telldir − return current location in directory stream
long telldir(DIR *dirp);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
telldir(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_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.
Invalid directory stream descriptor dirp.
For an explanation of the terms used in this section, see attributes(7).
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 file systems, the value returned by telldir() was a simple file offset within a directory. Modern file systems use tree or hash structures, rather than flat tables, to represent directories. On such file systems, 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)
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