GeezerVison is showing github.com — urllib.parse doesn't round-trip file URI's with multiple leading slashes · Issue #78457 · python/cpython
urllib.parse doesn't round-trip file URI's with multiple leading slashes #78457Description
Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.
Show more details
GitHub fields:
assignee = None
closed_at = None
created_at = <Date 2018-07-30.04:39:03.225>
labels = ['3.7', '3.8', 'type-bug', 'library', '3.9']
title = "urllib.parse doesn't round-trip file URI's with multiple leading slashes"
updated_at = <Date 2019-08-27.01:16:36.907>
user = 'https://github.com/cjerdonek' bugs.python.org fields:
activity = <Date 2019-08-27.01:16:36.907>
actor = 'epicfaace'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2018-07-30.04:39:03.225>
creator = 'chris.jerdonek'
dependencies = []
files = []
hgrepos = []
issue_num = 34276
keywords = ['patch']
message_count = 9.0
messages = ['322652', '322671', '322674', '322675', '322716', '322722', '322737', '322756', '324718']
nosy_count = 6.0
nosy_names = ['chris.jerdonek', 'martin.panter', 'piotr.dobrogost', 'xtreak', 'v2m', 'epicfaace']
pr_nums = ['15297']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue34276'
versions = ['Python 3.6', 'Python 3.7', 'Python 3.8', 'Python 3.9'] Linked PRs
Activitycjerdonek commented on Jul 30, 2018 urllib.parse doesn't seem to round-trip file URI's containing multiple leading slashes. For example, this--
import urllib.parse
def round_trip(url):
parsed = urllib.parse.urlsplit(url)
new_url = urllib.parse.urlunsplit(parsed)
print(f'{url} [{parsed}]\n{new_url}')
print('ROUNDTRIP: {}\n'.format(url == new_url))
for i in range(4):
round_trip('file://{}root/a'.format(i * '/'))results in--
file://root/a [SplitResult(scheme='file', netloc='root', path='/a', query='', fragment='')]
file://root/a
ROUNDTRIP: True
file:///root/a [SplitResult(scheme='file', netloc='', path='/root/a', query='', fragment='')]
file:///root/a
ROUNDTRIP: True
file:////root/a [SplitResult(scheme='file', netloc='', path='//root/a', query='', fragment='')]
file://root/a
ROUNDTRIP: False
file://///root/a [SplitResult(scheme='file', netloc='', path='///root/a', query='', fragment='')]
file:///root/a
ROUNDTRIP: False
URI's of the form file:////<host>/<share>/<path> occur, for example, when one wants to git-clone a UNC path on Windows:
https://stackoverflow.com/a/2520121/262819
Here is where CPython defines urlunsplit():
|
def urlunsplit(components): |
|
"""Combine the elements of a tuple as returned by urlsplit() into a |
|
complete URL as a string. The data argument can be any five-item iterable. |
|
This may result in a slightly different, but equivalent URL, if the URL that |
|
was parsed originally had unnecessary delimiters (for example, a ? with an |
|
empty query; the RFC states that these are equivalent).""" |
|
scheme, netloc, url, query, fragment, _coerce_result = ( |
|
_coerce_args(*components)) |
|
if netloc or (scheme and scheme in uses_netloc and url[:2] != '//'): |
|
if url and url[:1] != '/': url = '/' + url |
|
url = '//' + (netloc or '') + url |
|
if scheme: |
|
url = scheme + ':' + url |
|
if query: |
|
url = url + '?' + query |
|
if fragment: |
|
url = url + '#' + fragment |
|
return _coerce_result(url) |
(The '//' special-casing seems to occur in this line here:
|
if netloc or (scheme and scheme in uses_netloc and url[:2] != '//'): |
)
And here is where the round-tripping is tested:
(Three initial leading slashes is tested, but not the problem case of four or more.) tirkarthi commented on Jul 30, 2018 This is an issue with Python 2 too which I hope can be fixed too. The original logic in the code was committed around 16 years back : bbc0568 and tests are also around 10 years old too.
➜ cpython git:(2bea771) ✗ ./python.exe
Python 2.7.15+ (remotes/upstream/2.7:2bea771609, Jul 30 2018, 18:07:51)
[GCC 4.2.1 Compatible Apple LLVM 7.0.2 (clang-700.1.81)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>
➜ cpython git:(2bea771) ✗ ./python.exe bpo-34276.py
file://root/a [SplitResult(scheme='file', netloc='root', path='/a', query='', fragment='')]
file://root/a
ROUNDTRIP: True
file:///root/a [SplitResult(scheme='file', netloc='', path='/root/a', query='', fragment='')]
file:///root/a
ROUNDTRIP: True
file:////root/a [SplitResult(scheme='file', netloc='', path='//root/a', query='', fragment='')]
file://root/a
ROUNDTRIP: False
file://///root/a [SplitResult(scheme='file', netloc='', path='///root/a', query='', fragment='')]
file:///root/a
ROUNDTRIP: False
Thanks tirkarthi commented on Jul 30, 2018 I just checked back the behavior on Perl's https://github.com/libwww-perl/URI/ . It seems to handle that along with other additional cases. Maybe some of the tests can be adopted from there for better coverage too (https://github.com/libwww-perl/URI/blob/master/t/split.t)
$ cat bpo34276.pl
use URI::Split qw(uri_split uri_join); sub print_url{
my $uri = shift;
print "original uri ", $uri, "\n";
($scheme, $auth, $path, $query, $frag) = uri_split($uri);
$uri = uri_join($scheme, $auth, $path, $query, $frag);
print "returned uri ", $uri, "\n";
}
print_url("file://root/a");
print_url("file:///root/a");
print_url("file:////root/a");
print_url("file://///root/a");
$ perl bpo34276.pl
original uri file://root/a
returned uri file://root/a
original uri file:///root/a
returned uri file:///root/a
original uri file:////root/a
returned uri file:////root/a
original uri file://///root/a
returned uri file://///root/a Thanks vadmium commented on Jul 30, 2018 This may be a very old regression (from 2002) caused by bpo-591713 and Mercurial rev. 554f975073a0. The original check for the double slash, added in 0d6bd391acd8, “escapes” a path beginning with a double slash by prefixing it with two more slashes (empty “netloc”). This should round-trip Chris’s problem URLs.
I think the logic in “urlsplit” should always add the extra double slash for the netloc, regardless of path, at least if a scheme is present and it is registered in “uses_netloc”. This should fix Chris’s instance of the bug, since “file:” is registered. There is already a patch in bpo-1722348 which should do this (although it includes other changes as well).
The double slash should also be escaped if no scheme is present. (The empty scheme string is already in “uses_netloc”.) This might satisfy bpo-23505.
IMO it would be better to do the escaping by default, for all schemes unknown to “urllib”, and to blacklist specific schemes like “mailto:” instead. But that would be out of scope for a bug fix. cjerdonek commented on Jul 31, 2018 Thanks for all the extra info. A couple more comments:
-
I came across this issue when diagnosing the following pip issue ("pip install git+file://" not working for Windows UNC paths):
pip install git+file:// doesn't work with Windows UNC paths pypa/pip#3783
-
URLs of the form "file:////root" (with four or more leading slashes) are perhaps not valid URI's technically. See Section 3. "Syntax Components" of RFC 3986, where it says, "When authority [i.e. netloc] is not present, the path cannot begin with two slash characters ('//')":
https://tools.ietf.org/html/rfc3986#section-3
However, I don't think that means Python shouldn't try to roundtrip it successfully. Also, git-clone is apparently okay with URLs of this form, and does the right thing with them. vadmium commented on Jul 31, 2018 I think your URLs are valid by RFC 3986. "When authority is not present" refers to URLs without the double-slash prefix, like the "urn:example:animal:ferret:nose". The RFC treats empty authority and no authority as different cases. If authority is present, the format for hier-part has to be
"//" authority path-abempty
Authority may be an empty string:
authority = [userinfo "@"] host [":" port]
host = IP-literal / IPv4address / reg-name
reg-name = *(unreserved / pct-encoded / sub-delims) ; May be empty Path-abempty may begin with two slashes if the first two segments are empty strings:
path-abempty = *("/" segment)
segment = *pchar ; May be empty cjerdonek commented on Jul 31, 2018
The RFC treats empty authority and no authority as different cases.
I'm not well-versed on this. But I guess this means urllib.parse doesn't support this distinction. For example:
>>> urllib.parse.urlsplit('file:/foo')
SplitResult(scheme='file', netloc='', path='/foo', query='', fragment='')
>>> urllib.parse.urlsplit('file:///foo')
SplitResult(scheme='file', netloc='', path='/foo', query='', fragment='')
>>> urllib.parse.urlsplit('file:/foo') == \
urllib.parse.urlsplit('file:///foo')
TrueBoth have authority / netloc equal to the empty string, even though in the first example the authority isn't present per your comment. vadmium commented on Jul 31, 2018 Yes urllib doesn’t distinguish a missing authority/netloc from an empty string. The same for the ?query and #fragment parts. There is bpo-22852 open about that. vladima commented on Sep 7, 2018 serhiy-storchaka commented on Dec 29, 2023 vadmium commented on May 12, 2024 After seeing that the “mailto:” RFC 6068 says slashes (/) have to be encoded in e.g. mailto:%2F%2Flocal@domain, I agree with adding the extra double-slash (//) regardless of scheme. (Previously I believed mailto://local@domain to be valid for an address of //local@domain, but I take that back.)
MetadataMetadataDevelopmentNo branches or pull requestsIssue actions
|