UNC paths are broken when parsing file:// URIs (authority ignored, round-trip fails)

[t-onoz]

Title

UNC paths are broken when parsing file:// URIs (authority ignored, round-trip fails)

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Description

First of all, thank you for maintaining this great library — it’s very useful and appreciated.

I’ve encountered an issue when handling UNC paths via file:// URIs, where the authority component is ignored and the path is incorrectly interpreted as a local path.

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Reproduction

from upath import UPath

p = UPath(r'\\server\share\file')
uri = p.as_uri()
print(uri)
# 'file://server/share/file'

p2 = UPath(uri)
print(p2)
# 'file://C://server/share/file'

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Expected behavior

file://server/share/file represents a UNC path and should round-trip correctly:

UPath("file://server/share/file")
# -> WindowsUPath('//server/share/file')

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Actual behavior

The authority (server) is dropped and interpreted as part of a local path:

FilePath('C://server/share/file', protocol='file')

This is not equivalent to the original UNC path.

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Comparison with pathlib (Python 3.14)

from pathlib import Path

p = Path(r'\\server\share\file')
uri = p.as_uri()

Path.from_uri(uri)
# -> WindowsPath('//server/share/file')  # correct

pathlib correctly preserves UNC semantics, while UPath does not.

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Impact

• Round-trip is broken: p != UPath(p.as_uri())
• UNC paths are corrupted
• Produces invalid Windows paths

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Suggested fix

When parsing file:// URIs:

• If netloc (authority) is non-empty → treat as UNC:

  //{netloc}{path}
  

• Otherwise → handle as a local path (file:///C:/...)

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Environment

• upath: 0.3.10
• Python: 3.14
• OS: Windows

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Notes

I searched existing issues using:

• "UNC"
• "file URI"

but could not find a matching report.