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

NAME
       readdir - read directory entry

SYNOPSIS
       #include <sys/syscall.h>      /* Definition of SYS_* constants */
       #include <unistd.h>

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

       Note: There is no definition of struct old_linux_dirent; see NOTES.

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       call interface, which is superseded by getdents(2).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

RETURN VALUE
       On success, 1 is returned.  On end of directory, 0 is returned.  On error, -1 is returned, and errno is set to indicate the error.

ERRORS
       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.

       ENOTDIR
              File descriptor does not refer to a directory.

CONFORMING TO
       This system call is Linux-specific.

NOTES
       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.

SEE ALSO
       getdents(2), readdir(3)

Linux                                                                          2021-03-22                                                                     READDIR(2)