/* *  linux/fs/open.c * *  (C) 1991  Linus Torvalds */#include <string.h>#include <errno.h>#include <fcntl.h>#include <sys/types.h>#include <utime.h>#include <sys/stat.h>#include <linux/sched.h>#include <linux/tty.h>#include <linux/kernel.h>#include <asm/segment.h>int sys_ustat(int dev, struct ustat * ubuf){	return -ENOSYS;}int sys_utime(char * filename, struct utimbuf * times){	struct m_inode * inode;	long actime,modtime;	if (!(inode=namei(filename)))		return -ENOENT;	if (times) {		actime = get_fs_long((unsigned long *) &times->actime);		modtime = get_fs_long((unsigned long *) &times->modtime);	} else		actime = modtime = CURRENT_TIME;	inode->i_atime = actime;	inode->i_mtime = modtime;	inode->i_dirt = 1;	iput(inode);	return 0;}/* * XXX should we use the real or effective uid?  BSD uses the real uid, * so as to make this call useful to setuid programs. */int sys_access(const char * filename,int mode){	struct m_inode * inode;	int res, i_mode;	mode &= 0007;	if (!(inode=namei(filename)))		return -EACCES;	i_mode = res = inode->i_mode & 0777;	iput(inode);	if (current->uid == inode->i_uid)		res >>= 6;	else if (current->gid == inode->i_gid)		res >>= 6;	if ((res & 0007 & mode) == mode)		return 0;	/*	 * XXX we are doing this test last because we really should be	 * swapping the effective with the real user id (temporarily),	 * and then calling suser() routine.  If we do call the	 * suser() routine, it needs to be called last. 	 */	if ((!current->uid) &&	    (!(mode & 1) || (i_mode & 0111)))		return 0;	return -EACCES;}int sys_chdir(const char * filename){	struct m_inode * inode;	if (!(inode = namei(filename)))		return -ENOENT;	if (!S_ISDIR(inode->i_mode)) {		iput(inode);		return -ENOTDIR;	}	iput(current->pwd);	current->pwd = inode;	return (0);}int sys_chroot(const char * filename){	struct m_inode * inode;	if (!(inode=namei(filename)))		return -ENOENT;	if (!S_ISDIR(inode->i_mode)) {		iput(inode);		return -ENOTDIR;	}	iput(current->root);	current->root = inode;	return (0);}int sys_chmod(const char * filename,int mode){	struct m_inode * inode;	if (!(inode=namei(filename)))		return -ENOENT;	if ((current->euid != inode->i_uid) && !suser()) {		iput(inode);		return -EACCES;	}	inode->i_mode = (mode & 07777) | (inode->i_mode & ~07777);	inode->i_dirt = 1;	iput(inode);	return 0;}int sys_chown(const char * filename,int uid,int gid){	struct m_inode * inode;	if (!(inode=namei(filename)))		return -ENOENT;	if (!suser()) {		iput(inode);		return -EACCES;	}	inode->i_uid=uid;	inode->i_gid=gid;	inode->i_dirt=1;	iput(inode);	return 0;}int sys_open(const char * filename,int flag,int mode){	struct m_inode * inode;	struct file * f;	int i,fd;	mode &= 0777 & ~current->umask;	for(fd=0 ; fd<NR_OPEN ; fd++)		if (!current->filp[fd])			break;	if (fd>=NR_OPEN)		return -EINVAL;	current->close_on_exec &= ~(1<<fd);	f=0+file_table;	for (i=0 ; i<NR_FILE ; i++,f++)		if (!f->f_count) break;	if (i>=NR_FILE)		return -EINVAL;	(current->filp[fd]=f)->f_count++;	if ((i=open_namei(filename,flag,mode,&inode))<0) {		current->filp[fd]=NULL;		f->f_count=0;		return i;	}/* ttys are somewhat special (ttyxx major==4, tty major==5) */	if (S_ISCHR(inode->i_mode))		if (MAJOR(inode->i_zone[0])==4) {			if (current->leader && current->tty<0) {				current->tty = MINOR(inode->i_zone[0]);				tty_table[current->tty].pgrp = current->pgrp;			}		} else if (MAJOR(inode->i_zone[0])==5)			if (current->tty<0) {				iput(inode);				current->filp[fd]=NULL;				f->f_count=0;				return -EPERM;			}/* Likewise with block-devices: check for floppy_change */	if (S_ISBLK(inode->i_mode))		check_disk_change(inode->i_zone[0]);	f->f_mode = inode->i_mode;	f->f_flags = flag;	f->f_count = 1;	f->f_inode = inode;	f->f_pos = 0;	return (fd);}int sys_creat(const char * pathname, int mode){	return sys_open(pathname, O_CREAT | O_TRUNC, mode);}int sys_close(unsigned int fd){		struct file * filp;	if (fd >= NR_OPEN)		return -EINVAL;	current->close_on_exec &= ~(1<<fd);	if (!(filp = current->filp[fd]))		return -EINVAL;	current->filp[fd] = NULL;	if (filp->f_count == 0)		panic("Close: file count is 0");	if (--filp->f_count)		return (0);	iput(filp->f_inode);	return (0);}