'\" t

.\" Copyright (c) 2017 David Howells <dhowells@redhat.com>

.\"

.\" Derived from the stat.2 manual page:

.\"   Copyright (c) 1992 Drew Eckhardt (drew@cs.colorado.edu), March 28, 1992

.\"   Parts Copyright (c) 1995 Nicolai Langfeldt (janl@ifi.uio.no), 1/1/95

.\"   and Copyright (c) 2006, 2007, 2014 Michael Kerrisk <mtk.manpages@gmail.com>

.\"

.\" %%%LICENSE_START(VERBATIM)

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.\" manual provided the copyright notice and this permission notice are

.\" preserved on all copies.

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.\" manual under the conditions for verbatim copying, provided that the

.\" entire resulting derived work is distributed under the terms of a

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.\" Since the Linux kernel and libraries are constantly changing, this

.\" manual page may be incorrect or out-of-date.  The author(s) assume no

.\" responsibility for errors or omissions, or for damages resulting from

.\" the use of the information contained herein.  The author(s) may not

.\" have taken the same level of care in the production of this manual,

.\" which is licensed free of charge, as they might when working

.\" professionally.

.\"

.\" Formatted or processed versions of this manual, if unaccompanied by

.\" the source, must acknowledge the copyright and authors of this work.

.\" %%%LICENSE_END

.\"

.TH STATX 2 2017-09-15 "Linux" "Linux Programmer's Manual"

.SH NAME

statx \- get file status (extended)

.SH SYNOPSIS

.nf

.B #include <sys/types.h>

.B #include <sys/stat.h>

.B #include <unistd.h>

.BR "#include <fcntl.h>           " "/* Definition of AT_* constants */"

.PP

.BI "int statx(int " dirfd ", const char *" pathname ", int " flags ","

.BI "          unsigned int " mask ", struct statx *" statxbuf );

.fi

.PP

.IR Note :

There is no glibc wrapper for

.BR statx ();

see NOTES.

.SH DESCRIPTION

.PP

This function returns information about a file, storing it in the buffer

pointed to by

.IR statxbuf .

The returned buffer is a structure of the following type:

.PP

.in +4n

.EX

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 */

};

.EE

.in

.PP

The file timestamps are structures of the following type:

.PP

.in +4n

.EX

struct statx_timestamp {

    __s64 tv_sec;    /* Seconds since the Epoch (UNIX time) */

    __u32 tv_nsec;   /* Nanoseconds since tv_sec */

};

.EE

.in

.PP

(Note that reserved space and padding is omitted.)

.SS

Invoking \fBstatx\fR():

.PP

To access a file's status, no permissions are required on the file itself,

but in the case of

.BR statx ()

with a pathname,

execute (search) permission is required on all of the directories in

.I pathname

that lead to the file.

.PP

.BR statx ()

uses

.IR pathname ,

.IR dirfd ,

and

.IR flags

to identify the target file in one of the following ways:

.TP

An absolute pathname

If

.I pathname

begins with a slash,

then it is an absolute pathname that identifies the target file.

In this case,

.I dirfd

is ignored.

.TP

A relative pathname

If

.I pathname

is a string that begins with a character other than a slash and

.IR dirfd

is

.BR AT_FDCWD ,

then

.I pathname

is a relative pathname that is interpreted relative to the process's

current working directory.

.TP

A directory-relative pathname

If

.I pathname

is a string that begins with a character other than a slash and

.I dirfd

is a file descriptor that refers to a directory, then

.I pathname

is a relative pathname that is interpreted relative to the directory

referred to by

.IR dirfd .

.TP

By file descriptor

If

.IR pathname

is an empty string and the

.B AT_EMPTY_PATH

flag is specified in

.IR flags

(see below),

then the target file is the one referred to by the file descriptor

.IR dirfd .

.PP

.I flags

can be used to influence a pathname-based lookup.

A value for

.I flags

is constructed by ORing together zero or more of the following constants:

.TP

.BR AT_EMPTY_PATH

.\" commit 65cfc6722361570bfe255698d9cd4dccaf47570d

If

.I pathname

is an empty string, operate on the file referred to by

.IR dirfd

(which may have been obtained using the

.BR open (2)

.B O_PATH

flag).

In this case,

.I dirfd

can refer to any type of file, not just a directory.

.IP

If

.I dirfd

is

.BR AT_FDCWD ,

the call operates on the current working directory.

.IP

This flag is Linux-specific; define

.B _GNU_SOURCE

.\" Before glibc 2.16, defining _ATFILE_SOURCE sufficed

to obtain its definition.

.TP

.BR AT_NO_AUTOMOUNT

Don't automount the terminal ("basename") component of

.I pathname

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 can be used in tools that scan directories

to prevent mass-automounting of a directory of automount points.

The

.B AT_NO_AUTOMOUNT

flag has no effect if the mount point has already been mounted over.

This flag is Linux-specific; define

.B _GNU_SOURCE

.\" Before glibc 2.16, defining _ATFILE_SOURCE sufficed

to obtain its definition.

.TP

.B AT_SYMLINK_NOFOLLOW

If

.I pathname

is a symbolic link, do not dereference it:

instead return information about the link itself, like

.BR lstat (2).

.PP

.I 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:

.TP

.B AT_STATX_SYNC_AS_STAT

Do whatever

.BR stat (2)

does.

This is the default and is very much filesystem-specific.

.TP

.B 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.

.TP

.B 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.

.PP

The

.I mask

argument to

.BR statx ()

is used to tell the kernel which fields the caller is interested in.

.I mask

is an ORed combination of the following constants:

.PP

.in +4n

.TS

lB l.

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	[All currently available fields]

.TE

.in

.PP

Note that the kernel does

.I not

reject values in

.I mask

other than the above.

Instead, it simply informs the caller which values are supported

by this kernel and filesystem via the

.I statx.stx_mask

field.

Therefore,

.I "do not"

simply set

.I mask

to

.B UINT_MAX

(all bits set),

as one or more bits may, in the future, be used to specify an

extension to the buffer.

.SS

The returned information

.PP

The status information for the target file is returned in the

.I statx

structure pointed to by

.IR statxbuf .

Included in this is

.I stx_mask

which indicates what other information has been returned.

.I stx_mask

has the same format as the

.I mask

argument and bits are set in it to indicate

which fields have been filled in.

.PP

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,

.I stx_mask

will not be equal

.IR mask .

.PP

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

.I 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).

.PP

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

.IR stx_mask .

.PP

.\" Background: inode attributes are modified with i_mutex held, but

.\" read by stat() without taking the mutex.

.IR Note :

for performance and simplicity reasons, different fields in the

.I statx

structure may contain state information from different moments

during the execution of the system call.

For example, if

.IR stx_mode

or

.IR stx_uid

is changed by another process by calling

.BR chmod (2)

or

.BR chown (2),

.BR stat ()

might return the old

.I stx_mode

together with the new

.IR stx_uid ,

or the old

.I stx_uid

together with the new

.IR stx_mode .

.PP

Apart from

.I stx_mask

(which is described above), the fields in the

.I statx

structure are:

.TP

.I 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.)

.TP

.I stx_attributes

Further status information about the file (see below for more information).

.TP

.I stx_nlink

The number of hard links on a file.

.TP

.I stx_uid

This field contains the user ID of the owner of the file.

.TP

.I stx_gid

This field contains the ID of the group owner of the file.

.TP

.I stx_mode

The file type and mode.

See

.BR inode (7)

for details.

.TP

.I stx_ino

The inode number of the file.

.TP

.I 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.

.TP

.I stx_blocks

The number of blocks allocated to the file on the medium, in 512-byte units.

(This may be smaller than

.IR stx_size /512

when the file has holes.)

.TP

.I stx_attributes_mask

A mask indicating which bits in

.IR stx_attributes

are supported by the VFS and the filesystem.

.TP

.I stx_atime

The file's last access timestamp.

.TP

.I stx_btime

The file's creation timestamp.

.TP

.I stx_ctime

The file's last status change timestamp.

.TP

.I stx_mtime

The file's last modification timestamp.

.TP

.IR stx_dev_major " and "  stx_dev_minor

The device on which this file (inode) resides.

.TP

.IR stx_rdev_major " and "  stx_rdev_minor

The device that this file (inode) represents if the file is of block or

character device type.

.PP

For further information on the above fields, see

.BR inode (7).

.\"

.SS File attributes

.PP

The

.I 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

.I stx_attributes_mask

has no usable value here.

The bits in

.I stx_attributes_mask

correspond bit-by-bit to

.IR stx_attributes .

.PP

The flags are as follows:

.TP

.B STATX_ATTR_COMPRESSED

The file is compressed by the filesystem and may take extra resources

to access.

.TP

.B 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

.BR chattr (1).

.TP

.B STATX_ATTR_APPEND

The file can only be opened in append mode for writing.

Random access writing

is not permitted.

See

.BR chattr (1).

.TP

.B STATX_ATTR_NODUMP

File is not a candidate for backup when a backup program such as

.BR dump (8)

is run.

See

.BR chattr (1).

.TP

.B STATX_ATTR_ENCRYPTED

A key is required for the file to be encrypted by the filesystem.

.SH RETURN VALUE

On success, zero is returned.

On error, \-1 is returned, and

.I errno

is set appropriately.

.SH ERRORS

.TP

.B EACCES

Search permission is denied for one of the directories

in the path prefix of

.IR pathname .

(See also

.BR path_resolution (7).)

.TP

.B EBADF

.I dirfd

is not a valid open file descriptor.

.TP

.B EFAULT

.I pathname

or

.I statxbuf

is NULL or points to a location outside the process's

accessible address space.

.TP

.B EINVAL

Invalid flag specified in

.IR flags .

.TP

.B EINVAL

Reserved flag specified in

.IR mask .

.TP

.B ELOOP

Too many symbolic links encountered while traversing the pathname.

.TP

.B ENAMETOOLONG

.I pathname

is too long.

.TP

.B ENOENT

A component of

.I pathname

does not exist, or

.I pathname

is an empty string and

.B AT_EMPTY_PATH

was not specified in

.IR flags .

.TP

.B ENOMEM

Out of memory (i.e., kernel memory).

.TP

.B ENOTDIR

A component of the path prefix of

.I pathname

is not a directory or

.I pathname

is relative and

.I dirfd

is a file descriptor referring to a file other than a directory.

.SH VERSIONS

.BR statx ()

was added to Linux in kernel 4.11.

.SH CONFORMING TO

.BR statx ()

is Linux-specific.

.SH NOTES

Glibc does not (yet) provide a wrapper for the

.BR statx ()

system call; call it using

.BR syscall (2).

.SH SEE ALSO

.BR ls (1),

.BR stat (1),

.BR access (2),

.BR chmod (2),

.BR chown (2),

.BR readlink (2),

.BR stat (2),

.BR utime (2),

.BR capabilities (7),

.BR inode (7),

.BR symlink (7)

.SH COLOPHON

This page is part of release 4.15 of the Linux

.I man-pages

project.

A description of the project,

information about reporting bugs,

and the latest version of this page,

can be found at

\%https://www.kernel.org/doc/man\-pages/.