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       statx - get file status (extended)


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

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


       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 */

       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 pathname that is interpreted relative to
              the process's current working 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 directory, then pathname 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  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

       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:

              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.

              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 definition.

              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 kernel will do when
       querying a file on a remote filesystem.  This is done by ORing in  one  of  the  following

              Do  whatever  stat(2)  does.   This  is  the  default  and is very much filesystem-

              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.

              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_MNT_ID        Want stx_mnt_id (since Linux 5.8)
           STATX_ALL           [All currently available fields]

       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:

              The  "preferred"  block  size  for efficient filesystem I/O.  (Writing to a file in
              smaller chunks may cause an inefficient read-modify-rewrite.)

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

              The number of hard links on a file.

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

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

              The file type and mode.  See inode(7) for details.

              The inode number of the file.

              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.

              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.)

              A  mask  indicating  which  bits in stx_attributes are supported by the VFS and the

              The file's last access timestamp.

              The file's creation timestamp.

              The file's last status change timestamp.

              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.

              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.

       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:

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

              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).

              The  file  can only be opened in append mode for writing.  Random access writing is
              not permitted.  See chattr(1).

              File is not a candidate for backup when a backup program such as  dump(8)  is  run.
              See chattr(1).

              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_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.


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


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

       EBADF  pathname is relative but dirfd is neither AT_FDCWD nor a valid 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.  (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.

              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).

              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.


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


       statx() is Linux-specific.


       ls(1), stat(1), access(2), chmod(2), chown(2), name_to_handle_at(2), readlink(2), stat(2),
       utime(2), proc(5), capabilities(7), inode(7), symlink(7)


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