1.\" -*- nroff -*- 2.\" 3.\" Copyright (c) 1996 Doug Rabson 4.\" 5.\" All rights reserved. 6.\" 7.\" This program is free software. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR 19.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 20.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 21.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT, 22.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 23.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 24.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 25.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 26.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 27.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28.\" 29.\" $FreeBSD$ 30.\" 31.Dd July 24, 1996 32.Os 33.Dt VOP_READDIR 9 34.Sh NAME 35.Nm VOP_READDIR 36.Nd read contents of a directory 37.Sh SYNOPSIS 38.In sys/param.h 39.In sys/dirent.h 40.In sys/vnode.h 41.Ft int 42.Fn VOP_READDIR "struct vnode *vp" "struct uio *uio" "struct ucred *cred" "int *eofflag" "int *ncookies" "u_long **cookies" 43.Sh DESCRIPTION 44Read directory entries. 45.Bl -tag -width ncookies 46.It Fa vp 47the vnode of the directory 48.It Fa uio 49where to read the directory contents 50.It Fa cred 51the caller's credentials 52.It Fa eofflag 53return end of file status (NULL if not wanted) 54.It Fa ncookies 55number of directory cookies generated for NFS (NULL if not wanted) 56.It Fa cookies 57directory seek cookies generated for NFS (NULL if not wanted) 58.El 59The directory contents are read into 60.Vt struct dirent 61structures. 62If the on-disc data structures differ from this then they 63should be translated. 64.Sh LOCKS 65The directory should be locked on entry and will still be locked on exit. 66.Sh RETURN VALUES 67Zero is returned on success, otherwise an error code is returned. 68.Pp 69If this is called from the NFS server, the extra arguments 70.Fa eofflag , 71.Fa ncookies 72and 73.Fa cookies 74are given. 75The value of 76.Fa *eofflag 77should be set to TRUE if the end of the directory is reached while 78reading. 79The directory seek cookies are returned to the NFS client and may be used 80later to restart a directory read part way through the directory. 81There should be one cookie returned per directory entry. 82The value of 83the cookie should be the offset within the directory where the on-disc 84version of the appropriate directory entry starts. 85Memory for the cookies should be allocated using: 86.Pp 87.Bd -literal 88 ...; 89 *ncookies = number of entries read; 90 *cookies = (u_int*)# 91 malloc(*ncookies * sizeof(u_int), M_TEMP, M_WAITOK); 92.Ed 93.Sh PSEUDOCODE 94.Bd -literal 95int 96vop_readdir(struct vnode *vp, struct uio *uio, struct ucred *cred, 97 int *eofflag, int *ncookies, u_int **cookies) 98{ 99 off_t off; 100 int error = 0; 101 102 /* 103 * Remember the original offset to use later in generating cookies. 104 */ 105 off = uio->uio_offset; 106 107 /* 108 * Read directory contents starting at uio->uio_offset into buffer 109 * pointed to by uio. 110 */ 111 ...; 112 113 if (!error && ncookies != NULL) { 114 struct dirent *dpStart; 115 struct dirent *dpEnd; 116 struct dirent *dp; 117 int count; 118 u_int *cookiebuf; 119 u_int *cookiep; 120 121 if (uio->uio_segflg != UIO_SYSSPACE || uio->uio_iovcnt != 1) 122 panic("vop_readdir: unexpected uio from NFS server"); 123 124 /* 125 * Parse the stuff just read into the uio. 126 */ 127 dpStart = (struct dirent *) 128 ((char *)uio->uio_iov->iov_base - (uio->uio_offset - off)); 129 dpEnd = (struct dirent *) uio->uio_iov->iov_base; 130 131 /* 132 * Count number of entries. 133 */ 134 for (dp = dpStart, count = 0; 135 dp < dpEnd; 136 dp = (struct dirent *)((caddr_t) dp + dp->d_reclen)) 137 count++; 138 139 cookiebuf = (u_int *) malloc(count * sizeof(u_int), M_TEMP, M_WAITOK); 140 for (dp = dpStart; cookiep = cookiebuf; 141 dp < dpEnd; 142 dp = (struct dirent *)((caddr_t) dp + dp->d_reclen)) { 143 off += dp->d_reclen; 144 *cookiep++ = (u_int) off; 145 } 146 *ncookies = count; 147 *cookies = cookiebuf; 148 } 149 150 if (eofflag && uio->uio_offset is past the end of the directory) { 151 *eofflag = TRUE; 152 } 153 154 return error; 155} 156.Ed 157.Sh ERRORS 158.Bl -tag -width Er 159.It Bq Er EINVAL 160An attempt was made to read from an illegal offset in the directory. 161.It Bq Er EIO 162A read error occurred while reading the directory. 163.El 164.Sh SEE ALSO 165.Xr vnode 9 166.Sh AUTHORS 167This man page was written by 168.An Doug Rabson . 169