sysfile_read.c

来自「一款类linux的操作系统源码」· C语言 代码 · 共 51 行

/*
 *  Roadrunner/pk
 *    Copyright (C) 1989-2001  Cornfed Systems, Inc.
 *
 *  The Roadrunner/pk operating system is free software; you can
 *  redistribute and/or modify it under the terms of the GNU General
 *  Public License, version 2, as published by the Free Software
 *  Foundation.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public
 *  License along with this program; if not, write to the Free
 *  Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
 *  MA 02111-1307 USA
 *
 *  More information about the Roadrunner/pk operating system of
 *  which this file is a part is available on the World-Wide Web
 *  at: http://www.cornfed.com.
 *
 */

#include <errno.h>
#include <fs/sysfs.h>
#include <stdio.h>
#include <string.h>

int
sysfile_read(file_t file)
{
    int len;

    if (file->flags & F_EOF)
	return EINVAL;

    /* Assume fs layer has provided a buffer */

    if (file->filesize - file->pos > blen(file->buf) - bpos(file->buf))
	len = blen(file->buf) - bpos(file->buf);
    else
	len = file->filesize - file->pos;

    bcopy((char *) file->data + file->pos,
	  bstart(file->buf) + bpos(file->buf), len);

    return 0;
}