PROLOG

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

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 .