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statx(2)

STATX(2)                   Linux Programmer's Manual                  STATX(2)



NAME
       statx - get file status (extended)

SYNOPSIS
       #include <sys/types.h>
       #include <sys/stat.h>
       #include <unistd.h>
       #include <fcntl.h>           /* Definition of AT_* constants */

       int statx(int dirfd, const char *pathname, int flags,
                 unsigned int mask, struct statx *statxbuf);

DESCRIPTION
       This  function returns information about a file, storing it in the buf‐
       fer 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 */
           };

       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 pathname that lead
       to the file.

       statx() uses pathname, dirfd, and flags to identify the target file  in
       one of the following ways:

       An absolute pathname
              If pathname 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  pathname is a string that begins with a character other than
              a slash and dirfd is AT_FDCWD, then pathname is a relative path‐
              name that is interpreted relative to the process's current work‐
              ing directory.

       A directory-relative pathname
              If pathname is a string that begins with a character other  than
              a  slash  and dirfd is a file descriptor that refers to a direc‐
              tory, then pathname is a relative pathname that  is  interpreted
              relative to the directory referred to by dirfd.

       By file descriptor
              If  pathname  is  an  empty string 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  pathname is an empty string, 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.

              This  flag  is  Linux-specific; define _GNU_SOURCE to obtain its
              definition.

       AT_NO_AUTOMOUNT
              Don't automount the terminal ("basename") component of  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 AT_NO_AUTOMOUNT flag has no
              effect if the mount point has already been mounted  over.   This
              flag is Linux-specific; define _GNU_SOURCE to obtain its defini‐
              tion.

       AT_SYMLINK_NOFOLLOW
              If pathname 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 ker‐
       nel 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 informa‐
              tion 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 fol‐
       lowing constants:

           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]

       Note  that  the  kernel  does  not reject values in mask other than the
       above.  Instead, it simply informs the caller  which  values  are  sup‐
       ported  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  unrepre‐
       sentable  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 com‐
       patibility 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.  (Writ‐
              ing  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 and stx_dev_minor
              The device on which this file (inode) resides.

       stx_rdev_major and stx_rdev_minor
              The device that this file (inode) represents if the file  is  of
              block or character device type.

       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 writ‐
              ten 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  filesys‐
              tem.

RETURN VALUE
       On  success,  zero is returned.  On error, -1 is returned, and errno is
       set appropriately.

ERRORS
       EACCES Search permission is denied for one of the  directories  in  the
              path prefix of pathname.  (See also path_resolution(7).)

       EBADF  dirfd is not a valid open file descriptor.

       EFAULT pathname or statxbuf is NULL or points to a location outside the
              process's accessible address space.

       EINVAL Invalid flag specified in flags.

       EINVAL Reserved flag specified in mask.

       ELOOP  Too many symbolic links encountered while traversing  the  path‐
              name.

       ENAMETOOLONG
              pathname is too long.

       ENOENT A  component of pathname does not exist, or pathname 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 pathname is not a directory or
              pathname is relative and dirfd is a file descriptor referring to
              a file other than a directory.

VERSIONS
       statx() was added to Linux in kernel 4.11; library support was added in
       glibc 2.28.

CONFORMING TO
       statx() is Linux-specific.

SEE ALSO
       ls(1),  stat(1),  access(2),  chmod(2), chown(2), readlink(2), stat(2),
       utime(2), capabilities(7), inode(7), symlink(7)

COLOPHON
       This page is part of release 5.02 of the Linux  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/.



Linux                             2019-03-06                          STATX(2)
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