man-pages/man2/readdir.2

.\" Copyright (C) 1995 Andries Brouwer (aeb@cwi.nl)
.\"
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.\" Written 11 June 1995 by Andries Brouwer <aeb@cwi.nl>
.\" Modified 22 July 1995 by Michael Chastain <mec@duracef.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
.\"
.TH READDIR 2  1995-07-22 "Linux 1.3.6" "Linux Programmer's Manual"
.SH NAME
readdir \- read directory entry
.SH SYNOPSIS
.nf
.B #include <linux/types.h>
.B #include <linux/dirent.h>
.B #include <linux/unistd.h>
.B #include <errno.h>
.sp
.B _syscall3(int, readdir, unsigned int, fd, struct dirent *, dirp,
.B "          unsigned int, count)"
          /* Using \fBsyscall\fP(2) may be preferable; see \fBintro\fP(2) */
.sp
.BI "int readdir(unsigned int " fd ", struct dirent *" dirp ","
.BI "            unsigned int " count );
.fi
.SH DESCRIPTION
This is not the function you are interested in.
Look at
.BR 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which can change, and which is superseded by
.BR getdents (2).
.PP
.BR readdir ()
reads one
.I dirent
structure from the directory
pointed at by
.I fd
into the memory area pointed to by
.IR dirp .
The parameter 
.I count
is ignored; at most one dirent structure is read.
.PP
The
.I dirent
structure is declared as follows:
.PP
.RS
.nf
struct dirent
{
    long d_ino;                 /* inode number */
    off_t d_off;                /* offset to this \fIdirent\fP */
    unsigned short d_reclen;    /* length of this \fId_name\fP */
    char d_name [NAME_MAX+1];   /* filename (null-terminated) */
}
.fi
.RE
.PP
.I d_ino
is an inode number.
.I d_off
is the distance from the start of the directory to this
.IR dirent .
.I d_reclen
is the size of
.IR d_name ,
not counting the null terminator.
.I d_name
is a null-terminated filename.
.SH "RETURN VALUE"
On success, 1 is returned.
On end of directory, 0 is returned.
On error, \-1 is returned, and
.I errno
is set appropriately.
.SH ERRORS
.TP
.B EBADF
Invalid file descriptor
.IR fd .
.TP
.B EFAULT
Argument points outside the calling process's address space.
.TP
.B EINVAL
Result buffer is too small.
.TP
.B ENOENT
No such directory.
.TP
.B ENOTDIR
File descriptor does not refer to a directory.
.SH "CONFORMING TO"
This system call is Linux specific.
.SH "SEE ALSO"
.BR getdents (2),
.BR readdir (3)