1.\" $NetBSD: vnsubr.9,v 1.45 2017/01/05 09:54:03 wiz Exp $ 2.\" 3.\" Copyright (c) 2001, 2005, 2006 The NetBSD Foundation, Inc. 4.\" All rights reserved. 5.\" 6.\" This code is derived from software contributed to The NetBSD Foundation 7.\" by Gregory McGarry. 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 NETBSD FOUNDATION, INC. AND CONTRIBUTORS 19.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 20.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 21.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 22.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 23.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 24.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 25.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 26.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 27.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 28.\" POSSIBILITY OF SUCH DAMAGE. 29.\" 30.Dd January 2, 2017 31.Dt VNSUBR 9 32.Os 33.Sh NAME 34.Nm vnsubr , 35.Nm vn_bwrite , 36.Nm vn_close , 37.Nm vn_default_error , 38.Nm vn_isunder , 39.Nm vn_lock , 40.Nm vn_markexec , 41.Nm vn_marktext , 42.Nm vn_rdwr , 43.Nm vn_open , 44.Nm vn_stat , 45.Nm vn_writechk 46.Nd high-level convenience functions for vnode operations 47.Sh SYNOPSIS 48.In sys/param.h 49.In sys/lock.h 50.In sys/vnode.h 51.Ft int 52.Fn vn_bwrite "void *ap" 53.Ft int 54.Fn vn_close "struct vnode *vp" "int flags" "kauth_cred_t cred" 55.Ft int 56.Fn vn_default_error "void *v" 57.Ft int 58.Fn vn_isunder "struct vnode *dvp" "struct vnode *rvp" "struct lwp *l" 59.Ft int 60.Fn vn_lock "struct vnode *vp" "int flags" 61.Ft void 62.Fn vn_markexec "struct vnode *vp" 63.Ft void 64.Fn vn_marktext "struct vnode *vp" 65.Ft int 66.Fn vn_open "struct nameidata *ndp" "int fmode" "int cmode" 67.Ft int 68.Fo vn_rdwr 69.Fa "enum uio_rw rw" "struct vnode *vp" "void *base" 70.Fa "int len" "off_t offset" "enum uio_seg segflg" "int ioflg" 71.Fa "kauth_cred_t cred" "size_t *aresid" "struct lwp *l" 72.Fc 73.Ft int 74.Fn vn_readdir "file_t *fp" "char *buf" "int segflg" "u_int count" "int *done" "struct lwp *l" "off_t **cookies" "int *ncookies" 75.Ft int 76.Fn vn_stat "struct vnode *vp" "struct stat *sb" 77.Ft int 78.Fn vn_writechk "struct vnode *vp" 79.Sh DESCRIPTION 80The high-level functions described in this page are convenience 81functions for simplified access to the vnode operations described in 82.Xr vnodeops 9 . 83.Sh FUNCTIONS 84.Bl -tag -width compact 85.It Fn vn_bwrite "ap" 86Common code for block write operations. 87.It Fn vn_close "vp" "flags" "cred" 88Common code for a vnode close. 89The argument 90.Fa vp 91is the unlocked vnode of the vnode to close. 92.Fn vn_close 93simply locks the vnode, invokes the vnode operation 94.Xr VOP_CLOSE 9 95and calls 96.Fn vput 97to return the vnode to the freelist or holdlist. 98Note that 99.Fn vn_close 100expects an unlocked, referenced vnode and will dereference the vnode 101prior to returning. 102If the operation is successful zero is returned, 103otherwise an appropriate error is returned. 104.It Fn vn_default_error "v" 105A generic "default" routine that just returns error. 106It is used by a file system to specify unsupported operations in 107the vnode operations vector. 108.It Fn vn_isunder "dvp" "rvp" "l" 109Common code to check if one directory specified by the vnode 110.Fa rvp 111can be found inside the directory specified by the vnode 112.Fa dvp . 113The argument 114.Fa l 115is the calling process. 116.Fn vn_isunder 117is intended to be used in 118.Xr chroot 2 , 119.Xr chdir 2 , 120.Xr fchdir 2 , 121etc., to ensure that 122.Xr chroot 2 123actually means something. 124If the operation is successful zero is returned, otherwise 1 is returned. 125.It Fn vn_lock "vp" "flags" 126Common code to acquire the lock for vnode 127.Fa vp . 128The argument 129.Fa flags 130specifies the flags used to lock the vnode. 131There are the following flags: 132.Pp 133.Bl -tag -offset indent -width LK_EXCLUSIVE -compact 134.It LK_SHARED 135shared lock 136.It LK_EXCLUSIVE 137exclusive lock 138.It LK_NOWAIT 139do not sleep to await lock 140.It LK_RETRY 141allow lock operation on dead vnode 142.El 143.Pp 144If the operation is successful zero is returned, otherwise an 145appropriate error code is returned. 146.Pp 147.Fn vn_lock 148must not be called when the vnode's reference count is zero. 149.It Fn vn_markexec "vp" 150Common code to mark the vnode 151.Fa vp 152as containing executable code of a running process. 153.It Fn vn_marktext "vp" 154Common code to mark the vnode 155.Fa vp 156as being the text of a running process. 157.It Fn vn_open "ndp" "fmode" "cmode" 158Common code for vnode open operations. 159The pathname is described in the nameidata pointer (see 160.Xr namei 9 ) . 161The arguments 162.Fa fmode 163and 164.Fa cmode 165specify the 166.Xr open 2 167file mode and the access permissions for creation. 168.Fn vn_open 169checks permissions and invokes the 170.Xr VOP_OPEN 9 171or 172.Xr VOP_CREATE 9 173vnode operations. 174If the operation is successful zero is returned and the vnode is locked, 175otherwise an appropriate error code is returned. 176.It Fn vn_rdwr "rw" "vp" "base" "len" "offset" "segflg" "ioflg" "cred" "aresid" "l" 177Common code to package up an I/O request on a vnode into a uio and 178then perform the I/O. 179The argument 180.Fa rw 181specifies whether the I/O is a read 182.Dv ( UIO_READ ) 183or write 184.Dv ( UIO_WRITE ) 185operation. 186The vnode is specified by 187.Fa vp . 188The arguments 189.Fa l 190and 191.Fa cred 192are the calling lwp and its credentials. 193If 194.Fa ioflg 195contains 196.Dv IO_NODELOCKED , 197it is expected that the vnode is locked. 198.Fa ioflg 199will be passed to 200.Fn VOP_READ Ns No / Ns Fn VOP_WRITE . 201The remaining arguments specify the uio parameters. 202For further information on these parameters see 203.Xr uiomove 9 . 204.It Fn vn_readdir "fp" "buf" "segflg" "count" "done" "l" "cookies" "ncookies" 205Common code for reading the contents of a directory. 206The argument 207.Fa fp 208is the file structure, 209.Fa buf 210is the buffer for placing the struct dirent structures. 211The arguments 212.Fa cookies 213and 214.Fa ncookies 215specify the addresses for the list and number of directory seek 216cookies generated for NFS. 217Both 218.Fa cookies 219and 220.Fa ncookies 221should be 222.Dv NULL 223if they aren't required to be returned by 224.Fn vn_readdir . 225If the operation is successful zero is returned, otherwise an 226appropriate error code is returned. 227.It Fn vn_stat "vp" "sb" 228Common code for a vnode stat operation. 229The vnode is specified by the argument 230.Fa vp , 231and 232.Fa sb 233is the buffer to return the stat information. 234.Fn vn_stat 235basically calls the vnode operation 236.Xr VOP_GETATTR 9 237and transfers the contents of a vattr structure into a struct stat. 238If the operation is successful zero is returned, otherwise an 239appropriate error code is returned. 240.It Fn vn_writechk "vp" 241Common code to check for write permission on the vnode 242.Fa vp . 243A vnode is read-only if it is in use as a process's text image. 244If the vnode is read-only ETEXTBSY is returned, otherwise zero is 245returned to indicate that the vnode can be written to. 246.El 247.Sh ERRORS 248.Bl -tag -width Er 249.It Bq Er EBUSY 250The LK_NOWAIT flag was set and 251.Fn vn_lock 252would have slept. 253.It Bq Er ENOENT 254The vnode has been reclaimed and is dead. 255This error is only returned if the LK_RETRY flag is not passed to 256.Fn vn_lock . 257.It Bq Er ETXTBSY 258Cannot write to a vnode since is a process's text image. 259.El 260.Sh CODE REFERENCES 261The high-level convenience functions are implemented within the files 262.Pa sys/kern/vfs_vnops.c 263and 264.Pa sys/sys/vnode.h . 265.Sh SEE ALSO 266.Xr file 9 , 267.Xr intro 9 , 268.Xr lock 9 , 269.Xr namei 9 , 270.Xr vattr 9 , 271.Xr vfs 9 , 272.Xr vnode 9 , 273.Xr vnodeops 9 274