fp_read Kernel Service

Purpose

Performs a read on an open file with arguments passed.

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

int fp_read (fp, buf, nbytes, ext, segflag, countp) struct file * fp; char * buf; ssize_t nbytes; ext_t ext; int segflag; ssize_t * countp;

Item	Description
fp	Points to a file structure returned by the fp_open or fp_opendev kernel service.
buf	Points to the buffer where data read from the file is to be stored.
nbytes	Specifies the number of bytes to be read from the file into the buffer.
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 buffer specified by the buf parameter is located: SYS_ADSPACE The buffer specified by the buf parameter is in kernel memory. USER_ADSPACE The buffer specified by the buf 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_read kernel service is an internal interface to the function provided by the read subroutine.

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

Item	Description
0	Indicates successful completion.

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