Re: Use consistent errno for read(2) failure on directories

[Mouse <mouse%Rodents-Montreal.ORG@localhost>]

>> According to the online OpenGroup specification for read(2)
>> available at [1], read(2) on directories is implementation
>> dependant.  If unsupported, it shall fail with EISDIR.

>> Not all our file systems comply, and return random errno values in
>> this case (mostly EINVAL or ENOTSUP).

How does that not comply with "implementation dependent"?  From a
standards-conformance point of view, that's equivalent to "in this
implementation, read(2) on directories is supported: on $FILESYSTEM, it
always returns EINVAL, on $OTHER_FILESYSTEM, it works according to
$REFERENCE; on $THIRD_FILESYSTEM, it always returns EOPNOTSUPP".

This is not to say that it shouldn't be cleaned up.  Just that I don't
think it's actually nonconformant.

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