Fix File.exists? for special devices on Windows#15587
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straight-shoota merged 2 commits intocrystal-lang:masterfrom Mar 24, 2025
Merged
Fix File.exists? for special devices on Windows#15587straight-shoota merged 2 commits intocrystal-lang:masterfrom
File.exists? for special devices on Windows#15587straight-shoota merged 2 commits intocrystal-lang:masterfrom
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File.exists?(File::NULL) on WindowsFile.exists? for special devices on Windows
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There are [7 types of user-space paths on Win32](https://googleprojectzero.blogspot.com/2016/02/the-definitive-guide-on-win32-to-nt.html): * Drive-absolute (`C:\foo`) * Drive-relative (`C:foo`) * Rooted (`\foo`) * Relative (`foo`) * UNC absolute (`\\server\share\foo`) * Local device (`\\.\NUL`, `\\?\C:\foo`) * Root local device (`\\.`, `\\?`) Local device paths starting with exactly `\\?\` are also known as raw local device paths. Other than this prefix, all forward and backward slashes are interchangeable. `Path` already recognizes the first 5 of them; this PR adds the remaining 2. As noted in #15587, the `\\.\` prefix appears when dealing with special devices, such as `\\.\NUL` and `\\.\COM15`, as well as named pipes. The `\\?\` prefix is useful when passing paths to Win32 functions that are already normalized, or if the path exceeds 260 UTF-16 code units (see also #13420). This does not cover NT paths of the form `\??\...`. They appear in the reparse data area of Windows symbolic links.
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Fixes #15019.
Note that
File.realpath("nul")will now correctly return\\.\NUL. Support inPathwill be added shortly.