This file is indexed.

/usr/lib/python2.7/dist-packages/dulwich/client.py is in python-dulwich 0.9.7-3.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below.

   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
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
# client.py -- Implementation of the server side git protocols
# Copyright (C) 2008-2013 Jelmer Vernooij <jelmer@samba.org>
# Copyright (C) 2008 John Carr
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# or (at your option) a later version of the License.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
# MA  02110-1301, USA.

"""Client side support for the Git protocol.

The Dulwich client supports the following capabilities:

 * thin-pack
 * multi_ack_detailed
 * multi_ack
 * side-band-64k
 * ofs-delta
 * report-status
 * delete-refs

Known capabilities that are not supported:

 * shallow
 * no-progress
 * include-tag
"""

__docformat__ = 'restructuredText'

from io import BytesIO
import dulwich
import select
import socket
import subprocess
import urllib2
import urlparse

from dulwich.errors import (
    GitProtocolError,
    NotGitRepository,
    SendPackError,
    UpdateRefsError,
    )
from dulwich.protocol import (
    _RBUFSIZE,
    PktLineParser,
    Protocol,
    ProtocolFile,
    TCP_GIT_PORT,
    ZERO_SHA,
    extract_capabilities,
    )
from dulwich.pack import (
    write_pack_objects,
    )
from dulwich.refs import (
    read_info_refs,
    )


def _fileno_can_read(fileno):
    """Check if a file descriptor is readable."""
    return len(select.select([fileno], [], [], 0)[0]) > 0

COMMON_CAPABILITIES = ['ofs-delta', 'side-band-64k']
FETCH_CAPABILITIES = (['thin-pack', 'multi_ack', 'multi_ack_detailed'] +
                      COMMON_CAPABILITIES)
SEND_CAPABILITIES = ['report-status'] + COMMON_CAPABILITIES


class ReportStatusParser(object):
    """Handle status as reported by servers with 'report-status' capability.
    """

    def __init__(self):
        self._done = False
        self._pack_status = None
        self._ref_status_ok = True
        self._ref_statuses = []

    def check(self):
        """Check if there were any errors and, if so, raise exceptions.

        :raise SendPackError: Raised when the server could not unpack
        :raise UpdateRefsError: Raised when refs could not be updated
        """
        if self._pack_status not in ('unpack ok', None):
            raise SendPackError(self._pack_status)
        if not self._ref_status_ok:
            ref_status = {}
            ok = set()
            for status in self._ref_statuses:
                if ' ' not in status:
                    # malformed response, move on to the next one
                    continue
                status, ref = status.split(' ', 1)

                if status == 'ng':
                    if ' ' in ref:
                        ref, status = ref.split(' ', 1)
                else:
                    ok.add(ref)
                ref_status[ref] = status
            raise UpdateRefsError('%s failed to update' %
                                  ', '.join([ref for ref in ref_status
                                             if ref not in ok]),
                                  ref_status=ref_status)

    def handle_packet(self, pkt):
        """Handle a packet.

        :raise GitProtocolError: Raised when packets are received after a
            flush packet.
        """
        if self._done:
            raise GitProtocolError("received more data after status report")
        if pkt is None:
            self._done = True
            return
        if self._pack_status is None:
            self._pack_status = pkt.strip()
        else:
            ref_status = pkt.strip()
            self._ref_statuses.append(ref_status)
            if not ref_status.startswith('ok '):
                self._ref_status_ok = False


def read_pkt_refs(proto):
    server_capabilities = None
    refs = {}
    # Receive refs from server
    for pkt in proto.read_pkt_seq():
        (sha, ref) = pkt.rstrip('\n').split(None, 1)
        if sha == 'ERR':
            raise GitProtocolError(ref)
        if server_capabilities is None:
            (ref, server_capabilities) = extract_capabilities(ref)
        refs[ref] = sha

    if len(refs) == 0:
        return None, set([])
    return refs, set(server_capabilities)


# TODO(durin42): this doesn't correctly degrade if the server doesn't
# support some capabilities. This should work properly with servers
# that don't support multi_ack.
class GitClient(object):
    """Git smart server client.

    """

    def __init__(self, thin_packs=True, report_activity=None):
        """Create a new GitClient instance.

        :param thin_packs: Whether or not thin packs should be retrieved
        :param report_activity: Optional callback for reporting transport
            activity.
        """
        self._report_activity = report_activity
        self._report_status_parser = None
        self._fetch_capabilities = set(FETCH_CAPABILITIES)
        self._send_capabilities = set(SEND_CAPABILITIES)
        if not thin_packs:
            self._fetch_capabilities.remove('thin-pack')

    def send_pack(self, path, determine_wants, generate_pack_contents,
                  progress=None):
        """Upload a pack to a remote repository.

        :param path: Repository path
        :param generate_pack_contents: Function that can return a sequence of
            the shas of the objects to upload.
        :param progress: Optional progress function

        :raises SendPackError: if server rejects the pack data
        :raises UpdateRefsError: if the server supports report-status
                                 and rejects ref updates
        """
        raise NotImplementedError(self.send_pack)

    def fetch(self, path, target, determine_wants=None, progress=None):
        """Fetch into a target repository.

        :param path: Path to fetch from
        :param target: Target repository to fetch into
        :param determine_wants: Optional function to determine what refs
            to fetch
        :param progress: Optional progress function
        :return: remote refs as dictionary
        """
        if determine_wants is None:
            determine_wants = target.object_store.determine_wants_all
        f, commit, abort = target.object_store.add_pack()
        try:
            result = self.fetch_pack(
                path, determine_wants, target.get_graph_walker(), f.write,
                progress)
        except:
            abort()
            raise
        else:
            commit()
        return result

    def fetch_pack(self, path, determine_wants, graph_walker, pack_data,
                   progress=None):
        """Retrieve a pack from a git smart server.

        :param determine_wants: Callback that returns list of commits to fetch
        :param graph_walker: Object with next() and ack().
        :param pack_data: Callback called for each bit of data in the pack
        :param progress: Callback for progress reports (strings)
        """
        raise NotImplementedError(self.fetch_pack)

    def _parse_status_report(self, proto):
        unpack = proto.read_pkt_line().strip()
        if unpack != 'unpack ok':
            st = True
            # flush remaining error data
            while st is not None:
                st = proto.read_pkt_line()
            raise SendPackError(unpack)
        statuses = []
        errs = False
        ref_status = proto.read_pkt_line()
        while ref_status:
            ref_status = ref_status.strip()
            statuses.append(ref_status)
            if not ref_status.startswith('ok '):
                errs = True
            ref_status = proto.read_pkt_line()

        if errs:
            ref_status = {}
            ok = set()
            for status in statuses:
                if ' ' not in status:
                    # malformed response, move on to the next one
                    continue
                status, ref = status.split(' ', 1)

                if status == 'ng':
                    if ' ' in ref:
                        ref, status = ref.split(' ', 1)
                else:
                    ok.add(ref)
                ref_status[ref] = status
            raise UpdateRefsError('%s failed to update' %
                                  ', '.join([ref for ref in ref_status
                                             if ref not in ok]),
                                  ref_status=ref_status)

    def _read_side_band64k_data(self, proto, channel_callbacks):
        """Read per-channel data.

        This requires the side-band-64k capability.

        :param proto: Protocol object to read from
        :param channel_callbacks: Dictionary mapping channels to packet
            handlers to use. None for a callback discards channel data.
        """
        for pkt in proto.read_pkt_seq():
            channel = ord(pkt[0])
            pkt = pkt[1:]
            try:
                cb = channel_callbacks[channel]
            except KeyError:
                raise AssertionError('Invalid sideband channel %d' % channel)
            else:
                if cb is not None:
                    cb(pkt)

    def _handle_receive_pack_head(self, proto, capabilities, old_refs,
                                  new_refs):
        """Handle the head of a 'git-receive-pack' request.

        :param proto: Protocol object to read from
        :param capabilities: List of negotiated capabilities
        :param old_refs: Old refs, as received from the server
        :param new_refs: New refs
        :return: (have, want) tuple
        """
        want = []
        have = [x for x in old_refs.values() if not x == ZERO_SHA]
        sent_capabilities = False

        for refname in set(new_refs.keys() + old_refs.keys()):
            old_sha1 = old_refs.get(refname, ZERO_SHA)
            new_sha1 = new_refs.get(refname, ZERO_SHA)

            if old_sha1 != new_sha1:
                if sent_capabilities:
                    proto.write_pkt_line('%s %s %s' % (
                        old_sha1, new_sha1, refname))
                else:
                    proto.write_pkt_line(
                        '%s %s %s\0%s' % (old_sha1, new_sha1, refname,
                                          ' '.join(capabilities)))
                    sent_capabilities = True
            if new_sha1 not in have and new_sha1 != ZERO_SHA:
                want.append(new_sha1)
        proto.write_pkt_line(None)
        return (have, want)

    def _handle_receive_pack_tail(self, proto, capabilities, progress=None):
        """Handle the tail of a 'git-receive-pack' request.

        :param proto: Protocol object to read from
        :param capabilities: List of negotiated capabilities
        :param progress: Optional progress reporting function
        """
        if "side-band-64k" in capabilities:
            if progress is None:
                progress = lambda x: None
            channel_callbacks = {2: progress}
            if 'report-status' in capabilities:
                channel_callbacks[1] = PktLineParser(
                    self._report_status_parser.handle_packet).parse
            self._read_side_band64k_data(proto, channel_callbacks)
        else:
            if 'report-status' in capabilities:
                for pkt in proto.read_pkt_seq():
                    self._report_status_parser.handle_packet(pkt)
        if self._report_status_parser is not None:
            self._report_status_parser.check()

    def _handle_upload_pack_head(self, proto, capabilities, graph_walker,
                                 wants, can_read):
        """Handle the head of a 'git-upload-pack' request.

        :param proto: Protocol object to read from
        :param capabilities: List of negotiated capabilities
        :param graph_walker: GraphWalker instance to call .ack() on
        :param wants: List of commits to fetch
        :param can_read: function that returns a boolean that indicates
            whether there is extra graph data to read on proto
        """
        assert isinstance(wants, list) and isinstance(wants[0], str)
        proto.write_pkt_line('want %s %s\n' % (
            wants[0], ' '.join(capabilities)))
        for want in wants[1:]:
            proto.write_pkt_line('want %s\n' % want)
        proto.write_pkt_line(None)
        have = next(graph_walker)
        while have:
            proto.write_pkt_line('have %s\n' % have)
            if can_read():
                pkt = proto.read_pkt_line()
                parts = pkt.rstrip('\n').split(' ')
                if parts[0] == 'ACK':
                    graph_walker.ack(parts[1])
                    if parts[2] in ('continue', 'common'):
                        pass
                    elif parts[2] == 'ready':
                        break
                    else:
                        raise AssertionError(
                            "%s not in ('continue', 'ready', 'common)" %
                            parts[2])
            have = next(graph_walker)
        proto.write_pkt_line('done\n')

    def _handle_upload_pack_tail(self, proto, capabilities, graph_walker,
                                 pack_data, progress=None, rbufsize=_RBUFSIZE):
        """Handle the tail of a 'git-upload-pack' request.

        :param proto: Protocol object to read from
        :param capabilities: List of negotiated capabilities
        :param graph_walker: GraphWalker instance to call .ack() on
        :param pack_data: Function to call with pack data
        :param progress: Optional progress reporting function
        :param rbufsize: Read buffer size
        """
        pkt = proto.read_pkt_line()
        while pkt:
            parts = pkt.rstrip('\n').split(' ')
            if parts[0] == 'ACK':
                graph_walker.ack(pkt.split(' ')[1])
            if len(parts) < 3 or parts[2] not in (
                    'ready', 'continue', 'common'):
                break
            pkt = proto.read_pkt_line()
        if "side-band-64k" in capabilities:
            if progress is None:
                # Just ignore progress data
                progress = lambda x: None
            self._read_side_band64k_data(proto, {1: pack_data, 2: progress})
        else:
            while True:
                data = proto.read(rbufsize)
                if data == "":
                    break
                pack_data(data)


class TraditionalGitClient(GitClient):
    """Traditional Git client."""

    def _connect(self, cmd, path):
        """Create a connection to the server.

        This method is abstract - concrete implementations should
        implement their own variant which connects to the server and
        returns an initialized Protocol object with the service ready
        for use and a can_read function which may be used to see if
        reads would block.

        :param cmd: The git service name to which we should connect.
        :param path: The path we should pass to the service.
        """
        raise NotImplementedError()

    def send_pack(self, path, determine_wants, generate_pack_contents,
                  progress=None):
        """Upload a pack to a remote repository.

        :param path: Repository path
        :param generate_pack_contents: Function that can return a sequence of
            the shas of the objects to upload.
        :param progress: Optional callback called with progress updates

        :raises SendPackError: if server rejects the pack data
        :raises UpdateRefsError: if the server supports report-status
                                 and rejects ref updates
        """
        proto, unused_can_read = self._connect('receive-pack', path)
        with proto:
            old_refs, server_capabilities = read_pkt_refs(proto)
            negotiated_capabilities = self._send_capabilities & server_capabilities

            if 'report-status' in negotiated_capabilities:
                self._report_status_parser = ReportStatusParser()
            report_status_parser = self._report_status_parser

            try:
                new_refs = orig_new_refs = determine_wants(dict(old_refs))
            except:
                proto.write_pkt_line(None)
                raise

            if not 'delete-refs' in server_capabilities:
                # Server does not support deletions. Fail later.
                def remove_del(pair):
                    if pair[1] == ZERO_SHA:
                        if 'report-status' in negotiated_capabilities:
                            report_status_parser._ref_statuses.append(
                                'ng %s remote does not support deleting refs'
                                % pair[1])
                            report_status_parser._ref_status_ok = False
                        return False
                    else:
                        return True

                new_refs = dict(
                    filter(
                        remove_del,
                        [(ref, sha) for ref, sha in new_refs.iteritems()]))

            if new_refs is None:
                proto.write_pkt_line(None)
                return old_refs

            if len(new_refs) == 0 and len(orig_new_refs):
                # NOOP - Original new refs filtered out by policy
                proto.write_pkt_line(None)
                if self._report_status_parser is not None:
                    self._report_status_parser.check()
                return old_refs

            (have, want) = self._handle_receive_pack_head(
                proto, negotiated_capabilities, old_refs, new_refs)
            if not want and old_refs == new_refs:
                return new_refs
            objects = generate_pack_contents(have, want)
            if len(objects) > 0:
                entries, sha = write_pack_objects(proto.write_file(), objects)
            elif len(set(new_refs.values()) - set([ZERO_SHA])) > 0:
                # Check for valid create/update refs
                filtered_new_refs = \
                    dict([(ref, sha) for ref, sha in new_refs.iteritems()
                         if sha != ZERO_SHA])
                if len(set(filtered_new_refs.iteritems()) -
                        set(old_refs.iteritems())) > 0:
                    entries, sha = write_pack_objects(proto.write_file(), objects)

            self._handle_receive_pack_tail(
                proto, negotiated_capabilities, progress)
            return new_refs

    def fetch_pack(self, path, determine_wants, graph_walker, pack_data,
                   progress=None):
        """Retrieve a pack from a git smart server.

        :param determine_wants: Callback that returns list of commits to fetch
        :param graph_walker: Object with next() and ack().
        :param pack_data: Callback called for each bit of data in the pack
        :param progress: Callback for progress reports (strings)
        """
        proto, can_read = self._connect('upload-pack', path)
        with proto:
            refs, server_capabilities = read_pkt_refs(proto)
            negotiated_capabilities = (
                self._fetch_capabilities & server_capabilities)

            if refs is None:
                proto.write_pkt_line(None)
                return refs

            try:
                wants = determine_wants(refs)
            except:
                proto.write_pkt_line(None)
                raise
            if wants is not None:
                wants = [cid for cid in wants if cid != ZERO_SHA]
            if not wants:
                proto.write_pkt_line(None)
                return refs
            self._handle_upload_pack_head(
                proto, negotiated_capabilities, graph_walker, wants, can_read)
            self._handle_upload_pack_tail(
                proto, negotiated_capabilities, graph_walker, pack_data, progress)
            return refs

    def archive(self, path, committish, write_data, progress=None,
                write_error=None):
        proto, can_read = self._connect(b'upload-archive', path)
        with proto:
            proto.write_pkt_line("argument %s" % committish)
            proto.write_pkt_line(None)
            pkt = proto.read_pkt_line()
            if pkt == "NACK\n":
                return
            elif pkt == "ACK\n":
                pass
            elif pkt.startswith("ERR "):
                raise GitProtocolError(pkt[4:].rstrip("\n"))
            else:
                raise AssertionError("invalid response %r" % pkt)
            ret = proto.read_pkt_line()
            if ret is not None:
                raise AssertionError("expected pkt tail")
            self._read_side_band64k_data(proto, {
                1: write_data, 2: progress, 3: write_error})


class TCPGitClient(TraditionalGitClient):
    """A Git Client that works over TCP directly (i.e. git://)."""

    def __init__(self, host, port=None, *args, **kwargs):
        if port is None:
            port = TCP_GIT_PORT
        self._host = host
        self._port = port
        TraditionalGitClient.__init__(self, *args, **kwargs)

    def _connect(self, cmd, path):
        sockaddrs = socket.getaddrinfo(
            self._host, self._port, socket.AF_UNSPEC, socket.SOCK_STREAM)
        s = None
        err = socket.error("no address found for %s" % self._host)
        for (family, socktype, proto, canonname, sockaddr) in sockaddrs:
            s = socket.socket(family, socktype, proto)
            s.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
            try:
                s.connect(sockaddr)
                break
            except socket.error as err:
                if s is not None:
                    s.close()
                s = None
        if s is None:
            raise err
        # -1 means system default buffering
        rfile = s.makefile('rb', -1)
        # 0 means unbuffered
        wfile = s.makefile('wb', 0)
        def close():
            rfile.close()
            wfile.close()
            s.close()

        proto = Protocol(rfile.read, wfile.write, close,
                         report_activity=self._report_activity)
        if path.startswith("/~"):
            path = path[1:]
        proto.send_cmd('git-%s' % cmd, path, 'host=%s' % self._host)
        return proto, lambda: _fileno_can_read(s)


class SubprocessWrapper(object):
    """A socket-like object that talks to a subprocess via pipes."""

    def __init__(self, proc):
        self.proc = proc
        self.read = proc.stdout.read
        self.write = proc.stdin.write

    def can_read(self):
        if subprocess.mswindows:
            from msvcrt import get_osfhandle
            from win32pipe import PeekNamedPipe
            handle = get_osfhandle(self.proc.stdout.fileno())
            return PeekNamedPipe(handle, 0)[2] != 0
        else:
            return _fileno_can_read(self.proc.stdout.fileno())

    def close(self):
        self.proc.stdin.close()
        self.proc.stdout.close()
        if self.proc.stderr:
            self.proc.stderr.close()
        self.proc.wait()


class SubprocessGitClient(TraditionalGitClient):
    """Git client that talks to a server using a subprocess."""

    def __init__(self, *args, **kwargs):
        self._connection = None
        self._stderr = None
        self._stderr = kwargs.get('stderr')
        if 'stderr' in kwargs:
            del kwargs['stderr']
        TraditionalGitClient.__init__(self, *args, **kwargs)

    def _connect(self, service, path):
        import subprocess
        argv = ['git', service, path]
        p = SubprocessWrapper(
            subprocess.Popen(argv, bufsize=0, stdin=subprocess.PIPE,
                             stdout=subprocess.PIPE,
                             stderr=self._stderr))
        return Protocol(p.read, p.write, p.close,
                        report_activity=self._report_activity), p.can_read


class LocalGitClient(GitClient):
    """Git Client that just uses a local Repo."""

    def __init__(self, thin_packs=True, report_activity=None):
        """Create a new LocalGitClient instance.

        :param path: Path to the local repository
        :param thin_packs: Whether or not thin packs should be retrieved
        :param report_activity: Optional callback for reporting transport
            activity.
        """
        self._report_activity = report_activity
        # Ignore the thin_packs argument

    def send_pack(self, path, determine_wants, generate_pack_contents,
                  progress=None):
        """Upload a pack to a remote repository.

        :param path: Repository path
        :param generate_pack_contents: Function that can return a sequence of
            the shas of the objects to upload.
        :param progress: Optional progress function

        :raises SendPackError: if server rejects the pack data
        :raises UpdateRefsError: if the server supports report-status
                                 and rejects ref updates
        """
        raise NotImplementedError(self.send_pack)

    def fetch(self, path, target, determine_wants=None, progress=None):
        """Fetch into a target repository.

        :param path: Path to fetch from
        :param target: Target repository to fetch into
        :param determine_wants: Optional function to determine what refs
            to fetch
        :param progress: Optional progress function
        :return: remote refs as dictionary
        """
        from dulwich.repo import Repo
        r = Repo(path)
        return r.fetch(target, determine_wants=determine_wants,
                       progress=progress)

    def fetch_pack(self, path, determine_wants, graph_walker, pack_data,
                   progress=None):
        """Retrieve a pack from a git smart server.

        :param determine_wants: Callback that returns list of commits to fetch
        :param graph_walker: Object with next() and ack().
        :param pack_data: Callback called for each bit of data in the pack
        :param progress: Callback for progress reports (strings)
        """
        from dulwich.repo import Repo
        r = Repo(path)
        objects_iter = r.fetch_objects(determine_wants, graph_walker, progress)

        # Did the process short-circuit (e.g. in a stateless RPC call)? Note
        # that the client still expects a 0-object pack in most cases.
        if objects_iter is None:
            return
        write_pack_objects(ProtocolFile(None, pack_data), objects_iter)


# What Git client to use for local access
default_local_git_client_cls = SubprocessGitClient


class SSHVendor(object):
    """A client side SSH implementation."""

    def connect_ssh(self, host, command, username=None, port=None):
        import warnings
        warnings.warn(
            "SSHVendor.connect_ssh has been renamed to SSHVendor.run_command",
            DeprecationWarning)
        return self.run_command(host, command, username=username, port=port)

    def run_command(self, host, command, username=None, port=None):
        """Connect to an SSH server.

        Run a command remotely and return a file-like object for interaction
        with the remote command.

        :param host: Host name
        :param command: Command to run
        :param username: Optional ame of user to log in as
        :param port: Optional SSH port to use
        """
        raise NotImplementedError(self.run_command)


class SubprocessSSHVendor(SSHVendor):
    """SSH vendor that shells out to the local 'ssh' command."""

    def run_command(self, host, command, username=None, port=None):
        import subprocess
        #FIXME: This has no way to deal with passwords..
        args = ['ssh', '-x']
        if port is not None:
            args.extend(['-p', str(port)])
        if username is not None:
            host = '%s@%s' % (username, host)
        args.append(host)
        proc = subprocess.Popen(args + command,
                                stdin=subprocess.PIPE,
                                stdout=subprocess.PIPE)
        return SubprocessWrapper(proc)


try:
    import paramiko
except ImportError:
    pass
else:
    import threading

    class ParamikoWrapper(object):
        STDERR_READ_N = 2048  # 2k

        def __init__(self, client, channel, progress_stderr=None):
            self.client = client
            self.channel = channel
            self.progress_stderr = progress_stderr
            self.should_monitor = bool(progress_stderr) or True
            self.monitor_thread = None
            self.stderr = ''

            # Channel must block
            self.channel.setblocking(True)

            # Start
            if self.should_monitor:
                self.monitor_thread = threading.Thread(
                    target=self.monitor_stderr)
                self.monitor_thread.start()

        def monitor_stderr(self):
            while self.should_monitor:
                # Block and read
                data = self.read_stderr(self.STDERR_READ_N)

                # Socket closed
                if not data:
                    self.should_monitor = False
                    break

                # Emit data
                if self.progress_stderr:
                    self.progress_stderr(data)

                # Append to buffer
                self.stderr += data

        def stop_monitoring(self):
            # Stop StdErr thread
            if self.should_monitor:
                self.should_monitor = False
                self.monitor_thread.join()

                # Get left over data
                data = self.channel.in_stderr_buffer.empty()
                self.stderr += data

        def can_read(self):
            return self.channel.recv_ready()

        def write(self, data):
            return self.channel.sendall(data)

        def read_stderr(self, n):
            return self.channel.recv_stderr(n)

        def read(self, n=None):
            data = self.channel.recv(n)
            data_len = len(data)

            # Closed socket
            if not data:
                return

            # Read more if needed
            if n and data_len < n:
                diff_len = n - data_len
                return data + self.read(diff_len)
            return data

        def close(self):
            self.channel.close()
            self.stop_monitoring()

    class ParamikoSSHVendor(object):

        def __init__(self):
            self.ssh_kwargs = {}

        def run_command(self, host, command, username=None, port=None,
                        progress_stderr=None):

            # Paramiko needs an explicit port. None is not valid
            if port is None:
                port = 22

            client = paramiko.SSHClient()

            policy = paramiko.client.MissingHostKeyPolicy()
            client.set_missing_host_key_policy(policy)
            client.connect(host, username=username, port=port,
                           **self.ssh_kwargs)

            # Open SSH session
            channel = client.get_transport().open_session()

            # Run commands
            channel.exec_command(*command)

            return ParamikoWrapper(
                client, channel, progress_stderr=progress_stderr)


# Can be overridden by users
get_ssh_vendor = SubprocessSSHVendor


class SSHGitClient(TraditionalGitClient):

    def __init__(self, host, port=None, username=None, *args, **kwargs):
        self.host = host
        self.port = port
        self.username = username
        TraditionalGitClient.__init__(self, *args, **kwargs)
        self.alternative_paths = {}

    def _get_cmd_path(self, cmd):
        return self.alternative_paths.get(cmd, 'git-%s' % cmd)

    def _connect(self, cmd, path):
        if path.startswith("/~"):
            path = path[1:]
        con = get_ssh_vendor().run_command(
            self.host, ["%s '%s'" % (self._get_cmd_path(cmd), path)],
            port=self.port, username=self.username)
        return (Protocol(con.read, con.write, con.close, 
                         report_activity=self._report_activity), 
                con.can_read)


def default_user_agent_string():
    return "dulwich/%s" % ".".join([str(x) for x in dulwich.__version__])


def default_urllib2_opener(config):
    if config is not None:
        proxy_server = config.get("http", "proxy")
    else:
        proxy_server = None
    handlers = []
    if proxy_server is not None:
        handlers.append(urllib2.ProxyHandler({"http": proxy_server}))
    opener = urllib2.build_opener(*handlers)
    if config is not None:
        user_agent = config.get("http", "useragent")
    else:
        user_agent = None
    if user_agent is None:
        user_agent = default_user_agent_string()
    opener.addheaders = [('User-agent', user_agent)]
    return opener


class HttpGitClient(GitClient):

    def __init__(self, base_url, dumb=None, opener=None, config=None, *args,
                 **kwargs):
        self.base_url = base_url.rstrip("/") + "/"
        self.dumb = dumb
        if opener is None:
            self.opener = default_urllib2_opener(config)
        else:
            self.opener = opener
        GitClient.__init__(self, *args, **kwargs)

    def _get_url(self, path):
        return urlparse.urljoin(self.base_url, path).rstrip("/") + "/"

    def _http_request(self, url, headers={}, data=None):
        req = urllib2.Request(url, headers=headers, data=data)
        try:
            resp = self.opener.open(req)
        except urllib2.HTTPError as e:
            if e.code == 404:
                raise NotGitRepository()
            if e.code != 200:
                raise GitProtocolError("unexpected http response %d" % e.code)
        return resp

    def _discover_references(self, service, url):
        assert url[-1] == "/"
        url = urlparse.urljoin(url, "info/refs")
        headers = {}
        if self.dumb is not False:
            url += "?service=%s" % service
            headers["Content-Type"] = "application/x-%s-request" % service
        resp = self._http_request(url, headers)
        try:
            self.dumb = (not resp.info().gettype().startswith("application/x-git-"))
            if not self.dumb:
                proto = Protocol(resp.read, None)
                # The first line should mention the service
                pkts = list(proto.read_pkt_seq())
                if pkts != [('# service=%s\n' % service)]:
                    raise GitProtocolError(
                        "unexpected first line %r from smart server" % pkts)
                return read_pkt_refs(proto)
            else:
                return read_info_refs(resp), set()
        finally:
            resp.close()

    def _smart_request(self, service, url, data):
        assert url[-1] == "/"
        url = urlparse.urljoin(url, service)
        headers = {"Content-Type": "application/x-%s-request" % service}
        resp = self._http_request(url, headers, data)
        if resp.info().gettype() != ("application/x-%s-result" % service):
            raise GitProtocolError("Invalid content-type from server: %s"
                % resp.info().gettype())
        return resp

    def send_pack(self, path, determine_wants, generate_pack_contents,
                  progress=None):
        """Upload a pack to a remote repository.

        :param path: Repository path
        :param generate_pack_contents: Function that can return a sequence of
            the shas of the objects to upload.
        :param progress: Optional progress function

        :raises SendPackError: if server rejects the pack data
        :raises UpdateRefsError: if the server supports report-status
                                 and rejects ref updates
        """
        url = self._get_url(path)
        old_refs, server_capabilities = self._discover_references(
            "git-receive-pack", url)
        negotiated_capabilities = self._send_capabilities & server_capabilities

        if 'report-status' in negotiated_capabilities:
            self._report_status_parser = ReportStatusParser()

        new_refs = determine_wants(dict(old_refs))
        if new_refs is None:
            return old_refs
        if self.dumb:
            raise NotImplementedError(self.fetch_pack)
        req_data = BytesIO()
        req_proto = Protocol(None, req_data.write)
        (have, want) = self._handle_receive_pack_head(
            req_proto, negotiated_capabilities, old_refs, new_refs)
        if not want and old_refs == new_refs:
            return new_refs
        objects = generate_pack_contents(have, want)
        if len(objects) > 0:
            entries, sha = write_pack_objects(req_proto.write_file(), objects)
        resp = self._smart_request("git-receive-pack", url,
                                   data=req_data.getvalue())
        try:
            resp_proto = Protocol(resp.read, None)
            self._handle_receive_pack_tail(resp_proto, negotiated_capabilities,
                progress)
            return new_refs
        finally:
            resp.close()


    def fetch_pack(self, path, determine_wants, graph_walker, pack_data,
                   progress=None):
        """Retrieve a pack from a git smart server.

        :param determine_wants: Callback that returns list of commits to fetch
        :param graph_walker: Object with next() and ack().
        :param pack_data: Callback called for each bit of data in the pack
        :param progress: Callback for progress reports (strings)
        :return: Dictionary with the refs of the remote repository
        """
        url = self._get_url(path)
        refs, server_capabilities = self._discover_references(
            "git-upload-pack", url)
        negotiated_capabilities = self._fetch_capabilities & server_capabilities
        wants = determine_wants(refs)
        if wants is not None:
            wants = [cid for cid in wants if cid != ZERO_SHA]
        if not wants:
            return refs
        if self.dumb:
            raise NotImplementedError(self.send_pack)
        req_data = BytesIO()
        req_proto = Protocol(None, req_data.write)
        self._handle_upload_pack_head(
            req_proto, negotiated_capabilities, graph_walker, wants,
            lambda: False)
        resp = self._smart_request(
            "git-upload-pack", url, data=req_data.getvalue())
        try:
            resp_proto = Protocol(resp.read, None)
            self._handle_upload_pack_tail(resp_proto, negotiated_capabilities,
                graph_walker, pack_data, progress)
            return refs
        finally:
            resp.close()


def get_transport_and_path_from_url(url, config=None, **kwargs):
    """Obtain a git client from a URL.

    :param url: URL to open
    :param config: Optional config object
    :param thin_packs: Whether or not thin packs should be retrieved
    :param report_activity: Optional callback for reporting transport
        activity.
    :return: Tuple with client instance and relative path.
    """
    parsed = urlparse.urlparse(url)
    if parsed.scheme == 'git':
        return (TCPGitClient(parsed.hostname, port=parsed.port, **kwargs),
                parsed.path)
    elif parsed.scheme == 'git+ssh':
        path = parsed.path
        if path.startswith('/'):
            path = parsed.path[1:]
        return SSHGitClient(parsed.hostname, port=parsed.port,
                            username=parsed.username, **kwargs), path
    elif parsed.scheme in ('http', 'https'):
        return HttpGitClient(urlparse.urlunparse(parsed), config=config,
                **kwargs), parsed.path
    elif parsed.scheme == 'file':
        return default_local_git_client_cls(**kwargs), parsed.path

    raise ValueError("unknown scheme '%s'" % parsed.scheme)


def get_transport_and_path(location, **kwargs):
    """Obtain a git client from a URL.

    :param location: URL or path
    :param config: Optional config object
    :param thin_packs: Whether or not thin packs should be retrieved
    :param report_activity: Optional callback for reporting transport
        activity.
    :return: Tuple with client instance and relative path.
    """
    # First, try to parse it as a URL
    try:
        return get_transport_and_path_from_url(location, **kwargs)
    except ValueError:
        pass

    if ':' in location and not '@' in location:
        # SSH with no user@, zero or one leading slash.
        (hostname, path) = location.split(':')
        return SSHGitClient(hostname, **kwargs), path
    elif '@' in location and ':' in location:
        # SSH with user@host:foo.
        user_host, path = location.split(':')
        user, host = user_host.rsplit('@')
        return SSHGitClient(host, username=user, **kwargs), path

    # Otherwise, assume it's a local path.
    return default_local_git_client_cls(**kwargs), location