The prefix file:// results in ignoring the first path component. #108

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1. ap-- commented on Jun 21, 2023

   

   ap--

   on Jun 21, 2023

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   Hi @pedro-r-marques

   thank you for opening an issue!

   I do have a pretty good idea where the error is occurring here, but I'd love to have some more information from you beforehand.

   1. Could you tell me what the first thing you tried was, before you were investigating the behavior of the different amount of slashes after file:, i.e. how did you generate your URIs?
   2. Could you have a short read of this: https://en.wikipedia.org/wiki/File_URI_scheme#How_many_slashes? and let me know if it is clear to you why the behavior is different
   3. Would a warning have helped to address this?

   Basically file://var/tmp is interpreted as host=var and path=/tmp and we currently seem to ignore the host for local paths. The question is, how we should address this in the best way. Very likely with both: better documentation AND actually using the host and erroring with a clear error msg.

   Cheers,
   Andreas 😃
2. pedro-r-marques commented on Jun 22, 2023

   

   pedro-r-marques

   on Jun 22, 2023

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   I initially tried "file://" expecting it to follow other url-like parameters. If the implementation interprets the first string as hostname it should make sure that the value is usable and throw an error otherwise. i.e. if hostname != 'localhost' and hostname != '' then it should imho raise an ArgumentError.

   👍React with 👍1Reacted by Andreas Poehlmann
3. ap--

   added

   bug 🐛Something isn't workingSomething isn't working

   on Aug 2, 2023
4. ap-- commented on Aug 28, 2023

   

   ap--

   on Aug 28, 2023

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   Notes:

   We should provide a correct error message for now, and in case pathlib or we decide to support parsing relative path uri's we can switch, see:

   • 662c294#r123906140 expecting support for file:path/file.txt
   • GH-107465: Add pathlib.Path.from_uri() classmethod. python/cpython#107640

   moved to new issue #142
5. barneygale commented on Sep 2, 2023

   

   barneygale

   on Sep 2, 2023

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   file://foo/bar does not represent a relative path on Windows - it represents a UNC path \\foo\bar.

   In my CPython PR I made it work the same on POSIX, and so:

   >>> pathlib.Path.from_uri('file://var/tmp')
   PosixPath('//var/tmp')

   Note that paths with two leading slashes are allowed by POSIX:

   A pathname consisting of a single slash shall resolve to the root directory of the process. A null pathname shall not be successfully resolved. A pathname that begins with two successive slashes may be interpreted in an implementation-defined manner, although more than two leading slashes shall be treated as a single slash.
6. ap-- commented on Sep 3, 2023

   

   ap--

   on Sep 3, 2023

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   Thanks for the clarification @barneygale!

   So does that mean file://localhost/absolute/path/file.txt would actually not map to /absolute/path/file.txt on posix systems, but to the path //localhost/absolute/path/file.txt?

   how does that fit together with rfc8089? Are "file" ":" "//" "auth-part" -style URIs with a host not compatible with posix?
7. barneygale commented on Sep 3, 2023

   

   barneygale

   on Sep 3, 2023

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   I've never come across file URIs that use file://localhost/ in the wild, but they should probably be handled specially. I'll adjust the PR.

   The RFC also says:

      The "host" is the fully qualified domain name of the system on which
      the file is accessible.  This allows a client on another system to
      know that it cannot access the file system, or perhaps that it needs
      to use some other local mechanism to access the file.
   

   ... which works fine on Windows, but not on other systems :(

   👍React with 👍1Reacted by Andreas Poehlmann
8. ap-- commented on Feb 15, 2024

   

   ap--

   on Feb 15, 2024

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   Fixed in universal_pathlib==0.2.0. Behavior for "file://path" uris is now identical to fsspec.

   >>> import os
   >>> os.getcwd()
   '/home/user'
   >>> import upath
   >>> PATHS = ['/tmp/test', 'file:/tmp/test', 'file://tmp/test', 'file:///tmp/test']
   >>> {p: upath.UPath(p) for p in PATHS}
   {
     '/tmp/buh': PosixUPath('/tmp/buh'),
     'file:/tmp/buh': FilePath('file:///tmp/buh'),
     'file://tmp/buh': FilePath('file:///home/user/tmp/buh'),
     'file:///tmp/buh': FilePath('file:///tmp/buh'),
   }
9. ap--

   closed this as completedon Feb 15, 2024