Performs synchronous I/O.
Err DoIO( Item ior, const IOInfo *ioiP )
This procedure is the most efficient way to perform synchronous I/O (I/O in which the task waits for the I/O request to complete before continuing). It automatically requests quick I/O (see below), sends the I/O request, and then puts the calling task into wait state until the request is complete.
DoIO()
automatically sets the IO_QUICK flag in the IOInfo structure. This flag specifies quick I/O, which works as follows: The kernel tries to perform the I/O operation immediately and, if it is successful, it sends back the resulting IOReq immediately and returns 1 as the result code. The calling task can then get the necessary information from the IOReq. If quick I/O is not successful, the kernel performs normal asynchronous I/O and notifies the task with a signal or message when the I/O request is complete. This wakes up the task and DoIO() returns.
Starting with kernel folio V24, this function will automatically sample the io_Error field of the I/O request and return this to you. It is, therefore, no longer necessary to have code such as:
err = DoIO(iorItem,&ioinfo); 0r err = DoIO(iorItem,&ioinfo); if (err >= 0) err = ior->io_Error;
You can now just look at the return value of DoIO()
.
The procedure returns when the I/O was successful (which means that the IOReq structure has already been returned and its contents can be examined).
Convenience call implemented in clib.lib V20. Became a SWI in kernel folio V24.
AbortIO
(), CheckIO(), CreateIOReq(), DeleteIOReq(), SendIO(), WaitIO()