FSTAT(3)                   POSIX Programmer's Manual                  FSTAT(3)



PROLOG
       This manual page is part of the POSIX Programmer's Manual.  The OS
       implementation of this interface may differ (consult the corresponding
       OS manual page for details of OS behavior), or the interface may not be
       implemented on OS.

NAME
       fstat -- get file status

SYNOPSIS
       #include <sys/stat.h>

       int fstat(int fildes, struct stat *buf);

DESCRIPTION
       The fstat() function shall obtain information about an open file
       associated with the file descriptor fildes, and shall write it to the
       area pointed to by buf.

       If fildes references a shared memory object, the implementation shall
       update in the stat structure pointed to by the buf argument the st__uid,
       st__gid, st__size, and st__mode fields, and only the S_IRUSR, S_IWUSR,
       S_IRGRP, S_IWGRP, S_IROTH, and S_IWOTH file permission bits need be
       valid.  The implementation may update other fields and flags.

       If fildes references a typed memory object, the implementation shall
       update in the stat structure pointed to by the buf argument the st__uid,
       st__gid, st__size, and st__mode fields, and only the S_IRUSR, S_IWUSR,
       S_IRGRP, S_IWGRP, S_IROTH, and S_IWOTH file permission bits need be
       valid. The implementation may update other fields and flags.

       The buf argument is a pointer to a stat structure, as defined in
       <sys/stat.h>, into which information is placed concerning the file.

       For all other file types defined in this volume of POSIX.1-2017, the
       structure members st__mode, st__ino, st__dev, st__uid, st__gid, st__atim,
       st__ctim, and st__mtim shall have meaningful values and the value of the
       st__nlink member shall be set to the number of links to the file.

       An implementation that provides additional or alternative file access
       control mechanisms may, under implementation-defined conditions, cause
       fstat() to fail.

       The fstat() function shall update any time-related fields (as described
       in the Base Definitions volume of POSIX.1-2017, Section 4.9, File Times
       Update), before writing into the stat structure.

RETURN VALUE
       Upon successful completion, 0 shall be returned. Otherwise, -1 shall be
       returned and errno set to indicate the error.

ERRORS
       The fstat() function shall fail if:

       EBADF  The fildes argument is not a valid file descriptor.

       EIO    An I/O error occurred while reading from the file system.

       EOVERFLOW
              The file size in bytes or the number of blocks allocated to the
              file or the file serial number cannot be represented correctly
              in the structure pointed to by buf.

       The fstat() function may fail if:

       EOVERFLOW
              One of the values is too large to store into the structure
              pointed to by the buf argument.

       The following sections are informative.

EXAMPLES
   Obtaining File Status Information
       The following example shows how to obtain file status information for a
       file named /home/cnd/mod1.  The structure variable buffer is defined
       for the stat structure. The /home/cnd/mod1 file is opened with
       read/write privileges and is passed to the open file descriptor fildes.


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

           struct stat buffer;
           int         status;
           ...
           fildes = open("/home/cnd/mod1", O_RDWR);
           status = fstat(fildes, &buffer);

APPLICATION USAGE
       None.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       fstatat()

       The Base Definitions volume of POSIX.1-2017, Section 4.9, File Times
       Update, <sys_stat.h>, <sys_types.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1-2017, Standard for Information Technology --
       Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  In the event of any discrepancy between this version and the
       original IEEE and The Open Group Standard, the original IEEE and The
       Open Group Standard is the referee document. The original Standard can
       be obtained online at http://www.opengroup.org/unix/online.html .

       Any typographical or formatting errors that appear in this page are
       most likely to have been introduced during the conversion of the source
       files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .



IEEE/The Open Group                  2017                             FSTAT(3)
