HP 3000 Manuals HP 3000 Manuals
ACCEPT
C Interface
AF_UNIX only:
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>
int ns;
ns=accept(s, addr, addrlen)
int s;
struct sockaddr_un *addr;
int *addrlen;
AF_INET only:
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
int ns;
ns=accept(s, addr, addrlen)
int s;
struct sockaddr_in *addr;
int *addrlen;
Description
This call is used with connection-based socket types, such as
SOCK_STREAM. The argument s is a socket descriptor created with socket,
bound to an address with bind, and listening for connections after a
listen. If pending connections are present on the queue, the accept call
extracts the first connection on the queue, creates a new socket, and
allocates a new file descriptor, ns, for the socket. If no pending
connections are present on the queue and non-blocking mode has been
enabled using the O_NONBLOCK or O_NDELAY fcntl flags (refer to fcntl
section), accept returns an error as described in the Errors section
below. If no pending connections are present on the queue and
non-blocking mode has not been enabled, accept blocks the caller until a
connection is present. The accepted socket, ns, cannot be used to accept
more connections. The original socket s remains open. It is possible to
determine if a listening socket has pending connection requests ready for
an accept call by using select for reading.
The argument addr should point to a local socket address structure. The
accept call fills in this structure with the address of the connecting
entity, as known to the underlying protocol. The format of the address
depends upon the protocol and the address family of the socket s. The
addrlen is a pointer to int; it should initially contain the size of the
structure pointed to by addr. On return it contains the actual length
(in bytes) of the address returned. If the memory pointed to by addr is
not large enough to contain the entire address, only the first addrlen
bytes of the address are returned.
AF_UNIX only: The addr parameter to accept() is ignored.
Return Value
If the call is successful, a non-negative integer is returned, which is a
descriptor for the accepted socket. If the call fails, a -1 is returned
and an error code is stored in errno.
Errors
The following errors are returned by accept:
[EHOSTDOWN] The networking subsystem has not been started or has
been stopped.
[EBADF] The file descriptor s is invalid.
[ENOTSOCK] The argument s references a file, not a socket.
[EOPNOTSUPP] The socket referenced by s is not of type
SOCK_STREAM.
[EFAULT] The addr parameter is not a valid pointer.
[EWOULDBLOCK] Non-blocking I/O is enabled using O_NDELAY, and no
connections are present to be accepted.
[EMFILE] The maximum number of file descriptors for this
process are already currently open.
[ENFILE] The system's table of open files is full, and no more
accept calls can be accepted, temporarily.
[ENOBUFS] No buffer space is available. The accept cannot
complete. The queued socket connect request is
aborted.
[EINVAL] The socket referenced by s is not currently a listen
socket, or it has been shut down. A listen must be
done before an accept is allowed. This is also
returned if the length is less than zero.
[EINTR] The call was interrupted by a signal before a valid
connection arrived.
[EAGAIN] Non-blocking I/O is enabled using O_NONBLOCK, and no
connections are present to be accepted.
MPE/iX Specific
Connections are completely established in the accept call. The addr
returned from accept when a connection is made in loopback is the
loopback address (127.0.0.1). On HP-UX, the local host's IP address
would be returned in this case.
Author
UCB (University of California at Berkeley)
See Also
bind, connect, listen, select, socket