@c From: Alain Magloire <alainm@rcsm.ece.mcgill.ca>
@c Some modifications by Richard Dawe <richdawe@bigfoot.com>

@comment The start of a comment is indicated by the following comment. This
@comment syntax is used by the script funcstxh.sh: @comment function <name>

@comment function recvfrom

@node recvfrom, socket
@findex recvfrom

@subheading Syntax

@example
#include <sys/types.h>
#include <sys/socket.h>

ssize_t recvfrom (int s, void * buf, size_t len, unsigned int flags,
                  struct sockaddr *from, size_t *fromlen);
@end example	   

@subheading Description

@code{recvfrom()} is used to receive messages from a socket.
If @var{from} is non-NULL, the source address of the message is stored in it.
@var{fromlen} is a value-result parameter, it indicates the size of @var{from}
on entry and the size of @var{from} stored.  If @var{fromlen} was too small,
it is truncated to the initial size. @var{flags} may have the value zero or
be the bitwise OR of any combination of one or more of the values:

@table @samp
@item MSG_OOB
Receipt of out-of-band data that would not be received in the normal data
stream.  Application should use MSG_OOB flag after catching a SIGURG
or if @code{select()} (@pxref{select, , select, libc}) indicates
an exception condition.
@item MSG_PEEK
The receive operation data from the beginning of the receive queue without
removing that data from the queue.  Thus, a subsequent receive call will
return the same data.
@item MSG_WAITALL
Requests that the operation block until the full request is
satisfied.  However, the call may still return less data than requested if
a signal is caught, an error or disconnect occurs, or the next data to be
received is of a different type than that returned.
@end table

@subheading Return Values

On success the number of octets received is return, or -1 and
@var{errno} is set:

@table @samp
@item EWOULDBLOCK.
The socket is marked non-blocking and the receive operation would block.
@item EBADF
The paramater is not a valid descriptor.
@item ENOTCONN
The socket is associated with a connection-oriented protocol
and has not been connected.
@item ENOTSOCK
The argument does not refer to a socket.
@item EINTR 
The receive was interrupted by delivery of a signal before
any data were available.
@item EFAULT
The receive buffer pointer(s) point outside the process's
address space.
@end table

@subheading Portability

@portability posix, unix98

@subheading Example

@example
@end example