Metrologic Optimus S Programming Manual page 161

recv
Purpose To receive data from a connected or bound socket.
Syntax int recv (SOCKET s, char *buf, int len, int flags);
s
buf
len
flags
Example SOCKET s;
char buf[1024];
int len;
...................
if (socket_hasdata (s)) {
}
Description This routine reads incoming data from a specified buffer (buf) on a connected
socket.
The select() routine may be used to determine when more data arrives. (?)
Note that this is a blocking function. This routine will not return unless for the
following reason:
The application can avoid this blocking behavior by using socket_hasdata() to
make sure there is data available before calling recv().
Return If successful, it returns a non-negative integer (>=0) indicating the number of
bytes received and stored into buffer.
On error, it returns -1.
The global variable errno is set to indicate the error condition encountered.
Chapter 3 Terminal Specific Function Library
Descriptor identifying a connected socket
Pointer to the buffer in which data is received
Maximum number of bytes to be received
MSG_OOB: process out-of-band data
MSG_PEEK: peek at incoming data
len = recv (s, buf, sizeof (buf), 0);
if (len < 0) {
printf ("recv fails on socket: %d", s);
...................
}
The flags argument allows one of the following values:
MSG_OOB returns urgent data (out-of-bound data)
MSG_PEEK returns data but do not remove it from buffer,
allowing it to be read again on subsequent calls
an error happens
data is received
the receive action times out
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