In issue 37834, I posted a suggest implementation of win32_xstat_impl that included the following snippet of code: if (!GetFileInformationByHandle(hFile, &fileInfo)) { error = GetLastError(); if (error != ERROR_INVALID_PARAMETER && error != ERROR_INVALID_FUNCTION && error != ERROR_NOT_SUPPORTED) { retval = -1; goto cleanup; } /* Volumes and physical disks are block devices, e.g. \\.\C: and \\.\PhysicalDrive0. */ memset(result, 0, sizeof(*result)); result->st_mode = 0x6000; /* S_IFBLK */ goto cleanup; } This is meant to handle the above errors. We know we have FILE_TYPE_DISK. If GetFileInformationByHandle fails with one of the above error codes, then we must have a disk or volume device without a mounted file-system device. This should be reported as a block device. However it was changed in the final version as follows: if (!GetFileInformationByHandle(hFile, &fileInfo)) { switch (GetLastError()) { case ERROR_INVALID_PARAMETER: case ERROR_INVALID_FUNCTION: case ERROR_NOT_SUPPORTED: retval = -1; goto cleanup; } /* Volumes and physical disks are block devices, e.g. \\.\C: and \\.\PhysicalDrive0. */ memset(result, 0, sizeof(*result)); result->st_mode = 0x6000; /* S_IFBLK */ goto cleanup; } Now it's failing on the errors that should be handled, and succeeding on all other errors that should fail. If we want to use a switch statement here, I suggest the following: if (!GetFileInformationByHandle(hFile, &fileInfo)) { switch (GetLastError()) { case ERROR_INVALID_PARAMETER: case ERROR_INVALID_FUNCTION: case ERROR_NOT_SUPPORTED: /* Volumes and physical disks are block devices, e.g. \\.\C: and \\.\PhysicalDrive0. */ memset(result, 0, sizeof(*result)); result->st_mode = 0x6000; /* S_IFBLK */ goto cleanup; } retval = -1; goto cleanup; }

 New changeset 772ec0fad57412daa53d16d7019b6b2fe6e94942 by Steve Dower in branch 'master': bpo-38030: Fix os.stat failures on block devices on Windows (GH-15681) https://github.com/python/cpython/commit/772ec0fad57412daa53d16d7019b6b2fe6e94942 

 New changeset cad7abf8abe657b696b9c8deb4b727e0cefaf36d by Miss Islington (bot) in branch '3.8': bpo-38030: Fix os.stat failures on block devices on Windows (GH-15681) https://github.com/python/cpython/commit/cad7abf8abe657b696b9c8deb4b727e0cefaf36d