Let's take a look at the struct dirent structure, since that's the data structure returned by the io_read() function in case of a directory read. We'll also take a quick look at the client calls that deal with directory entries, since there are some interesting relations to the struct dirent structure.
In order for a client to work with directories, the client uses the functions closedir(), opendir(), readdir(), rewinddir(), seekdir(), and telldir().
Notice the similarity to the "normal" file-type functions (and the commonality of the resource manager messages):
| Directory Function | File Function | Message (resmgr) |
|---|---|---|
| closedir() | close() | _IO_CLOSE_DUP |
| opendir() | open() | _IO_CONNECT |
| readdir() | read() | _IO_READ |
| rewinddir() | lseek() | _IO_LSEEK |
| seekdir() | lseek() | _IO_LSEEK |
| telldir() | tell() | _IO_LSEEK |
If we assume for a moment that the opendir() and closedir() functions will be handled automatically for us, we can focus on just the _IO_READ and _IO_LSEEK messages and related functions.