writes data to a specified open file descriptor using
from the specified
virtual ring buffer until the specified maximum length has been written,
the buffer is full, or an error is returned
(including EAGAIN or EWOULDBLOCK for a non-blocking descriptor).
specifies which virtual ring buffer.
specifies the open file descriptor to write to
specifies the maximum length to write, or
for unlimited (all of buffer).
If successful, the actual length of data written from the buffer is returned.
If no data was available to be written, 0 will be returned.
If an error occurs from
the return value is ~0 and
errno is set by
If an error is returned, then
will have one of the following values:
An end-of-file has occurred.
Note that this is a different way of returning an end-of-file
An invalid virtual ring buffer pointer was specified.