#include "sys.h"
#include "inode.h"
#include "file.h"
#include "proc.h"

       /*
	* Break system call
	*/
brake(addr)
	int addr;
	{
	if (addr > u.sp - 12 && u.brake < u.sp)
		{
		u.error = ENOMEM;
		return;
		}
	u.brake = addr;
	}

       /*
	* Chdir system call
	*/
chdir(name)
	char* name;
	{
	fast struct inode *i;

	if ((i = iname(name)) == NULL)
		return;
	if ((i->mode & ITYPE) != IDIR)
		{
		u.error = ENOTDIR;
		goto out;
		}
	if (!access(i, IEXEC))
		goto out;
	u.cdir->count--;
	idec(u.cdir);
	u.cdir = i;
	i->count++;
    out:
	irelse(i);
	}

       /*
	* Chmod system call
	*/
chmod(name, mode)
	char* name;
	int mode;
	{
	fast struct inode *i;
	#define MBITS	07777	/* user changable mode bits */

	if ((i = iname(name)) == NULL)
		return;
	if (!ronly(i) && (u.euid == i->uid || super()))
		{
		i->mode &= ~MBITS;
		i->mode |= (mode & MBITS);
		i->flags |= IMOD;
		}
	irelse(i);
	}

       /*
	* Chown system call
	*/
chown(name, owner)
	char *name;
	uns  owner;
	{
	fast struct inode *ip;

	if (!super())
		return;
	if ((ip = iname(name)) == NULL)
		return;
	if (!ronly(ip))
		{
		ip->uid = owner;
		ip->gid = owner >> 8;
		ip->flags |= IMOD;
		}
	irelse(ip);
	}

       /*
	* Dup system call
	*/
dup(fd)
	int fd;
	{
	fast struct file *fp;

	if ((fp = ofile(fd)) == NULL)
		return;
	if ((fd = oalloc()) == ERROR)
		return;
	u.olist[fd] = fp;
	fp->count++;
	return (fd);
	}

       /*
	* Sync system call
	*/
sync()
	{
	isync();
	bsync();
	}

       /*
	* Getuid system call
	*/
getuid()
	{
	return ((u.gid << 8) | u.uid);
	}

       /*
	* Setuid system call
	*/
setuid(id)
	unsigned int id;
	{
	fast char uid, gid;

	uid = (char)id;
	gid = id >> 8;
	if ((uid == u.uid && gid == u.gid) || super())
		{
		u.p->uid = uid;
		u.uid = uid;
		u.gid = gid;
		u.euid = uid;
		u.egid = gid;
		}
	}

	/*
	 * Nice system call
	 */
nice(n)
	int n;
	{
	fast char nice;

	nice = n;
	if (nice < 0 && !super())
		return;
	u.p->nice = 128 - nice;
	}

	/*
	 * Make up for the Decision's lack of console switches
	 */
unsigned	switches = 0;

	/*
	 * Set the switches
	 */
ssw(arg)
	int arg;
	{
	switches = arg;
	}

	/*
	 * Read the switches
	 */
csw()
	{
	return (switches);
	}