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Document the getdents(2) system call. The documentation was
added to the getdirentries(2) man page because 95%+ of that man page comprised the text of the getdents(2) man page I obtained from NetBSD.
This commit is contained in:
Mike Pritchard
parent
217c350824
commit
afb7dc43a9
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=49256
@ -1,5 +1,5 @@
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# @(#)Makefile.inc 8.3 (Berkeley) 10/24/94
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# $Id: Makefile.inc,v 1.63 1999/07/30 09:01:45 mpp Exp $
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# $Id: Makefile.inc,v 1.64 1999/07/30 10:08:21 mpp Exp $
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# sys sources
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.PATH: ${.CURDIR}/../libc/${MACHINE_ARCH}/sys ${.CURDIR}/../libc/sys
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@ -109,6 +109,7 @@ MLINKS+=chflags.2 fchflags.2
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MLINKS+=chmod.2 fchmod.2 chmod.2 lchmod.2
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MLINKS+=chown.2 fchown.2 chown.2 lchown.2
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MLINKS+=clock_gettime.2 clock_getres.2 clock_gettime.2 clock_settime.2
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MLINKS+=getdirentries.2 getdents.2
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MLINKS+=getgid.2 getegid.2
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MLINKS+=getitimer.2 setitimer.2
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MLINKS+=getlogin.2 setlogin.2
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@ -1,151 +0,0 @@
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.\" $NetBSD: getdents.2,v 1.4 1999/04/17 10:15:34 kleink Exp $
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.\"
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.\" Copyright (c) 1989, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)getdirentries.2 8.1 (Berkeley) 6/9/93
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.\"
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.Dd June 9, 1993
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.Dt GETDENTS 2
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.Os
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.Sh NAME
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.Nm getdents
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.Nd "get directory entries in a filesystem independent format"
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.Sh SYNOPSIS
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.Fd #include <dirent.h>
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.Ft int
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.Fn getdents "int fd" "char *buf" "size_t nbytes"
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.Sh DESCRIPTION
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.Fn getdents
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reads directory entries from the directory
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referenced by the file descriptor
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.Fa fd
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into the buffer pointed to by
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.Fa buf ,
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in a filesystem independent format.
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Up to
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.Fa nbytes
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of data will be transferred.
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.Fa nbytes
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must be greater than or equal to the
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block size associated with the file,
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see
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.Xr stat 2 .
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Some filesystems may not support
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.Fn getdents
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with buffers smaller than this size.
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.Pp
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The data in the buffer is a series of
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.Em dirent
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structures each containing the following entries:
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.Bd -literal -offset indent
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unsigned long d_fileno;
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unsigned short d_reclen;
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unsigned short d_namlen;
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char d_name[MAXNAMELEN + 1]; /* see below */
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.Ed
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.Pp
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The
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.Fa d_fileno
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entry is a number which is unique for each
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distinct file in the filesystem.
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Files that are linked by hard links (see
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.Xr link 2 )
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have the same
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.Fa d_fileno .
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The
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.Fa d_reclen
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entry is the length, in bytes, of the directory record.
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The
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.Fa d_name
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entry contains a null terminated file name.
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The
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.Fa d_namlen
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entry specifies the length of the file name excluding the null byte.
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Thus the actual size of
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.Fa d_name
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may vary from 1 to
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.Dv MAXNAMELEN
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\&+ 1.
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.Pp
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Entries may be separated by extra space.
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The
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.Fa d_reclen
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entry may be used as an offset from the start of a
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.Fa dirent
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structure to the next structure, if any.
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.Pp
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The actual number of bytes transferred is returned.
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The current position pointer associated with
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.Fa fd
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is set to point to the next block of entries.
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The pointer may not advance by the number of bytes returned by
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.Fn getdents .
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A value of zero is returned when
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the end of the directory has been reached.
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.Pp
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The current position pointer may be set and retrieved by
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.Xr lseek 2 .
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The current position pointer should only be set to a value returned by
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.Xr lseek 2 ,
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or zero.
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.Sh RETURN VALUES
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If successful, the number of bytes actually transferred is returned.
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Otherwise, -1 is returned and the global variable
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.Va errno
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is set to indicate the error.
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.Sh ERRORS
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.Fn gtdents
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will fail if:
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.Bl -tag -width Er
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.It Bq Er EBADF
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.Fa fd
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is not a valid file descriptor open for reading.
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.It Bq Er EFAULT
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Either
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.Fa buf
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points outside the allocated address space.
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.It Bq Er EIO
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An
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.Tn I/O
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error occurred while reading from or writing to the file system.
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.It Bq Er EINVAL
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A directory was being read on NFS, but it was modified on the server while
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it was being read.
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.El
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.Sh SEE ALSO
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.Xr open 2 ,
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.Xr lseek 2
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.Sh HISTORY
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The
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.Fn getdents
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function first appeared in
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.Nx 1.3 .
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@ -30,22 +30,28 @@
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)getdirentries.2 8.2 (Berkeley) 5/3/95
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.\" $Id$
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.\" $Id: getdirentries.2,v 1.10 1999/07/12 20:48:23 nik Exp $
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.\"
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.Dd May 3, 1995
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.Dt GETDIRENTRIES 2
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.Os
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.Sh NAME
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.Nm getdirentries
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.Nm getdirentries ,
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.Nm getdents
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.Nd "get directory entries in a filesystem independent format"
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.Sh SYNOPSIS
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.Fd #include <sys/types.h>
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.Fd #include <dirent.h>
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.Ft int
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.Fn getdirentries "int fd" "char *buf" "int nbytes" "long *basep"
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.Ft int
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.Fn getdents "int fd" "char *buf" "int nbytes"
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.Sh DESCRIPTION
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.Fn Getdirentries
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reads directory entries from the directory
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The
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.Fn getdirentries
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and
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.Fn getdents
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functions read directory entries from the directory
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referenced by the file descriptor
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.Fa fd
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into the buffer pointed to by
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@ -54,13 +60,13 @@ in a filesystem independent format.
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Up to
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.Fa nbytes
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of data will be transferred.
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.Fa Nbytes
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must be greater than or equal to the
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The
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.Fa nbytes
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argument must be greater than or equal to the
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block size associated with the file,
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see
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.Xr stat 2 .
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Some filesystems may not support
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.Fn getdirentries
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Some filesystems may not support these functions
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with buffers smaller than this size.
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.Pp
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The data in the buffer is a series of
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@ -114,19 +120,23 @@ The current position pointer associated with
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.Fa fd
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is set to point to the next block of entries.
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The pointer may not advance by the number of bytes returned by
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.Fn getdirentries .
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.Fn getdirentries
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or
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.Fn getdents .
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A value of zero is returned when
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the end of the directory has been reached.
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.Pp
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.Fn Getdirentries
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writes the position of the block read into the location pointed to by
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The
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.Fn getdirentries
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function writes the position of the block read into the location pointed to by
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.Fa basep .
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Alternatively, the current position pointer may be set and retrieved by
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.Xr lseek 2 .
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The current position pointer should only be set to a value returned by
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.Xr lseek 2 ,
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a value returned in the location pointed to by
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.Fa basep ,
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.Fa basep ( Ns Fn getdirentries
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only)
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or zero.
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.Sh IMPLEMENTATION NOTES
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.Pp
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@ -158,7 +168,7 @@ is set to indicate the error.
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.Sh ERRORS
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.Fn Getdirentries
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will fail if:
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.Bl -tag -width [EFAULT]
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.Bl -tag -width Er
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.It Bq Er EBADF
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.Fa fd
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is not a valid file descriptor open for reading.
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@ -188,3 +198,7 @@ The
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.Fn getdirentries
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function first appeared in
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.Bx 4.4 .
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The
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.Fn getdents
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function first appeared in
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.Fx 3.0 .
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