#include "../h/param.h"#include "../h/systm.h"#include "../h/dir.h"#include "../h/user.h"#include "../h/reg.h"#include "../h/file.h"#include "../h/inode.h"/* * read system call */read(){	rdwr(FREAD);}/* * write system call */write(){	rdwr(FWRITE);}/* * common code for read and write calls: * check permissions, set base, count, and offset, * and switch out to readi, writei, or pipe code. */rdwr(mode)register mode;{	register struct file *fp;	register struct inode *ip;	register struct a {		int	fdes;		char	*cbuf;		unsigned count;	} *uap;	uap = (struct a *)u.u_ap;	fp = getf(uap->fdes);	if(fp == NULL)		return;	if((fp->f_flag&mode) == 0) {		u.u_error = EBADF;		return;	}	u.u_base = (caddr_t)uap->cbuf;	u.u_count = uap->count;	u.u_segflg = 0;	if((fp->f_flag&FPIPE) != 0) {		if(mode == FREAD)			readp(fp);		else			writep(fp);	} else {		ip = fp->f_inode;		if (fp->f_flag&FMP)			u.u_offset = 0;		else			u.u_offset = fp->f_un.f_offset;		if((ip->i_mode&(IFCHR&IFBLK)) == 0)			plock(ip);		if(mode == FREAD)			readi(ip);		else			writei(ip);		if((ip->i_mode&(IFCHR&IFBLK)) == 0)			prele(ip);		if ((fp->f_flag&FMP) == 0)			fp->f_un.f_offset += uap->count-u.u_count;	}	u.u_r.r_val1 = uap->count-u.u_count;}/* * open system call */open(){	register struct inode *ip;	register struct a {		char	*fname;		int	rwmode;	} *uap;	uap = (struct a *)u.u_ap;	ip = namei(uchar, 0);	if(ip == NULL)		return;	open1(ip, ++uap->rwmode, 0);}/* * creat system call */creat(){	register struct inode *ip;	register struct a {		char	*fname;		int	fmode;	} *uap;	uap = (struct a *)u.u_ap;	ip = namei(uchar, 1);	if(ip == NULL) {		if(u.u_error)			return;		ip = maknode(uap->fmode&07777&(~ISVTX));		if (ip==NULL)			return;		open1(ip, FWRITE, 2);	} else		open1(ip, FWRITE, 1);}/* * common code for open and creat. * Check permissions, allocate an open file structure, * and call the device open routine if any. */open1(ip, mode, trf)register struct inode *ip;register mode;{	register struct file *fp;	int i;	if(trf != 2) {		if(mode&FREAD)			access(ip, IREAD);		if(mode&FWRITE) {			access(ip, IWRITE);			if((ip->i_mode&IFMT) == IFDIR)				u.u_error = EISDIR;		}	}	if(u.u_error)		goto out;	if(trf == 1)		itrunc(ip);	prele(ip);	if ((fp = falloc()) == NULL)		goto out;	fp->f_flag = mode&(FREAD|FWRITE);	fp->f_inode = ip;	i = u.u_r.r_val1;	openi(ip, mode&FWRITE);	if(u.u_error == 0)		return;	u.u_ofile[i] = NULL;	fp->f_count--;out:	iput(ip);}/* * close system call */close(){	register struct file *fp;	register struct a {		int	fdes;	} *uap;	uap = (struct a *)u.u_ap;	fp = getf(uap->fdes);	if(fp == NULL)		return;	u.u_ofile[uap->fdes] = NULL;	closef(fp);}/* * seek system call */seek(){	register struct file *fp;	register struct a {		int	fdes;		off_t	off;		int	sbase;	} *uap;	uap = (struct a *)u.u_ap;	fp = getf(uap->fdes);	if(fp == NULL)		return;	if(fp->f_flag&(FPIPE|FMP)) {		u.u_error = ESPIPE;		return;	}	if(uap->sbase == 1)		uap->off += fp->f_un.f_offset;	else if(uap->sbase == 2)		uap->off += fp->f_inode->i_size;	fp->f_un.f_offset = uap->off;	u.u_r.r_off = uap->off;}/* * link system call */link(){	register struct inode *ip, *xp;	register struct a {		char	*target;		char	*linkname;	} *uap;	uap = (struct a *)u.u_ap;	ip = namei(uchar, 0);	if(ip == NULL)		return;	if((ip->i_mode&IFMT)==IFDIR && !suser())		goto out;	/*	 * Unlock to avoid possibly hanging the namei.	 * Sadly, this means races. (Suppose someone	 * deletes the file in the meantime?)	 * Nor can it be locked again later	 * because then there will be deadly	 * embraces.	 */	prele(ip);	u.u_dirp = (caddr_t)uap->linkname;	xp = namei(uchar, 1);	if(xp != NULL) {		u.u_error = EEXIST;		iput(xp);		goto out;	}	if (u.u_error)		goto out;	if(u.u_pdir->i_dev != ip->i_dev) {		iput(u.u_pdir);		u.u_error = EXDEV;		goto out;	}	wdir(ip);	if (u.u_error==0) {		ip->i_nlink++;		ip->i_flag |= ICHG;	}out:	iput(ip);}/* * mknod system call */mknod(){	register struct inode *ip;	register struct a {		char	*fname;		int	fmode;		int	dev;	} *uap;	uap = (struct a *)u.u_ap;	if(suser()) {		ip = namei(uchar, 1);		if(ip != NULL) {			u.u_error = EEXIST;			goto out;		}	}	if(u.u_error)		return;	ip = maknode(uap->fmode);	if (ip == NULL)		return;	ip->i_un.i_rdev = (dev_t)uap->dev;out:	iput(ip);}/* * access system call */saccess(){	register svuid, svgid;	register struct inode *ip;	register struct a {		char	*fname;		int	fmode;	} *uap;	uap = (struct a *)u.u_ap;	svuid = u.u_uid;	svgid = u.u_gid;	u.u_uid = u.u_ruid;	u.u_gid = u.u_rgid;	ip = namei(uchar, 0);	if (ip != NULL) {		if (uap->fmode&(IREAD>>6))			access(ip, IREAD);		if (uap->fmode&(IWRITE>>6))			access(ip, IWRITE);		if (uap->fmode&(IEXEC>>6))			access(ip, IEXEC);		iput(ip);	}	u.u_uid = svuid;	u.u_gid = svgid;}