pSOSystem System Calls - Read

ecv pNA+ System Calls
Return Value
If s is a datagram socket, every recv() call receives one datagram.
The sender defines the size of the datagram. If the len parameter is
less than the size of the datagram, part of the datagram is discarded.
The next recv() call reads the next datagram received but not the
unread part of the previous datagram. Unless ioctl() was used to
mark the socket non-blocking, recv() blocks the caller until a datagram
is available at the socket. If the socket has been marked nonblocking,
recv() returns immediately whether or not datagrams are
received.
If s is a raw socket, every recv() call receives one raw datagram.
The size of the raw datagram is defined by the sender. If the len parameter
is less than the size of the raw datagram, part of the raw datagram
is discarded. The next recv() call reads the next raw
datagram received, not the unread part of the previous raw datagram.
Unless ioctl() was used to mark the socket non-blocking,
recv() blocks the caller until a raw datagram is available at the
socket. If the socket has been marked non-blocking, recv() returns
immediately whether or not raw datagrams are received. The packet
contains an IP header along with the packet body, if any.
buf Points to the user buffer where the data is stored.
len Specifies the size in bytes of the buffer.
flags Specifies usage options and is the result of an OR operation performed
on one or more of the following symbolic constants (defined
in ). Can also be set to 0.
MSG_OOB Specifies that you want recv() to read any out-ofband
data present on the socket, rather than the
regular in-band data.
MSG_PEEK Specifies that you want recv() to peek at the data
present on the socket; the data is returned, but not
consumed, so that a subsequent receive operation
sees the same data.
MSG_RAWMEM Specifies that you have set buf to point to a linked
list of mblks and len to the total size of the message.
This system call returns either the number of bytes received or -1 if an error occurs.
When the receive is shutdown by either end of the connection, a value of 0 is
returned.
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