READDIR(2)                 Linux Programmer's Manual                READDIR(2)

       readdir - read directory entry

       int readdir(unsigned int fd, struct old_linux_dirent *dirp,
                   unsigned int count);

       Note: There is no glibc wrapper for this system call; see NOTES.

       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       kernel system call interface, which is superseded by getdents(2).

       readdir() reads one old_linux_dirent structure from the directory
       referred to by the file descriptor fd into the buffer pointed to by
       dirp.  The argument count is ignored; at most one old_linux_dirent
       structure is read.

       The old_linux_dirent structure is declared (privately in Linux kernel
       file fs/readdir.c) as follows:

           struct old_linux_dirent {
               unsigned long d_ino;     /* inode number */
               unsigned long d_offset;  /* offset to this old_linux_dirent */
               unsigned short d_namlen; /* length of this d_name */
               char  d_name[1];         /* filename (null-terminated) */

       d_ino is an inode number.  d_offset is the distance from the start of
       the directory to this old_linux_dirent.  d_reclen is the size of
       d_name, not counting the terminating null byte ('\0').  d_name is a
       null-terminated filename.

       On success, 1 is returned.  On end of directory, 0 is returned.  On
       error, -1 is returned, and errno is set appropriately.

       EBADF  Invalid file descriptor fd.

       EFAULT Argument points outside the calling process's address space.

       EINVAL Result buffer is too small.

       ENOENT No such directory.

              File descriptor does not refer to a directory.

       This system call is Linux-specific.

       Glibc does not provide a wrapper for this system call; call it using
       syscall(2).  You will need to define the old_linux_dirent structure
       yourself.  However, probably you should use readdir(3) instead.

       This system call does not exist on x86-64.

       getdents(2), readdir(3)

       This page is part of release 5.06 of the Linux man-pages project.  A
       description of the project, information about reporting bugs, and the
       latest version of this page, can be found at

Linux                             2019-03-06                        READDIR(2)