Content-type: text/html Man page of accept

accept

Section: System Calls (2)
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NAME

accept - Accepts a new connection on a socket  

SYNOPSIS

#include <sys/socket.h>

int accept (        int socket,
       struct sockaddr *address,
       size_t *address_len );

[POSIX]  The definition of the accept() function in POSIX.1g Draft 6.6 uses a socklen_t data type instead of a size_t data type as specified in XNS4.0 (the previous definition).

[DIGITAL]  The following definition of the accept() function does not conform to current standards and is supported only for backward compatibility (see standards(5)):

int accept (        int socket,
       struct sockaddr *address,
       int *address_len );
 

STANDARDS

Interfaces documented on this reference page conform to industry standards as follows:

accept(): XNS4.0

The accept function also supports POSIX.1g Draft 6.6.

Refer to the standards(5) reference page for more information about industry standards and associated tags.  

PARAMETERS

Specifies a file descriptor for the socket that was created with the socket() function, has been bound to an address with the bind() function, and has issued a successful call to the listen() function. Points to a sockaddr structure, the format of which is determined by the domain and by the behavior requested for the socket. The sockaddr structure is an overlay for a sockaddr_in, or sockaddr_un structure, depending on which of the supported address families is active.

[DIGITAL]   If the compile-time option _SOCKADDR_LEN is defined before the sys/socket.h header file is included, the sockaddr structure takes 4.4BSD behavior, with a field for specifying the length of the socket address. Otherwise, the default 4.3BSD sockaddr structure is used, with the length of the socket address assumed to be 14 bytes or less.
You can specify NULL to indicate that the address of the peer is not required.
If _SOCKADDR_LEN is defined, the 4.3BSD sockaddr structure is defined with the name osockaddr. Specifies the length of the sockaddr structure pointed to by the address parameter. If the address parameter is NULL then this parameter is ignored.
 

DESCRIPTION

The accept() function extracts the first connection on the queue of pending connections, creates a new socket with the same properties as the specified socket, and allocates a new file descriptor for that socket.

If the listen() queue is empty of connection requests, the accept() function blocks a calling socket of the blocking type until a connection is present, or returns an [EWOULDBLOCK] for sockets marked nonblocking.

The accepted socket cannot itself accept more connections. The original socket remains open and can accept more connections.  

NOTES

[DIGITAL]  When compiled in the X/Open UNIX environment or the POSIX.1g socket environment, calls to the accept() function are internally renamed by prepending _E to the function name. When you are debugging a module that includes the accept() function and for which _XOPEN_SOURCE_EXTENDED or _POSIX_PII_SOCKET has been defined, use _Eaccept to refer to the accept() call. See standards(5) for further information.  

RETURN VALUES

Upon successful completion, the accept() function returns the nonnegative socket descriptor of the accepted socket. Additionally, if the address parameter was specified then it places the address of the peer in the sockaddr structure pointed to by the address, and sets the address_len parameter to the length of address. If the accept() function fails, a value of -1 is returned and errno is set to indicate the error.  

ERRORS

If the accept() function fails, errno may be set to one of the following values: The socket parameter is not valid. A connection has been aborted. The address parameter is not in a writable part of the user address space. The accept() function was interrupted by a signal that was caught before a valid connection arrived. The socket is not accepting connections. There are too many open file descriptors. The maximum number of file descriptors in the system are already open. [POSIX]  Insufficient resources are available in the system to complete the call. The system was unable to allocate kernel memory to increase the process descriptor table. The socket parameter refers to a file, not a socket. The referenced socket can not accept connections. The socket is marked nonblocking, and no connections are present to be accepted.  

RELATED INFORMATION

Functions: bind(2), connect(2), listen(2), socket(2).

Standards: standards(5). delim off


 

Index

NAME
SYNOPSIS
STANDARDS
PARAMETERS
DESCRIPTION
NOTES
RETURN VALUES
ERRORS
RELATED INFORMATION

This document was created by man2html, using the manual pages.
Time: 02:40:14 GMT, October 02, 2010