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 June 30, 2020 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 will invoke the clone handler specified by 80.Fa nhandler 81when it is opened. 82If the 83.Fa bitmap 84argument is specified, it will be initialized using 85.Fn devfs_clone_bitmap_init . 86.Pp 87The clone handler must be defined as follows: 88.Bd -literal -offset indent 89d_clone_t mydev_clone; 90 91int 92mydev_clone(struct dev_clone_args *ap) 93{ 94}; 95.Ed 96.Pp 97When called, the handler is passed a pointer to a populated 98.Vt dev_clone_args 99structure, which is defined as follows: 100.Bd -literal -offset indent 101struct dev_clone_args { 102 struct dev_generic_args a_head; 103 struct cdev *a_dev; 104 const char *a_name; 105 size_t a_namelen; 106 struct ucred *a_cred; 107 int a_mode; 108}; 109.Ed 110.Pp 111The 112.Fa a_head.a_dev 113is the 114.Vt cdev_t 115of the accessed autoclone device. 116The 117.Fa a_name 118and 119.Fa a_namelen 120are the registered clonable base name and its length, as specified to 121.Fn make_autoclone_dev . 122The 123.Fa a_mode 124and 125.Fa a_cred 126contain the mode and credential passed to the 127.Fn open 128of the autoclone device. 129.Pp 130The clone handler must set 131.Fa a_dev 132to a new 133.Vt cdev_t 134that is returned by a call to 135.Fn make_only_dev . 136The new 137.Vt cdev_t 138will be automatically made visible and linked into 139.Xr devfs 5 140namespace, as if it was created with 141.Fn make_dev . 142Thus, 143.Fn destroy_dev 144should be used to destroy the cloned 145.Vt cdev_t 146once it is no longer required, 147usually during 148.Fn close . 149.Pp 150.Fn destroy_autoclone_dev 151destroys a 152.Vt cdev_t 153created by 154.Fn make_autoclone_dev 155unregistering its clone handler and (if non-NULL) also uninitializes its 156.Fa bitmap 157using 158.Fn devfs_clone_bitmap_uninit . 159.Pp 160.Fn devfs_clone_bitmap_init 161initializes the given clone 162.Fa bitmap 163so it is ready to use. 164.Pp 165.Fn devfs_clone_bitmap_uninit 166frees the memory associated with the specified clone 167.Fa bitmap 168and leaves it unusable. 169.Pp 170.Fn devfs_clone_bitmap_chk 171checks if 172.Fa unit 173is in use (set) and returns 1 if it is; otherwise 0 is returned. 174.Pp 175.Fn devfs_clone_bitmap_set 176marks 177.Fa unit 178in the 179.Fa bitmap 180as used, so further calls to 181.Fn devfs_clone_bitmap_get 182cannot retrieve it. 183The function returns -1 if the unit is already allocated, otherwise 0. 184If one intends to use a clone handler along with preallocated devices, it 185is recommended to block the unit numbers of the preallocated devices by 186calling 187.Fn devfs_clone_bitmap_set 188on them. 189.Pp 190.Fn devfs_clone_bitmap_get 191will return the first unused unit number and also mark it as used 192in the 193.Fa bitmap . 194If the 195.Fa limit 196argument is greater than 0, the requested unit number cannot be greater 197than the given 198.Fa limit . 199The function returns -1 if no more units are available. 200.Pp 201.Fn devfs_clone_bitmap_put 202marks 203.Fa unit 204in the 205.Fa bitmap 206as unused so further calls to 207.Fn devfs_clone_bitmap_get 208can retrieve it again. 209It is recommended that the associated device be destroyed prior to 210making the 211.Fa unit 212available in the bitmap again, to avoid racing against a new clone. 213.Pp 214The 215.Fn DEVFS_DEFINE_CLONE_BITMAP 216macro defines a clone bitmap with the specified 217.Fa name . 218As long as the name specified is unique, this macro can be used to define 219global variables. 220Similarly, 221.Fn DEVFS_DECLARE_CLONE_BITMAP 222declares a clone bitmap. 223.Pp 224The 225.Fn DEVFS_CLONE_BITMAP 226is a macro which expands the specified 227.Fa name 228to the full name of a clone bitmap. 229It is used in conjunction with 230.Fn DEVFS_DEFINE_CLONE_BITMAP 231and 232.Fn DEVFS_DECLARE_CLONE_BITMAP , 233as it uses the same name. 234.Sh SEE ALSO 235.Xr devfs 5 , 236.Xr destroy_dev 9 , 237.Xr make_dev 9 , 238.Xr make_only_dev 9 239.Sh HISTORY 240The 241.Xr devfs 5 242clone facilities and the associated functions all appeared in 243.Dx 2.3 . 244.Sh AUTHORS 245.An Alex Hornung 246