Source

setuptools / setuptools / package_index.py

   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
"""PyPI and direct package downloading"""
import sys
import os
import re
import shutil
import socket
import base64
import hashlib
from functools import wraps

from pkg_resources import (
    CHECKOUT_DIST, Distribution, BINARY_DIST, normalize_path, SOURCE_DIST,
    require, Environment, find_distributions, safe_name, safe_version,
    to_filename, Requirement, DEVELOP_DIST,
)
from setuptools import ssl_support
from distutils import log
from distutils.errors import DistutilsError
from setuptools.compat import (urllib2, httplib, StringIO, HTTPError,
                               urlparse, urlunparse, unquote, splituser,
                               url2pathname, name2codepoint,
                               unichr, urljoin, urlsplit, urlunsplit,
                               ConfigParser)
from setuptools.compat import filterfalse
from fnmatch import translate
from setuptools.py26compat import strip_fragment
from setuptools.py27compat import get_all_headers

EGG_FRAGMENT = re.compile(r'^egg=([-A-Za-z0-9_.]+)$')
HREF = re.compile("""href\\s*=\\s*['"]?([^'"> ]+)""", re.I)
# this is here to fix emacs' cruddy broken syntax highlighting
PYPI_MD5 = re.compile(
    '<a href="([^"#]+)">([^<]+)</a>\n\s+\\(<a (?:title="MD5 hash"\n\s+)'
    'href="[^?]+\?:action=show_md5&amp;digest=([0-9a-f]{32})">md5</a>\\)'
)
URL_SCHEME = re.compile('([-+.a-z0-9]{2,}):',re.I).match
EXTENSIONS = ".tar.gz .tar.bz2 .tar .zip .tgz".split()

__all__ = [
    'PackageIndex', 'distros_for_url', 'parse_bdist_wininst',
    'interpret_distro_name',
]

_SOCKET_TIMEOUT = 15

def parse_bdist_wininst(name):
    """Return (base,pyversion) or (None,None) for possible .exe name"""

    lower = name.lower()
    base, py_ver, plat = None, None, None

    if lower.endswith('.exe'):
        if lower.endswith('.win32.exe'):
            base = name[:-10]
            plat = 'win32'
        elif lower.startswith('.win32-py',-16):
            py_ver = name[-7:-4]
            base = name[:-16]
            plat = 'win32'
        elif lower.endswith('.win-amd64.exe'):
            base = name[:-14]
            plat = 'win-amd64'
        elif lower.startswith('.win-amd64-py',-20):
            py_ver = name[-7:-4]
            base = name[:-20]
            plat = 'win-amd64'
    return base,py_ver,plat


def egg_info_for_url(url):
    scheme, server, path, parameters, query, fragment = urlparse(url)
    base = unquote(path.split('/')[-1])
    if server=='sourceforge.net' and base=='download':    # XXX Yuck
        base = unquote(path.split('/')[-2])
    if '#' in base: base, fragment = base.split('#',1)
    return base,fragment

def distros_for_url(url, metadata=None):
    """Yield egg or source distribution objects that might be found at a URL"""
    base, fragment = egg_info_for_url(url)
    for dist in distros_for_location(url, base, metadata): yield dist
    if fragment:
        match = EGG_FRAGMENT.match(fragment)
        if match:
            for dist in interpret_distro_name(
                url, match.group(1), metadata, precedence = CHECKOUT_DIST
            ):
                yield dist

def distros_for_location(location, basename, metadata=None):
    """Yield egg or source distribution objects based on basename"""
    if basename.endswith('.egg.zip'):
        basename = basename[:-4]    # strip the .zip
    if basename.endswith('.egg') and '-' in basename:
        # only one, unambiguous interpretation
        return [Distribution.from_location(location, basename, metadata)]
    if basename.endswith('.exe'):
        win_base, py_ver, platform = parse_bdist_wininst(basename)
        if win_base is not None:
            return interpret_distro_name(
                location, win_base, metadata, py_ver, BINARY_DIST, platform
            )
    # Try source distro extensions (.zip, .tgz, etc.)
    #
    for ext in EXTENSIONS:
        if basename.endswith(ext):
            basename = basename[:-len(ext)]
            return interpret_distro_name(location, basename, metadata)
    return []  # no extension matched

def distros_for_filename(filename, metadata=None):
    """Yield possible egg or source distribution objects based on a filename"""
    return distros_for_location(
        normalize_path(filename), os.path.basename(filename), metadata
    )


def interpret_distro_name(
        location, basename, metadata, py_version=None, precedence=SOURCE_DIST,
        platform=None
        ):
    """Generate alternative interpretations of a source distro name

    Note: if `location` is a filesystem filename, you should call
    ``pkg_resources.normalize_path()`` on it before passing it to this
    routine!
    """
    # Generate alternative interpretations of a source distro name
    # Because some packages are ambiguous as to name/versions split
    # e.g. "adns-python-1.1.0", "egenix-mx-commercial", etc.
    # So, we generate each possible interepretation (e.g. "adns, python-1.1.0"
    # "adns-python, 1.1.0", and "adns-python-1.1.0, no version").  In practice,
    # the spurious interpretations should be ignored, because in the event
    # there's also an "adns" package, the spurious "python-1.1.0" version will
    # compare lower than any numeric version number, and is therefore unlikely
    # to match a request for it.  It's still a potential problem, though, and
    # in the long run PyPI and the distutils should go for "safe" names and
    # versions in distribution archive names (sdist and bdist).

    parts = basename.split('-')
    if not py_version:
        for i,p in enumerate(parts[2:]):
            if len(p)==5 and p.startswith('py2.'):
                return # It's a bdist_dumb, not an sdist -- bail out

    for p in range(1,len(parts)+1):
        yield Distribution(
            location, metadata, '-'.join(parts[:p]), '-'.join(parts[p:]),
            py_version=py_version, precedence = precedence,
            platform = platform
        )

# From Python 2.7 docs
def unique_everseen(iterable, key=None):
    "List unique elements, preserving order. Remember all elements ever seen."
    # unique_everseen('AAAABBBCCDAABBB') --> A B C D
    # unique_everseen('ABBCcAD', str.lower) --> A B C D
    seen = set()
    seen_add = seen.add
    if key is None:
        for element in filterfalse(seen.__contains__, iterable):
            seen_add(element)
            yield element
    else:
        for element in iterable:
            k = key(element)
            if k not in seen:
                seen_add(k)
                yield element

def unique_values(func):
    """
    Wrap a function returning an iterable such that the resulting iterable
    only ever yields unique items.
    """
    @wraps(func)
    def wrapper(*args, **kwargs):
        return unique_everseen(func(*args, **kwargs))
    return wrapper

REL = re.compile("""<([^>]*\srel\s*=\s*['"]?([^'">]+)[^>]*)>""", re.I)
# this line is here to fix emacs' cruddy broken syntax highlighting

@unique_values
def find_external_links(url, page):
    """Find rel="homepage" and rel="download" links in `page`, yielding URLs"""

    for match in REL.finditer(page):
        tag, rel = match.groups()
        rels = set(map(str.strip, rel.lower().split(',')))
        if 'homepage' in rels or 'download' in rels:
            for match in HREF.finditer(tag):
                yield urljoin(url, htmldecode(match.group(1)))

    for tag in ("<th>Home Page", "<th>Download URL"):
        pos = page.find(tag)
        if pos!=-1:
            match = HREF.search(page,pos)
            if match:
                yield urljoin(url, htmldecode(match.group(1)))

user_agent = "Python-urllib/%s setuptools/%s" % (
    sys.version[:3], require('setuptools')[0].version
)

class ContentChecker(object):
    """
    A null content checker that defines the interface for checking content
    """
    def feed(self, block):
        """
        Feed a block of data to the hash.
        """
        return

    def is_valid(self):
        """
        Check the hash. Return False if validation fails.
        """
        return True

    def report(self, reporter, template):
        """
        Call reporter with information about the checker (hash name)
        substituted into the template.
        """
        return

class HashChecker(ContentChecker):
    pattern = re.compile(
        r'(?P<hash_name>sha1|sha224|sha384|sha256|sha512|md5)='
        r'(?P<expected>[a-f0-9]+)'
    )

    def __init__(self, hash_name, expected):
        self.hash_name = hash_name
        self.hash = hashlib.new(hash_name)
        self.expected = expected

    @classmethod
    def from_url(cls, url):
        "Construct a (possibly null) ContentChecker from a URL"
        fragment = urlparse(url)[-1]
        if not fragment:
            return ContentChecker()
        match = cls.pattern.search(fragment)
        if not match:
            return ContentChecker()
        return cls(**match.groupdict())

    def feed(self, block):
        self.hash.update(block)

    def is_valid(self):
        return self.hash.hexdigest() == self.expected

    def report(self, reporter, template):
        msg = template % self.hash_name
        return reporter(msg)


class PackageIndex(Environment):
    """A distribution index that scans web pages for download URLs"""

    def __init__(
            self, index_url="https://pypi.python.org/simple", hosts=('*',),
            ca_bundle=None, verify_ssl=True, *args, **kw
            ):
        Environment.__init__(self,*args,**kw)
        self.index_url = index_url + "/"[:not index_url.endswith('/')]
        self.scanned_urls = {}
        self.fetched_urls = {}
        self.package_pages = {}
        self.allows = re.compile('|'.join(map(translate,hosts))).match
        self.to_scan = []
        if verify_ssl and ssl_support.is_available and (ca_bundle or ssl_support.find_ca_bundle()):
            self.opener = ssl_support.opener_for(ca_bundle)
        else: self.opener = urllib2.urlopen

    def process_url(self, url, retrieve=False):
        """Evaluate a URL as a possible download, and maybe retrieve it"""
        if url in self.scanned_urls and not retrieve:
            return
        self.scanned_urls[url] = True
        if not URL_SCHEME(url):
            self.process_filename(url)
            return
        else:
            dists = list(distros_for_url(url))
            if dists:
                if not self.url_ok(url):
                    return
                self.debug("Found link: %s", url)

        if dists or not retrieve or url in self.fetched_urls:
            list(map(self.add, dists))
            return  # don't need the actual page

        if not self.url_ok(url):
            self.fetched_urls[url] = True
            return

        self.info("Reading %s", url)
        self.fetched_urls[url] = True   # prevent multiple fetch attempts
        f = self.open_url(url, "Download error on %s: %%s -- Some packages may not be found!" % url)
        if f is None: return
        self.fetched_urls[f.url] = True
        if 'html' not in f.headers.get('content-type', '').lower():
            f.close()   # not html, we can't process it
            return

        base = f.url     # handle redirects
        page = f.read()
        if not isinstance(page, str): # We are in Python 3 and got bytes. We want str.
            if isinstance(f, HTTPError):
                # Errors have no charset, assume latin1:
                charset = 'latin-1'
            else:
                charset = f.headers.get_param('charset') or 'latin-1'
            page = page.decode(charset, "ignore")
        f.close()
        for match in HREF.finditer(page):
            link = urljoin(base, htmldecode(match.group(1)))
            self.process_url(link)
        if url.startswith(self.index_url) and getattr(f,'code',None)!=404:
            page = self.process_index(url, page)

    def process_filename(self, fn, nested=False):
        # process filenames or directories
        if not os.path.exists(fn):
            self.warn("Not found: %s", fn)
            return

        if os.path.isdir(fn) and not nested:
            path = os.path.realpath(fn)
            for item in os.listdir(path):
                self.process_filename(os.path.join(path,item), True)

        dists = distros_for_filename(fn)
        if dists:
            self.debug("Found: %s", fn)
            list(map(self.add, dists))

    def url_ok(self, url, fatal=False):
        s = URL_SCHEME(url)
        if (s and s.group(1).lower()=='file') or self.allows(urlparse(url)[1]):
            return True
        msg = ("\nNote: Bypassing %s (disallowed host; see "
            "http://bit.ly/1dg9ijs for details).\n")
        if fatal:
            raise DistutilsError(msg % url)
        else:
            self.warn(msg, url)

    def scan_egg_links(self, search_path):
        for item in search_path:
            if os.path.isdir(item):
                for entry in os.listdir(item):
                    if entry.endswith('.egg-link'):
                        self.scan_egg_link(item, entry)

    def scan_egg_link(self, path, entry):
        lines = [_f for _f in map(str.strip,
                                  open(os.path.join(path, entry))) if _f]
        if len(lines)==2:
            for dist in find_distributions(os.path.join(path, lines[0])):
                dist.location = os.path.join(path, *lines)
                dist.precedence = SOURCE_DIST
                self.add(dist)

    def process_index(self,url,page):
        """Process the contents of a PyPI page"""
        def scan(link):
            # Process a URL to see if it's for a package page
            if link.startswith(self.index_url):
                parts = list(map(
                    unquote, link[len(self.index_url):].split('/')
                ))
                if len(parts)==2 and '#' not in parts[1]:
                    # it's a package page, sanitize and index it
                    pkg = safe_name(parts[0])
                    ver = safe_version(parts[1])
                    self.package_pages.setdefault(pkg.lower(),{})[link] = True
                    return to_filename(pkg), to_filename(ver)
            return None, None

        # process an index page into the package-page index
        for match in HREF.finditer(page):
            try:
                scan(urljoin(url, htmldecode(match.group(1))))
            except ValueError:
                pass

        pkg, ver = scan(url)   # ensure this page is in the page index
        if pkg:
            # process individual package page
            for new_url in find_external_links(url, page):
                # Process the found URL
                base, frag = egg_info_for_url(new_url)
                if base.endswith('.py') and not frag:
                    if ver:
                        new_url+='#egg=%s-%s' % (pkg,ver)
                    else:
                        self.need_version_info(url)
                self.scan_url(new_url)

            return PYPI_MD5.sub(
                lambda m: '<a href="%s#md5=%s">%s</a>' % m.group(1,3,2), page
            )
        else:
            return ""   # no sense double-scanning non-package pages

    def need_version_info(self, url):
        self.scan_all(
            "Page at %s links to .py file(s) without version info; an index "
            "scan is required.", url
        )

    def scan_all(self, msg=None, *args):
        if self.index_url not in self.fetched_urls:
            if msg: self.warn(msg,*args)
            self.info(
                "Scanning index of all packages (this may take a while)"
            )
        self.scan_url(self.index_url)

    def find_packages(self, requirement):
        self.scan_url(self.index_url + requirement.unsafe_name+'/')

        if not self.package_pages.get(requirement.key):
            # Fall back to safe version of the name
            self.scan_url(self.index_url + requirement.project_name+'/')

        if not self.package_pages.get(requirement.key):
            # We couldn't find the target package, so search the index page too
            self.not_found_in_index(requirement)

        for url in list(self.package_pages.get(requirement.key,())):
            # scan each page that might be related to the desired package
            self.scan_url(url)

    def obtain(self, requirement, installer=None):
        self.prescan()
        self.find_packages(requirement)
        for dist in self[requirement.key]:
            if dist in requirement:
                return dist
            self.debug("%s does not match %s", requirement, dist)
        return super(PackageIndex, self).obtain(requirement,installer)

    def check_hash(self, checker, filename, tfp):
        """
        checker is a ContentChecker
        """
        checker.report(self.debug,
            "Validating %%s checksum for %s" % filename)
        if not checker.is_valid():
            tfp.close()
            os.unlink(filename)
            raise DistutilsError(
                "%s validation failed for %s; "
                "possible download problem?" % (
                                checker.hash.name, os.path.basename(filename))
            )

    def add_find_links(self, urls):
        """Add `urls` to the list that will be prescanned for searches"""
        for url in urls:
            if (
                self.to_scan is None        # if we have already "gone online"
                or not URL_SCHEME(url)      # or it's a local file/directory
                or url.startswith('file:')
                or list(distros_for_url(url))   # or a direct package link
            ):
                # then go ahead and process it now
                self.scan_url(url)
            else:
                # otherwise, defer retrieval till later
                self.to_scan.append(url)

    def prescan(self):
        """Scan urls scheduled for prescanning (e.g. --find-links)"""
        if self.to_scan:
            list(map(self.scan_url, self.to_scan))
        self.to_scan = None     # from now on, go ahead and process immediately

    def not_found_in_index(self, requirement):
        if self[requirement.key]:   # we've seen at least one distro
            meth, msg = self.info, "Couldn't retrieve index page for %r"
        else:   # no distros seen for this name, might be misspelled
            meth, msg = (self.warn,
                "Couldn't find index page for %r (maybe misspelled?)")
        meth(msg, requirement.unsafe_name)
        self.scan_all()

    def download(self, spec, tmpdir):
        """Locate and/or download `spec` to `tmpdir`, returning a local path

        `spec` may be a ``Requirement`` object, or a string containing a URL,
        an existing local filename, or a project/version requirement spec
        (i.e. the string form of a ``Requirement`` object).  If it is the URL
        of a .py file with an unambiguous ``#egg=name-version`` tag (i.e., one
        that escapes ``-`` as ``_`` throughout), a trivial ``setup.py`` is
        automatically created alongside the downloaded file.

        If `spec` is a ``Requirement`` object or a string containing a
        project/version requirement spec, this method returns the location of
        a matching distribution (possibly after downloading it to `tmpdir`).
        If `spec` is a locally existing file or directory name, it is simply
        returned unchanged.  If `spec` is a URL, it is downloaded to a subpath
        of `tmpdir`, and the local filename is returned.  Various errors may be
        raised if a problem occurs during downloading.
        """
        if not isinstance(spec,Requirement):
            scheme = URL_SCHEME(spec)
            if scheme:
                # It's a url, download it to tmpdir
                found = self._download_url(scheme.group(1), spec, tmpdir)
                base, fragment = egg_info_for_url(spec)
                if base.endswith('.py'):
                    found = self.gen_setup(found,fragment,tmpdir)
                return found
            elif os.path.exists(spec):
                # Existing file or directory, just return it
                return spec
            else:
                try:
                    spec = Requirement.parse(spec)
                except ValueError:
                    raise DistutilsError(
                        "Not a URL, existing file, or requirement spec: %r" %
                        (spec,)
                    )
        return getattr(self.fetch_distribution(spec, tmpdir),'location',None)

    def fetch_distribution(
            self, requirement, tmpdir, force_scan=False, source=False,
            develop_ok=False, local_index=None
            ):
        """Obtain a distribution suitable for fulfilling `requirement`

        `requirement` must be a ``pkg_resources.Requirement`` instance.
        If necessary, or if the `force_scan` flag is set, the requirement is
        searched for in the (online) package index as well as the locally
        installed packages.  If a distribution matching `requirement` is found,
        the returned distribution's ``location`` is the value you would have
        gotten from calling the ``download()`` method with the matching
        distribution's URL or filename.  If no matching distribution is found,
        ``None`` is returned.

        If the `source` flag is set, only source distributions and source
        checkout links will be considered.  Unless the `develop_ok` flag is
        set, development and system eggs (i.e., those using the ``.egg-info``
        format) will be ignored.
        """
        # process a Requirement
        self.info("Searching for %s", requirement)
        skipped = {}
        dist = None

        def find(req, env=None):
            if env is None:
                env = self
            # Find a matching distribution; may be called more than once

            for dist in env[req.key]:

                if dist.precedence==DEVELOP_DIST and not develop_ok:
                    if dist not in skipped:
                        self.warn("Skipping development or system egg: %s",dist)
                        skipped[dist] = 1
                    continue

                if dist in req and (dist.precedence<=SOURCE_DIST or not source):
                    return dist

        if force_scan:
            self.prescan()
            self.find_packages(requirement)
            dist = find(requirement)

        if local_index is not None:
            dist = dist or find(requirement, local_index)

        if dist is None:
            if self.to_scan is not None:
                self.prescan()
            dist = find(requirement)

        if dist is None and not force_scan:
            self.find_packages(requirement)
            dist = find(requirement)

        if dist is None:
            self.warn(
                "No local packages or download links found for %s%s",
                (source and "a source distribution of " or ""),
                requirement,
            )
        else:
            self.info("Best match: %s", dist)
            return dist.clone(location=self.download(dist.location, tmpdir))

    def fetch(self, requirement, tmpdir, force_scan=False, source=False):
        """Obtain a file suitable for fulfilling `requirement`

        DEPRECATED; use the ``fetch_distribution()`` method now instead.  For
        backward compatibility, this routine is identical but returns the
        ``location`` of the downloaded distribution instead of a distribution
        object.
        """
        dist = self.fetch_distribution(requirement,tmpdir,force_scan,source)
        if dist is not None:
            return dist.location
        return None

    def gen_setup(self, filename, fragment, tmpdir):
        match = EGG_FRAGMENT.match(fragment)
        dists = match and [
            d for d in
            interpret_distro_name(filename, match.group(1), None) if d.version
        ] or []

        if len(dists)==1:   # unambiguous ``#egg`` fragment
            basename = os.path.basename(filename)

            # Make sure the file has been downloaded to the temp dir.
            if os.path.dirname(filename) != tmpdir:
                dst = os.path.join(tmpdir, basename)
                from setuptools.command.easy_install import samefile
                if not samefile(filename, dst):
                    shutil.copy2(filename, dst)
                    filename=dst

            file = open(os.path.join(tmpdir, 'setup.py'), 'w')
            file.write(
                "from setuptools import setup\n"
                "setup(name=%r, version=%r, py_modules=[%r])\n"
                % (
                    dists[0].project_name, dists[0].version,
                    os.path.splitext(basename)[0]
                )
            )
            file.close()
            return filename

        elif match:
            raise DistutilsError(
                "Can't unambiguously interpret project/version identifier %r; "
                "any dashes in the name or version should be escaped using "
                "underscores. %r" % (fragment,dists)
            )
        else:
            raise DistutilsError(
                "Can't process plain .py files without an '#egg=name-version'"
                " suffix to enable automatic setup script generation."
            )

    dl_blocksize = 8192
    def _download_to(self, url, filename):
        self.info("Downloading %s", url)
        # Download the file
        fp, tfp, info = None, None, None
        try:
            checker = HashChecker.from_url(url)
            fp = self.open_url(strip_fragment(url))
            if isinstance(fp, HTTPError):
                raise DistutilsError(
                    "Can't download %s: %s %s" % (url, fp.code,fp.msg)
                )
            headers = fp.info()
            blocknum = 0
            bs = self.dl_blocksize
            size = -1
            if "content-length" in headers:
                # Some servers return multiple Content-Length headers :(
                sizes = get_all_headers(headers, 'Content-Length')
                size = max(map(int, sizes))
                self.reporthook(url, filename, blocknum, bs, size)
            tfp = open(filename,'wb')
            while True:
                block = fp.read(bs)
                if block:
                    checker.feed(block)
                    tfp.write(block)
                    blocknum += 1
                    self.reporthook(url, filename, blocknum, bs, size)
                else:
                    break
            self.check_hash(checker, filename, tfp)
            return headers
        finally:
            if fp: fp.close()
            if tfp: tfp.close()

    def reporthook(self, url, filename, blocknum, blksize, size):
        pass    # no-op

    def open_url(self, url, warning=None):
        if url.startswith('file:'):
            return local_open(url)
        try:
            return open_with_auth(url, self.opener)
        except (ValueError, httplib.InvalidURL):
            v = sys.exc_info()[1]
            msg = ' '.join([str(arg) for arg in v.args])
            if warning:
                self.warn(warning, msg)
            else:
                raise DistutilsError('%s %s' % (url, msg))
        except urllib2.HTTPError:
            v = sys.exc_info()[1]
            return v
        except urllib2.URLError:
            v = sys.exc_info()[1]
            if warning:
                self.warn(warning, v.reason)
            else:
                raise DistutilsError("Download error for %s: %s"
                                     % (url, v.reason))
        except httplib.BadStatusLine:
            v = sys.exc_info()[1]
            if warning:
                self.warn(warning, v.line)
            else:
                raise DistutilsError(
                    '%s returned a bad status line. The server might be '
                    'down, %s' %
                    (url, v.line)
                )
        except httplib.HTTPException:
            v = sys.exc_info()[1]
            if warning:
                self.warn(warning, v)
            else:
                raise DistutilsError("Download error for %s: %s"
                                     % (url, v))

    def _download_url(self, scheme, url, tmpdir):
        # Determine download filename
        #
        name, fragment = egg_info_for_url(url)
        if name:
            while '..' in name:
                name = name.replace('..','.').replace('\\','_')
        else:
            name = "__downloaded__"    # default if URL has no path contents

        if name.endswith('.egg.zip'):
            name = name[:-4]    # strip the extra .zip before download

        filename = os.path.join(tmpdir,name)

        # Download the file
        #
        if scheme=='svn' or scheme.startswith('svn+'):
            return self._download_svn(url, filename)
        elif scheme=='git' or scheme.startswith('git+'):
            return self._download_git(url, filename)
        elif scheme.startswith('hg+'):
            return self._download_hg(url, filename)
        elif scheme=='file':
            return url2pathname(urlparse(url)[2])
        else:
            self.url_ok(url, True)   # raises error if not allowed
            return self._attempt_download(url, filename)

    def scan_url(self, url):
        self.process_url(url, True)

    def _attempt_download(self, url, filename):
        headers = self._download_to(url, filename)
        if 'html' in headers.get('content-type','').lower():
            return self._download_html(url, headers, filename)
        else:
            return filename

    def _download_html(self, url, headers, filename):
        file = open(filename)
        for line in file:
            if line.strip():
                # Check for a subversion index page
                if re.search(r'<title>([^- ]+ - )?Revision \d+:', line):
                    # it's a subversion index page:
                    file.close()
                    os.unlink(filename)
                    return self._download_svn(url, filename)
                break   # not an index page
        file.close()
        os.unlink(filename)
        raise DistutilsError("Unexpected HTML page found at "+url)

    def _download_svn(self, url, filename):
        url = url.split('#',1)[0]   # remove any fragment for svn's sake
        creds = ''
        if url.lower().startswith('svn:') and '@' in url:
            scheme, netloc, path, p, q, f = urlparse(url)
            if not netloc and path.startswith('//') and '/' in path[2:]:
                netloc, path = path[2:].split('/',1)
                auth, host = splituser(netloc)
                if auth:
                    if ':' in auth:
                        user, pw = auth.split(':',1)
                        creds = " --username=%s --password=%s" % (user, pw)
                    else:
                        creds = " --username="+auth
                    netloc = host
                    url = urlunparse((scheme, netloc, url, p, q, f))
        self.info("Doing subversion checkout from %s to %s", url, filename)
        os.system("svn checkout%s -q %s %s" % (creds, url, filename))
        return filename

    @staticmethod
    def _vcs_split_rev_from_url(url, pop_prefix=False):
        scheme, netloc, path, query, frag = urlsplit(url)

        scheme = scheme.split('+', 1)[-1]

        # Some fragment identification fails
        path = path.split('#',1)[0]

        rev = None
        if '@' in path:
            path, rev = path.rsplit('@', 1)

        # Also, discard fragment
        url = urlunsplit((scheme, netloc, path, query, ''))

        return url, rev

    def _download_git(self, url, filename):
        filename = filename.split('#',1)[0]
        url, rev = self._vcs_split_rev_from_url(url, pop_prefix=True)

        self.info("Doing git clone from %s to %s", url, filename)
        os.system("git clone --quiet %s %s" % (url, filename))

        if rev is not None:
            self.info("Checking out %s", rev)
            os.system("(cd %s && git checkout --quiet %s)" % (
                filename,
                rev,
            ))

        return filename

    def _download_hg(self, url, filename):
        filename = filename.split('#',1)[0]
        url, rev = self._vcs_split_rev_from_url(url, pop_prefix=True)

        self.info("Doing hg clone from %s to %s", url, filename)
        os.system("hg clone --quiet %s %s" % (url, filename))

        if rev is not None:
            self.info("Updating to %s", rev)
            os.system("(cd %s && hg up -C -r %s >&-)" % (
                filename,
                rev,
            ))

        return filename

    def debug(self, msg, *args):
        log.debug(msg, *args)

    def info(self, msg, *args):
        log.info(msg, *args)

    def warn(self, msg, *args):
        log.warn(msg, *args)

# This pattern matches a character entity reference (a decimal numeric
# references, a hexadecimal numeric reference, or a named reference).
entity_sub = re.compile(r'&(#(\d+|x[\da-fA-F]+)|[\w.:-]+);?').sub

def uchr(c):
    if not isinstance(c, int):
        return c
    if c>255: return unichr(c)
    return chr(c)

def decode_entity(match):
    what = match.group(1)
    if what.startswith('#x'):
        what = int(what[2:], 16)
    elif what.startswith('#'):
        what = int(what[1:])
    else:
        what = name2codepoint.get(what, match.group(0))
    return uchr(what)

def htmldecode(text):
    """Decode HTML entities in the given text."""
    return entity_sub(decode_entity, text)

def socket_timeout(timeout=15):
    def _socket_timeout(func):
        def _socket_timeout(*args, **kwargs):
            old_timeout = socket.getdefaulttimeout()
            socket.setdefaulttimeout(timeout)
            try:
                return func(*args, **kwargs)
            finally:
                socket.setdefaulttimeout(old_timeout)
        return _socket_timeout
    return _socket_timeout

def _encode_auth(auth):
    """
    A function compatible with Python 2.3-3.3 that will encode
    auth from a URL suitable for an HTTP header.
    >>> str(_encode_auth('username%3Apassword'))
    'dXNlcm5hbWU6cGFzc3dvcmQ='

    Long auth strings should not cause a newline to be inserted.
    >>> long_auth = 'username:' + 'password'*10
    >>> chr(10) in str(_encode_auth(long_auth))
    False
    """
    auth_s = unquote(auth)
    # convert to bytes
    auth_bytes = auth_s.encode()
    # use the legacy interface for Python 2.3 support
    encoded_bytes = base64.encodestring(auth_bytes)
    # convert back to a string
    encoded = encoded_bytes.decode()
    # strip the trailing carriage return
    return encoded.replace('\n','')

class Credential(object):
    """
    A username/password pair. Use like a namedtuple.
    """
    def __init__(self, username, password):
        self.username = username
        self.password = password

    def __iter__(self):
        yield self.username
        yield self.password

    def __str__(self):
        return '%(username)s:%(password)s' % vars(self)

class PyPIConfig(ConfigParser.ConfigParser):

    def __init__(self):
        """
        Load from ~/.pypirc
        """
        defaults = dict.fromkeys(['username', 'password', 'repository'], '')
        ConfigParser.ConfigParser.__init__(self, defaults)

        rc = os.path.join(os.path.expanduser('~'), '.pypirc')
        if os.path.exists(rc):
            self.read(rc)

    @property
    def creds_by_repository(self):
        sections_with_repositories = [
            section for section in self.sections()
            if self.get(section, 'repository').strip()
        ]

        return dict(map(self._get_repo_cred, sections_with_repositories))

    def _get_repo_cred(self, section):
        repo = self.get(section, 'repository').strip()
        return repo, Credential(
            self.get(section, 'username').strip(),
            self.get(section, 'password').strip(),
        )

    def find_credential(self, url):
        """
        If the URL indicated appears to be a repository defined in this
        config, return the credential for that repository.
        """
        for repository, cred in self.creds_by_repository.items():
            if url.startswith(repository):
                return cred


def open_with_auth(url, opener=urllib2.urlopen):
    """Open a urllib2 request, handling HTTP authentication"""

    scheme, netloc, path, params, query, frag = urlparse(url)

    # Double scheme does not raise on Mac OS X as revealed by a
    # failing test. We would expect "nonnumeric port". Refs #20.
    if netloc.endswith(':'):
        raise httplib.InvalidURL("nonnumeric port: ''")

    if scheme in ('http', 'https'):
        auth, host = splituser(netloc)
    else:
        auth = None

    if not auth:
        cred = PyPIConfig().find_credential(url)
        if cred:
            auth = str(cred)
            info = cred.username, url
            log.info('Authenticating as %s for %s (from .pypirc)' % info)

    if auth:
        auth = "Basic " + _encode_auth(auth)
        new_url = urlunparse((scheme,host,path,params,query,frag))
        request = urllib2.Request(new_url)
        request.add_header("Authorization", auth)
    else:
        request = urllib2.Request(url)

    request.add_header('User-Agent', user_agent)
    fp = opener(request)

    if auth:
        # Put authentication info back into request URL if same host,
        # so that links found on the page will work
        s2, h2, path2, param2, query2, frag2 = urlparse(fp.url)
        if s2==scheme and h2==host:
            fp.url = urlunparse((s2,netloc,path2,param2,query2,frag2))

    return fp

# adding a timeout to avoid freezing package_index
open_with_auth = socket_timeout(_SOCKET_TIMEOUT)(open_with_auth)


def fix_sf_url(url):
    return url      # backward compatibility

def local_open(url):
    """Read a local path, with special support for directories"""
    scheme, server, path, param, query, frag = urlparse(url)
    filename = url2pathname(path)
    if os.path.isfile(filename):
        return urllib2.urlopen(url)
    elif path.endswith('/') and os.path.isdir(filename):
        files = []
        for f in os.listdir(filename):
            if f=='index.html':
                fp = open(os.path.join(filename,f),'r')
                body = fp.read()
                fp.close()
                break
            elif os.path.isdir(os.path.join(filename,f)):
                f+='/'
            files.append("<a href=%r>%s</a>" % (f,f))
        else:
            body = ("<html><head><title>%s</title>" % url) + \
                "</head><body>%s</body></html>" % '\n'.join(files)
        status, message = 200, "OK"
    else:
        status, message, body = 404, "Path not found", "Not found"

    headers = {'content-type': 'text/html'}
    return HTTPError(url, status, message, headers, StringIO(body))