1.\" $NetBSD: getdents.2,v 1.1 1997/10/10 02:15:50 fvdl 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. All advertising materials mentioning features or use of this software 15.\" must display the following acknowledgement: 16.\" This product includes software developed by the University of 17.\" California, Berkeley and its contributors. 18.\" 4. Neither the name of the University nor the names of its contributors 19.\" may be used to endorse or promote products derived from this software 20.\" without specific prior written permission. 21.\" 22.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32.\" SUCH DAMAGE. 33.\" 34.\" @(#)getdirentries.2 8.1 (Berkeley) 6/9/93 35.\" 36.Dd June 9, 1993 37.Dt GETDENTS 2 38.Os 39.Sh NAME 40.Nm getdents 41.Nd "get directory entries in a filesystem independent format" 42.Sh SYNOPSIS 43.Fd #include <dirent.h> 44.Ft int 45.Fn getdents "int fd" "char *buf" "size_t nbytes" 46.Sh DESCRIPTION 47.Fn Getdents 48reads directory entries from the directory 49referenced by the file descriptor 50.Fa fd 51into the buffer pointed to by 52.Fa buf , 53in a filesystem independent format. 54Up to 55.Fa nbytes 56of data will be transferred. 57.Fa Nbytes 58must be greater than or equal to the 59block size associated with the file, 60see 61.Xr stat 2 . 62Some filesystems may not support 63.Fn getdents 64with buffers smaller than this size. 65.Pp 66The data in the buffer is a series of 67.Em dirent 68structures each containing the following entries: 69.Bd -literal -offset indent 70unsigned long d_fileno; 71unsigned short d_reclen; 72unsigned short d_namlen; 73char d_name[MAXNAMELEN + 1]; /* see below */ 74.Ed 75.Pp 76The 77.Fa d_fileno 78entry is a number which is unique for each 79distinct file in the filesystem. 80Files that are linked by hard links (see 81.Xr link 2 ) 82have the same 83.Fa d_fileno . 84The 85.Fa d_reclen 86entry is the length, in bytes, of the directory record. 87The 88.Fa d_name 89entry contains a null terminated file name. 90The 91.Fa d_namlen 92entry specifies the length of the file name excluding the null byte. 93Thus the actual size of 94.Fa d_name 95may vary from 1 to 96.Dv MAXNAMELEN 97\&+ 1. 98.Pp 99Entries may be separated by extra space. 100The 101.Fa d_reclen 102entry may be used as an offset from the start of a 103.Fa dirent 104structure to the next structure, if any. 105.Pp 106The actual number of bytes transferred is returned. 107The current position pointer associated with 108.Fa fd 109is set to point to the next block of entries. 110The pointer may not advance by the number of bytes returned by 111.Fn getdents . 112A value of zero is returned when 113the end of the directory has been reached. 114.Pp 115The current position pointer may be set and retrieved by 116.Xr lseek 2 . 117The current position pointer should only be set to a value returned by 118.Xr lseek 2 , 119or zero. 120.Sh RETURN VALUES 121If successful, the number of bytes actually transferred is returned. 122Otherwise, -1 is returned and the global variable 123.Va errno 124is set to indicate the error. 125.Sh ERRORS 126.Fn Getdirentries 127will fail if: 128.Bl -tag -width Er 129.It Bq Er EBADF 130.Fa fd 131is not a valid file descriptor open for reading. 132.It Bq Er EFAULT 133Either 134.Fa buf 135points outside the allocated address space. 136.It Bq Er EIO 137An 138.Tn I/O 139error occurred while reading from or writing to the file system. 140.It Bq Er EINVAL 141A directory was being read on NFS, but it was modified on the server while 142it was being read. 143.El 144.Sh SEE ALSO 145.Xr open 2 , 146.Xr lseek 2 147.Sh HISTORY 148The 149.Fn getdents 150function first appeared in NetBSD 1.3 151