fp_readv Kernel Service

AIX Version 4.3 Kernel and Subsystems Technical Reference, Volume 1

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, 
segflag, countp)
struct file *fp;
char *iov;
int iovcnt;
int  ext;
int segflag;
int *countp;

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.

segflag

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.

0	Indicates a successful operation.

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

The fp_readv kernel service is part of Base Operating System (BOS) Runtime.

The readv subroutine.

Logical File System Kernel Services in AIX Version 4.3 Kernel Extensions and Device Support Programming Concepts.