Login or Register to Ask a Question and Join Our Community


UNIX for Dummies Questions & Answers

seekdir()? what does it do?

 
Thread Tools Search this Thread
Top Forums UNIX for Dummies Questions & Answers seekdir()? what does it do?
# 8  
Old 01-24-2011
seekdir() is optional on POSIX.

Quote:
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.
 
Login or Register to Ask a Question

Previous Thread | Next Thread
Login or Register to Ask a Question

LEARN ABOUT XFREE86

seekdir

SEEKDIR(3)						     Linux Programmer's Manual							SEEKDIR(3)

NAME

       seekdir - set the position of the next readdir() call in the directory stream.

SYNOPSIS

       #include <dirent.h>

       void seekdir(DIR *dirp, long loc);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       seekdir():
	_XOPEN_SOURCE
	   || /* Glibc since 2.19: */ _DEFAULT_SOURCE
	   || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION

       The  seekdir()  function sets the location in the directory stream from which the next readdir(2) call will start.  The loc argument should
       be a value returned by a previous call to telldir(3).

RETURN VALUE

       The seekdir() function returns no value.

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       +----------+---------------+---------+
       |Interface | Attribute	  | Value   |
       +----------+---------------+---------+
       |seekdir() | Thread safety | MT-Safe |
       +----------+---------------+---------+
CONFORMING TO

       POSIX.1-2001, POSIX.1-2008, 4.3BSD.

NOTES

       In glibc up to version 2.1.1, the type of the loc argument was off_t.  POSIX.1-2001 specifies long, and this is the type used  since  glibc
       2.1.2.  See telldir(3) for information on why you should be careful in making any assumptions about the value in this argument.

SEE ALSO

       lseek(2), closedir(3), opendir(3), readdir(3), rewinddir(3), scandir(3), telldir(3)

COLOPHON

       This  page is part of release 4.15 of the Linux man-pages project.  A description of the project, information about reporting bugs, and the
       latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.

								    2016-03-15								SEEKDIR(3)