NAME

telldir - return current location in directory stream

LIBRARY

Standard C library (libc, -lc)

SYNOPSIS

#include <dirent.h>
long telldir(DIR *dirp);

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

telldir():

    _XOPEN_SOURCE
       || /* glibc >= 2.19: */ _DEFAULT_SOURCE
       || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION

The telldir() function returns the current location associated with the directory stream dirp.

RETURN VALUE

On success, the telldir() function returns the current location in the directory stream. On error, -1 is returned, and errno is set to indicate the error.

ERRORS

EBADF: Invalid directory stream descriptor dirp.

ATTRIBUTES

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

Interface	Attribute	Value
telldir()	Thread safety	MT-Safe

STANDARDS

POSIX.1-2008.

HISTORY

POSIX.1-2001, 4.3BSD.

Up to glibc 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.