io_tryread(3)io_tryread(3)NAMEio_tryread - read from a descriptor without blocking
SYNTAX
#include <io.h>
int io_tryread(int64 fd,char* buf,int64 len);
DESCRIPTIONio_tryread 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_tryread 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_tryread always suc‐
ceeds in reading exactly len bytes.
· io_tryread 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.
· io_tryread returns -1, setting errno to EAGAIN: No bytes were read,
because the descriptor is not ready. For example, the descriptor is
reading an empty pipe that could still be written to.
· io_tryread 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).
io_tryread does not pause waiting for a descriptor that is not ready.
If you want to pause, use io_waitread or io_wait.
You can make io_tryread faster and more efficient by making the socket
non-blocking with io_nonblock().
SEE ALSOio_nonblock(3), io_waitread(3), io_tryreadtimeout(3)io_tryread(3)
