I'd like to add the following function to
-- | 'hGetBufSome' @hdl buf count@ reads data from the handle @hdl@ -- into the buffer @buf@. If there is any data available to read, -- then 'hGetBufSome' returns it immediately; it only blocks if there -- is no data to be read. -- -- It returns the number of bytes actually read. This may be zero if -- EOF was reached before any data was read (or if @count@ is zero). -- -- 'hGetBufSome' never raises an EOF exception, instead it returns a value -- smaller than @count@. -- -- If the handle is a pipe or socket, and the writing end -- is closed, 'hGetBufSome' will behave as if EOF was reached. -- -- 'hGetBufSome' ignores the prevailing 'TextEncoding' and 'NewlineMode' -- on the 'Handle', and reads bytes directly.
We need it to properly fix #4041 (closed) and #3808 (closed). It corresponds more closely to the semantics of Unix
read(), and I've found this to be the most useful low-level API for reading in practice.
In the long term we'd like to provide a better binary I/O API, and we might even get around to doing that before 6.14.1, but if not we'll need this.
Deadline: 2 weeks.