bionic (3) seekdir.3posix.gz

Provided by: manpages-posix-dev_2013a-2_all bug

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
       seekdir — set the position of a directory stream


SYNOPSIS
       #include <dirent.h>

       void seekdir(DIR *dirp, long loc);


DESCRIPTION
       The  seekdir()  function  shall  set the position of the next readdir() operation on the directory stream
       specified by dirp to the position specified by loc.  The value of loc should have been returned  from  an
       earlier call to telldir() using the same directory stream. The new position reverts to the one associated
       with the directory stream when telldir() was performed.

       If the value of loc was not obtained from an earlier call to telldir(),  or  if  a  call  to  rewinddir()
       occurred  between  the  call  to  telldir() and the call to seekdir(), the results of subsequent calls to
       readdir() are unspecified.


RETURN VALUE
       The seekdir() function shall not return a value.


ERRORS
       No errors are defined.

       The following sections are informative.


EXAMPLES
       None.


APPLICATION USAGE
       None.


RATIONALE
       The original standard developers perceived that there were restrictions on the use of the  seekdir()  and
       telldir()  functions  related  to implementation details, and for that reason these functions need not be
       supported on all POSIX-conforming systems. They  are  required  on  implementations  supporting  the  XSI
       option.

       One  of  the  perceived  problems  of implementation is that returning to a given point in a directory is
       quite difficult to describe formally, in spite of its intuitive appeal, when systems  that  use  B-trees,
       hashing  functions, or other similar mechanisms to order their directories are considered. The definition
       of seekdir() and telldir() does not specify whether, when using these interfaces, a given directory entry
       will be seen at all, or more than once.

       On  systems  not  supporting  these functions, their capability can sometimes be accomplished by saving a
       filename found by readdir() and later using rewinddir() and a loop on readdir() to relocate the  position
       from which the filename was saved.


FUTURE DIRECTIONS
       None.


SEE ALSO
       fdopendir(), readdir(), telldir()

       The Base Definitions volume of POSIX.1‐2008, <dirent.h>, <sys_types.h>


       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2013 Edition,
       Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open  Group  Base
       Specifications  Issue 7, Copyright (C) 2013 by the Institute of Electrical and Electronics Engineers, Inc
       and The Open Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/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 .