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33 .Nd "Userland character device library"
37 To load the required kernel module at boot time, place the following line in
39 .Bd -literal -offset indent
47 library contains functions to create a character device in userspace.
50 library is thread safe.
51 .Sh LIBRARY INITIALISATION / DEINITIALISATION
53 .Fn "cuse_init" "void"
54 This function initialises
56 Must be called at the beginning of the program.
57 This function returns 0 on success or a negative value on failure.
60 for known error codes.
61 If the cuse kernel module is not loaded,
62 .Dv CUSE_ERR_NOT_LOADED
66 .Fn "cuse_uninit" "void"
69 Can be called at the end of the application.
70 This function returns 0 on success or a negative value on failure.
73 for known error codes.
76 .Fn "cuse_alloc_unit_number" "int *"
77 This function stores a uniq system unit number at the pointed
79 This function returns 0 on success or a negative value on failure.
82 for known error codes.
85 .Fn "cuse_alloc_unit_number_by_id" "int *" "int id"
86 This function stores a unique system unit number at the pointed
88 The returned unit number is uniq within the given ID.
89 Valid ID values are defined by the cuse include file.
92 macros for more information.
93 This function returns 0 on success or a negative value on failure.
96 for known error codes.
99 .Fn "cuse_free_unit_number" "int"
100 This function frees the given allocated system unit number.
101 This function returns 0 on success or a negative value on failure.
104 for known error codes.
107 .Fn "cuse_free_unit_number_by_id" "int unit" "int id"
108 This function frees the given allocated system unit number belonging
110 If both the unit and id argument is -1, all allocated units will be freed.
111 This function returns 0 on success or a negative value on failure.
114 for known error codes.
117 .Fn "cuse_vmalloc" "int size"
118 This function allocates
121 Only memory allocated by this function can be memory
124 This function returns a valid data pointer on success or
129 .Fn "cuse_is_vmalloc_addr" "void *"
130 This function returns non-zero if the passed pointer points to a valid
131 and non-freed allocation, as returned by
133 Else this function returns zero.
136 .Fn "cuse_vmfree" "void *"
137 This function frees memory allocated by
140 cuse library will internally not free the memory until the
142 function is called and that the number of unique
143 allocations is limited.
146 .Fn "cuse_vmoffset" "void *"
147 This function returns the mmap offset that the client must use to
148 access the allocated memory.
150 .Ft "struct cuse_dev *"
151 .Fn "cuse_dev_create" "const struct cuse_methods *mtod" "void *priv0" "void *priv1" "uid_t" "gid_t" "int permission" "const char *fmt" "..."
152 This function creates a new character device according to the given
154 This function returns a valid cuse_dev structure pointer
158 The device name can only contain a-z,
159 A-Z, 0-9, dot, / and underscore characters.
162 .Fn "cuse_dev_destroy" "struct cuse_dev *"
163 This functions destroys a previously created character device.
166 .Fn "cuse_dev_get_priv0" "struct cuse_dev *" ,
168 .Fn "cuse_dev_get_priv1" "struct cuse_dev *" ,
170 .Fn "cuse_dev_set_priv0" "struct cuse_dev *" "void *" ,
172 .Fn "cuse_dev_set_priv1" "struct cuse_dev *" "void *"
173 These functions are used to set and get the private data of the given
177 .Fn "cuse_wait_and_process" "void"
178 This function will block and do event processing.
180 required multiple threads must be created looping on this
182 This function returns 0 on success or a negative value on failure.
185 for known error codes.
188 .Fn "cuse_dev_get_per_file_handle" "struct cuse_dev *" ,
190 .Fn "cuse_dev_set_per_file_handle" "struct cuse_dev *" "void *"
191 These functions are used to set and get the per-file-open specific handle
192 and should only be used inside the cuse file operation callbacks.
195 .Fn "cuse_set_local" "int"
196 This function instructs
201 user pointer is local, if the argument passed to it is non-zero.
202 Else the user pointer is assumed to be at the peer application.
203 This function should only be used inside the cuse file operation callbacks.
204 The value is reset to zero when the given file operation returns, and
205 does not affect any other file operation callbacks.
208 .Fn "cuse_get_local" "void"
209 Returns the current local state.
214 .Fn "cuse_copy_out" "const void *src" "void *peer_dst" "int len" ,
216 .Fn "cuse_copy_in" "const void *peer_src" "void *dst" "int len"
217 These functions are used to transfer data between the local
218 application and the peer application.
219 These functions must be used
220 when operating on the data pointers passed to the
226 These functions return 0 on success or a negative value on failure.
229 for known error codes.
232 .Fn "cuse_got_peer_signal" "void"
233 This function is used to check if a signal has been delivered to the
234 peer application and should only be used inside the cuse file
236 This function returns 0 if a signal has been
237 delivered to the caller.
238 Else it returns a negative value.
241 for known error codes.
243 .Ft "struct cuse_dev *"
244 .Fn "cuse_dev_get_current" "int *pcmd"
245 This function is used to get the current cuse device pointer and the
246 currently executing command, by
254 This function should only be used inside the
255 cuse file operation callbacks.
256 On success a valid cuse device pointer
263 .Fn "cuse_poll_wakeup" "void"
264 This function will wake up any file pollers.
265 .Sh LIBRARY LIMITATIONS
272 should not exceed what can fit into a 32-bit signed integer and is
276 Transfer lengths for ioctls should not exceed what is defined by the
279 .Sh LIBRARY CALLBACK METHODS
280 In general fflags are defined by
282 and errors are defined by
284 .Bd -literal -offset indent
322 .Fn "cuse_open_t" "struct cuse_dev *" "int fflags"
323 This function returns a
328 .Fn "cuse_close_t" "struct cuse_dev *" "int fflags"
329 This function returns a
334 .Fn "cuse_read_t" "struct cuse_dev *" "int fflags" "void *peer_ptr" "int len"
335 This function returns a
337 value in case of failure or the
338 actually transferred length in case of success.
342 must be used to transfer data to and from the
346 .Fn "cuse_write_t" "struct cuse_dev *" "int fflags" "const void *peer_ptr" "int len"
347 This function returns a
349 value in case of failure or the
350 actually transferred length in case of success.
354 must be used to transfer data to and from the
358 .Fn "cuse_ioctl_t" "struct cuse_dev *" "int fflags" "unsigned long cmd" "void *peer_data"
359 This function returns a
361 value in case of failure or zero
367 transfer data to and from the
371 .Fn "cuse_poll_t" "struct cuse_dev *" "int fflags" "int events"
372 This function returns a mask of
374 values in case of failure and success.
375 The events argument is also a mask of
378 .Bd -literal -offset indent
379 struct cuse_methods {
380 cuse_open_t *cm_open;
381 cuse_close_t *cm_close;
382 cuse_read_t *cm_read;
383 cuse_write_t *cm_write;
384 cuse_ioctl_t *cm_ioctl;
385 cuse_poll_t *cm_poll;
390 was written by Hans Petter Selasky.