Chris> I am wondering what the defined action/status of sane_read()
Chris> should be if when it returns, the *len == 0. Is this
Chris> considered an error?
No. It simply means that no data is available.
Doesn't it matter whether or not the IO mode is set to blocking versus
non-blocking? The spec states that in blocking mode, sane_read must
return at least one byte of data for each call, blocking until it's got
at least that one byte to give (otherwise, a front-end would have to
keep polling, yuck --- non-blocking mode allows you to do a select on
the device and wake up when data arrives).
So, if your backend is doing the simple blocking mode only, it *should*
keep reading from from scanner until it has something to return to the
frontend.
-matt m.
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