telldir - return current location in directory stream
#include <dirent.h>
long telldir(DIR *dirp);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
telldir(): _XOPEN_SOURCE || /* Glibc since 2.19: */ _DEFAULT_SOURCE || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
The telldir() function returns the current location
associated with the directory stream dirp
.
On success, the telldir() function returns the
current location in the directory stream. On error, -1 is returned, and
errno
is set appropriately.
Invalid directory stream descriptor dirp
.
For an explanation of the terms used in this section, see attributes(7).
Interface | Attribute | Value |
telldir() | Thread safety | MT-Safe |
POSIX.1-2001, POSIX.1-2008, 4.3BSD.
In glibc up to version 2.1.1, the return type of
telldir() was off_t
. POSIX.1-2001 specifies
long
, and this is the type used since glibc 2.1.2.
In early filesystems, the value returned by
telldir() was a simple file offset within a directory.
Modern filesystems use tree or hash structures, rather than flat tables,
to represent directories. On such filesystems, the value returned by
telldir() (and used internally by
readdir(3)) is a "cookie" that is used by the
implementation to derive a position within a directory. Application
programs should treat this strictly as an opaque value, making
no
assumptions about its contents.
This page is part of release 5.10 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/.