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.
- EBADF
- 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.
closedir(3),
opendir(3),
readdir(3),
rewinddir(3),
scandir(3),
seekdir(3)