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# readdir() - Unix, Linux System Call

# NAME

readdir - read directory entry

# SYNOPSIS

    #include <linux/types.h>
    #include <linux/dirent.h>

    int readdir(unsigned int fd, struct dirent *dirp,
                unsigned int count);

# 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 This page documents the bare kernel system call interface, which can change, and which is superseded by getdents(2).

readdir() reads one dirent structure from the directory pointed at by fd into the memory area pointed to by dirp. The parameter count is ignored; at most one dirent structure is read.

The dirent structure is declared as follows:

    struct dirent
    {
        long d_ino;                 /* inode number */
        off_t d_off;                /* offset to this 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 dirent. d_reclen is the size of d_name, not counting the null terminator. 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

Tag | Description
--- | ---
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).

# SEE ALSO

- getdents (2)

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