telldir(3)

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
 | 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.

SEE ALSO
closedir(3), opendir(3), readdir(3), rewinddir(3), scandir(3), seekdir(3)