/* *  linux/fs/fcntl.c * *  (C) 1991  Linus Torvalds */#include <string.h>#include <errno.h>#include <linux/sched.h>#include <linux/kernel.h>#include <asm/segment.h>#include <fcntl.h>#include <sys/stat.h>extern int sys_close(int fd);static int dupfd(unsigned int fd, unsigned int arg){	if (fd >= NR_OPEN || !current->filp[fd])		return -EBADF;	if (arg >= NR_OPEN)		return -EINVAL;	while (arg < NR_OPEN)		if (current->filp[arg])			arg++;		else			break;	if (arg >= NR_OPEN)		return -EMFILE;	current->close_on_exec &= ~(1<<arg);	(current->filp[arg] = current->filp[fd])->f_count++;	return arg;}int sys_dup2(unsigned int oldfd, unsigned int newfd){	sys_close(newfd);	return dupfd(oldfd,newfd);}int sys_dup(unsigned int fildes){	return dupfd(fildes,0);}int sys_fcntl(unsigned int fd, unsigned int cmd, unsigned long arg){		struct file * filp;	if (fd >= NR_OPEN || !(filp = current->filp[fd]))		return -EBADF;	switch (cmd) {		case F_DUPFD:			return dupfd(fd,arg);		case F_GETFD:			return (current->close_on_exec>>fd)&1;		case F_SETFD:			if (arg&1)				current->close_on_exec |= (1<<fd);			else				current->close_on_exec &= ~(1<<fd);			return 0;		case F_GETFL:			return filp->f_flags;		case F_SETFL:			filp->f_flags &= ~(O_APPEND | O_NONBLOCK);			filp->f_flags |= arg & (O_APPEND | O_NONBLOCK);			return 0;		case F_GETLK:	case F_SETLK:	case F_SETLKW:			return -1;		default:			return -1;	}}