telldir - return current location in directory stream
long telldir(DIR *dirp);
|| /* 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
- Invalid directory stream descriptor dirp.
For an explanation of the terms used in this section, see attributes(7).
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.
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