(split) LDP_man-pages: release ioctl.2 [JM:00378]

[linuxjm/LDP_man-pages.git] / draft / man3 / readdir.3

.\" Copyright (C) 1993 David Metcalfe (david@prism.demon.co.uk)
.\"
.\" 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.\" manual page may be incorrect or out-of-date.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.
.\"
.\" References consulted:
.\"     Linux libc source code
.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
.\"     386BSD man pages
.\" Modified Sat Jul 24 16:09:49 1993 by Rik Faith (faith@cs.unc.edu)
.\" Modified 11 June 1995 by Andries Brouwer (aeb@cwi.nl)
.\" Modified 22 July 1996 by Andries Brouwer (aeb@cwi.nl)
.\" 2007-07-30 Ulrich Drepper <drepper@redhat.com>, mtk:
.\"     Rework discussion of nonstandard structure fields.
.\" 2008-09-11, mtk, Document readdir_r().
.\"
.\" Japanese Version Copyright (c) 1997 HIROFUMI Nishizuka
.\"     all rights reserved.
.\" Translated 1997-12-24, HIROFUMI Nishizuka <nishi@rpts.cl.nec.co.jp>
.\" Updated & Modified 2002-03-24, Yuichi SATO <ysato@h4.dion.ne.jp>
.\" Updated & Modified 2005-01-16, Yuichi SATO <ysato444@yahoo.co.jp>
.\" Updated & Modified 2005-09-06, Akihiro MOTOKI <amotoki@dd.iij4u.or.jp>
.\" Updated 2008-08-11, Akihiro MOTOKI <amotoki@dd.iij4u.or.jp>, LDP v3.05
.\"
.TH READDIR 3  2010-09-10 "" "Linux Programmer's Manual"
.\"O .SH NAME
.SH ̾Á°
.\"O readdir, readdir_r \- read a directory
readdir, readdir_r \- ¥Ç¥£¥ì¥¯¥È¥ê¤òÆɤ߹þ¤à
.\"O .SH SYNOPSIS
.SH ½ñ¼°
.nf
.B #include <dirent.h>
.sp
.BI "struct dirent *readdir(DIR *" dirp );
.sp
.BI "int readdir_r(DIR *" dirp ", struct dirent *" entry \
", struct dirent **" result );
.fi
.sp
.in -4n
.\"O Feature Test Macro Requirements for glibc (see
.\"O .BR feature_test_macros (7)):
glibc ¸þ¤±¤Îµ¡Ç½¸¡ºº¥Þ¥¯¥í¤ÎÍ×·ï
.RB ( feature_test_macros (7)
»²¾È):
.ad l
.in
.sp
.BR readdir_r ():
.RS 4
_POSIX_C_SOURCE\ >=\ 1 || _XOPEN_SOURCE || _BSD_SOURCE ||
_SVID_SOURCE || _POSIX_SOURCE
.RE
.ad b
.\"O .SH DESCRIPTION
.SH ÀâÌÀ
.\"O The
.\"O .BR readdir ()
.\"O function returns a pointer to a \fIdirent\fP structure
.\"O representing the next directory entry in the directory stream pointed
.\"O to by \fIdirp\fP.
.\"O It returns NULL on reaching the end of the directory stream or if
.\"O an error occurred.
.BR readdir ()
´Ø¿ô¤Ï¡¢\fIdirp\fP ¤¬»Ø¤¹¥Ç¥£¥ì¥¯¥È¥ê¥¹¥È¥ê¡¼¥à¤ÎÃæ¤Ç¡¢
¼¡¤Î¥Ç¥£¥ì¥¯¥È¥ê¥¨¥ó¥È¥ê¤òɽ¤¹ \fIdirent\fP ¹½Â¤ÂΤؤΥݥ¤¥ó¥¿¤òÊÖ¤¹¡£
¥Ç¥£¥ì¥¯¥È¥ê¥¹¥È¥ê¡¼¥à¤ÎËöÈø¤Ë㤷¤¿¾ì¹ç¤ä¡¢
¥¨¥é¡¼¤¬È¯À¸¤·¤¿¾ì¹ç¤Ï¡¢ NULL ¤òÊÖ¤¹¡£
.PP
.\"O On Linux, the
.\"O .I dirent
.\"O structure is defined as follows:
Linux ¤Ç¤Ï
.I dirent
¹½Â¤ÂΤϰʲ¼¤Î¤è¤¦¤ËÄêµÁ¤µ¤ì¤Æ¤¤¤ë¡£
.PP
.in +4n
.nf
struct dirent {
.\"O     ino_t          d_ino;       /* inode number */
.\"O     off_t          d_off;       /* offset to the next dirent */
.\"O     unsigned short d_reclen;    /* length of this record */
.\"O     unsigned char  d_type;      /* type of file; not supported
.\"O                                    by all file system types */
.\"O     char           d_name[256]; /* filename */
    ino_t          d_ino;       /* inode ÈÖ¹æ */
    off_t          d_off;       /* ¼¡¤Î dirent ¤Ø¤Î¥ª¥Õ¥»¥Ã¥È */
    unsigned short d_reclen;    /* ¤³¤Î¥ì¥³¡¼¥É¤ÎŤµ */
    unsigned char  d_type;      /* ¥Õ¥¡¥¤¥ë¼ïÊÌ¡£Á´¥Õ¥¡¥¤¥ë¥·¥¹¥Æ¥à */
                                   ¤Ç¥µ¥Ý¡¼¥È¤µ¤ì¤Æ¤¤¤ë¤ï¤±¤Ç¤Ï¤Ê¤¤ */
    char           d_name[256]; /* ¥Õ¥¡¥¤¥ë̾ */
};
.fi
.in
.PP
.\"O The only fields in the
.\"O .I dirent
.\"O structure that are mandated by POSIX.1 are:
.\"O .IR d_name [],
.\"O of unspecified size, with at most
.\"O .B NAME_MAX
.\"O characters preceding the terminating null byte;
.\"O and (as an XSI extension)
.\"O .IR d_ino .
.I dirent
¹½Â¤ÂΤΥե£¡¼¥ë¥É¤Ç POSIX.1 ¤ÇÍ׵ᤵ¤ì¤Æ¤¤¤ë¤Î¤Ï¡¢
.IR d_name []
¤È (XSI ³ÈÄ¥¤Ç¤Î)
.I d_ino
¤À¤±¤Ç¤¢¤ë¡£
.IR d_name []
¤Ï¤½¤ÎÂ礭¤µ¤âµ¬Äꤵ¤ì¤Æ¤ª¤é¤º¡¢
¤³¤Î¥Õ¥£¡¼¥ë¥É¤Ë¤ÏºÇÂç¤Ç
.B NAME_MAX
¸Ä¤Îʸ»ú¤È¡¢¤½¤ì¤Ë³¤¯½ªÃ¼¤Î NULL ¥Ð¥¤¥È¤¬³ÊǼ¤µ¤ì¤ë¡£
.\"O The other fields are unstandardized, and not present on all systems;
.\"O see NOTES below for some further details.
¾¤Î¥Õ¥£¡¼¥ë¥É¤ÏÈóɸ½à¤Ç¤¢¤ê¡¢Á´¤Æ¤Î¥·¥¹¥Æ¥à¤Ë¸ºß¤¹¤ë¤ï¤±¤Ç¤Ï¤Ê¤¤¡£
¾ÜºÙ¤Ë¤Ä¤¤¤Æ¤Ï¡¢²¼µ­¤Î¡ÖÃí°Õ¡×¤ò»²¾È¤Î¤³¤È¡£
.PP
.\"O The data returned by
.\"O .BR readdir ()
.\"O may be overwritten by subsequent calls to
.\"O .BR readdir ()
.\"O for the same directory stream.
.BR readdir ()
¤Ë¤è¤Ã¤ÆÊÖ¤µ¤ì¤ë¥Ç¡¼¥¿¤Ï¡¢¤½¤ì°Ê¹ß¤ÎƱ¤¸¥¹¥È¥ê¡¼¥à¤ËÂФ¹¤ë
.BR readdir ()
¤Î¸Æ¤Ó½Ð¤·¤Ë¤è¤Ã¤Æ¾å½ñ¤­¤µ¤ì¤ë²ÄǽÀ­¤¬¤¢¤ë¡£

.\"O The
.\"O .BR readdir_r ()
.\"O function is a reentrant version of
.\"O .BR readdir ().
.\"O It reads the next directory entry from the directory stream
.\"O .IR dirp ,
.\"O and returns it in the caller-allocated buffer pointed to by
.\"O .IR entry .
.\"O (See NOTES for information on allocating this buffer.)
.\"O A pointer to the returned item is placed in
.\"O .IR *result ;
.\"O if the end of the directory stream was encountered,
.\"O then NULL is instead returned in
.\"O .IR *result .
.BR readdir_r ()
´Ø¿ô¤Ï
.BR readdir ()
¤Î¥ê¥¨¥ó¥È¥é¥ó¥ÈÈǤǤ¢¤ë¡£
¤³¤Î´Ø¿ô¤Ï¥Ç¥£¥ì¥¯¥È¥ê¥¹¥È¥ê¡¼¥à
.I dirp
¤«¤é¼¡¤Î¥Ç¥£¥ì¥¯¥È¥ê¥¨¥ó¥È¥ê¤òÆɤ߹þ¤ß¡¢
.I entry
¤¬»Ø¤¹¸Æ¤Ó½Ð¤·¸µ¤¬³ä¤êÅö¤Æ¤¿¥Ð¥Ã¥Õ¥¡¤Ë¤½¤Î¥¨¥ó¥È¥ê¤ò³ÊǼ¤·¤ÆÊÖ¤¹
(¤³¤Î¥Ð¥Ã¥Õ¥¡¤Î³ä¤êÅö¤Æ¤Ë¤Ä¤¤¤Æ¤Ï¡ÖÃí°Õ¡×¤ÎÀá¤ò»²¾È¤Î¤³¤È)¡£
ÊÖ¤µ¤ì¤ë¥¨¥ó¥È¥ê¤Ø¤Î¥Ý¥¤¥ó¥¿¤¬
.I *result
¤Ë³ÊǼ¤µ¤ì¤ë¡£¥Ç¥£¥ì¥¯¥È¥ê¥¹¥È¥ê¡¼¥à¤ÎËöÈø¤Ë㤷¤¿¾ì¹ç¤Ï¡¢
NULL ¤¬
.I *result
¤Ë³ÊǼ¤µ¤ì¤ë¡£
.\"O .SH "RETURN VALUE"
.SH ÊÖ¤êÃÍ
.\"O On success,
.\"O .BR readdir ()
.\"O returns a pointer to a
.\"O .I dirent
.\"O structure.
.\"O (This structure may be statically allocated; do not attempt to
.\"O .BR free (3)
.\"O it.)
.\"O If the end of the directory stream is reached, NULL is returned and
.\"O .I errno
.\"O is not changed.
À®¸ù¤¹¤ë¤È¡¢
.BR readdir ()
¤Ï
.I dirent
¹½Â¤ÂΤؤΥݥ¤¥ó¥¿¤òÊÖ¤¹¡£
(¤³¤Î¹½Â¤ÂΤÏÀÅŪ¤Ë³ä¤êÅö¤Æ¤é¤ì¤Æ¤¤¤ë¤«¤â¤·¤ì¤Ê¤¤¡£
¤³¤Î¥Ý¥¤¥ó¥¿¤ò
.BR free (3)
¤·¤è¤¦¤È¤·¤Ê¤¤¤³¤È¡£)
¥Ç¥£¥ì¥¯¥È¥ê¥¹¥È¥ê¡¼¥à¤ÎËöÈø¤Ë㤷¤¿¾ì¹ç¤Ë¤Ï¡¢NULL ¤¬ÊÖ¤µ¤ì¡¢
.I errno
¤ÏÊѲ½¤·¤Ê¤¤¡£
.\"O If an error occurs, NULL is returned and
.\"O .I errno
.\"O is set appropriately.
¥¨¥é¡¼¤¬È¯À¸¤·¤¿¾ì¹ç¡¢NULL ¤¬ÊÖ¤µ¤ì¡¢
.I errno
¤¬Å¬ÀÚ¤ËÀßÄꤵ¤ì¤ë¡£

.\"O The
.\"O .BR readdir_r ()
.\"O function returns 0 on success.
.\"O On error, it returns a positive error number (listed under ERRORS).
.\"O If the end of the directory stream is reached,
.\"O .BR readdir_r ()
.\"O returns 0, and returns NULL in
.\"O .IR *result .
À®¸ù¤¹¤ë¤È¡¢
.BR readdir_r ()
´Ø¿ô¤Ï 0 ¤òÊÖ¤¹¡£
¥¨¥é¡¼¤Î¾ì¹ç¡¢(¡Ö¥¨¥é¡¼¡×¤ÎÀá¤Î¥ê¥¹¥È¤ËºÜ¤Ã¤Æ¤¤¤ë) Àµ¤Î¥¨¥é¡¼ÈÖ¹æ¤òÊÖ¤¹¡£
¥Ç¥£¥ì¥¯¥È¥ê¥¹¥È¥ê¡¼¥à¤ÎËöÈø¤Ë㤷¤¿¾ì¹ç¡¢
.BR readdir_r ()
¤ÏÊÖ¤êÃͤȤ·¤Æ 0 ¤òÊÖ¤·¡¢
.I *result
¤Ë NULL ¤ò³ÊǼ¤¹¤ë¡£
.\"O .SH ERRORS
.SH ¥¨¥é¡¼
.TP
.B EBADF
.\"O Invalid directory stream descriptor \fIdirp\fP.
¥Ç¥£¥ì¥¯¥È¥ê¥¹¥È¥ê¡¼¥à¥Ç¥£¥¹¥¯¥ê¥×¥¿ \fIdirp\fP ¤¬Ìµ¸ú¡£
.\"O .SH "CONFORMING TO"
.SH ½àµò
SVr4, 4.3BSD, POSIX.1-2001.
.\"O .SH NOTES
.SH Ãí°Õ
.\"O Only the fields
.\"O .I d_name
.\"O and
.\"O .I d_ino
.\"O are specified in POSIX.1-2001.
.\"O The remaining fields are available on many, but not all systems.
.\"O Under glibc,
.\"O programs can check for the availability of the fields not defined
.\"O in POSIX.1 by testing whether the macros
.\"O .BR _DIRENT_HAVE_D_NAMLEN ,
.\"O .BR _DIRENT_HAVE_D_RECLEN ,
.\"O .BR _DIRENT_HAVE_D_OFF ,
.\"O or
.\"O .B _DIRENT_HAVE_D_TYPE
.\"O are defined.
¥Õ¥£¡¼¥ë¥É
.I d_name
¤È
.I d_ino
¤À¤±¤¬ POSIX.1-2001 ¤Çµ¬Äꤵ¤ì¤Æ¤¤¤ë¡£
»Ä¤ê¤Î¥Õ¥£¡¼¥ë¥É¤Ï¿¤¯¤Î¥·¥¹¥Æ¥à¤Ë¸ºß¤¹¤ë¤¬¡¢Á´¤Æ¤Î¥·¥¹¥Æ¥à¤Ë
¸ºß¤¹¤ë¤ï¤±¤Ç¤Ï¤Ê¤¤¡£
glibc ¤Ç¤Ï¡¢¥×¥í¥°¥é¥à¤¬ POSIX.1 ¤ÇÄêµÁ¤µ¤ì¤Æ¤¤¤Ê¤¤¥Õ¥£¡¼¥ë¥É¤¬
ÍøÍѤǤ­¤ë¤«¤ò¥Á¥§¥Ã¥¯¤¹¤ë¤³¤È¤¬¤Ç¤­¤ë¡£
¥Á¥§¥Ã¥¯¤¹¤ë¤Ë¤Ï¡¢¥Þ¥¯¥í
.BR _DIRENT_HAVE_D_NAMLEN ,
.BR _DIRENT_HAVE_D_RECLEN ,
.BR _DIRENT_HAVE_D_OFF ,
.B _DIRENT_HAVE_D_TYPE
¤¬ÄêµÁ¤µ¤ì¤Æ¤¤¤ë¤«¤ò¥Æ¥¹¥È¤¹¤ì¤Ð¤è¤¤¡£

.\"O Other than Linux, the
.\"O .I d_type
.\"O field is available mainly only on BSD systems.
.I d_type
¥Õ¥£¡¼¥ë¥É¤Ï¡¢Linux °Ê³°¤Ç¤Ï¡¢
¼ç¤Ë BSD ·Ï¤Î¥·¥¹¥Æ¥à¤Ë¤À¤±Â¸ºß¤¹¤ë¡£
.\"O This field makes it possible to avoid the expense of calling
.\"O .BR lstat (2)
.\"O if further actions depend on the type of the file.
¤³¤Î¥Õ¥£¡¼¥ë¥É¤ò»È¤¦¤È¡¢
¤½¤Î¸å¤ÎÆ°ºî¤¬¥Õ¥¡¥¤¥ë¤Î¼ïÊ̤ˤè¤ê·è¤Þ¤ë¾ì¹ç¤Ë¡¢
.BR lstat (2)
¤ò¸Æ¤Ó½Ð¤¹¥³¥¹¥È¤òÈò¤±¤ë¤³¤È¤¬¤Ç¤­¤ë¡£
.\"O If the
.\"O .B _BSD_SOURCE
.\"O feature test macro is defined,
.\"O then glibc defines the following macro constants
.\"O for the value returned in
.\"O .IR d_type :
µ¡Ç½¸¡ºº¥Þ¥¯¥í
.B _BSD_SOURCE
¤¬ÄêµÁ¤µ¤ì¤¿¾ì¹ç¡¢glibc ¤Ï
.I d_type
¤ÇÊÖ¤µ¤ì¤ëÃͤȤ·¤Æ°Ê²¼¤Î¥Þ¥¯¥íÄê¿ô¤òÄêµÁ¤¹¤ë¡£
.TP 12
.B DT_BLK
.\"O This is a block device.
¥Ö¥í¥Ã¥¯¡¦¥Ç¥Ð¥¤¥¹¤Ç¤¢¤ë¡£
.TP
.B DT_CHR
.\"O This is a character device.
¥­¥ã¥é¥¯¥¿¡¦¥Ç¥Ð¥¤¥¹¤Ç¤¢¤ë¡£
.TP
.B DT_DIR
.\"O This is a directory.
¥Ç¥£¥ì¥¯¥È¥ê¤Ç¤¢¤ë¡£
.TP
.B DT_FIFO
.\"O This is a named pipe (FIFO).
̾Á°ÉÕ¤­¥Ñ¥¤¥× (FIFO) ¤Ç¤¢¤ë¡£
.TP
.B DT_LNK
.\"O This is a symbolic link.
¥·¥ó¥Ü¥ê¥Ã¥¯¡¦¥ê¥ó¥¯¤Ç¤¢¤ë¡£
.TP
.B DT_REG
.\"O This is a regular file.
Ä̾ï¤Î¥Õ¥¡¥¤¥ë¤Ç¤¢¤ë¡£
.TP
.B DT_SOCK
.\"O This is a UNIX domain socket.
UNIX ¥É¥á¥¤¥ó¥½¥±¥Ã¥È¤Ç¤¢¤ë¡£
.TP
.B DT_UNKNOWN
.\"O The file type is unknown.
¥Õ¥¡¥¤¥ë¥¿¥¤¥×¤¬ÉÔÌÀ¤Ç¤¢¤ë¡£
.\" The glibc manual says that on some systems this is the only
.\" value returned
.PP
.\"O If the file type could not be determined, the value
.\"O .B DT_UNKNOWN
.\"O is returned in
.\"O .IR d_type .
¥Õ¥¡¥¤¥ë¼ïÊ̤ò·èÄê¤Ç¤­¤Ê¤«¤Ã¤¿¾ì¹ç¤Ë¤Ï¡¢
.I d_type
¤Ë
.B DT_UNKNOWN
¤¬Æþ¤ë¡£

.\"O Currently,
.\"O .\" kernel 2.6.27
.\"O .\" The same sentence is in readdir.2
.\"O only some file systems (among them: Btrfs, ext2, etx3, and ext4)
.\"O have full support returning the file type in
.\"O .IR d_type .
.\"O All applications must properly handle a return of
.\"O .BR DT_UNKNOWN .
¸½ºß¤Î¤È¤³¤í¡¢
.\" ¥«¡¼¥Í¥ë 2.6.27
.\" Ʊ¤¸ÀâÌÀʸ¤¬ readdir.2 ¤Ë¤â¤¢¤ë¡£
.I d_type
¤Ç¥Õ¥¡¥¤¥ë¥¿¥¤¥×¤òÊÖ¤¹µ¡Ç½¤¬´°Á´¤Ë¥µ¥Ý¡¼¥È¤µ¤ì¤Æ¤¤¤ë¤Î¤Ï¡¢
¤¤¤¯¤Ä¤«¤Î¥Õ¥¡¥¤¥ë¥·¥¹¥Æ¥à¤Ë¤ª¤¤¤Æ¤Î¤ß¤Ç¤¢¤ë
(Btrfs, ext2, ext3, ext4 ¤Ï¥µ¥Ý¡¼¥È¤·¤Æ¤¤¤ë)¡£
¤É¤Î¥¢¥×¥ê¥±¡¼¥·¥ç¥ó¤â¡¢
.B DT_UNKNOWN
¤¬ÊÖ¤µ¤ì¤¿ºÝ¤ËŬÀڤ˽èÍý¤Ç¤­¤Ê¤±¤ì¤Ð¤Ê¤é¤Ê¤¤¡£

.\"O Since POSIX.1 does not specify the size of the
.\"O .I d_name
.\"O field, and other nonstandard fields may precede that field within the
.\"O .I dirent
.\"O structure, portable applications that use
.\"O .BR readdir_r ()
.\"O should allocate the buffer whose address is passed in
.\"O .IR entry
.\"O as follows:
POSIX.1 ¤Ç¤Ï
.I d_name
¥Õ¥£¡¼¥ë¥É¤Î¥µ¥¤¥º¤Ïµ¬Äꤵ¤ì¤Æ¤ª¤é¤º¡¢
.I dirent
¹½Â¤ÂΤÎ
.I d_name
¤Î¸å¤í¤Ë¾¤ÎÈóɸ½à¤Î¥Õ¥£¡¼¥ë¥É¤¬¤¢¤ë¤«¤â¤·¤ì¤Ê¤¤¤Î¤Ç¡¢
°Ü¿¢À­¤¬É¬Íפʥ¢¥×¥ê¥±¡¼¥·¥ç¥ó¤Ç
.BR readdir_r ()
¤ò»È¤¦¾ì¹ç¤Ï
.I entry
¤ËÅϤ¹¥Ð¥Ã¥Õ¥¡¤ò¼¡¤Î¤è¤¦¤Ë¤·¤Æ³ä¤êÅö¤Æ¤ë¤Ù¤­¤Ç¤¢¤ë¡£
.in +4n
.nf

len = offsetof(struct dirent, d_name) +
          pathconf(dirpath, _PC_NAME_MAX) + 1
entryp = malloc(len);

.fi
.in
.\"O (POSIX.1 requires that
.\"O .I d_name
.\"O is the last field in a
.\"O .IR "struct dirent" .)
(POSIX.1 ¤Ç¤Ï
.I "struct dirent"
¤ÎºÇ¸å¤Î¥Õ¥£¡¼¥ë¥É¤¬
.I d_name
¤Ç¤¢¤ë¤³¤È¤òÍ׵ᤷ¤Æ¤¤¤ë¡£)
.\"O .SH "SEE ALSO"
.SH ´ØÏ¢¹àÌÜ
.BR getdents (2),
.BR read (2),
.BR closedir (3),
.BR dirfd (3),
.BR ftw (3),
.BR offsetof (3),
.BR opendir (3),
.BR rewinddir (3),
.BR scandir (3),
.BR seekdir (3),
.BR telldir (3)