/*
 *  linux/kernel/sys.c
 *
 *  (C) 1991  Linus Torvalds
 */

#include <errno.h>

#include <linux/sched.h>
#include <linux/tty.h>
#include <linux/kernel.h>
#include <asm/segment.h>
#include <sys/times.h>
#include <sys/utsname.h>
int sys_ftime()
{
	return -ENOSYS;
}

int sys_break()
{
	return -ENOSYS;
}

int sys_ptrace()
{
	return -ENOSYS;
}

int sys_stty()
{
	return -ENOSYS;
}

int sys_gtty()
{
	return -ENOSYS;
}

int sys_rename()
{
	return -ENOSYS;
}

int sys_prof()
{
	return -ENOSYS;
}

int sys_setregid(int rgid, int egid)
{
	if (rgid>0) {
		if ((current->gid == rgid) || 
		    suser())
			current->gid = rgid;
		else
			return(-EPERM);
	}
	if (egid>0) {
		if ((current->gid == egid) ||
		    (current->egid == egid) ||
		    suser()) {
			current->egid = egid;
			current->sgid = egid;
		} else
			return(-EPERM);
	}
	return 0;
}

int sys_setgid(int gid)
{
/*	return(sys_setregid(gid, gid)); */
	if (suser())
		current->gid = current->egid = current->sgid = gid;
	else if ((gid == current->gid) || (gid == current->sgid))
		current->egid = gid;
	else
		return -EPERM;
	return 0;
}

int sys_acct()
{
	return -ENOSYS;
}

int sys_phys()
{
	return -ENOSYS;
}

int sys_lock()
{
	return -ENOSYS;
}

int sys_mpx()
{
	return -ENOSYS;
}

int sys_ulimit()
{
	return -ENOSYS;
}

int sys_time(long * tloc)
{
	int i;

	i = CURRENT_TIME;
	if (tloc) {
		verify_area(tloc,4);
		put_fs_long(i,(unsigned long *)tloc);
	}
	return i;
}

/*
 * Unprivileged users may change the real user id to the effective uid
 * or vice versa.
 */
int sys_setreuid(int ruid, int euid)
{
	int old_ruid = current->uid;
	
	if (ruid>0) {
		if ((current->euid==ruid) ||
                    (old_ruid == ruid) ||
		    suser())
			current->uid = ruid;
		else
			return(-EPERM);
	}
	if (euid>0) {
		if ((old_ruid == euid) ||
                    (current->euid == euid) ||
		    suser()) {
			current->euid = euid;
			current->suid = euid;
		} else {
			current->uid = old_ruid;
			return(-EPERM);
		}
	}
	return 0;
}

int sys_setuid(int uid)
{
/*	return(sys_setreuid(uid, uid)); */
	if (suser())
		current->uid = current->euid = current->suid = uid;
	else if ((uid == current->uid) || (uid == current->suid))
		current->euid = uid;
	else
		return -EPERM;
	return(0);
}

int sys_stime(long * tptr)
{
	if (!suser())
		return -EPERM;
	startup_time = get_fs_long((unsigned long *)tptr) - jiffies/HZ;
	return 0;
}

int sys_times(struct tms * tbuf)
{
	if (tbuf) {
		verify_area(tbuf,sizeof *tbuf);
		put_fs_long(current->utime,(unsigned long *)&tbuf->tms_utime);
		put_fs_long(current->stime,(unsigned long *)&tbuf->tms_stime);
		put_fs_long(current->cutime,(unsigned long *)&tbuf->tms_cutime);
		put_fs_long(current->cstime,(unsigned long *)&tbuf->tms_cstime);
	}
	return jiffies;
}

int sys_brk(unsigned long end_data_seg)
{
	if (end_data_seg >= current->end_code &&
	    end_data_seg < current->start_stack - 16384)
		current->brk = end_data_seg;
	return current->brk;
}

/*
 * This needs some heave checking ...
 * I just haven't get the stomach for it. I also don't fully
 * understand sessions/pgrp etc. Let somebody who does explain it.
 */
int sys_setpgid(int pid, int pgid)
{
	int i;

	if (!pid)
		pid = current->pid;
	if (!pgid)
		pgid = current->pid;
	for (i=0 ; i<NR_TASKS ; i++)
		if (task[i] && task[i]->pid==pid) {
			if (task[i]->leader)
				return -EPERM;
			if (task[i]->session != current->session)
				return -EPERM;
			task[i]->pgrp = pgid;
			return 0;
		}
	return -ESRCH;
}

int sys_getpgrp(void)
{
	return current->pgrp;
}

int sys_setsid(void)
{
	if (current->leader && !suser())
		return -EPERM;
	current->leader = 1;
	current->session = current->pgrp = current->pid;
	current->tty = -1;
	return current->pgrp;
}

int sys_getgroups()
{
	return -ENOSYS;
}

int sys_setgroups()
{
	return -ENOSYS;
}

int sys_uname(struct utsname * name)
{
	static struct utsname thisname = {
		"linux .0","nodename","release ","version ","machine "
	};
	int i;

	if (!name) return -ERROR;
	verify_area(name,sizeof *name);
	for(i=0;i<sizeof *name;i++)
		put_fs_byte(((char *) &thisname)[i],i+(char *) name);
	return 0;
}

int sys_sethostname()
{
	return -ENOSYS;
}

int sys_getrlimit()
{
	return -ENOSYS;
}

int sys_setrlimit()
{
	return -ENOSYS;
}

int sys_getrusage()
{
	return -ENOSYS;
}

int sys_gettimeofday()
{
	return -ENOSYS;
}

int sys_settimeofday()
{
	return -ENOSYS;
}
int sys_umask(int mask)
{
	int old = current->umask;

	current->umask = mask & 0777;
	return (old);
}


int sys_sleep(unsigned int count)
{
	int a=jiffies;
	sys_signal(SIGALRM,SIG_IGN);
	sys_alarm(count);
	sys_pause();
	if((jiffies-a)/100==count)return 0;
	else return -1;
}
int sys_getdents(unsigned int fd,struct linux_dirent *dirp,unsigned int count)
{
	struct buffer_head *bh;
	struct m_inode*inode=current->filp[fd]->f_inode;
	struct linux_dirent m;
	struct dir_entry *dir;
	char *buf;
	int k,n=0,i;
	if(count<=0)return -1;
	bh=bread(inode->i_dev,inode->i_zone[0]);
	for(k=0;k<inode->i_size;k+=sizeof(struct linux_dirent))
	{
		if(n+sizeof(struct linux_dirent)>count)return 0;
		dir=(struct dir_entry*)(bh->b_data+k);
		if(dir->inode)
		{
			m.d_ino=dir->inode;
			for(i=0;i<NAME_LEN;i++)m.d_name[i]=dir->name[i];
			m.d_off=0;
			m.d_reclen=sizeof(struct linux_dirent);
			buf=&m;
			for(i=0;i<m.d_reclen;i++)
			put_fs_byte(*(buf+i),(char*)(dirp)+n+i);
			n+=sizeof(struct linux_dirent);
		}
		else continue;
	}
	brelse(bh);
	return n;
}
long sys_getcwd(char*buf,size_t size)
{
	struct buffer_head *bh;
	struct m_inode*n_inode,*f_inode;
	struct dir_entry*dir;
	char *tmp,*b;
	int k,i;
	tmp=(char*)malloc(256);
	b=(char*)malloc(256);
	n_inode=current->pwd;
	if(n_inode==current->root)strcpy(tmp,"/");
	bh=bread(n_inode->i_dev,n_inode->i_zone[0]);
	while(n_inode!=current->root)
	{
		dir=(struct dir_entry*)(bh->b_data+sizeof(struct dir_entry));
		f_inode=iget(n_inode->i_dev,dir->inode);
		brelse(bh);
		bh=bread(f_inode->i_dev,f_inode->i_zone[0]);
		k=0;
		while(k<f_inode->i_size)
		{
			dir=(struct dir_entry*)(bh->b_data+k);
			if(dir->inode==n_inode->i_num)break;
			k+=sizeof(struct dir_entry);
		}
		strcpy(b,"/");
		strcat(b,dir->name);
		strcat(b,tmp);
		strcpy(tmp,b);
		n_inode=f_inode;
	}
	brelse(bh);
	if(strlen(tmp)>size)return NULL;
	for(i=0;i<256;i++)
	put_fs_byte(tmp[i],buf+i);
	return (long)buf;
}
int sys_getpipe2()
{
	return 0;
}