#include <linux/compiler.h>#include <linux/file.h>#include <linux/fs.h>#include <linux/linkage.h>#include <linux/mount.h>#include <linux/namei.h>#include <linux/sched.h>#include <linux/stat.h>#include <linux/utime.h>#include <linux/syscalls.h>#include <asm/uaccess.h>#include <asm/unistd.h> #ifdef __ARCH_WANT_SYS_UTIME /* * sys_utime() can be implemented in user-level using sys_utimes(). * Is this for backwards compatibility?  If so, why not move it * into the appropriate arch directory (for those architectures that * need it). */ /* If times==NULL, set access and modification to current time, * must be owner or have write permission. * Else, update from *times, must be owner or super user. */SYSCALL_DEFINE2(utime, char __user *, filename, struct utimbuf __user *, times){	struct timespec tv[2]; 	if (times) {		if (get_user(tv[0].tv_sec, &times->actime) ||		    get_user(tv[1].tv_sec, &times->modtime))			return -EFAULT;		tv[0].tv_nsec = 0;		tv[1].tv_nsec = 0;	}	return do_utimes(AT_FDCWD, filename, times ? tv : NULL, 0);} #endif static bool nsec_valid(long nsec){	if (nsec == UTIME_OMIT || nsec == UTIME_NOW)		return true; 	return nsec >= 0 && nsec <= 999999999;} static int utimes_common(struct path *path, struct timespec *times){	int error;	struct iattr newattrs;	struct inode *inode = path->dentry->d_inode; 	error = mnt_want_write(path->mnt);	if (error)		goto out; 	if (times && times[0].tv_nsec == UTIME_NOW &&		     times[1].tv_nsec == UTIME_NOW)		times = NULL; 	newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;	if (times) {		if (times[0].tv_nsec == UTIME_OMIT)			newattrs.ia_valid &= ~ATTR_ATIME;		else if (times[0].tv_nsec != UTIME_NOW) {			newattrs.ia_atime.tv_sec = times[0].tv_sec;			newattrs.ia_atime.tv_nsec = times[0].tv_nsec;			newattrs.ia_valid |= ATTR_ATIME_SET;		} 		if (times[1].tv_nsec == UTIME_OMIT)			newattrs.ia_valid &= ~ATTR_MTIME;		else if (times[1].tv_nsec != UTIME_NOW) {			newattrs.ia_mtime.tv_sec = times[1].tv_sec;			newattrs.ia_mtime.tv_nsec = times[1].tv_nsec;			newattrs.ia_valid |= ATTR_MTIME_SET;		}		/*		 * Tell inode_change_ok(), that this is an explicit time		 * update, even if neither ATTR_ATIME_SET nor ATTR_MTIME_SET		 * were used.		 */		newattrs.ia_valid |= ATTR_TIMES_SET;	} else {		/*		 * If times is NULL (or both times are UTIME_NOW),		 * then we need to check permissions, because		 * inode_change_ok() won't do it.		 */		error = -EACCES;                if (IS_IMMUTABLE(inode))			goto mnt_drop_write_and_out; 		if (!inode_owner_or_capable(inode)) {			error = inode_permission(inode, MAY_WRITE);			if (error)				goto mnt_drop_write_and_out;		}	}	mutex_lock(&inode->i_mutex);	error = notify_change(path->dentry, &newattrs);	mutex_unlock(&inode->i_mutex); mnt_drop_write_and_out:	mnt_drop_write(path->mnt);out:	return error;} /* * do_utimes - change times on filename or file descriptor * @dfd: open file descriptor, -1 or AT_FDCWD * @filename: path name or NULL * @times: new times or NULL * @flags: zero or more flags (only AT_SYMLINK_NOFOLLOW for the moment) * * If filename is NULL and dfd refers to an open file, then operate on * the file.  Otherwise look up filename, possibly using dfd as a * starting point. * * If times==NULL, set access and modification to current time, * must be owner or have write permission. * Else, update from *times, must be owner or super user. */long do_utimes(int dfd, const char __user *filename, struct timespec *times,	       int flags){	int error = -EINVAL; 	if (times && (!nsec_valid(times[0].tv_nsec) ||		      !nsec_valid(times[1].tv_nsec))) {		goto out;	} 	if (flags & ~AT_SYMLINK_NOFOLLOW)		goto out; 	if (filename == NULL && dfd != AT_FDCWD) {		int fput_needed;		struct file *file; 		if (flags & AT_SYMLINK_NOFOLLOW)			goto out; 		file = fget_light(dfd, &fput_needed);		error = -EBADF;		if (!file)			goto out; 		error = utimes_common(&file->f_path, times);		fput_light(file, fput_needed);	} else {		struct path path;		int lookup_flags = 0; 		if (!(flags & AT_SYMLINK_NOFOLLOW))			lookup_flags |= LOOKUP_FOLLOW; 		error = user_path_at(dfd, filename, lookup_flags, &path);		if (error)			goto out; 		error = utimes_common(&path, times);		path_put(&path);	} out:	return error;} SYSCALL_DEFINE4(utimensat, int, dfd, const char __user *, filename,		struct timespec __user *, utimes, int, flags){	struct timespec tstimes[2]; 	if (utimes) {		if (copy_from_user(&tstimes, utimes, sizeof(tstimes)))			return -EFAULT; 		/* Nothing to do, we must not even check the path.  */		if (tstimes[0].tv_nsec == UTIME_OMIT &&		    tstimes[1].tv_nsec == UTIME_OMIT)			return 0;	} 	return do_utimes(dfd, filename, utimes ? tstimes : NULL, flags);} SYSCALL_DEFINE3(futimesat, int, dfd, const char __user *, filename,		struct timeval __user *, utimes){	struct timeval times[2];	struct timespec tstimes[2]; 	if (utimes) {		if (copy_from_user(&times, utimes, sizeof(times)))			return -EFAULT; 		/* This test is needed to catch all invalid values.  If we		   would test only in do_utimes we would miss those invalid		   values truncated by the multiplication with 1000.  Note		   that we also catch UTIME_{NOW,OMIT} here which are only		   valid for utimensat.  */		if (times[0].tv_usec >= 1000000 || times[0].tv_usec < 0 ||		    times[1].tv_usec >= 1000000 || times[1].tv_usec < 0)			return -EINVAL; 		tstimes[0].tv_sec = times[0].tv_sec;		tstimes[0].tv_nsec = 1000 * times[0].tv_usec;		tstimes[1].tv_sec = times[1].tv_sec;		tstimes[1].tv_nsec = 1000 * times[1].tv_usec;	} 	return do_utimes(dfd, filename, utimes ? tstimes : NULL, 0);} SYSCALL_DEFINE2(utimes, char __user *, filename,		struct timeval __user *, utimes){	return sys_futimesat(AT_FDCWD, filename, utimes);}