READDIR

Section: Linux Programmer's Manual (2)
Updated: 2019-03-06
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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 This page documents the bare kernel system call interface, which is superseded by getdents(2).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 (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 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

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