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statx.2: Remove information migrated to inode(7)
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
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Michael Kerrisk
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man2/statx.2
212
man2/statx.2
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@ -337,7 +337,9 @@ structure are:
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.TP
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.I stx_mode
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The file type and mode.
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This is described in more detail below.
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See
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.BR inode (7)
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for details.
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.TP
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.I stx_size
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The size of the file (if it is a regular file or a symbolic link) in bytes.
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@ -376,63 +378,18 @@ Further status information about the file (see below for more information).
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.TP
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.I stx_atime
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The file's last access timestamp.
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This field is changed by file accesses, for example, by
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.BR execve (2),
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.BR mknod (2),
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.BR pipe (2),
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.BR utime (2),
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and
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.BR read (2)
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(of more than zero bytes).
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Other routines, such as
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.BR mmap (2),
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may or may not update it.
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.TP
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.I stx_btime
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The file's creation timestamp.
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This is set on file creation and not changed subsequently.
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.TP
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.I stx_ctime
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The file's last status change timestamp.
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This field is changed by writing or
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by setting inode information (i.e., owner, group, link count, mode, etc.).
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.TP
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.I stx_mtime
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The file's last modification timestamp.
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This is changed by file modifications,
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for example, by
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.BR mknod (2),
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.BR truncate (2),
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.BR utime (2),
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and
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.BR write (2)
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(of more than zero bytes).
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Moreover, the modification time of a directory is
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changed by the creation or deletion of files in that directory.
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This field is
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.I not
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changed for changes in owner, group, hard link count, or mode.
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.PP
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Not all of the Linux filesystems implement all of the timestamp fields.
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Some filesystems allow mounting in such a way that file and/or
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directory accesses do not cause an update of the
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.I stx_atime
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field.
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(See
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.IR noatime ,
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.IR nodiratime ,
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and
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.I relatime
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in
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.BR mount (8),
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and related information in
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.BR mount (2).)
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In addition,
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.I stx_atime
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is not updated if a file is opened with the
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.BR O_NOATIME ;
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see
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.BR open (2).
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For further information on the above fields, see
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.BR inode (7).
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.\"
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.SS File attributes
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.PP
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@ -466,165 +423,6 @@ See
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.TP
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.B STATX_ATTR_ENCRYPTED
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A key is required for the file to be encrypted by the filesystem.
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.SS File type and mode
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.PP
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The
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.I stx_mode
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field contains the combined file type and mode.
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POSIX refers to the bits in
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this field corresponding to the mask
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.B S_IFMT
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(see below) as the
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.IR "file type" ,
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the 12 bits corresponding to the mask 07777 as the
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.IR "file mode bits"
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and the least significant 9 bits (0777) as the
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.IR "file permission bits" .
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.IP
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The following mask values are defined for the file type of the
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.I stx_mode
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field:
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.in +4n
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.TS
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lB l l.
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S_IFMT 0170000 bit mask for the file type bit field
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S_IFSOCK 0140000 socket
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S_IFLNK 0120000 symbolic link
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S_IFREG 0100000 regular file
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S_IFBLK 0060000 block device
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S_IFDIR 0040000 directory
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S_IFCHR 0020000 character device
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S_IFIFO 0010000 FIFO
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.TE
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.in
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.IP
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Note that
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.I stx_mode
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has two mask flags covering it: one for the type and one for the mode bits.
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.PP
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To test for a regular file (for example), one could write:
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.nf
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.in +4n
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statx(AT_FDCWD, pathname, 0, STATX_TYPE, &sb);
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if ((sb.stx_mask & STATX_TYPE) && (sb.stx_mode & S_IFMT) == S_IFREG) {
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/* Handle regular file */
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}
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.in
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.fi
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.PP
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Because tests of the above form are common, additional macros are defined by
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POSIX to allow the test of the file type in
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.I stx_mode
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to be written more concisely:
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.RS 4
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.TS
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lB l.
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\fBS_ISREG\fR(m) Is it a regular file?
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\fBS_ISDIR\fR(m) Is it a directory?
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\fBS_ISCHR\fR(m) Is it a character device?
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\fBS_ISBLK\fR(m) Is it a block device?
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\fBS_ISFIFO\fR(m) Is it a FIFO (named pipe)?
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\fBS_ISLNK\fR(m) Is it a symbolic link? (Not in POSIX.1-1996.)
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\fBS_ISSOCK\fR(m) Is it a socket? (Not in POSIX.1-1996.)
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.TE
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.RE
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.PP
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The preceding code snippet could thus be rewritten as:
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.nf
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.in +4n
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statx(AT_FDCWD, pathname, 0, STATX_TYPE, &sb);
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if ((sb.stx_mask & STATX_TYPE) && S_ISREG(sb.stx_mode)) {
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/* Handle regular file */
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}
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.in
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.fi
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.PP
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The definitions of most of the above file type test macros
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are provided if any of the following feature test macros is defined:
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.BR _BSD_SOURCE
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(in glibc 2.19 and earlier),
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.BR _SVID_SOURCE
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(in glibc 2.19 and earlier),
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or
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.BR _DEFAULT_SOURCE
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(in glibc 2.20 and later).
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In addition, definitions of all of the above macros except
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.BR S_IFSOCK
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and
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.BR S_ISSOCK ()
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are provided if
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.BR _XOPEN_SOURCE
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is defined.
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The definition of
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.BR S_IFSOCK
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can also be exposed by defining
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.BR _XOPEN_SOURCE
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with a value of 500 or greater.
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The definition of
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.BR S_ISSOCK ()
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is exposed if any of the following feature test macros is defined:
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.BR _BSD_SOURCE
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(in glibc 2.19 and earlier),
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.BR _DEFAULT_SOURCE
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(in glibc 2.20 and later),
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.BR _XOPEN_SOURCE
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with a value of 500 or greater, or
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.BR _POSIX_C_SOURCE
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with a value of 200112L or greater.
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.PP
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The following mask values are defined for
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the file mode component of the
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.I stx_mode
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field:
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.in +4n
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.TS
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lB l l.
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S_ISUID 04000 set-user-ID bit
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S_ISGID 02000 set-group-ID bit (see below)
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S_ISVTX 01000 sticky bit (see below)
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S_IRWXU 00700 owner has read, write, and execute permission
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S_IRUSR 00400 owner has read permission
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S_IWUSR 00200 owner has write permission
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S_IXUSR 00100 owner has execute permission
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S_IRWXG 00070 group has read, write, and execute permission
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S_IRGRP 00040 group has read permission
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S_IWGRP 00020 group has write permission
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S_IXGRP 00010 group has execute permission
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S_IRWXO 00007 T{
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others (not in group) have read, write, and execute permission
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T}
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S_IROTH 00004 others have read permission
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S_IWOTH 00002 others have write permission
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S_IXOTH 00001 others have execute permission
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.TE
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.in
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.P
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The set-group-ID bit
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.RB ( S_ISGID )
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has several special uses.
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For a directory, it indicates that BSD semantics is to be used
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for that directory: files created there inherit their group ID from
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the directory, not from the effective group ID of the creating process,
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and directories created there will also get the
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.B S_ISGID
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bit set.
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For a file that does not have the group execution bit
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.RB ( S_IXGRP )
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set,
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the set-group-ID bit indicates mandatory file/record locking.
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.P
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The sticky bit
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.RB ( S_ISVTX )
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on a directory means that a file
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in that directory can be renamed or deleted only by the owner
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of the file, by the owner of the directory, and by a privileged
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process.
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.SH RETURN VALUE
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On success, zero is returned.
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On error, \-1 is returned, and
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