readdir(2) — Linux manual pages

Linux manual pages	Section 2

Name

readdir — read directory entry

Synopsis

`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.

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 This page documents the bare kernel system call interface, which is superseded by getdents(2).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 as follows:

struct old_linux_dirent {

long d_ino;
/* inode number */

off_t d_off;
/* offset to this old_linux_dirent */

unsigned short d_reclen;
/* length of this d_name */

char d_name[NAME_MAX+1];
/* filename (null-terminated) */

};

d_ino is an inode number. d_off 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 appropriately.

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

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.

COLOPHON

This page is part of release 4.07 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/.

  Copyright (C) 1995 Andries Brouwer (aebcwi.nl)

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Written 11 June 1995 by Andries Brouwer <aebcwi.nl>
Modified 22 July 1995 by Michael Chastain <mecduracef.shout.net>:
  In 1.3.X, returns only one entry each time; return value is different.
Modified 2004-12-01, mtk, fixed headers listed in SYNOPSIS

struct	old_linux_dirent {
	long	`d_ino`;	/* inode number */
	off_t	`d_off`;	/* offset to this old_linux_dirent */
	unsigned short	`d_reclen`;	/* length of this d_name */
	char	`d_name`[NAME_MAX+1];	/* filename (null-terminated) */
};