When a server receives a connection request, it can complete the
connection by accepting the request. Use the function
to do this.
A socket that has been established as a server can accept connection
requests from multiple clients. The server's original socket
does not become part of the connection; instead,
makes a new socket which participates in the connection.
accept returns the descriptor for this socket. The server's
original socket remains available for listening for further connection
The number of pending connection requests on a server socket is finite.
If connection requests arrive from clients faster than the server can
act upon them, the queue can fill up and additional requests are refused
ECONNREFUSED error. You can specify the maximum length of
this queue as an argument to the
listen function, although the
system may also impose its own internal limit on the length of this
This function is used to accept a connection request on the server socket socket.
acceptfunction waits if there are no connections pending, unless the socket socket has nonblocking mode set. (You can use
selectto wait for a pending connection, with a nonblocking socket.) See File Status Flags, for information about nonblocking mode.
The addr and length-ptr arguments are used to return information about the name of the client socket that initiated the connection. See Socket Addresses, for information about the format of the information.
Accepting a connection does not make socket part of the connection. Instead, it creates a new socket which becomes connected. The normal return value of
acceptis the file descriptor for the new socket.
accept, the original socket socket remains open and unconnected, and continues listening until you close it. You can accept further connections with socket by calling
If an error occurs,
-1. The following
errnoerror conditions are defined for this function:
- The socket argument is not a valid file descriptor.
- The descriptor socket argument is not a socket.
- The descriptor socket does not support this operation.
- socket has nonblocking mode set, and there are no pending connections immediately available.
This function is defined as a cancellation point in multi-threaded programs, so one has to be prepared for this and make sure that allocated resources (like memory, files descriptors, semaphores or whatever) are freed even if the thread is canceled.
accept function is not allowed for sockets using
connectionless communication styles.