fp_readv Kernel Service

Purpose

Performs a read operation on an open file with arguments passed in iovec elements.

#include <sys/types.h>
#include <sys/errno.h>

int fp_readv (fp, iov, iovcnt, ext, seg, countp) struct file * fp; struct iovec * iov; ssize_t iovcnt; ext_t ext; int seg; ssize_t countp;

Item	Description
fp	Points to a file structure returned by the fp_open kernel service.
iov	Points to an array of iovec elements. Each iovec element describes a buffer where data to be read from the file is to be stored.
iovcnt	Specifies the number of iovec elements in the array pointed to by the iov parameter.
ext	Specifies an extension argument required by some device drivers. Its content, form, and use are determined by the individual driver.
seg	Indicates in which part of memory the array specified by the iov parameter is located: SYS_ADSPACE The array specified by the iov parameter is in kernel memory. USER_ADSPACE The array specified by the iov parameter is in application memory.
countp	Points to the location where the count of bytes actually read from the file is to be returned.

The fp_readv kernel service is an internal interface to the function provided by the readv subroutine.

The fp_readv kernel service can be called from the process environment only.

Item	Description
0	Indicates a successful operation.

If an error occurs, one of the values from the /usr/include/sys/errno.h file is returned.