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Author eryksun
Recipients Jairo Llopis, eryksun, paul.moore, steve.dower, tim.golden, zach.ware
Date 2021-02-01.21:33:03
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Marked as misclassified Yes
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When an open attempts to access a directory as data, the error code from WinAPI CreateFileW is ERROR_ACCESS_DENIED (5), which maps to C EACCES and thus raises Python PermissionError. 

Python's io.FileIO() type could handle an EACCES error in Windows by checking for a directory. There's a race condition to consider in which an inaccessible file is replaced by a directory, but that seems to be a trivial concern.

io.FileIO() could also use the undocumented _O_OBTAIN_DIR (0x2000) open flag. This opens with backup semantics, which allows opening directories. Then, as already implemented in POSIX, fail with EISDIR if a directory is opened. For example:

    >>> fd ='C:/Temp', 0x2000)
    >>> stat.S_ISDIR(os.fstat(fd).st_mode)
Date User Action Args
2021-02-01 21:33:03eryksunsetrecipients: + eryksun, paul.moore, tim.golden, zach.ware, steve.dower, Jairo Llopis
2021-02-01 21:33:03eryksunsetmessageid: <>
2021-02-01 21:33:03eryksunlinkissue43095 messages
2021-02-01 21:33:03eryksuncreate