# statx

## NAME



           statx - get file status (extended)
    


## LIBRARY



           Standard C library (_libc_ , _-lc_)
    


## SYNOPSIS



           **#define _GNU_SOURCE** /* See feature_test_macros(7) */
           **#include <fcntl.h>           **/* Definition of **AT_*** constants */
           **#include <sys/stat.h>**
    
           **int statx(int** _dirfd_**, const char *_Nullable restrict** _path_**,**
                     **int** _flags_**, unsigned int** _mask_**,**
                     **struct statx *restrict** _statxbuf_**);**
    


## DESCRIPTION



           This function returns information about a file, storing it in the
           buffer pointed to by _statxbuf_.  The returned buffer is a structure
           of the following type:
    
               struct statx {
                   __u32 stx_mask;        /* Mask of bits indicating
                                             filled fields */
                   __u32 stx_blksize;     /* Block size for filesystem I/O */
                   __u64 stx_attributes;  /* Extra file attribute indicators */
                   __u32 stx_nlink;       /* Number of hard links */
                   __u32 stx_uid;         /* User ID of owner */
                   __u32 stx_gid;         /* Group ID of owner */
                   __u16 stx_mode;        /* File type and mode */
                   __u64 stx_ino;         /* Inode number */
                   __u64 stx_size;        /* Total size in bytes */
                   __u64 stx_blocks;      /* Number of 512B blocks allocated */
                   __u64 stx_attributes_mask;
                                          /* Mask to show what's supported
                                             in stx_attributes */
    
                   /* The following fields are file timestamps */
                   struct statx_timestamp stx_atime;  /* Last access */
                   struct statx_timestamp stx_btime;  /* Creation */
                   struct statx_timestamp stx_ctime;  /* Last status change */
                   struct statx_timestamp stx_mtime;  /* Last modification */
    
                   /* If this file represents a device, then the next two
                      fields contain the ID of the device */
                   __u32 stx_rdev_major;  /* Major ID */
                   __u32 stx_rdev_minor;  /* Minor ID */
    
                   /* The next two fields contain the ID of the device
                      containing the filesystem where the file resides */
                   __u32 stx_dev_major;   /* Major ID */
                   __u32 stx_dev_minor;   /* Minor ID */
    
                   __u64 stx_mnt_id;      /* Mount ID */
    
                   /* Direct I/O alignment restrictions */
                   __u32 stx_dio_mem_align;
                   __u32 stx_dio_offset_align;
    
                   __u64 stx_subvol;      /* Subvolume identifier */
    
                   /* Direct I/O atomic write limits */
                   __u32 stx_atomic_write_unit_min;
                   __u32 stx_atomic_write_unit_max;
                   __u32 stx_atomic_write_segments_max;
    
                   /* File offset alignment for direct I/O reads */
                   __u32 stx_dio_read_offset_align;
    
                   /* Direct I/O atomic write max opt limit */
                   __u32 stx_atomic_write_unit_max_opt;
               };
    
           The file timestamps are structures of the following type:
    
               struct statx_timestamp {
                   __s64 tv_sec;    /* Seconds since the Epoch (UNIX time) */
                   __u32 tv_nsec;   /* Nanoseconds since tv_sec */
               };
    
           (Note that reserved space and padding is omitted.)
    
       **Invoking statx():**
           To access a file's status, no permissions are required on the file
           itself, but in the case of **statx**() with a pathname, execute
           (search) permission is required on all of the directories in _path_
           that lead to the file.
    
           **statx**() uses _path_ , _dirfd_ , and _flags_ to identify the target file in
           one of the following ways:
    
           An absolute pathname
                  If _path_ begins with a slash, then it is an absolute
                  pathname that identifies the target file.  In this case,
                  _dirfd_ is ignored.
    
           A relative pathname
                  If _path_ is a string that begins with a character other than
                  a slash and _dirfd_ is **AT_FDCWD** , then _path_ is a relative
                  pathname that is interpreted relative to the process's
                  current working directory.
    
           A directory-relative pathname
                  If _path_ is a string that begins with a character other than
                  a slash and _dirfd_ is a file descriptor that refers to a
                  directory, then _path_ is a relative pathname that is
                  interpreted relative to the directory referred to by _dirfd_.
                  (See openat(2) for an explanation of why this is useful.)
    
           By file descriptor
                  If _path_ is an empty string (or NULL since Linux 6.11) and
                  the **AT_EMPTY_PATH** flag is specified in _flags_ (see below),
                  then the target file is the one referred to by the file
                  descriptor _dirfd_.
    
           _flags_ can be used to influence a pathname-based lookup.  A value
           for _flags_ is constructed by ORing together zero or more of the
           following constants:
    
           **AT_EMPTY_PATH**
                  If _path_ is an empty string (or NULL since Linux 6.11),
                  operate on the file referred to by _dirfd_ (which may have
                  been obtained using the open(2) **O_PATH** flag).  In this
                  case, _dirfd_ can refer to any type of file, not just a
                  directory.
    
                  If _dirfd_ is **AT_FDCWD** , the call operates on the current
                  working directory.
    
           **AT_NO_AUTOMOUNT**
                  Don't automount the terminal ("basename") component of _path_
                  if it is a directory that is an automount point.  This
                  allows the caller to gather attributes of an automount
                  point (rather than the location it would mount).  This flag
                  has no effect if the mount point has already been mounted
                  over.
    
                  The **AT_NO_AUTOMOUNT** flag can be used in tools that scan
                  directories to prevent mass-automounting of a directory of
                  automount points.
    
                  All of stat(2), lstat(2), and fstatat(2) act as though
                  **AT_NO_AUTOMOUNT** was set.
    
           **AT_SYMLINK_NOFOLLOW**
                  If _path_ is a symbolic link, do not dereference it: instead
                  return information about the link itself, like lstat(2).
    
           _flags_ can also be used to control what sort of synchronization the
           kernel will do when querying a file on a remote filesystem.  This
           is done by ORing in one of the following values:
    
           **AT_STATX_SYNC_AS_STAT**
                  Do whatever stat(2) does.  This is the default and is very
                  much filesystem-specific.
    
           **AT_STATX_FORCE_SYNC**
                  Force the attributes to be synchronized with the server.
                  This may require that a network filesystem perform a data
                  writeback to get the timestamps correct.
    
           **AT_STATX_DONT_SYNC**
                  Don't synchronize anything, but rather just take whatever
                  the system has cached if possible.  This may mean that the
                  information returned is approximate, but, on a network
                  filesystem, it may not involve a round trip to the server -
                  even if no lease is held.
    
           The _mask_ argument to **statx**() is used to tell the kernel which
           fields the caller is interested in.  _mask_ is an ORed combination
           of the following constants:
    
            **STATX_TYPE** Want stx_mode & S_IFMT
            **STATX_MODE** Want stx_mode & ~S_IFMT
            **STATX_NLINK** Want stx_nlink
            **STATX_UID** Want stx_uid
            **STATX_GID** Want stx_gid
            **STATX_ATIME** Want stx_atime
            **STATX_MTIME** Want stx_mtime
            **STATX_CTIME** Want stx_ctime
            **STATX_INO** Want stx_ino
            **STATX_SIZE** Want stx_size
            **STATX_BLOCKS** Want stx_blocks
            **STATX_BASIC_STATS**[All of the above]
            **STATX_BTIME** Want stx_btime
            **STATX_ALL** The same as STATX_BASIC_STATS | STATX_BTIME.
                                   It is deprecated and should not be used.
            **STATX_MNT_ID** Want stx_mnt_id (since Linux 5.8)
            **STATX_DIOALIGN** Want stx_dio_mem_align and stx_dio_offset_align.
                                   (since Linux 6.1; support varies by filesystem)
            **STATX_MNT_ID_UNIQUE** Want unique stx_mnt_id (since Linux 6.8)
            **STATX_SUBVOL** Want stx_subvol
                                   (since Linux 6.10; support varies by filesystem)
            **STATX_WRITE_ATOMIC** Want stx_atomic_write_unit_min,
                                   stx_atomic_write_unit_max,
                                   stx_atomic_write_segments_max,
                                   and stx_atomic_write_unit_max_opt.
                                   (since Linux 6.11; support varies by filesystem)
            **STATX_DIO_READ_ALIGN** Want stx_dio_read_offset_align.
                                   (since Linux 6.14; support varies by filesystem)
    
           Note that, in general, the kernel does _not_ reject values in _mask_
           other than the above.  (For an exception, see **EINVAL** in errors.)
           Instead, it simply informs the caller which values are supported
           by this kernel and filesystem via the _statx.stx_mask_ field.
           Therefore, _do not_ simply set _mask_ to **UINT_MAX**(all bits set), as
           one or more bits may, in the future, be used to specify an
           extension to the buffer.
    
       **The returned information**
           The status information for the target file is returned in the
           _statx_ structure pointed to by _statxbuf_.  Included in this is
           _stx_mask_ which indicates what other information has been returned.
           _stx_mask_ has the same format as the _mask_ argument and bits are set
           in it to indicate which fields have been filled in.
    
           It should be noted that the kernel may return fields that weren't
           requested and may fail to return fields that were requested,
           depending on what the backing filesystem supports.  (Fields that
           are given values despite being unrequested can just be ignored.)
           In either case, _stx_mask_ will not be equal _mask_.
    
           If a filesystem does not support a field or if it has an
           unrepresentable value (for instance, a file with an exotic type),
           then the mask bit corresponding to that field will be cleared in
           _stx_mask_ even if the user asked for it and a dummy value will be
           filled in for compatibility purposes if one is available (e.g., a
           dummy UID and GID may be specified to mount under some
           circumstances).
    
           A filesystem may also fill in fields that the caller didn't ask
           for if it has values for them available and the information is
           available at no extra cost.  If this happens, the corresponding
           bits will be set in _stx_mask_.
    
           _Note_ : for performance and simplicity reasons, different fields in
           the _statx_ structure may contain state information from different
           moments during the execution of the system call.  For example, if
           _stx_mode_ or _stx_uid_ is changed by another process by calling
           chmod(2) or chown(2), **stat**() might return the old _stx_mode_
           together with the new _stx_uid_ , or the old _stx_uid_ together with
           the new _stx_mode_.
    
           Apart from _stx_mask_ (which is described above), the fields in the
           _statx_ structure are:
    
           _stx_blksize_
                  The "preferred" block size for efficient filesystem I/O.
                  (Writing to a file in smaller chunks may cause an
                  inefficient read-modify-rewrite.)
    
           _stx_attributes_
                  Further status information about the file (see below for
                  more information).
    
           _stx_nlink_
                  The number of hard links on a file.
    
           _stx_uid_
                  This field contains the user ID of the owner of the file.
    
           _stx_gid_
                  This field contains the ID of the group owner of the file.
    
           _stx_mode_
                  The file type and mode.  See inode(7) for details.
    
           _stx_ino_
                  The inode number of the file.
    
           _stx_size_
                  The size of the file (if it is a regular file or a symbolic
                  link) in bytes.  The size of a symbolic link is the length
                  of the pathname it contains, without a terminating null
                  byte.
    
           _stx_blocks_
                  The number of blocks allocated to the file on the medium,
                  in 512-byte units.  (This may be smaller than _stx_size_ /512
                  when the file has holes.)
    
           _stx_attributes_mask_
                  A mask indicating which bits in _stx_attributes_ are
                  supported by the VFS and the filesystem.
    
           _stx_atime_
                  The file's last access timestamp.
    
           _stx_btime_
                  The file's creation timestamp.
    
           _stx_ctime_
                  The file's last status change timestamp.
    
           _stx_mtime_
                  The file's last modification timestamp.
    
           _stx_dev_major_
           _stx_dev_minor_
                  The device on which this file (inode) resides.
    
           _stx_rdev_major_
           _stx_rdev_minor_
                  The device that this file (inode) represents if the file is
                  of block or character device type.
    
           _stx_mnt_id_
                  If using STATX_MNT_ID, this is the mount ID of the mount
                  containing the file.  This is the same number reported by
                  name_to_handle_at(2) and corresponds to the number in the
                  first field in one of the records in _/proc/self/mountinfo_.
    
                  If using STATX_MNT_ID_UNIQUE, this is the unique mount ID
                  of the mount containing the file.  This is the number
                  reported by listmount(2) and is the ID used to query the
                  mount with statmount(2).  It is guaranteed to not be reused
                  while the system is running.
    
           _stx_dio_mem_align_
                  The alignment (in bytes) required for user memory buffers
                  for direct I/O (**O_DIRECT**) on this file, or 0 if direct I/O
                  is not supported on this file.
    
                  **STATX_DIOALIGN**(_stx_dio_mem_align_ and _stx_dio_offset_align_)
                  is supported on block devices since Linux 6.1.  The support
                  on regular files varies by filesystem; it is supported by
                  ext4, f2fs, and xfs since Linux 6.1.
    
           _stx_dio_offset_align_
                  The alignment (in bytes) required for file offsets and I/O
                  segment lengths for direct I/O (**O_DIRECT**) on this file, or
                  0 if direct I/O is not supported on this file.  This will
                  only be nonzero if _stx_dio_mem_align_ is nonzero, and vice
                  versa.
    
           _stx_dio_read_offset_align_
                  The alignment (in bytes) required for file offsets and I/O
                  segment lengths for direct I/O reads (**O_DIRECT**) on this
                  file.  If zero, the limit in _stx_dio_offset_align_ applies
                  for reads as well.  If non-zero, this value must be smaller
                  than or equal to _stx_dio_offset_align_ which must be
                  provided by the file system if requested by the
                  application.  The memory alignment in _stx_dio_mem_align_ is
                  not affected by this value.
    
                  **STATX_DIO_READ_ALIGN**(_stx_dio_offset_align_) is supported by
                  xfs on regular files since Linux 6.14.
    
           _stx_subvol_
                  Subvolume number of the current file.
    
                  Subvolumes are fancy directories, i.e. they form a tree
                  structure that may be walked recursively.  Support varies
                  by filesystem; it is supported by bcachefs and btrfs since
                  Linux 6.10.
    
           _stx_atomic_write_unit_min_
           _stx_atomic_write_unit_max_
                  The minimum and maximum sizes (in bytes) supported for
                  direct I/O (**O_DIRECT**) on the file to be written with torn-
                  write protection.  These values are each guaranteed to be a
                  power-of-2.
    
                  **STATX_WRITE_ATOMIC**(_stx_atomic_write_unit_min_ ,
                  _stx_atomic_write_unit_max_ , and
                  _stx_atomic_write_segments_max_) is supported on block
                  devices since Linux 6.11.  The support on regular files
                  varies by filesystem; it is supported by xfs and ext4 since
                  Linux 6.13.
    
           _stx_atomic_write_unit_max_opt_
                  The maximum size (in bytes) which is optimised for writes
                  issued with torn-write protection.  If non-zero, this value
                  will not exceed the value in _stx_atomic_write_unit_max_ and
                  will not be less than the value in
                  _stx_atomic_write_unit_min_.  A value of zero indicates that
                  _stx_atomic_write_unit_max_ is the optimised limit.  Slower
                  writes may be experienced when the size of the write
                  exceeds _stx_atomic_write_unit_max_opt_ (when non-zero).
    
           _stx_atomic_write_segments_max_
                  The maximum number of elements in an array of vectors for a
                  write with torn-write protection enabled.  See **RWF_ATOMIC**
                  flag for pwritev2(2).
    
           For further information on the above fields, see inode(7).
    
       **File attributes**
           The _stx_attributes_ field contains a set of ORed flags that
           indicate additional attributes of the file.  Note that any
           attribute that is not indicated as supported by
           _stx_attributes_mask_ has no usable value here.  The bits in
           _stx_attributes_mask_ correspond bit-by-bit to _stx_attributes_.
    
           The flags are as follows:
    
           **STATX_ATTR_COMPRESSED**
                  The file is compressed by the filesystem and may take extra
                  resources to access.
    
           **STATX_ATTR_IMMUTABLE**
                  The file cannot be modified: it cannot be deleted or
                  renamed, no hard links can be created to this file and no
                  data can be written to it.  See chattr(1).
    
           **STATX_ATTR_APPEND**
                  The file can only be opened in append mode for writing.
                  Random access writing is not permitted.  See chattr(1).
    
           **STATX_ATTR_NODUMP**
                  File is not a candidate for backup when a backup program
                  such as **dump**(8) is run.  See chattr(1).
    
           **STATX_ATTR_ENCRYPTED**
                  A key is required for the file to be encrypted by the
                  filesystem.
    
           **STATX_ATTR_VERITY**(since Linux 5.5)
                  The file has fs-verity enabled.  It cannot be written to,
                  and all reads from it will be verified against a
                  cryptographic hash that covers the entire file (e.g., via a
                  Merkle tree).
    
           **STATX_ATTR_WRITE_ATOMIC**(since Linux 6.11)
                  The file supports torn-write protection.
    
           **STATX_ATTR_DAX**(since Linux 5.8)
                  The file is in the DAX (cpu direct access) state.  DAX
                  state attempts to minimize software cache effects for both
                  I/O and memory mappings of this file.  It requires a file
                  system which has been configured to support DAX.
    
                  DAX generally assumes all accesses are via CPU load / store
                  instructions which can minimize overhead for small
                  accesses, but may adversely affect CPU utilization for
                  large transfers.
    
                  File I/O is done directly to/from user-space buffers and
                  memory mapped I/O may be performed with direct memory
                  mappings that bypass the kernel page cache.
    
                  While the DAX property tends to result in data being
                  transferred synchronously, it does not give the same
                  guarantees as the **O_SYNC** flag (see open(2)), where data and
                  the necessary metadata are transferred together.
    
                  A DAX file may support being mapped with the **MAP_SYNC** flag,
                  which enables a program to use CPU cache flush instructions
                  to persist CPU store operations without an explicit
                  fsync(2).  See mmap(2) for more information.
    
           **STATX_ATTR_MOUNT_ROOT**(since Linux 5.8)
                  The file is the root of a mount.
    


## RETURN VALUE



           On success, zero is returned.  On error, -1 is returned, and _errno_
           is set to indicate the error.
    


## ERRORS



           **EACCES** Search permission is denied for one of the directories in
                  the path prefix of _path_.  (See also path_resolution(7).)
    
           **EBADF** _path_ is relative but _dirfd_ is neither **AT_FDCWD** nor a valid
                  file descriptor.
    
           **EFAULT** _path_ or _statxbuf_ points to a location outside the process's
                  accessible address space or is NULL (except since Linux
                  6.11 if **AT_EMPTY_PATH** is specified in _flags_ , _path_ is
                  allowed to be NULL).
    
           **EINVAL** Invalid flag specified in _flags_.
    
           **EINVAL** Reserved flag specified in _mask_.  (Currently, there is one
                  such flag, designated by the constant **STATX__RESERVED** , with
                  the value 0x80000000U.)
    
           **ELOOP** Too many symbolic links encountered while traversing the
                  pathname.
    
           **ENAMETOOLONG**
                  _path_ is too long.
    
           **ENOENT** A component of _path_ does not exist, or _path_ is an empty
                  string and **AT_EMPTY_PATH** was not specified in _flags_.
    
           **ENOMEM** Out of memory (i.e., kernel memory).
    
           **ENOTDIR**
                  A component of the path prefix of _path_ is not a directory
                  or _path_ is relative and _dirfd_ is a file descriptor
                  referring to a file other than a directory.
    


## STANDARDS



           Linux.
    


* * *