opendir - open a directory
The opendir() function opens a directory stream
corresponding to the directory name, and returns a
pointer to the directory stream. The stream is positioned at
the first entry in the directory.
The opendir() function returns a pointer to the
directory stream or NULL if an error occurred.
Too many file descriptors in use by process.
Too many files are currently open in the
Directory does not exist, or name is an empty
Insufficient memory to complete the operation.
name is not a directory.
SVID 3, POSIX, BSD 4.3
open(2), readdir(3), closedir(3),
rewinddir(3), seekdir(3), telldir(3),