28 lines
1.4 KiB
Markdown
28 lines
1.4 KiB
Markdown
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# Dunce (de-UNC)
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In Windows the regular paths (`C:\foo`) are supported by all programs,
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but have lots of bizarre restrictions for backwards compatibility with MS-DOS.
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There are also Windows NT UNC paths (`\\?\C:\foo`), which are more robust and with fewer gotchas,
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but are rarely supported by Windows programs — even Microsoft's own!
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This crate converts Windows UNC paths to the MS-DOS-compatible format whenever possible,
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but leaves UNC paths as-is when they can't be unambiguously expressed in a simpler way.
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This allows legacy programs to access all paths they can possibly access,
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and doesn't break any paths for UNC-aware programs.
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For example, `\\?\C:\Windows` will be converted to `C:\Windows`, but `\\?\C:\COM` will be
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left as-is, because it contains a reserved filename.
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In Rust the worst UNC offender is the `fs::canonicalize()` function. This crate provides
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a drop-in replacement for it that returns paths you'd expect.
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On non-Windows platforms these functions leave paths unmodified, so it's safe to use them
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unconditionally for all platforms.
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This crate's handling of UNC paths is safer than just unconditionally stripping the `\\` prefix,
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because naively stripped UNC paths with hostnames change to relative directory paths. There are
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other normalization rules, special characters, and length limits that could change meaning
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of the path.
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Parsing is based on <https://msdn.microsoft.com/en-us/library/windows/desktop/aa365247(v=vs.85).aspx>.
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