This is not the function you are interested in. Look at readdir(3) for the POSIX conforming C library interface. This page documents the bare kernel system call interface.
The system call getdents reads several dirent structures from the directory pointed at by fd into the memory area pointed to by dirp. The parameter count is the size of the memory area.
The dirent structure is declared as follows:
long d_ino; /* inode number */
off_t d_off; /* offset to next dirent */
unsigned short d_reclen; /* length of this dirent */
char d_name [NAME_MAX+1]; /* file name (null-terminated) */
d_ino is an inode number. d_off is the distance from the start of the directory to the start of the next dirent. d_reclen is the size of this entire dirent. d_name is a null-terminated file name.
This call supersedes readdir(2).
On success, the number of bytes read is returned. On end of directory, 0 is returned. On error, -1 is returned, and errno is set appropriately.