Adjust the docs for the renaming of devfs_clone_bitmap_rst() to _put().
[dragonfly.git] / share / man / man9 / make_autoclone_dev.9
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5fccb22f 32.Dd August 13, 2010
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33.Os
34.Dt MAKE_AUTOCLONE_DEV 9
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_fff ,
41.Nm devfs_clone_bitmap_chk ,
42.Nm devfs_clone_bitmap_set ,
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43.Nm devfs_clone_bitmap_get ,
44.Nm devfs_clone_bitmap_put ,
45.Nm DEVFS_DECLARE_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
4aff68f4 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" "..."
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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 void
61.Fn devfs_clone_bitmap_fff "struct devfs_bitmap *bitmap"
62.Ft int
4aff68f4 63.Fn devfs_clone_bitmap_chk "struct devfs_bitmap *bitmap" "int unit"
2c8ac1b3 64.Ft void
4aff68f4 65.Fn devfs_clone_bitmap_set "struct devfs_bitmap *bitmap" "int unit"
2c8ac1b3 66.Ft int
4aff68f4 67.Fn devfs_clone_bitmap_get "struct devfs_bitmap *bitmap" "int limit"
2c8ac1b3 68.Ft void
4aff68f4 69.Fn devfs_clone_bitmap_put "struct devfs_bitmap *bitmap" "int unit"
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70.Fn DEVFS_DECLARE_CLONE_BITMAP "name"
71.Fn DEVFS_CLONE_BITMAP "name"
72.Sh DESCRIPTION
73.Fn make_autoclone_dev
74creates a
75.Vt cdev_t
76with the default
77.Fa ops ,
78visible in the
79.Xr devfs 5
80namespace, that (when opened) will invoke the clone handler specified by
81.Fa nhandler .
82If a
83.Vt devfs_bitmap *
84is specified, the given
85.Fa bitmap
86is initialized using
87.Fn devfs_clone_bitmap_init .
88.Pp
89The clone handler must be defined as follows:
90.Bd -literal
91d_clone_t mydev_clone;
92
93int
94mydev_clone(struct dev_clone_args *ap)
95{
96};
97.Ed
98.Pp
99When called, the handler is passed a pointer to a populated
100.Vt dev_clone_args
101structure, which is defined as follows:
102.Bd -literal
103struct dev_clone_args {
104 struct dev_generic_args a_head;
105 struct cdev *a_dev;
106 const char *a_name;
107 size_t a_namelen;
108 struct ucred *a_cred;
109 int a_mode;
110};
111.Ed
112.Pp
113.Fa a_head.a_dev
114is the
115.Vt cdev_t
116of the accessed autoclone device.
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 .
122.Fa a_mode
123and
124.Fa a_cred
125contain the mode and cred passed to the autoclone device's
126.Fn open .
127.Pp
128The clone handler must set
129.Fa a_dev
130to a new
131.Vt cdev_t ,
132returned by a call to
133.Fn make_only_dev .
134.Fa a_dev
135may also be set to
136.Dv NULL ,
137in which case the
138.Fn open
139will ultimately fail with
140.Er ENXIO .
141If
142.Fa a_dev
143is
144.Pf non- Ns Dv NULL ,
145it is automatically made visible and linked into
146.Xr devfs 5
147as if it was created with
148.Fn make_dev .
149Thus,
150.Fn destroy_dev
151should be used to destroy the cloned
152.Vt cdev_t
153once it is no longer required,
154usually during
155.Fn close .
156.Pp
157.Fn destroy_autoclone_dev
158destroys a
159.Vt cdev_t
160created by
161.Fn make_autoclone_dev
162unregistering its clone handler and (if non-NULL) also uninitializes its
163.Fa bitmap
164using
165.Fn devfs_clone_bitmap_uninit .
166.Pp
167.Fn devfs_clone_bitmap_init
168initializes the given clone
169.Fa bitmap
170so it is ready to use.
171.Pp
172.Fn devfs_clone_bitmap_uninit
173frees the memory associated with the specified clone
174.Fa bitmap
175and leaves it unusable.
176.Pp
177.Fn devfs_clone_bitmap_fff
178returns the first unused unit in
179.Fa bitmap .
180To use this unit, it has to be acquired by a call to
181.Fn devfs_clone_bitmap_set .
182.Pp
183.Fn devfs_clone_bitmap_chk
184checks if
185.Fa unit
186is in use (set) and returns 1 if it is; otherwise 0 is returned.
187.Pp
188.Fn devfs_clone_bitmap_set
189marks
190.Fa unit
191in
192.Fa bitmap
193as used, so further calls to
194.Fn devfs_clone_bitmap_fff
195or
196.Fn devfs_clone_bitmap_get
197cannot retrieve it.
198If one intends to use a clone handler along with preallocated devices, it
199is recommended to block the unit numbers of the preallocated devices by
200calling
201.Fn devfs_clone_bitmap_set
202on them.
203.Pp
5fccb22f 204.Fn devfs_clone_bitmap_put
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205marks
206.Fa unit
207in the
208.Fa bitmap
209as unused so further calls to
210.Fn devfs_clone_bitmap_fff
211or
212.Fn devfs_clone_bitmap_get
213can retrieve it again.
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214.Pp
215.Fn devfs_clone_bitmap_get
216is a shortcut to
217.Fn devfs_clone_bitmap_fff
218and
219.Fn devfs_clone_bitmap_set .
220It will return the first unused unit number and also mark it as used.
221.Pp
222The
223.Fn DEVFS_DECLARE_CLONE_BITMAP
224macro declares a clone bitmap with the specified
225.Fa name .
226As long as the name specified is unique, this macro can be used to declare
227global variables.
228.Pp
229The
230.Fn DEVFS_CLONE_BITMAP
231is a macro which expands the specified
232.Fa name
233to the full name of a clone bitmap.
234It is used in conjunction with
235.Fn DEVFS_DECLARE_CLONE_BITMAP ,
236as it uses the same name.
237.Sh HISTORY
238The
239.Xr devfs 5
240clone facilities and the associated functions all appeared in
241.Dx 2.3 .
242.Sh AUTHOR
243.An Alex Hornung