.\" Copyright (C) 1995 Andries Brouwer (aeb@cwi.nl)
.\"
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date.  The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein.  The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\"
.\" Written 11 June 1995 by Andries Brouwer <aeb@cwi.nl>
.\" Modified 22 July 1995 by Michael Chastain <mec@duracef.shout.net>:
.\"   Derived from 'readdir.2'.
.\" Modified Tue Oct 22 08:11:14 EDT 1996 by Eric S. Raymond <esr@thyrsus.com>
.\"
.\" Japanese Version Copyright (c) 1997 HANATAKA Shinya
.\"         all rights reserved.
.\" Translated Sat Feb 22 20:15:56 JST 1997
.\"         by HANATAKA Shinya <hanataka@abyss.rim.or.jp>
.\" Updated Sun Oct 12 JST 2003 by Kentaro Shirakata <argrath@ub32.org>
.\" Updated Wed Jul 30 JST 2008 by Kentaro Shirakata <argrath@ub32.org>
.\" Updated 2009-02-12 by Kentaro Shirakata <argrath@ub32.org>
.\"
.\"WORD:	directory		ǥ쥯ȥ
.\"WORD:	entry			ȥ
.\"WORD:	memory area		ΰ
.\"WORD:	parameter		ѥ᡼
.\"WORD:	inode number		inode ֹ
.\"WORD:	null			̥ʸ
.\"
.TH GETDENTS 2  2009-01-23 "Linux" "Linux Programmer's Manual"
.SH ̾
getdents \- ǥ쥯ȥꡦȥ
.SH 
.nf
.BI "int getdents(unsigned int " fd ", struct linux_dirent *" dirp ,
.BI "             unsigned int " count );
.fi
.SH 
Ϥʤδؿ褦ʴؿǤϤʤ
POSIX  C 饤֥ꥤ󥿡եˤĤƤ
.BR readdir (3)
򸫤뤳ȡ
Υڡϡͥ륷ƥॳΥ󥿡եˤĤ
ܤΤǤ롣
.PP
.BR getdents ()
ƥॳϡץѤߤΥե뵭һ
.I fd
ǻȤǥ쥯ȥ꤫
.I linux_dirent
¤Τ򤤤Ĥɤ߽Ф
.I dirp
ؤƤХåե˳Ǽ롣
.I count
ϤΥХåեΥ򼨤
.PP
.I linux_dirent
¤ΤϰʲΤ褦Ƥ:
.PP
.in +4n
.nf
struct linux_dirent {
    unsigned long  d_ino;     /* Inode number */
    unsigned long  d_off;     /* Offset to next \fIlinux_dirent\fP */
    unsigned short d_reclen;  /* Length of this \fIlinux_dirent\fP */
    char           d_name[];  /* Filename (null-terminated) */
                        /* length is actually (d_reclen \- 2 \-
                           offsetof(struct linux_dirent, d_name) */
    /*
    char           pad;       // Zero padding byte */
    char           d_type;    // File type (only since Linux 2.6.4;
                              // offset is (d_reclen \- 1))
    */

}
.fi
.in
.PP
.I d_ino
 inode ֹǤ롣
.I d_off
ϥǥ쥯ȥƬ鼡
.I linux_dirent
ƬޤǤεΥǤ롣
.I d_reclen
Ϥ
.I linux_dirent
ΤΥǤ롣
.I d_name
ϥ̥(null)ʸǽե̾Ǥ롣

.I d_type
ϡ¤ΤκǸΥХȤǤꡢե륿פ򼨤
.I d_type
ϰʲͤΰĤ
.RI ( <dirent.h>
Ƥ)
.TP 12
.B DT_BLK
֥åǥХǤ롣
.TP
.B DT_CHR
饯ǥХǤ롣
.TP
.B DT_DIR
ǥ쥯ȥǤ롣
.TP
.B DT_FIFO
̾Ĥѥ (FIFO) Ǥ롣
.TP
.B DT_LNK
ܥå󥯤Ǥ롣
.TP
.B DT_REG
̾ΥեǤ롣
.TP
.B DT_SOCK
Unix ɥᥤ󥽥åȤǤ롣
.TP
.B DT_UNKNOWN
ե륿פǤ롣
.PP
.I d_type
եɤ Linux 2.6.4 Ƥ롣

.I linux_dirent
¤ΤΤϥƤ֤֤Ƥ롣
äơ2.6.3 ΥͥǤϡΥեɤ˥褦Ȥ
 0
.RB ( DT_UNKNOWN )
֤롣
.PP
ߤΤȤ
.\" ͥ 2.6.27
.\" Ʊʸ readdir.2 ˤ⤢롣
.I d_type
ǥե륿פ֤ǽ˥ݡȤƤΤϡ
ĤΥե륷ƥˤƤΤߤǤ
(ext2, ext3, ext4 ϥݡȤƤ)
ɤΥץꥱ⡢
.B DT_UNKNOWN
֤줿ݤŬڤ˽ǤʤФʤʤ
.SH ֤
ϡɤ߹Хȿ֤롣
ǥ쥯ȥνʤ 0 ֤롣
顼ξ \-1 ֤졢
.I errno
Ŭڤͤꤵ롣
.SH 顼
.TP
.B EBADF
ե뵭һ
.I fd
̵Ǥ롣
.TP
.B EFAULT
ƤӽФץΥɥ쥹ֳؤƤ롣
.TP
.B EINVAL
ѤΥХåե롣
.TP
.B ENOENT
Τ褦ʥǥ쥯ȥ¸ߤʤ
.TP
.B ENOTDIR
ե뵭һҤǥ쥯ȥ򻲾ȤƤʤ
.SH 
SVr4.
.\" SVr4 Ǥϡ¾ ENOLINK, EIO 顼֤ˤĤƤ⵭ҤƤ롣
.SH 
glibc ϤΥƥॳФåѡؿ󶡤ƤʤΤǡ
.BR syscall (2)
ȤäƸƤӽФȡ
.I linux_dirent
¤Τϼʬɬפ롣

Υƥॳ
.BR readdir (2)
֤ΤǤ롣
.SH 
Υץ
.BR getdents ()
λ򼨤ΤǤ롣
ʲϡΥץ ext2 ǥ쥯ȥǼ¹Ԥݤ
ϤǤ롣

.in +4n
.nf
.RB "$" " ./a.out /testfs/"
--------------- nread=120 ---------------
i-node#  file type  d_reclen  d_off   d_name
       2  directory    16         12  .
       2  directory    16         24  ..
      11  directory    24         44  lost+found
      12  regular      16         56  a
  228929  directory    16         68  sub
   16353  directory    16         80  sub2
  130817  directory    16       4096  sub3
.fi
.in
.SS ץΥ
\&
.nf
#define _GNU_SOURCE
#include <dirent.h>     /* Defines DT_* constants */
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/syscall.h>

#define handle_error(msg) \\
        do { perror(msg); exit(EXIT_FAILURE); } while (0)

struct linux_dirent {
    long           d_ino;
    off_t          d_off;
    unsigned short d_reclen;
    char           d_name[];
};

#define BUF_SIZE 1024

int
main(int argc, char *argv[])
{
    int fd, nread;
    char buf[BUF_SIZE];
    struct linux_dirent *d;
    int bpos;
    char d_type;

    fd = open(argc > 1 ? argv[1] : ".", O_RDONLY | O_DIRECTORY);
    if (fd == \-1)
        handle_error("open");

    for ( ; ; ) {
        nread = syscall(SYS_getdents, fd, buf, BUF_SIZE);
        if (nread == \-1)
            handle_error("getdents");

        if (nread == 0)
            break;

        printf("\--------------- nread=%d ---------------\\n", nread);
        printf("i\-node#  file type  d_reclen  d_off   d_name\\n");
        for (bpos = 0; bpos < nread;) {
            d = (struct linux_dirent *) (buf + bpos);
            printf("%8ld  ", d\->d_ino);
            d_type = *(buf + bpos + d\->d_reclen - 1);
            printf("%\-10s ", (d_type == DT_REG) ?  "regular" :
                             (d_type == DT_DIR) ?  "directory" :
                             (d_type == DT_FIFO) ? "FIFO" :
                             (d_type == DT_SOCK) ? "socket" :
                             (d_type == DT_LNK) ?  "symlink" :
                             (d_type == DT_BLK) ?  "block dev" :
                             (d_type == DT_CHR) ?  "char dev" : "???");
            printf("%4d %10lld  %s\\n", d\->d_reclen,
                    (long long) d\->d_off, (char *) d->d_name);
            bpos += d\->d_reclen;
        }
    }

    exit(EXIT_SUCCESS);
}
.fi
.SH Ϣ
.BR readdir (2),
.BR readdir (3)