debian man page for io_waitread

io_waitread(3)						     Library Functions Manual						    io_waitread(3)

NAME
       io_waitread - read from a descriptor

SYNTAX
       #include <io.h>

       int io_waitread(int64 fd,char* buf,int64 len);

DESCRIPTION
       io_waitread tries to read len bytes of data from descriptor fd into buf[0], buf[1], ..., buf[len-1]. (The effects are undefined if len is 0
       or smaller.) There are several possible results:

       o  o_waitread returns an integer between 1 and len: This number of bytes was available for immediate reading; the bytes were read into  the
	  beginning  of buf. Note that this number can be, and often is, smaller than len; you must not assume that io_waitread always succeeds in
	  reading exactly len bytes.

       o  io_waitread returns 0: No bytes were read, because the descriptor is at end of file. For example, this descriptor has reached the end of
	  a disk file, or is reading an empty pipe that has been closed by all writers.

       o  io_waitread returns -3, setting errno to something other than EAGAIN: No bytes were read, because the read attempt encountered a persis-
	  tent error, such as a serious disk failure (EIO), an unreachable network (ENETUNREACH), or an invalid descriptor number (EBADF).

SEE ALSO
       io_nonblock(3), io_waitread(3), io_waitreadtimeout(3)

																    io_waitread(3)