#/* */#include "../param.h"#include "../inode.h"#include "../user.h"#include "../buf.h"#include "../conf.h"#include "../systm.h"/* * Read the file corresponding to * the inode pointed at by the argument. * The actual read arguments are found * in the variables: *	u_base		core address for destination *	u_offset	byte offset in file *	u_count		number of bytes to read *	u_segflg	read to kernel/user */readi(aip)struct inode *aip;{	int *bp;	int lbn, bn, on;	register dn, n;	register struct inode *ip;	ip = aip;	if(u.u_count == 0)		return;	ip->i_flag =| IACC;	if((ip->i_mode&IFMT) == IFCHR) {		(*cdevsw[ip->i_addr[0].d_major].d_read)(ip->i_addr[0]);		return;	}	do {		lbn = bn = lshift(u.u_offset, -9);		on = u.u_offset[1] & 0777;		n = min(512-on, u.u_count);		if((ip->i_mode&IFMT) != IFBLK) {			dn = dpcmp(ip->i_size0&0377, ip->i_size1,				u.u_offset[0], u.u_offset[1]);			if(dn <= 0)				return;			n = min(n, dn);			if ((bn = bmap(ip, lbn)) == 0)				return;			dn = ip->i_dev;		} else {			dn = ip->i_addr[0];			rablock = bn+1;		}		if (ip->i_lastr+1 == lbn)			bp = breada(dn, bn, rablock);		else			bp = bread(dn, bn);		ip->i_lastr = lbn;		iomove(bp, on, n, B_READ);		brelse(bp);	} while(u.u_error==0 && u.u_count!=0);}/* * Write the file corresponding to * the inode pointed at by the argument. * The actual write arguments are found * in the variables: *	u_base		core address for source *	u_offset	byte offset in file *	u_count		number of bytes to write *	u_segflg	write to kernel/user */writei(aip)struct inode *aip;{	int *bp;	int n, on;	register dn, bn;	register struct inode *ip;	ip = aip;	ip->i_flag =| IACC|IUPD;	if((ip->i_mode&IFMT) == IFCHR) {		(*cdevsw[ip->i_addr[0].d_major].d_write)(ip->i_addr[0]);		return;	}	if (u.u_count == 0)		return;	do {		bn = lshift(u.u_offset, -9);		on = u.u_offset[1] & 0777;		n = min(512-on, u.u_count);		if((ip->i_mode&IFMT) != IFBLK) {			if ((bn = bmap(ip, bn)) == 0)				return;			dn = ip->i_dev;		} else			dn = ip->i_addr[0];		if(n == 512) 			bp = getblk(dn, bn); else			bp = bread(dn, bn);		iomove(bp, on, n, B_WRITE);		if(u.u_error != 0)			brelse(bp); else		if ((u.u_offset[1]&0777)==0)			bawrite(bp); else			bdwrite(bp);		if(dpcmp(ip->i_size0&0377, ip->i_size1,		  u.u_offset[0], u.u_offset[1]) < 0 &&		  (ip->i_mode&(IFBLK&IFCHR)) == 0) {			ip->i_size0 = u.u_offset[0];			ip->i_size1 = u.u_offset[1];		}		ip->i_flag =| IUPD;	} while(u.u_error==0 && u.u_count!=0);}/* * Return the logical maximum * of the 2 arguments. */max(a, b)char *a, *b;{	if(a > b)		return(a);	return(b);}/* * Return the logical minimum * of the 2 arguments. */min(a, b)char *a, *b;{	if(a < b)		return(a);	return(b);}/* * Move 'an' bytes at byte location * &bp->b_addr[o] to/from (flag) the * user/kernel (u.segflg) area starting at u.base. * Update all the arguments by the number * of bytes moved. * * There are 2 algorithms, * if source address, dest address and count * are all even in a user copy, * then the machine language copyin/copyout * is called. * If not, its done byte-by-byte with * cpass and passc. */iomove(bp, o, an, flag)struct buf *bp;{	register char *cp;	register int n, t;	n = an;	cp = bp->b_addr + o;	if(u.u_segflg==0 && ((n | cp | u.u_base)&01)==0) {		if (flag==B_WRITE)			cp = copyin(u.u_base, cp, n);		else			cp = copyout(cp, u.u_base, n);		if (cp) {			u.u_error = EFAULT;			return;		}		u.u_base =+ n;		dpadd(u.u_offset, n);		u.u_count =- n;		return;	}	if (flag==B_WRITE) {		while(n--) {			if ((t = cpass()) < 0)				return;			*cp++ = t;		}	} else		while (n--)			if(passc(*cp++) < 0)				return;}