1.\" 2.\" Copyright (c) 2009 3.\" The DragonFly Project. All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 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 13.\" the documentation and/or other materials provided with the 14.\" distribution. 15.\" 3. Neither the name of The DragonFly Project nor the names of its 16.\" contributors may be used to endorse or promote products derived 17.\" from this software without specific, prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 20.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 21.\" LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 22.\" FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 23.\" COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 24.\" INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, 25.\" BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 26.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 27.\" AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 28.\" OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 29.\" OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.Dd August 22, 2019 33.Dt MAKE_AUTOCLONE_DEV 9 34.Os 35.Sh NAME 36.Nm make_autoclone_dev , 37.Nm destroy_autoclone_dev , 38.Nm devfs_clone_bitmap_init , 39.Nm devfs_clone_bitmap_uninit , 40.Nm devfs_clone_bitmap_chk , 41.Nm devfs_clone_bitmap_set , 42.Nm devfs_clone_bitmap_get , 43.Nm devfs_clone_bitmap_put , 44.Nm DEVFS_DECLARE_CLONE_BITMAP , 45.Nm DEVFS_DEFINE_CLONE_BITMAP , 46.Nm DEVFS_CLONE_BITMAP 47.Nd device clone functions 48.Sh SYNOPSIS 49.In sys/types.h 50.In sys/conf.h 51.In sys/devfs.h 52.Ft cdev_t 53.Fn make_autoclone_dev "struct dev_ops *ops" "struct devfs_bitmap *bitmap" "d_clone_t *nhandler" "uid_t uid" "gid_t gid" "int perms" "const char *fmt" "..." 54.Ft void 55.Fn destroy_autoclone_dev "cdev_t dev" "struct devfs_bitmap *bitmap" 56.Ft void 57.Fn devfs_clone_bitmap_init "struct devfs_bitmap *bitmap" 58.Ft void 59.Fn devfs_clone_bitmap_uninit "struct devfs_bitmap *bitmap" 60.Ft int 61.Fn devfs_clone_bitmap_chk "struct devfs_bitmap *bitmap" "int unit" 62.Ft int 63.Fn devfs_clone_bitmap_set "struct devfs_bitmap *bitmap" "int unit" 64.Ft int 65.Fn devfs_clone_bitmap_get "struct devfs_bitmap *bitmap" "int limit" 66.Ft void 67.Fn devfs_clone_bitmap_put "struct devfs_bitmap *bitmap" "int unit" 68.Fn DEVFS_DECLARE_CLONE_BITMAP "name" 69.Fn DEVFS_DEFINE_CLONE_BITMAP "name" 70.Fn DEVFS_CLONE_BITMAP "name" 71.Sh DESCRIPTION 72.Fn make_autoclone_dev 73creates a 74.Vt cdev_t 75with the default 76.Fa ops , 77visible in the 78.Xr devfs 5 79namespace, that (when opened) will invoke the clone handler specified by 80.Fa nhandler . 81If a 82.Vt devfs_bitmap * 83is specified, the given 84.Fa bitmap 85is initialized using 86.Fn devfs_clone_bitmap_init . 87.Pp 88The clone handler must be defined as follows: 89.Bd -literal 90d_clone_t mydev_clone; 91 92int 93mydev_clone(struct dev_clone_args *ap) 94{ 95}; 96.Ed 97.Pp 98When called, the handler is passed a pointer to a populated 99.Vt dev_clone_args 100structure, which is defined as follows: 101.Bd -literal 102struct dev_clone_args { 103 struct dev_generic_args a_head; 104 struct cdev *a_dev; 105 const char *a_name; 106 size_t a_namelen; 107 struct ucred *a_cred; 108 int a_mode; 109}; 110.Ed 111.Pp 112.Fa a_head.a_dev 113is the 114.Vt cdev_t 115of the accessed autoclone device. 116.Fa a_name 117and 118.Fa a_namelen 119are the registered clonable base name and its length, as specified to 120.Fn make_autoclone_dev . 121.Fa a_mode 122and 123.Fa a_cred 124contain the mode and cred passed to the autoclone device's 125.Fn open . 126.Pp 127The clone handler must set 128.Fa a_dev 129to a new 130.Vt cdev_t , 131returned by a call to 132.Fn make_only_dev . 133.Fa a_dev 134may also be set to 135.Dv NULL , 136in which case the 137.Fn open 138will ultimately fail with 139.Er ENXIO . 140If 141.Fa a_dev 142is 143.Pf non- Ns Dv NULL , 144it is automatically made visible and linked into 145.Xr devfs 5 146as if it was created with 147.Fn make_dev . 148Thus, 149.Fn destroy_dev 150should be used to destroy the cloned 151.Vt cdev_t 152once it is no longer required, 153usually during 154.Fn close . 155.Pp 156.Fn destroy_autoclone_dev 157destroys a 158.Vt cdev_t 159created by 160.Fn make_autoclone_dev 161unregistering its clone handler and (if non-NULL) also uninitializes its 162.Fa bitmap 163using 164.Fn devfs_clone_bitmap_uninit . 165.Pp 166.Fn devfs_clone_bitmap_init 167initializes the given clone 168.Fa bitmap 169so it is ready to use. 170.Pp 171.Fn devfs_clone_bitmap_uninit 172frees the memory associated with the specified clone 173.Fa bitmap 174and leaves it unusable. 175.Pp 176.Fn devfs_clone_bitmap_chk 177checks if 178.Fa unit 179is in use (set) and returns 1 if it is; otherwise 0 is returned. 180.Pp 181.Fn devfs_clone_bitmap_set 182marks 183.Fa unit 184in 185.Fa bitmap 186as used, so further calls to 187.Fn devfs_clone_bitmap_get 188cannot retrieve it. 189If one intends to use a clone handler along with preallocated devices, it 190is recommended to block the unit numbers of the preallocated devices by 191calling 192.Fn devfs_clone_bitmap_set 193on them. 194The function returns -1 if the unit is already allocated, otherwise 0. 195.Pp 196.Fn devfs_clone_bitmap_put 197marks 198.Fa unit 199in the 200.Fa bitmap 201as unused so further calls to 202.Fn devfs_clone_bitmap_fff 203or 204.Fn devfs_clone_bitmap_get 205can retrieve it again. 206It is recommended that the associated device be destroyed prior to 207making the 208.Fa unit 209available in the bitmap again, to avoid racing against a new clone. 210.Pp 211.Fn devfs_clone_bitmap_get 212will return the first unused unit number and also mark it as used 213in the 214.Fa bitmap . 215.Pp 216The 217.Fn DEVFS_DEFINE_CLONE_BITMAP 218macro defines a clone bitmap with the specified 219.Fa name . 220As long as the name specified is unique, this macro can be used to define 221global variables. 222Similarly, 223.Fn DEVFS_DECLARE_CLONE_BITMAP 224declares a clone bitmap. 225.Pp 226The 227.Fn DEVFS_CLONE_BITMAP 228is a macro which expands the specified 229.Fa name 230to the full name of a clone bitmap. 231It is used in conjunction with 232.Fn DEVFS_DEFINE_CLONE_BITMAP 233and 234.Fn DEVFS_DECLARE_CLONE_BITMAP , 235as it uses the same name. 236.Sh HISTORY 237The 238.Xr devfs 5 239clone facilities and the associated functions all appeared in 240.Dx 2.3 . 241.Sh AUTHORS 242.An Alex Hornung 243