1.\" $NetBSD: getdents.2,v 1.11 2002/08/12 21:52:37 wiz 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 LIBRARY 43.Lb libc 44.Sh SYNOPSIS 45.Fd #include \*[Lt]dirent.h\*[Gt] 46.Ft int 47.Fn getdents "int fd" "char *buf" "size_t nbytes" 48.Sh DESCRIPTION 49.Fn getdents 50reads directory entries from the directory 51referenced by the file descriptor 52.Fa fd 53into the buffer pointed to by 54.Fa buf , 55in a filesystem independent format. 56Up to 57.Fa nbytes 58of data will be transferred. 59.Fa nbytes 60must be greater than or equal to the 61block size associated with the file, 62see 63.Xr stat 2 . 64Some filesystems may not support 65.Fn getdents 66with buffers smaller than this size. 67.Pp 68The data in the buffer is a series of 69.Em dirent 70structures each containing the following entries: 71.Bd -literal -offset indent 72u_int32_t d_fileno; 73u_int16_t d_reclen; 74u_int8_t d_type; 75u_int8_t d_namlen; 76char d_name[MAXNAMLEN + 1]; /* see below */ 77.Ed 78.Pp 79The 80.Fa d_fileno 81entry is a number which is unique for each 82distinct file in the filesystem. 83Files that are linked by hard links (see 84.Xr link 2 ) 85have the same 86.Fa d_fileno . 87If 88.Fa d_fileno 89is zero, the entry refers to a deleted file. 90.Pp 91The 92.Fa d_reclen 93entry is the length, in bytes, of the directory record. 94.Pp 95The 96.Fa d_type 97is the type of file, where the following are possible types: 98.Dv DT_UNKNOWN , 99.Dv DT_FIFO , 100.Dv DT_CHR , 101.Dv DT_DIR , 102.Dv DT_BLK , 103.Dv DT_REG , 104.Dv DT_LNK , 105.Dv DT_SOCK , 106and 107.Dv DT_WHT . 108.Pp 109The 110.Fa d_namlen 111entry specifies the length of the file name excluding the null byte. 112Thus the actual size of 113.Fa d_name 114may vary from 1 to 115.Dv MAXNAMLEN 116\&+ 1. 117.Pp 118The 119.Fa d_name 120entry contains a null terminated file name. 121.Pp 122Entries may be separated by extra space. 123The 124.Fa d_reclen 125entry may be used as an offset from the start of a 126.Fa dirent 127structure to the next structure, if any. 128.Pp 129The actual number of bytes transferred is returned. 130The current position pointer associated with 131.Fa fd 132is set to point to the next block of entries. 133The pointer may not advance by the number of bytes returned by 134.Fn getdents . 135A value of zero is returned when 136the end of the directory has been reached. 137.Pp 138The current position pointer may be set and retrieved by 139.Xr lseek 2 . 140The current position pointer should only be set to a value returned by 141.Xr lseek 2 , 142or zero. 143.Sh RETURN VALUES 144If successful, the number of bytes actually transferred is returned. 145Otherwise, -1 is returned and the global variable 146.Va errno 147is set to indicate the error. 148.Sh ERRORS 149.Fn getdents 150will fail if: 151.Bl -tag -width Er 152.It Bq Er EBADF 153.Fa fd 154is not a valid file descriptor open for reading. 155.It Bq Er EFAULT 156Either 157.Fa buf 158points outside the allocated address space. 159.It Bq Er EIO 160An 161.Tn I/O 162error occurred while reading from or writing to the file system. 163.It Bq Er EINVAL 164A directory was being read on NFS, but it was modified on the server while 165it was being read. 166.El 167.Sh SEE ALSO 168.Xr lseek 2 , 169.Xr open 2 , 170.Xr dirent 5 171.Sh HISTORY 172The 173.Fn getdents 174function first appeared in 175.Nx 1.3 . 176