1.\" $NetBSD: getdents.2,v 1.22 2010/06/04 05:42:24 jruoho Exp $ 2.\" 3.\" Copyright (c) 1989, 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. Neither the name of the University nor the names of its contributors 15.\" may be used to endorse or promote products derived from this software 16.\" without specific prior written permission. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28.\" SUCH DAMAGE. 29.\" 30.\" @(#)getdirentries.2 8.1 (Berkeley) 6/9/93 31.\" 32.Dd June 4, 2010 33.Dt GETDENTS 2 34.Os 35.Sh NAME 36.Nm getdents 37.Nd "get directory entries in a filesystem independent format" 38.Sh LIBRARY 39.Lb libc 40.Sh SYNOPSIS 41.In dirent.h 42.Ft int 43.Fn getdents "int fd" "char *buf" "size_t nbytes" 44.Sh DESCRIPTION 45.Fn getdents 46reads directory entries from the directory 47referenced by the file descriptor 48.Fa fd 49into the buffer pointed to by 50.Fa buf , 51in a filesystem independent format. 52Up to 53.Fa nbytes 54of data will be transferred. 55.Fa nbytes 56must be greater than or equal to the 57block size associated with the file, 58see 59.Xr stat 2 . 60Some filesystems may not support 61.Fn getdents 62with buffers smaller than this size. 63.Pp 64The data in the buffer is a series of 65.Em dirent 66structures: 67.Bd -literal -offset indent 68struct dirent { 69 ino_t d_fileno; /* file number of entry */ 70 uint16_t d_reclen; /* length of this record */ 71 uint16_t d_namlen; /* length of d_name */ 72 uint8_t d_type; /* file type, see below */ 73 char d_name[MAXNAMELEN + 1]; 74}; 75.Ed 76.Pp 77The structure is described in 78.Xr dirent 3 . 79.Pp 80Entries may be separated by extra space. 81The 82.Fa d_reclen 83entry may be used as an offset from the start of a 84.Fa dirent 85structure to the next structure, if any. 86.Pp 87The actual number of bytes transferred is returned. 88The current position pointer associated with 89.Fa fd 90is set to point to the next block of entries. 91The pointer may not advance by the number of bytes returned by 92.Fn getdents . 93A value of zero is returned when 94the end of the directory has been reached. 95.Pp 96The current position pointer may be set and retrieved by 97.Xr lseek 2 . 98The current position pointer should only be set to a value returned by 99.Xr lseek 2 , 100or zero. 101.Sh RETURN VALUES 102If successful, the number of bytes actually transferred is returned. 103Otherwise, \-1 is returned and the global variable 104.Va errno 105is set to indicate the error. 106.Sh ERRORS 107.Fn getdents 108will fail if: 109.Bl -tag -width "[EINVAL]" 110.It Bq Er EBADF 111.Fa fd 112is not a valid file descriptor open for reading. 113.It Bq Er EFAULT 114Either 115.Fa buf 116points outside the allocated address space. 117.It Bq Er EINVAL 118A directory was being read on NFS, but it was modified on the server while 119it was being read. 120.It Bq Er EIO 121An 122.Tn I/O 123error occurred while reading from or writing to the file system. 124.El 125.Sh SEE ALSO 126.Xr lseek 2 , 127.Xr open 2 , 128.Xr dirent 3 129.Sh HISTORY 130The 131.Fn getdents 132function first appeared in 133.Nx 1.3 . 134