (no_data)
		return;

	if (is_null_oid(oid))
		return;

	object = lookup_object(oid->hash);
	if (object && object->flags & SHOWN)
		return;

	if (anonymize) {
		buf = anonymize_blob(&size);
		object = (struct object *)lookup_blob(oid);
		eaten = 0;
	} else {
		buf = read_object_file(oid, &type, &size);
		if (!buf)
			die ("Could not read blob %s", oid_to_hex(oid));
		if (check_object_signature(oid, buf, size, type_name(type)) < 0)
			die("sha1 mismatch in blob %s", oid_to_hex(oid));
		object = parse_object_buffer(oid, type, size, buf, &eaten);
	}

	if (!object)
		die("Could not read blob %s", oid_to_hex(oid));

	mark_next_object(object);

	printf("blob\nmark :%"PRIu32"\ndata %lu\n", last_idnum, size);
	if (size && fwrite(buf, size, 1, stdout) != 1)
		die_errno ("Could not write blob '%s'", oid_to_hex(oid));
	printf("\n");

	show_progress();

	object->flags |= SHOWN;
	if (!eaten)
		free(buf);
}

static int depth_first(const void *a_, const void *b_)
{
	const struct diff_filepair *a = *((const struct diff_filepair **)a_);
	const struct diff_filepair *b = *((const struct diff_filepair **)b_);
	const char *name_a, *name_b;
	int len_a, len_b, len;
	int cmp;

	name_a = a->one ? a->one->path : a->two->path;
	name_b = b->one ? b->one->path : b->two->path;

	len_a = strlen(name_a);
	len_b = strlen(name_b);
	len = (len_a < len_b) ? len_a : len_b;

	/* strcmp will sort 'd' before 'd/e', we want 'd/e' before 'd' */
	cmp = memcmp(name_a, name_b, len);
	if (cmp)
		return cmp;
	cmp = len_b - len_a;
	if (cmp)
		return cmp;
	/*
	 * Move 'R'ename entries last so that all references of the file
	 * appear in the output before it is renamed (e.g., when a file
	 * was copied and renamed in the same commit).
	 */
	return (a->status == 'R') - (b->status == 'R');
}

static void print_path_1(const char *path)
{
	int need_quote = quote_c_style(path, NULL, NULL, 0);
	if (need_quote)
		quote_c_style(path, NULL, stdout, 0);
	else if (strchr(path, ' '))
		printf("\"%s\"", path);
	else
		printf("%s", path);
}

static void *anonymize_path_component(const void *path, size_t *len)
{
	static int counter;
	struct strbuf out = STRBUF_INIT;
	strbuf_addf(&out, "path%d", counter++);
	return strbuf_detach(&out, len);
}

static void print_path(const char *path)
{
	if (!anonymize)
		print_path_1(path);
	else {
		static struct hashmap paths;
		static struct strbuf anon = STRBUF_INIT;

		anonymize_path(&anon, path, &paths, anonymize_path_component);
		print_path_1(anon.buf);
		strbuf_reset(&anon);
	}
}

static void *generate_fake_oid(const void *old, size_t *len)
{
	static uint32_t counter = 1; /* avoid null sha1 */
	unsigned char *out = xcalloc(GIT_SHA1_RAWSZ, 1);
	put_be32(out + GIT_SHA1_RAWSZ - 4, counter++);
	return out;
}

static const unsigned char *anonymize_sha1(const struct object_id *oid)
{
	static struct hashmap sha1s;
	size_t len = GIT_SHA1_RAWSZ;
	return anonymize_mem(&sha1s, generate_fake_oid, oid, &len);
}

static void show_filemodify(struct diff_queue_struct *q,
			    struct diff_options *options, void *data)
{
	int i;
	struct string_list *changed = data;

	/*
	 * Handle files below a directory first, in case they are all deleted
	 * and the directory changes to a file or symlink.
	 */
	QSORT(q->queue, q->nr, depth_first);

	for (i = 0; i < q->nr; i++) {
		struct diff_filespec *ospec = q->queue[i]->one;
		struct diff_filespec *spec = q->queue[i]->two;

		switch (q->queue[i]->status) {
		case DIFF_STATUS_DELETED:
			printf("D ");
			print_path(spec->path);
			string_list_insert(changed, spec->path);
			putchar('\n');
			break;

		case DIFF_STATUS_COPIED:
		case DIFF_STATUS_RENAMED:
			/*
			 * If a change in the file corresponding to ospec->path
			 * has been observed, we cannot trust its contents
			 * because the diff is calculated based on the prior
			 * contents, not the current contents.  So, declare a
			 * copy or rename only if there was no change observed.
			 */
			if (!string_list_has_string(changed, ospec->path)) {
				printf("%c ", q->queue[i]->status);
				print_path(ospec->path);
				putchar(' ');
				print_path(spec->path);
				string_list_insert(changed, spec->path);
				putchar('\n');

				if (!oidcmp(&ospec->oid, &spec->oid) &&
				    ospec->mode == spec->mode)
					break;
			}
			/* fallthrough */

		case DIFF_STATUS_TYPE_CHANGED:
		case DIFF_STATUS_MODIFIED:
		case DIFF_STATUS_ADDED:
			/*
			 * Links refer to objects in another repositories;
			 * output the SHA-1 verbatim.
			 */
			if (no_data || S_ISGITLINK(spec->mode))
				printf("M %06o %s ", spec->mode,
				       sha1_to_hex(anonymize ?
						   anonymize_sha1(&spec->oid) :
						   spec->oid.hash));
			else {
				struct object *object = lookup_object(spec->oid.hash);
				printf("M %06o :%d ", spec->mode,
				       get_object_mark(object));
			}
			print_path(spec->path);
			string_list_insert(changed, spec->path);
			putchar('\n');
			break;

		default:
			die("Unexpected comparison status '%c' for %s, %s",
				q->queue[i]->status,
				ospec->path ? ospec->path : "none",
				spec->path ? spec->path : "none");
		}
	}
}

static const char *find_encoding(const char *begin, const char *end)
{
	const char *needle = "\nencoding ";
	char *bol, *eol;

	bol = memmem(begin, end ? end - begin : strlen(begin),
		     needle, strlen(needle));
	if (!bol)
		return git_commit_encoding;
	bol += strlen(needle);
	eol = strchrnul(bol, '\n');
	*eol = '\0';
	return bol;
}

static void *anonymize_ref_component(const void *old, size_t *len)
{
	static int counter;
	struct strbuf out = STRBUF_INIT;
	strbuf_addf(&out, "ref%d", counter++);
	return strbuf_detach(&out, len);
}

static const char *anonymize_refname(const char *refname)
{
	/*
	 * If any of these prefixes is found, we will leave it intact
	 * so that tags remain tags and so forth.
	 */
	static const char *prefixes[] = {
		"refs/heads/",
		"refs/tags/",
		"refs/remotes/",
		"refs/"
	};
	static struct hashmap refs;
	static struct strbuf anon = STRBUF_INIT;
	int i;

	/*
	 * We also leave "master" as a special case, since it does not reveal
	 * anything interesting.
	 */
	if (!strcmp(refname, "refs/heads/master"))
		return refname;

	strbuf_reset(&anon);
	for (i = 0; i < ARRAY_SIZE(prefixes); i++) {
		if (skip_prefix(refname, prefixes[i], &refname)) {
			strbuf_addstr(&anon, prefixes[i]);
			break;
		}
	}

	anonymize_path(&anon, refname, &refs, anonymize_ref_component);
	return anon.buf;
}

/*
 * We do not even bother to cache commit messages, as they are unlikely
 * to be repeated verbatim, and it is not that interesting when they are.
 */
static char *anonymize_commit_message(const char *old)
{
	static int counter;
	return xstrfmt("subject %d\n\nbody\n", counter++);
}

static struct hashmap idents;
static void *anonymize_ident(const void *old, size_t *len)
{
	static int counter;
	struct strbuf out = STRBUF_INIT;
	strbuf_addf(&out, "User %d <user%d@example.com>", counter, counter);
	counter++;
	return strbuf_detach(&out, len);
}

/*
 * Our strategy here is to anonymize the names and email addresses,
 * but keep timestamps intact, as they influence things like traversal
 * order (and by themselves should not be too revealing).
 */
static void anonymize_ident_line(const char **beg, const char **end)
{
	static struct strbuf buffers[] = { STRBUF_INIT, STRBUF_INIT };
	static unsigned which_buffer;

	struct strbuf *out;
	struct ident_split split;
	const char *end_of_header;

	out = &buffers[which_buffer++];
	which_buffer %= ARRAY_SIZE(buffers);
	strbuf_reset(out);

	/* skip "committer", "author", "tagger", etc */
	end_of_header = strchr(*beg, ' ');
	if (!end_of_header)
		die("BUG: malformed line fed to anonymize_ident_line: %.*s",
		    (int)(*end - *beg), *beg);
	end_of_header++;
	strbuf_add(out, *beg, end_of_header - *beg);

	if (!split_ident_line(&split, end_of_header, *end - end_of_header) &&
	    split.date_begin) {
		const char *ident;
		size_t len;

		len = split.mail_end - split.name_begin;
		ident = anonymize_mem(&idents, anonymize_ident,
				      split.name_begin, &len);
		strbuf_add(out, ident, len);
		strbuf_addch(out, ' ');
		strbuf_add(out, split.date_begin, split.tz_end - split.date_begin);
	} else {
		strbuf_addstr(out, "Malformed Ident <malformed@example.com> 0 -0000");
	}

	*beg = out->buf;
	*end = out->buf + out->len;
}

static void handle_commit(struct commit *commit, struct rev_info *rev,
			  struct string_list *paths_of_changed_objects)
{
	int saved_output_format = rev->diffopt.output_format;
	const char *commit_buffer;
	const char *author, *author_end, *committer, *committer_end;
	const char *encoding, *message;
	char *reencoded = NULL;
	struct commit_list *p;
	const char *refname;
	int i;

	rev->diffopt.output_format = DIFF_FORMAT_CALLBACK;

	parse_commit_or_die(commit);
	commit_buffer = get_commit_buffer(commit, NULL);
	author = strstr(commit_buffer, "\nauthor ");
	if (!author)
		die ("Could not find author in commit %s",
		     oid_to_hex(&commit->object.oid));
	author++;
	author_end = strchrnul(author, '\n');
	committer = strstr(author_end, "\ncommitter ");
	if (!committer)
		die ("Could not find committer in commit %s",
		     oid_to_hex(&commit->object.oid));
	committer++;
	committer_end = strchrnul(committer, '\n');
	message = strstr(committer_end, "\n\n");
	encoding = find_encoding(committer_end, message);
	if (message)
		message += 2;

	if (commit->parents &&
	    get_object_mark(&commit->parents->item->object) != 0 &&
	    !full_tree) {
		parse_commit_or_die(commit->parents->item);
		diff_tree_oid(&commit->parents->item->tree->object.oid,
			      &commit->tree->object.oid, "", &rev->diffopt);
	}
	else
		diff_root_tree_oid(&commit->tree->object.oid,
				   "", &rev->diffopt);

	/* Export the referenced blobs, and remember the marks. */
	for (i = 0; i < diff_queued_diff.nr; i++)
		if (!S_ISGITLINK(diff_queued_diff.queue[i]->two->mode))
			export_blob(&diff_queued_diff.queue[i]->two->oid);

	refname = commit->util;
	if (anonymize) {
		refname = anonymize_refname(refname);
		anonymize_ident_line(&committer, &committer_end);
		anonymize_ident_line(&author, &author_end);
	}

	mark_next_object(&commit->object);
	if (anonymize)
		reencoded = anonymize_commit_message(message);
	else if (!is_encoding_utf8(encoding))
		reencoded = reencode_string(message, "UTF-8", encoding);
	if (!commit->parents)
		printf("reset %s\n", refname);
	printf("commit %s\nmark :%"PRIu32"\n%.*s\n%.*s\ndata %u\n%s",
	       refname, last_idnum,
	       (int)(author_end - author), author,
	       (int)(committer_end - committer), committer,
	       (unsigned)(reencoded
			  ? strlen(reencoded) : message
			  ? strlen(message) : 0),
	       reencoded ? reencoded : message ? message : "");
	free(reencoded);
	unuse_commit_buffer(commit, commit_buffer);

	for (i = 0, p = commit->parents; p; p = p->next) {
		int mark = get_object_mark(&p->item->object);
		if (!mark)
			continue;
		if (i == 0)
			printf("from :%d\n", mark);
		else
			printf("merge :%d\n", mark);
		i++;
	}

	if (full_tree)
		printf("deleteall\n");
	log_tree_diff_flush(rev);
	string_list_clear(paths_of_changed_objects, 0);
	rev->diffopt.output_format = saved_output_format;

	printf("\n");

	show_progress();
}

static void *anonymize_tag(const void *old, size_t *len)
{
	static int counter;
	struct strbuf out = STRBUF_INIT;
	strbuf_addf(&out, "tag message %d", counter++);
	return strbuf_detach(&out, len);
}

static void handle_tail(struct object_array *commits, struct rev_info *revs,
			struct string_list *paths_of_changed_objects)
{
	struct commit *commit;
	while (commits->nr) {
		commit = (struct commit *)object_array_pop(commits);
		if (has_unshown_parent(commit)) {
			/* Queue again, to be handled later */
			add_object_array(&commit->object, NULL, commits);
			return;
		}
		handle_commit(commit, revs, paths_of_changed_objects);
	}
}

static void handle_tag(const char *name, struct tag *tag)
{
	unsigned long size;
	enum object_type type;
	char *buf;
	const char *tagger, *tagger_end, *message;
	size_t message_size = 0;
	struct object *tagged;
	int tagged_mark;
	struct commit *p;

	/* Trees have no identifier in fast-export output, thus we have no way
	 * to output tags of trees, tags of tags of trees, etc.  Simply omit
	 * such tags.
	 */
	tagged = tag->tagged;
	while (tagged->type == OBJ_TAG) {
		tagged = ((struct tag *)tagged)->tagged;
	}
	if (tagged->type == OBJ_TREE) {
		warning("Omitting tag %s,\nsince tags of trees (or tags of tags of trees, etc.) are not supported.",
			oid_to_hex(&tag->object.oid));
		return;
	}

	buf = read_object_file(&tag->object.oid, &type, &size);
	if (!buf)
		die ("Could not read tag %s", oid_to_hex(&tag->object.oid));
	message = memmem(buf, size, "\n\n", 2);
	if (message) {
		message += 2;
		message_size = strlen(message);
	}
	tagger = memmem(buf, message ? message - buf : size, "\ntagger ", 8);
	if (!tagger) {
		if (fake_missing_tagger)
			tagger = "tagger Unspecified Tagger "
				"<unspecified-tagger> 0 +0000";
		else
			tagger = "";
		tagger_end = tagger + strlen(tagger);
	} else {
		tagger++;
		tagger_end = strchrnul(tagger, '\n');
		if (anonymize)
			anonymize_ident_line(&tagger, &tagger_end);
	}

	if (anonymize) {
		name = anonymize_refname(name);
		if (message) {
			static struct hashmap tags;
			message = anonymize_mem(&tags, anonymize_tag,
						message, &message_size);
		}
	}

	/* handle signed tags */
	if (message) {
		const char *signature = strstr(message,
					       "\n-----BEGIN PGP SIGNATURE-----\n");
		if (signature)
			switch(signed_tag_mode) {
			case ABORT:
				die ("Encountered signed tag %s; use "
				     "--signed-tags=<mode> to handle it.",
				     oid_to_hex(&tag->object.oid));
			case WARN:
				warning ("Exporting signed tag %s",
					 oid_to_hex(&tag->object.oid));
				/* fallthru */
			case VERBATIM:
				break;
			case WARN_STRIP:
				warning ("Stripping signature from tag %s",
					 oid_to_hex(&tag->object.oid));
				/* fallthru */
			case STRIP:
				message_size = signature + 1 - message;
				break;
			}
	}

	/* handle tag->tagged having been filtered out due to paths specified */
	tagged = tag->tagged;
	tagged_mark = get_object_mark(tagged);
	if (!tagged_mark) {
		switch(tag_of_filtered_mode) {
		case ABORT:
			die ("Tag %s tags unexported object; use "
			     "--tag-of-filtered-object=<mode> to handle it.",
			     oid_to_hex(&tag->object.oid));
		case DROP:
			/* Ignore this tag altogether */
			free(buf);
			return;
		case REWRITE:
			if (tagged->type != OBJ_COMMIT) {
				die ("Tag %s tags unexported %s!",
				     oid_to_hex(&tag->object.oid),
				     type_name(tagged->type));
			}
			p = (struct commit *)tagged;
			for (;;) {
				if (p->parents && p->parents->next)
					break;
				if (p->object.flags & UNINTERESTING)
					break;
				if (!(p->object.flags & TREESAME))
					break;
				if (!p->parents)
					die ("Can't find replacement commit for tag %s\n",
					     oid_to_hex(&tag->object.oid));
				p = p->parents->item;
			}
			tagged_mark = get_object_mark(&p->object);
		}
	}

	if (starts_with(name, "refs/tags/"))
		name += 10;
	printf("tag %s\nfrom :%d\n%.*s%sdata %d\n%.*s\n",
	       name, tagged_mark,
	       (int)(tagger_end - tagger), tagger,
	       tagger == tagger_end ? "" : "\n",
	       (int)message_size, (int)message_size, message ? message : "");
	free(buf);
}

static struct commit *get_commit(struct rev_cmdline_entry *e, char *full_name)
{
	switch (e->item->type) {
	case OBJ_COMMIT:
		return (struct commit *)e->item;
	case OBJ_TAG: {
		struct tag *tag = (struct tag *)e->item;

		/* handle nested tags */
		while (tag && tag->object.type == OBJ_TAG) {
			parse_object(&tag->object.oid);
			string_list_append(&extra_refs, full_name)->util = tag;
			tag = (struct tag *)tag->tagged;
		}
		if (!tag)
			die("Tag %s points nowhere?", e->name);
		return (struct commit *)tag;
		break;
	}
	default:
		return NULL;
	}
}

static void get_tags_and_duplicates(struct rev_cmdline_info *info)
{
	int i;

	for (i = 0; i < info->nr; i++) {
		struct rev_cmdline_entry *e = info->rev + i;
		struct object_id oid;
		struct commit *commit;
		char *full_name;

		if (e->flags & UNINTERESTING)
			continue;

		if (dwim_ref(e->name, strlen(e->name), &oid, &full_name) != 1)
			continue;

		if (refspecs.nr) {
			char *private;
			private = apply_refspecs(refspecs.items, refspecs.nr, full_name);
			if (private) {
				free(full_name);
				full_name = private;
			}
		}

		commit = get_commit(e, full_name);
		if (!commit) {
			warning("%s: Unexpected object of type %s, skipping.",
				e->name,
				type_name(e->item->type));
			continue;
		}

		switch(commit->object.type) {
		case OBJ_COMMIT:
			break;
		case OBJ_BLOB:
			export_blob(&commit->object.oid);
			continue;
		default: /* OBJ_TAG (nested tags) is already handled */
			warning("Tag points to object of unexpected type %s, skipping.",
				type_name(commit->object.type));
			continue;
		}

		/*
		 * This ref will not be updated through a commit, lets make
		 * sure it gets properly updated eventually.
		 */
		if (commit->util || commit->object.flags & SHOWN)
			string_list_append(&extra_refs, full_name)->util = commit;
		if (!commit->util)
			commit->util = full_name;
	}
}

static void handle_tags_and_duplicates(void)
{
	struct commit *commit;
	int i;

	for (i = extra_refs.nr - 1; i >= 0; i--) {
		const char *name = extra_refs.items[i].string;
		struct object *object = extra_refs.items[i].util;
		switch (object->type) {
		case OBJ_TAG:
			handle_tag(name, (struct tag *)object);
			break;
		case OBJ_COMMIT:
			if (anonymize)
				name = anonymize_refname(name);
			/* create refs pointing to already seen commits */
			commit = (struct commit *)object;
			printf("reset %s\nfrom :%d\n\n", name,
			       get_object_mark(&commit->object));
			show_progress();
			break;
		}
	}
}

static void export_marks(char *file)
{
	unsigned int i;
	uint32_t mark;
	struct decoration_entry *deco = idnums.entries;
	FILE *f;
	int e = 0;

	f = fopen_for_writing(file);
	if (!f)
		die_errno("Unable to open marks file %s for writing.", file);

	for (i = 0; i < idnums.size; i++) {
		if (deco->base && deco->base->type == 1) {
			mark = ptr_to_mark(deco->decoration);
			if (fprintf(f, ":%"PRIu32" %s\n", mark,
				oid_to_hex(&deco->base->oid)) < 0) {
			    e = 1;
			    break;
			}
		}
		deco++;
	}

	e |= ferror(f);
	e |= fclose(f);
	if (e)
		error("Unable to write marks file %s.", file);
}

static void import_marks(char *input_file)
{
	char line[512];
	FILE *f = xfopen(input_file, "r");

	while (fgets(line, sizeof(line), f)) {
		uint32_t mark;
		char *line_end, *mark_end;
		struct object_id oid;
		struct object *object;
		struct commit *commit;
		enum object_type type;

		line_end = strchr(line, '\n');
		if (line[0] != ':' || !line_end)
			die("corrupt mark line: %s", line);
		*line_end = '\0';

		mark = strtoumax(line + 1, &mark_end, 10);
		if (!mark || mark_end == line + 1
			|| *mark_end != ' ' || get_oid_hex(mark_end + 1, &oid))
			die("corrupt mark line: %s", line);

		if (last_idnum < mark)
			last_idnum = mark;

		type = oid_object_info(&oid, NULL);
		if (type < 0)
			die("object not found: %s", oid_to_hex(&oid));

		if (type != OBJ_COMMIT)
			/* only commits */
			continue;

		commit = lookup_commit(&oid);
		if (!commit)
			die("not a commit? can't happen: %s", oid_to_hex(&oid));

		object = &commit->object;

		if (object->flags & SHOWN)
			error("Object %s already has a mark", oid_to_hex(&oid));

		mark_object(object, mark);

		object->flags |= SHOWN;
	}
	fclose(f);
}

static void handle_deletes(void)
{
	int i;
	for (i = 0; i < refspecs.nr; i++) {
		struct refspec_item *refspec = &refspecs.items[i];
		if (*refspec->src)
			continue;

		printf("reset %s\nfrom %s\n\n",
				refspec->dst, sha1_to_hex(null_sha1));
	}
}

int cmd_fast_export(int argc, const char **argv, const char *prefix)
{
	struct rev_info revs;
	struct object_array commits = OBJECT_ARRAY_INIT;
	struct commit *commit;
	char *export_filename = NULL, *import_filename = NULL;
	uint32_t lastimportid;
	struct string_list refspecs_list = STRING_LIST_INIT_NODUP;
	struct string_list paths_of_changed_objects = STRING_LIST_INIT_DUP;
	struct option options[] = {
		OPT_INTEGER(0, "progress", &progress,
			    N_("show progress after <n> objects")),
		OPT_CALLBACK(0, "signed-tags", &signed_tag_mode, N_("mode"),
			     N_("select handling of signed tags"),
			     parse_opt_signed_tag_mode),
		OPT_CALLBACK(0, "tag-of-filtered-object", &tag_of_filtered_mode, N_("mode"),
			     N_("select handling of tags that tag filtered objects"),
			     parse_opt_tag_of_filtered_mode),
		OPT_STRING(0, "export-marks", &export_filename, N_("file"),
			     N_("Dump marks to this file")),
		OPT_STRING(0, "import-marks", &import_filename, N_("file"),
			     N_("Import marks from this file")),
		OPT_BOOL(0, "fake-missing-tagger", &fake_missing_tagger,
			 N_("Fake a tagger when tags lack one")),
		OPT_BOOL(0, "full-tree", &full_tree,
			 N_("Output full tree for each commit")),
		OPT_BOOL(0, "use-done-feature", &use_done_feature,
			     N_("Use the done feature to terminate the stream")),
		OPT_BOOL(0, "no-data", &no_data, N_("Skip output of blob data")),
		OPT_STRING_LIST(0, "refspec", &refspecs_list, N_("refspec"),
			     N_("Apply refspec to exported refs")),
		OPT_BOOL(0, "anonymize", &anonymize, N_("anonymize output")),
		OPT_END()
	};

	if (argc == 1)
		usage_with_options (fast_export_usage, options);

	/* we handle encodings */
	git_config(git_default_config, NULL);

	init_revisions(&revs, prefix);
	revs.topo_order = 1;
	revs.show_source = 1;
	revs.rewrite_parents = 1;
	argc = parse_options(argc, argv, prefix, options, fast_export_usage,
			PARSE_OPT_KEEP_ARGV0 | PARSE_OPT_KEEP_UNKNOWN);
	argc = setup_revisions(argc, argv, &revs, NULL);
	if (argc > 1)
		usage_with_options (fast_export_usage, options);

	if (refspecs_list.nr) {
		int i;

		for (i = 0; i < refspecs_list.nr; i++)
			refspec_append(&refspecs, refspecs_list.items[i].string);

		string_list_clear(&refspecs_list, 1);
	}

	if (use_done_feature)
		printf("feature done\n");

	if (import_filename)
		import_marks(import_filename);
	lastimportid = last_idnum;

	if (import_filename && revs.prune_data.nr)
		full_tree = 1;

	get_tags_and_duplicates(&revs.cmdline);

	if (prepare_revision_walk(&revs))
		die("revision walk setup failed");
	revs.diffopt.format_callback = show_filemodify;
	revs.diffopt.format_callback_data = &paths_of_changed_objects;
	revs.diffopt.flags.recursive = 1;
	while ((commit = get_revision(&revs))) {
		if (has_unshown_parent(commit)) {
			add_object_array(&commit->object, NULL, &commits);
		}
		else {
			handle_commit(commit, &revs, &paths_of_changed_objects);
			handle_tail(&commits, &revs, &paths_of_changed_objects);
		}
	}

	handle_tags_and_duplicates();
	handle_deletes();

	if (export_filename && lastimportid != last_idnum)
		export_marks(export_filename);

	if (use_done_feature)
		printf("done\n");

	refspec_clear(&refspecs);

	return 0;
}
debug log:

solving 143999738 ...
found 143999738 in https://80x24.org/mirrors/git.git

git@vger.kernel.org list mirror (unofficial, one of many)

Archives are clonable:
	git clone --mirror https://public-inbox.org/git
	git clone --mirror http://ou63pmih66umazou.onion/git
	git clone --mirror http://czquwvybam4bgbro.onion/git
	git clone --mirror http://hjrcffqmbrq6wope.onion/git

Example config snippet for mirrors

Newsgroups are available over NNTP:
	nntp://news.public-inbox.org/inbox.comp.version-control.git
	nntp://ou63pmih66umazou.onion/inbox.comp.version-control.git
	nntp://czquwvybam4bgbro.onion/inbox.comp.version-control.git
	nntp://hjrcffqmbrq6wope.onion/inbox.comp.version-control.git
	nntp://news.gmane.org/gmane.comp.version-control.git

 note: .onion URLs require Tor: https://www.torproject.org/

AGPL code for this site: git clone https://public-inbox.org/public-inbox.git