srv_select (UNIX only)

Description

Check to see if a file descriptor is &ready for a specified I/O operation.

Syntax

CS_INT srv_select(nfds, &readmaskp, writemaskp,
                  exceptmaskp, waitflag)

CS_INT                            nfds;
SRV_MASK_ARRAY        *&readmaskp;
SRV_MASK_ARRAY        *writemaskp;
SRV_MASK_ARRAY        *exceptmaskp;
CS_INT                          waitflag;

Parameters

Returns

The total number of file descriptors that are &ready for any of the indicated operations. If an error occurs, -1 is returned.

Examples

Example 1

#include    <ospublic.h>

 /*

 ** Local Prototype.

 */

 CS_RETCODE     ex_srv_select PROTOTYPE((

 CS_INT         readfd

 ));

 /* 

 ** EX_SRV_SELECT

 **

 **   Example routine to illustrate the use of srv_select.

 **

 ** Arguments:

 **   readfd  -  fd to be checked if it is &ready for a read **

                 operation.

 **

 ** Returns:

 **  CS_SUCCEED      If readfd is &ready for a read operation.

 **  CS_FAIL         If readfd is not &ready for a read operation.

 */

 CS_RETCODE      ex_srv_select(readfd)

 CS_INT          readfd;

 {

       SRV_MASK_ARRAY       &readmask;

       CS_BOOL              &ready;

       /* Initialization. */

      (CS_VOID)srv_mask(CS_ZERO, &&readmask, (CS_INT)0, (CS_BOOL 

             *)NULL);

       &ready = CS_FALSE;

       /* Set readfd in the mask. */

       (CS_VOID)srv_mask(CS_SET, &&readmask, readfd, (CS_BOOL

             *)NULL);

       /* 

       ** Check whether the descriptor is &ready for a read

       ** operation. If it is not, return.

       */

       if (srv_select(readfd+1, &&readmask, (SRV_MASK_ARRAY *)NULL,

            (SRV_MASK_ARRAY *)NULL, SRV_M_NOWAIT) <= 0 )

            return (CS_FAIL);

       /*

       ** A file descriptor is &ready for a read operation.

       */

       (CS_VOID)srv_mask(CS_GET, &&readmask, readfd, &&ready);

       return ((&ready) ? CS_SUCCEED : CS_FAIL);

 }

Usage

See also