readdir(2) - Linux manual page (original) (raw)

readdir(2) System Calls Manual readdir(2)

NAME top

   readdir - read directory entry

LIBRARY top

   Standard C library (_libc_, _-lc_)

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
   VERSIONS.

DESCRIPTION top

   This is not the function you are interested in.  Look at
   [readdir(3)](../man3/readdir.3.html) for the POSIX conforming C library interface.  This
   page documents the bare kernel system call interface, which is
   superseded by [getdents(2)](../man2/getdents.2.html).

   **readdir**() reads one _oldlinuxdirent_ 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
   _oldlinuxdirent_ structure is read.

   The _oldlinuxdirent_ 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 _oldlinuxdirent_ */
           unsigned short d_namlen; /* length of this _dname_ */
           char  d_name[1];         /* filename (null-terminated) */
       }

   _dino_ is an inode number.  _doffset_ is the distance from the start
   of the directory to this _oldlinuxdirent_.  _dreclen_ is the size
   of _dname_, not counting the terminating null byte ('\0').  _dname_
   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](../man3/errno.3.html)_ 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.

VERSIONS top

   You will need to define the _oldlinuxdirent_ structure yourself.
   However, probably you should use [readdir(3)](../man3/readdir.3.html) instead.

   This system call does not exist on x86-64.

STANDARDS top

   Linux.

SEE ALSO top

   [getdents(2)](../man2/getdents.2.html), [readdir(3)](../man3/readdir.3.html)

COLOPHON top

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Linux man-pages 6.10 2024-07-23 readdir(2)

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