STAT(2)                   NetBSD System Calls Manual                   STAT(2)

NAME
     stat, lstat, fstat, fstatat, -- get file status

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <sys/stat.h>

     int
     stat(const char *path, struct stat *sb);

     int
     lstat(const char *path, struct stat *sb);

     int
     fstat(int fd, struct stat *sb);

     #include <sys/stat.h>
     #include <fcntl.h>

     int
     fstatat(int fd, const char *path, struct stat *sb, int flag);

DESCRIPTION
     The stat() function obtains information about the file pointed to by
     path.  Read, write or execute permission of the named file is not
     required, but all directories listed in the path name leading to the file
     must be searchable.

     The function lstat() is like stat() except in the case where the named
     file is a symbolic link, in which case lstat() returns information about
     the link, while stat() returns information about the file the link refer-
     ences.  The fstat() function obtains the same information about an open
     file known by the file descriptor fd.

     fstatat() works the same way as stat() (or lstat() if AT_SYMLINK_NOFOLLOW
     is set in flag) except if path is relative.  In that case, it is looked
     up from a directory whose file descriptor was passed as fd.  Search per-
     mission is required on this directory.  fd can be set to AT_FDCWD in
     order to specify the current directory.

     The sb argument is a pointer to a stat structure as defined by
     <sys/stat.h> and into which information is placed concerning the file.

   The Standard Structure
     The following standards-compliant fields are defined in the structure:

           Type        Entry        Description
           dev_t       st_dev       device ID containing the file
           ino_t       st_ino       serial number of the file (inode number)
           mode_t      st_mode      mode of the file
           nlink_t     st_nlink     number of hard links to the file
           uid_t       st_uid       user ID of the owner
           gid_t       st_gid       group ID of the owner
           dev_t       st_rdev      device type (character or block special)
           off_t       st_size      size of the file in bytes
           time_t      st_atime     time of last access
           time_t      st_mtime     time of last data modification
           time_t      st_ctime     time of last file status change
           blksize_t   st_blksize   preferred I/O block size (fs-specific)
           blkcnt_t    st_blocks    blocks allocated for the file

     These are specified in the IEEE Std 1003.1-2004 (``POSIX.1'') standard.
     The st_ino and st_dev fields taken together uniquely identify the file
     within the system.  Most of the types are defined in types(3).

     The time-related fields are:

           st_atime    Time when file data was last accessed.  Changed by the
                       mknod(2), utimes(2), and read(2) system calls.

           st_mtime    Time when file data was last modified.  Changed by the
                       mknod(2), utimes(2), and write(2) system calls.

           st_ctime    Time when file status was last changed (file metadata
                       modification).  Changed by the chflags(2), chmod(2),
                       chown(2), link(2), mknod(2), rename(2), unlink(2),
                       utimes(2), and write(2) system calls.

     The size-related fields of the struct stat are as follows:

           st_size     The size of the file in bytes.  The meaning of the size
                       reported for a directory is file system dependent.
                       Some file systems (e.g. FFS) return the total size used
                       for the directory metadata, possibly including free
                       slots; others (notably ZFS) return the number of
                       entries in the directory.  Some may also return other
                       things or always report zero.

           st_blksize  The optimal I/O block size for the file.

           st_blocks   The actual number of blocks allocated for the file in
                       512-byte units.  As short symbolic links are stored in
                       the inode, this number may be zero.

     The status information word st_mode contains bits that define the access
     mode (see chmod(2)) and the type (see dirent(3)) of the file.  The fol-
     lowing macros can be used to test whether a file is of the specified
     type.  The value m supplied to the macros is the value of st_mode.

           S_ISBLK(m)   Test for a block special file.

           S_ISCHR(m)   Test for a character special file.

           S_ISDIR(m)   Test for a directory.

           S_ISFIFO(m)  Test for a pipe or FIFO special file.

           S_ISREG(m)   Test for a regular file.

           S_ISLNK(m)   Test for a symbolic link.

           S_ISSOCK(m)  Test for a socket.

     The macros evaluate to a non-zero value if the test is true or to the
     value 0 if the test is false.

   NetBSD Extensions
     The following additional NetBSD specific fields are present:

           Type        Entry               Description
           long        st_atimensec        last access (nanoseconds)
           long        st_mtimensec        last modification (nanoseconds)
           long        st_ctimensec        last status change (nanoseconds)
           time_t      st_birthtime        time of inode creation
           long        st_birthtimensec    inode creation (nanoseconds)
           uint32_t    st_flags            user defined flags for the file
           uint32_t    st_gen              file generation number
           uint32_t    st_spare[2]         implementation detail

     However, if _NETBSD_SOURCE is furthermore defined, instead of the above,
     the following are present in the structure:

           Type                Entry               Description
           struct timespec     st_atimespec        time of last access
           struct timespec     st_mtimespec        time of last modification
           struct timespec     st_birthtimespec    time of creation
           uint32_t            st_flags            user defined flags
           uint32_t            st_gen              file generation number
           uint32_t            st_spare[2]         implementation detail

     In this case the following macros are provided for convenience:

           #if defined(_NETBSD_SOURCE)
             #define st_atime                st_atimespec.tv_sec
             #define st_atimensec            st_atimespec.tv_nsec
             #define st_mtime                st_mtimespec.tv_sec
             #define st_mtimensec            st_mtimespec.tv_nsec
             #define st_ctime                st_ctimespec.tv_sec
             #define st_ctimensec            st_ctimespec.tv_nsec
             #define st_birthtime            st_birthtimespec.tv_sec
             #define st_birthtimensec        st_birthtimespec.tv_nsec
           #endif

     The status information word st_flags has the following bits:

           Constant            Description
           UF_NODUMP           do not dump a file
           UF_IMMUTABLE        file may not be changed
           UF_APPEND           writes to file may only append
           UF_OPAQUE           directory is opaque wrt. union
           SF_ARCHIVED         file is archived
           SF_IMMUTABLE        file may not be changed
           SF_APPEND           writes to file may only append

     For a description of the flags, see chflags(2).

RETURN VALUES
     The stat(), lstat(), fstat(), and fstatat() functions return the value 0
     if successful; otherwise the value -1 is returned and the global variable
     errno is set to indicate the error.

COMPATIBILITY
     Previous versions of the system used different types for the st_dev,
     st_uid, st_gid, st_rdev, st_size, st_blksize and st_blocks fields.

ERRORS
     stat(), lstat() and fstatat() will fail if:

     [EACCES]           Search permission is denied for a component of the
                        path prefix.

     [EBADF]            A badly formed vnode was encountered.  This can happen
                        if a file system information node is incorrect.

     [EFAULT]           sb or path points to an invalid address.

     [EIO]              An I/O error occurred while reading from or writing to
                        the file system.

     [ELOOP]            Too many symbolic links were encountered in translat-
                        ing the pathname.

     [ENAMETOOLONG]     A component of a pathname exceeded {NAME_MAX} charac-
                        ters, or an entire path name exceeded {PATH_MAX} char-
                        acters.

     [ENOENT]           The named file does not exist.

     [ENOTDIR]          A component of the path prefix is not a directory.

     [ENXIO]            The named file is a character special or block special
                        file, and the device associated with this special file
                        does not exist.

     In addition, fstatat() will fail if:

     [EBADF]            path does not specify an absolute path and fd is nei-
                        ther AT_FDCWD nor a valid file descriptor open for
                        reading or searching.

     [ENOTDIR]          path is not an absolute path and fd is a file descrip-
                        tor associated with a non-directory file.

     fstat() will fail if:

     [EBADF]            fd is not a valid open file descriptor.

     [EFAULT]           sb points to an invalid address.

     [EIO]              An I/O error occurred while reading from or writing to
                        the file system.

SEE ALSO
     chflags(2), chmod(2), chown(2), utimes(2), dirent(3), types(3),
     symlink(7)

STANDARDS
     stat(), lstat(), and fstat() conform to IEEE Std 1003.1-2004
     (``POSIX.1'').  fstatat() conforms to IEEE Std 1003.1-2008 (``POSIX.1'').

HISTORY
     A stat() function call appeared in Version 2 AT&T UNIX.  A lstat() func-
     tion call appeared in 4.2BSD.

BUGS
     Applying fstat() to a socket (and thus to a pipe) returns a zero'd
     buffer, except for the blocksize field, and a unique device and file
     serial number.

NetBSD 6.0                      April 10, 2014                      NetBSD 6.0

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