telldir - return current location in directory stream
long telldir(DIR *dirp);
Feature Test Macro Requirements for glibc (see feature_test_macros
|| /* Glibc since 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
() 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
- Invalid directory stream descriptor dirp.
For an explanation of the terms used in this section, see attributes
POSIX.1-2001, POSIX.1-2008, 4.3BSD.
In glibc up to version 2.1.1, the return type of telldir
. 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
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.