TutSocketCheck

Name

TutSocketCheck — check if data can be read from or written to a socket

Synopsis

T_BOOL TutSocketCheck(socket_fd, check_mode, timeout) 
T_INT4 socket_fd; 
T_IO_CHECK_MODE check_mode; 
T_REAL8 timeout;

Arguments

socket_fd — socket file descriptor to check

check_mode — how to check the socket availability

timeout — maximum number of seconds to wait for availability

Return Values

TRUE if data can be read/written, FALSE if timeout reached or error occurred.

Diagnostics

If TutSocketCheck fails, it returns FALSE and sets the global SmartSockets error number to one of:

T_ERR_C — a C error has occurred. The function TutErrNumGetC should be called to obtain the related C error value.

T_ERR_OS — an operating system error has occurred. The function TutErrNumGetOs should be called to obtain the related OS error value.

T_ERR_SOCKET — a socket error has occurred. The function TutErrNumGetSocket should be called to obtain the related socket error value.

T_ERR_VAL_TOO_SMALL — the socket file descriptor was a negative number or the timeout was a negative number.

T_ERR_TIMEOUT_REACHED — the timeout period was reached

Description

TutSocketCheck is a convenience function that provides a simplified interface to the select function. If check_mode is T_IO_CHECK_READ, then TutSocketCheck checks if data is available to be read from the socket. If check_mode is T_IO_CHECK_WRITE, then TutSocketCheck checks if data can be written to the socket without blocking. TutSocketCheck returns TRUE if the socket is available and FALSE otherwise. The timeout controls how long TutSocketCheck waits for availability. To wait indefinitely, use the constant T_TIMEOUT_FOREVER for the timeout. To poll the socket without blocking, use a timeout of 0.

Server sockets may use TutSocketCheck to check if a client has connected.

Caution

None

Examples

This example uses TutSocketCheck to wait for up to 10 seconds for a new client to connect to a server socket, then accepts the new client with TutSocketAccept:

if (!TutSocketCheck(server_fd, T_IO_CHECK_READ, 10.0)) { 
  /* error */ 
}  
else { 
  client_fd = TutSocketAccept(server_fd); 
  if (client_fd == -1) { 
    /* error */ 
  }  
}