readdir(2) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | CONFORMING TO | NOTES | SEE ALSO | COLOPHON

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

NAME         top

       readdir - read directory entry

SYNOPSIS         top

       #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         top

       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       superseded by getdents(2).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         top

       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         top

       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         top

       This system call is Linux-specific.

NOTES         top

       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         top

       getdents(2), readdir(3)

COLOPHON         top

       This page is part of release 5.12 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
       https://www.kernel.org/doc/man-pages/.

Linux                          2021-03-22                     READDIR(2)

Pages that refer to this page: fanotify_mark(2)getdents(2)read(2)syscalls(2)seekdir(3)fanotify(7)