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Handle leading // for posixpath.realpath #117338
Description
Bug report
Bug description:
>>> import posixpath
>>> posixpath.realpath("//foo")
'/foo'Expected: //foo with precisely two leading slashes, see: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap04.html#tag_04_13
This can be quite easily solved using posixpath.splitroot, see the PR.
CPython versions tested on:
CPython main branch
Operating systems tested on:
macOS
Activity
barneygale commented on Mar 28, 2024
os.path.realpath() resolves the path using the current OS's rules, which might be more specific than POSIX. Both my Linux and macOS machines resolve //foo to /foo. Are there any supported Python platforms where // isn't resolved to /?
nineteendo commented on Mar 28, 2024
I'm currently on my Windows laptop, so I can't check.
In any case, the old implementation can never return //foo because path is set to os.sep.
Is there a "needs investigation" label?
barneygale commented on Mar 28, 2024
There doesn't seem to be anything like a "needs investigation" label.
Happy to leave this issue open for a bit while you further research a repro case, but if we can't find one, then I think this issue should be closed as "can't repro".
nineteendo commented on Mar 28, 2024
Also, the current behaviour is undocumented:
Normalizing doesn't touch the double slash & // is not a symlink.
barneygale commented on Mar 28, 2024
You're quoting a comment above the internal _joinrealpath() function.
Both the posixpath.realpath() docstring, and the online docs, describe it as returning a canonical path. The online docs add:
nineteendo commented on Mar 28, 2024
OK, but that comment doesn't document this feature, which it probably should, in case this works correctly.
bluss commented on Mar 29, 2024
Why do you want to fix this, and could you describe in more detail how the changes relate to the specification you are pointing to? I don't see what in the specification requires this.
nineteendo commented on Mar 29, 2024
Yep, the old behaviour seems to be correct (cd doesn't resolve symlinks), in that case the feature should just be documented and tested.
barneygale commented on Mar 29, 2024
We don't need to document every detail of what realpath() does. Tests would be welcome, though
nineteendo commented on Mar 29, 2024
I've added just one sentence in this pull request: #117350.
Where should I add the test though? It doesn't really fit in with the rest of the changes.