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#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) {
struct file *file;

if (flags & AT_SYMLINK_NOFOLLOW)
goto out;

file = fget(dfd);
error = -EBADF;
if (!file)
goto out;

error = utimes_common(&file->f_path, times);
fput(file);
} 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);
}
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