pSOSystem System Calls - Read

pNA+ System Calls recv
recv Receives data from a socket.
#include
long recv(
int s, /* socket descriptor */
char *buf, /* packet */
int len, /* packet length */
int flags /* packet attributes */
)
Description
Arguments
The recv() system call is used to receive data from the specified socket. The
behavior of this system call depends on the socket type, as described under
“Arguments.”
The recv() system call returns the number of bytes received, and this value should
always be checked because this is the only way to detect the actual number of data
bytes stored in the user buffer.
Applications can use this call to receive messages from the pNA+ network manager
in a linked list of mblks (message blocks) by setting the MSG_RAWMEM flag. Using
mblks eliminates the data copy performed in the pNA+ network manager during the
data transfer between the application and the pNA+ network manager.
s Specifies the socket from which data is received. s can be a stream,
a datagram, or a raw socket.
If s is a stream socket, recv() copies whatever data is available at
the socket to the user buffer and returns. recv() never copies more
than len bytes of data to the user buffer, but it can copy less, if less
than len bytes are available. Unless ioctl() was used to mark the
socket non-blocking, recv() blocks the caller if no data is available
at the socket. The caller is unblocked when data is received. If the
socket has been marked non-blocking, recv() returns immediately
whether or not data is received.
pSOSystem System Calls 4-45
4