1 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
2  * Copyright by The HDF Group.                                               *
3  * All rights reserved.                                                      *
4  *                                                                           *
5  * This file is part of HDF5.  The full HDF5 copyright notice, including     *
6  * terms governing use, modification, and redistribution, is contained in    *
7  * the COPYING file, which can be found at the root of the source code       *
8  * distribution tree, or in https://www.hdfgroup.org/licenses.               *
9  * If you do not have access to either file, you may request a copy from     *
10  * help@hdfgroup.org.                                                        *
11  * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
12 
13 /*
14  * This file contains public declarations for authoring VOL connectors.
15  */
16 
17 #ifndef H5VLconnector_H
18 #define H5VLconnector_H
19 
20 /* Public headers needed by this file */
21 #include "H5public.h"   /* Generic Functions                    */
22 #include "H5Apublic.h"  /* Attributes                           */
23 #include "H5ESpublic.h" /* Event Stack                          */
24 #include "H5Fpublic.h"  /* Files                                */
25 #include "H5Ipublic.h"  /* IDs                                  */
26 #include "H5Lpublic.h"  /* Links                                */
27 #include "H5Opublic.h"  /* Objects                              */
28 #include "H5Rpublic.h"  /* References                           */
29 #include "H5VLpublic.h" /* Virtual Object Layer                 */
30 
31 /*****************/
32 /* Public Macros */
33 /*****************/
34 
35 /* Capability flags for connector */
36 #define H5VL_CAP_FLAG_NONE       0    /* No special connector capabilities */
37 #define H5VL_CAP_FLAG_THREADSAFE 0x01 /* Connector is threadsafe */
38 
39 /* Container info version */
40 #define H5VL_CONTAINER_INFO_VERSION 0x01 /* Container info struct version */
41 
42 /* The maximum size allowed for blobs */
43 #define H5VL_MAX_BLOB_ID_SIZE (16) /* Allow for 128-bits blob IDs */
44 
45 /*******************/
46 /* Public Typedefs */
47 /*******************/
48 
49 /* types for attribute GET callback */
50 typedef enum H5VL_attr_get_t {
51     H5VL_ATTR_GET_ACPL,         /* creation property list              */
52     H5VL_ATTR_GET_INFO,         /* info                                */
53     H5VL_ATTR_GET_NAME,         /* access property list                */
54     H5VL_ATTR_GET_SPACE,        /* dataspace                           */
55     H5VL_ATTR_GET_STORAGE_SIZE, /* storage size                        */
56     H5VL_ATTR_GET_TYPE          /* datatype                            */
57 } H5VL_attr_get_t;
58 
59 /* types for attribute SPECFIC callback */
60 typedef enum H5VL_attr_specific_t {
61     H5VL_ATTR_DELETE, /* H5Adelete(_by_name/idx)             */
62     H5VL_ATTR_EXISTS, /* H5Aexists(_by_name)                 */
63     H5VL_ATTR_ITER,   /* H5Aiterate(_by_name)                */
64     H5VL_ATTR_RENAME  /* H5Arename(_by_name)                 */
65 } H5VL_attr_specific_t;
66 
67 /* Typedef for VOL connector attribute optional VOL operations */
68 typedef int H5VL_attr_optional_t;
69 
70 /* types for dataset GET callback */
71 typedef enum H5VL_dataset_get_t {
72     H5VL_DATASET_GET_DAPL,         /* access property list                */
73     H5VL_DATASET_GET_DCPL,         /* creation property list              */
74     H5VL_DATASET_GET_SPACE,        /* dataspace                           */
75     H5VL_DATASET_GET_SPACE_STATUS, /* space status                        */
76     H5VL_DATASET_GET_STORAGE_SIZE, /* storage size                        */
77     H5VL_DATASET_GET_TYPE          /* datatype                            */
78 } H5VL_dataset_get_t;
79 
80 /* types for dataset SPECFIC callback */
81 typedef enum H5VL_dataset_specific_t {
82     H5VL_DATASET_SET_EXTENT, /* H5Dset_extent                       */
83     H5VL_DATASET_FLUSH,      /* H5Dflush                            */
84     H5VL_DATASET_REFRESH     /* H5Drefresh                          */
85 } H5VL_dataset_specific_t;
86 
87 /* Typedef for VOL connector dataset optional VOL operations */
88 typedef int H5VL_dataset_optional_t;
89 
90 /* types for datatype GET callback */
91 typedef enum H5VL_datatype_get_t {
92     H5VL_DATATYPE_GET_BINARY, /* get serialized form of transient type    */
93     H5VL_DATATYPE_GET_TCPL    /* datatype creation property list          */
94 } H5VL_datatype_get_t;
95 
96 /* types for datatype SPECFIC callback */
97 typedef enum H5VL_datatype_specific_t { H5VL_DATATYPE_FLUSH, H5VL_DATATYPE_REFRESH } H5VL_datatype_specific_t;
98 
99 /* Typedef and values for native VOL connector named datatype optional VOL operations */
100 typedef int H5VL_datatype_optional_t;
101 /* (No optional named datatype VOL operations currently) */
102 
103 /* types for file GET callback */
104 typedef enum H5VL_file_get_t {
105     H5VL_FILE_GET_CONT_INFO, /* file get container info              */
106     H5VL_FILE_GET_FAPL,      /* file access property list            */
107     H5VL_FILE_GET_FCPL,      /* file creation property list          */
108     H5VL_FILE_GET_FILENO,    /* file number                          */
109     H5VL_FILE_GET_INTENT,    /* file intent                          */
110     H5VL_FILE_GET_NAME,      /* file name                            */
111     H5VL_FILE_GET_OBJ_COUNT, /* object count in file                 */
112     H5VL_FILE_GET_OBJ_IDS    /* object ids in file                   */
113 } H5VL_file_get_t;
114 
115 /* types for file SPECIFIC callback */
116 typedef enum H5VL_file_specific_t {
117     H5VL_FILE_FLUSH,         /* Flush file                       */
118     H5VL_FILE_REOPEN,        /* Reopen the file                  */
119     H5VL_FILE_MOUNT,         /* Mount a file                     */
120     H5VL_FILE_UNMOUNT,       /* Unmount a file                   */
121     H5VL_FILE_IS_ACCESSIBLE, /* Check if a file is accessible    */
122     H5VL_FILE_DELETE,        /* Delete a file                    */
123     H5VL_FILE_IS_EQUAL       /* Check if two files are the same  */
124 } H5VL_file_specific_t;
125 
126 /* Typedef for VOL connector file optional VOL operations */
127 typedef int H5VL_file_optional_t;
128 
129 /* types for group GET callback */
130 typedef enum H5VL_group_get_t {
131     H5VL_GROUP_GET_GCPL, /* group creation property list     */
132     H5VL_GROUP_GET_INFO  /* group info                       */
133 } H5VL_group_get_t;
134 
135 /* types for group SPECFIC callback */
136 typedef enum H5VL_group_specific_t { H5VL_GROUP_FLUSH, H5VL_GROUP_REFRESH } H5VL_group_specific_t;
137 
138 /* Typedef for VOL connector group optional VOL operations */
139 typedef int H5VL_group_optional_t;
140 
141 /* link create types for VOL */
142 typedef enum H5VL_link_create_type_t {
143     H5VL_LINK_CREATE_HARD,
144     H5VL_LINK_CREATE_SOFT,
145     H5VL_LINK_CREATE_UD
146 } H5VL_link_create_type_t;
147 
148 /* types for link GET callback */
149 typedef enum H5VL_link_get_t {
150     H5VL_LINK_GET_INFO, /* link info                         */
151     H5VL_LINK_GET_NAME, /* link name                         */
152     H5VL_LINK_GET_VAL   /* link value                        */
153 } H5VL_link_get_t;
154 
155 /* types for link SPECIFIC callback */
156 typedef enum H5VL_link_specific_t {
157     H5VL_LINK_DELETE, /* H5Ldelete(_by_idx)                */
158     H5VL_LINK_EXISTS, /* link existence                    */
159     H5VL_LINK_ITER    /* H5Literate/visit(_by_name)              */
160 } H5VL_link_specific_t;
161 
162 /* Typedef and values for native VOL connector link optional VOL operations */
163 typedef int H5VL_link_optional_t;
164 /* (No optional link VOL operations currently) */
165 
166 /* types for object GET callback */
167 typedef enum H5VL_object_get_t {
168     H5VL_OBJECT_GET_FILE, /* object file                       */
169     H5VL_OBJECT_GET_NAME, /* object name                       */
170     H5VL_OBJECT_GET_TYPE, /* object type                       */
171     H5VL_OBJECT_GET_INFO  /* H5Oget_info(_by_idx|name)         */
172 } H5VL_object_get_t;
173 
174 /* types for object SPECIFIC callback */
175 typedef enum H5VL_object_specific_t {
176     H5VL_OBJECT_CHANGE_REF_COUNT, /* H5Oincr/decr_refcount             */
177     H5VL_OBJECT_EXISTS,           /* H5Oexists_by_name                 */
178     H5VL_OBJECT_LOOKUP,           /* Lookup object                     */
179     H5VL_OBJECT_VISIT,            /* H5Ovisit(_by_name)                */
180     H5VL_OBJECT_FLUSH,            /* H5{D|G|O|T}flush                  */
181     H5VL_OBJECT_REFRESH           /* H5{D|G|O|T}refresh                */
182 } H5VL_object_specific_t;
183 
184 /* Typedef for VOL connector object optional VOL operations */
185 typedef int H5VL_object_optional_t;
186 
187 /* types for async request SPECIFIC callback */
188 typedef enum H5VL_request_specific_t {
189     H5VL_REQUEST_WAITANY,  /* Wait until any request completes */
190     H5VL_REQUEST_WAITSOME, /* Wait until at least one requesst completes */
191     H5VL_REQUEST_WAITALL   /* Wait until all requests complete */
192 } H5VL_request_specific_t;
193 
194 /* Typedef and values for native VOL connector request optional VOL operations */
195 typedef int H5VL_request_optional_t;
196 /* (No optional request VOL operations currently) */
197 
198 /* types for 'blob' SPECIFIC callback */
199 typedef enum H5VL_blob_specific_t {
200     H5VL_BLOB_DELETE,  /* Delete a blob (by ID) */
201     H5VL_BLOB_GETSIZE, /* Get size of blob */
202     H5VL_BLOB_ISNULL,  /* Check if a blob ID is "null" */
203     H5VL_BLOB_SETNULL  /* Set a blob ID to the connector's "null" blob ID value */
204 } H5VL_blob_specific_t;
205 
206 /* Typedef and values for native VOL connector blob optional VOL operations */
207 typedef int H5VL_blob_optional_t;
208 /* (No optional blob VOL operations currently) */
209 
210 /* Types for different ways that objects are located in an HDF5 container */
211 typedef enum H5VL_loc_type_t {
212     H5VL_OBJECT_BY_SELF,
213     H5VL_OBJECT_BY_NAME,
214     H5VL_OBJECT_BY_IDX,
215     H5VL_OBJECT_BY_TOKEN
216 } H5VL_loc_type_t;
217 
218 typedef struct H5VL_loc_by_name {
219     const char *name;
220     hid_t       lapl_id;
221 } H5VL_loc_by_name_t;
222 
223 typedef struct H5VL_loc_by_idx {
224     const char *    name;
225     H5_index_t      idx_type;
226     H5_iter_order_t order;
227     hsize_t         n;
228     hid_t           lapl_id;
229 } H5VL_loc_by_idx_t;
230 
231 typedef struct H5VL_loc_by_token {
232     H5O_token_t *token;
233 } H5VL_loc_by_token_t;
234 
235 /* Structure to hold parameters for object locations.
236  * Either: BY_SELF, BY_NAME, BY_IDX, BY_TOKEN
237  *
238  * Note: Leave loc_by_token as the first union member so we
239  *       can perform the simplest initialization of the struct
240  *       without raising warnings.
241  *
242  * Note: BY_SELF requires no union members.
243  */
244 typedef struct H5VL_loc_params_t {
245     H5I_type_t      obj_type;
246     H5VL_loc_type_t type;
247     union {
248         H5VL_loc_by_token_t loc_by_token;
249         H5VL_loc_by_name_t  loc_by_name;
250         H5VL_loc_by_idx_t   loc_by_idx;
251     } loc_data;
252 } H5VL_loc_params_t;
253 
254 /* Info for H5VL_FILE_GET_CONT_INFO */
255 typedef struct H5VL_file_cont_info_t {
256     unsigned version;       /* version information (keep first) */
257     uint64_t feature_flags; /* Container feature flags          */
258                             /* (none currently defined)         */
259     size_t token_size;      /* Size of tokens                   */
260     size_t blob_id_size;    /* Size of blob IDs                 */
261 } H5VL_file_cont_info_t;
262 
263 /* VOL connector info fields & callbacks */
264 typedef struct H5VL_info_class_t {
265     size_t size;                     /* Size of the VOL info                         */
266     void *(*copy)(const void *info); /* Callback to create a copy of the VOL info    */
267     herr_t (*cmp)(int *cmp_value, const void *info1, const void *info2); /* Callback to compare VOL info */
268     herr_t (*free)(void *info);                     /* Callback to release a VOL info               */
269     herr_t (*to_str)(const void *info, char **str); /* Callback to serialize connector's info into a string */
270     herr_t (*from_str)(const char *str,
271                        void **     info); /* Callback to deserialize a string into connector's info */
272 } H5VL_info_class_t;
273 
274 /* VOL object wrap / retrieval callbacks */
275 /* (These only need to be implemented by "pass through" VOL connectors) */
276 typedef struct H5VL_wrap_class_t {
277     void *(*get_object)(const void *obj); /* Callback to retrieve underlying object       */
278     herr_t (*get_wrap_ctx)(
279         const void *obj,
280         void **     wrap_ctx); /* Callback to retrieve the object wrapping context for the connector */
281     void *(*wrap_object)(void *obj, H5I_type_t obj_type,
282                          void *wrap_ctx); /* Callback to wrap a library object */
283     void *(*unwrap_object)(void *obj);    /* Callback to unwrap a library object */
284     herr_t (*free_wrap_ctx)(
285         void *wrap_ctx); /* Callback to release the object wrapping context for the connector */
286 } H5VL_wrap_class_t;
287 
288 /* H5A routines */
289 typedef struct H5VL_attr_class_t {
290     void *(*create)(void *obj, const H5VL_loc_params_t *loc_params, const char *attr_name, hid_t type_id,
291                     hid_t space_id, hid_t acpl_id, hid_t aapl_id, hid_t dxpl_id, void **req);
292     void *(*open)(void *obj, const H5VL_loc_params_t *loc_params, const char *attr_name, hid_t aapl_id,
293                   hid_t dxpl_id, void **req);
294     herr_t (*read)(void *attr, hid_t mem_type_id, void *buf, hid_t dxpl_id, void **req);
295     herr_t (*write)(void *attr, hid_t mem_type_id, const void *buf, hid_t dxpl_id, void **req);
296     herr_t (*get)(void *obj, H5VL_attr_get_t get_type, hid_t dxpl_id, void **req, va_list arguments);
297     herr_t (*specific)(void *obj, const H5VL_loc_params_t *loc_params, H5VL_attr_specific_t specific_type,
298                        hid_t dxpl_id, void **req, va_list arguments);
299     herr_t (*optional)(void *obj, H5VL_attr_optional_t opt_type, hid_t dxpl_id, void **req,
300                        va_list arguments);
301     herr_t (*close)(void *attr, hid_t dxpl_id, void **req);
302 } H5VL_attr_class_t;
303 
304 /* H5D routines */
305 typedef struct H5VL_dataset_class_t {
306     void *(*create)(void *obj, const H5VL_loc_params_t *loc_params, const char *name, hid_t lcpl_id,
307                     hid_t type_id, hid_t space_id, hid_t dcpl_id, hid_t dapl_id, hid_t dxpl_id, void **req);
308     void *(*open)(void *obj, const H5VL_loc_params_t *loc_params, const char *name, hid_t dapl_id,
309                   hid_t dxpl_id, void **req);
310     herr_t (*read)(void *dset, hid_t mem_type_id, hid_t mem_space_id, hid_t file_space_id, hid_t dxpl_id,
311                    void *buf, void **req);
312     herr_t (*write)(void *dset, hid_t mem_type_id, hid_t mem_space_id, hid_t file_space_id, hid_t dxpl_id,
313                     const void *buf, void **req);
314     herr_t (*get)(void *obj, H5VL_dataset_get_t get_type, hid_t dxpl_id, void **req, va_list arguments);
315     herr_t (*specific)(void *obj, H5VL_dataset_specific_t specific_type, hid_t dxpl_id, void **req,
316                        va_list arguments);
317     herr_t (*optional)(void *obj, H5VL_dataset_optional_t opt_type, hid_t dxpl_id, void **req,
318                        va_list arguments);
319     herr_t (*close)(void *dset, hid_t dxpl_id, void **req);
320 } H5VL_dataset_class_t;
321 
322 /* H5T routines*/
323 typedef struct H5VL_datatype_class_t {
324     void *(*commit)(void *obj, const H5VL_loc_params_t *loc_params, const char *name, hid_t type_id,
325                     hid_t lcpl_id, hid_t tcpl_id, hid_t tapl_id, hid_t dxpl_id, void **req);
326     void *(*open)(void *obj, const H5VL_loc_params_t *loc_params, const char *name, hid_t tapl_id,
327                   hid_t dxpl_id, void **req);
328     herr_t (*get)(void *obj, H5VL_datatype_get_t get_type, hid_t dxpl_id, void **req, va_list arguments);
329     herr_t (*specific)(void *obj, H5VL_datatype_specific_t specific_type, hid_t dxpl_id, void **req,
330                        va_list arguments);
331     herr_t (*optional)(void *obj, H5VL_datatype_optional_t opt_type, hid_t dxpl_id, void **req,
332                        va_list arguments);
333     herr_t (*close)(void *dt, hid_t dxpl_id, void **req);
334 } H5VL_datatype_class_t;
335 
336 /* H5F routines */
337 typedef struct H5VL_file_class_t {
338     void *(*create)(const char *name, unsigned flags, hid_t fcpl_id, hid_t fapl_id, hid_t dxpl_id,
339                     void **req);
340     void *(*open)(const char *name, unsigned flags, hid_t fapl_id, hid_t dxpl_id, void **req);
341     herr_t (*get)(void *obj, H5VL_file_get_t get_type, hid_t dxpl_id, void **req, va_list arguments);
342     herr_t (*specific)(void *obj, H5VL_file_specific_t specific_type, hid_t dxpl_id, void **req,
343                        va_list arguments);
344     herr_t (*optional)(void *obj, H5VL_file_optional_t opt_type, hid_t dxpl_id, void **req,
345                        va_list arguments);
346     herr_t (*close)(void *file, hid_t dxpl_id, void **req);
347 } H5VL_file_class_t;
348 
349 /* H5G routines */
350 typedef struct H5VL_group_class_t {
351     void *(*create)(void *obj, const H5VL_loc_params_t *loc_params, const char *name, hid_t lcpl_id,
352                     hid_t gcpl_id, hid_t gapl_id, hid_t dxpl_id, void **req);
353     void *(*open)(void *obj, const H5VL_loc_params_t *loc_params, const char *name, hid_t gapl_id,
354                   hid_t dxpl_id, void **req);
355     herr_t (*get)(void *obj, H5VL_group_get_t get_type, hid_t dxpl_id, void **req, va_list arguments);
356     herr_t (*specific)(void *obj, H5VL_group_specific_t specific_type, hid_t dxpl_id, void **req,
357                        va_list arguments);
358     herr_t (*optional)(void *obj, H5VL_group_optional_t opt_type, hid_t dxpl_id, void **req,
359                        va_list arguments);
360     herr_t (*close)(void *grp, hid_t dxpl_id, void **req);
361 } H5VL_group_class_t;
362 
363 /* H5L routines */
364 typedef struct H5VL_link_class_t {
365     herr_t (*create)(H5VL_link_create_type_t create_type, void *obj, const H5VL_loc_params_t *loc_params,
366                      hid_t lcpl_id, hid_t lapl_id, hid_t dxpl_id, void **req, va_list arguments);
367     herr_t (*copy)(void *src_obj, const H5VL_loc_params_t *loc_params1, void *dst_obj,
368                    const H5VL_loc_params_t *loc_params2, hid_t lcpl_id, hid_t lapl_id, hid_t dxpl_id,
369                    void **req);
370     herr_t (*move)(void *src_obj, const H5VL_loc_params_t *loc_params1, void *dst_obj,
371                    const H5VL_loc_params_t *loc_params2, hid_t lcpl_id, hid_t lapl_id, hid_t dxpl_id,
372                    void **req);
373     herr_t (*get)(void *obj, const H5VL_loc_params_t *loc_params, H5VL_link_get_t get_type, hid_t dxpl_id,
374                   void **req, va_list arguments);
375     herr_t (*specific)(void *obj, const H5VL_loc_params_t *loc_params, H5VL_link_specific_t specific_type,
376                        hid_t dxpl_id, void **req, va_list arguments);
377     herr_t (*optional)(void *obj, H5VL_link_optional_t opt_type, hid_t dxpl_id, void **req,
378                        va_list arguments);
379 } H5VL_link_class_t;
380 
381 /* H5O routines */
382 typedef struct H5VL_object_class_t {
383     void *(*open)(void *obj, const H5VL_loc_params_t *loc_params, H5I_type_t *opened_type, hid_t dxpl_id,
384                   void **req);
385     herr_t (*copy)(void *src_obj, const H5VL_loc_params_t *loc_params1, const char *src_name, void *dst_obj,
386                    const H5VL_loc_params_t *loc_params2, const char *dst_name, hid_t ocpypl_id, hid_t lcpl_id,
387                    hid_t dxpl_id, void **req);
388     herr_t (*get)(void *obj, const H5VL_loc_params_t *loc_params, H5VL_object_get_t get_type, hid_t dxpl_id,
389                   void **req, va_list arguments);
390     herr_t (*specific)(void *obj, const H5VL_loc_params_t *loc_params, H5VL_object_specific_t specific_type,
391                        hid_t dxpl_id, void **req, va_list arguments);
392     herr_t (*optional)(void *obj, H5VL_object_optional_t opt_type, hid_t dxpl_id, void **req,
393                        va_list arguments);
394 } H5VL_object_class_t;
395 
396 /* Asynchronous request 'notify' callback */
397 typedef herr_t (*H5VL_request_notify_t)(void *ctx, H5ES_status_t status);
398 
399 /* "Levels" for 'get connector class' introspection callback */
400 typedef enum H5VL_get_conn_lvl_t {
401     H5VL_GET_CONN_LVL_CURR, /* Get "current" connector (for this object) */
402     H5VL_GET_CONN_LVL_TERM  /* Get "terminal" connector (for this object) */
403                             /* (Recursively called, for pass-through connectors) */
404                             /* (Connectors that "split" must choose which connector to return) */
405 } H5VL_get_conn_lvl_t;
406 
407 /* Forward declaration of H5VL_class_t, defined later in this file */
408 struct H5VL_class_t;
409 
410 /* Container/connector introspection routines */
411 typedef struct H5VL_introspect_class_t {
412     herr_t (*get_conn_cls)(void *obj, H5VL_get_conn_lvl_t lvl, const struct H5VL_class_t **conn_cls);
413     herr_t (*opt_query)(void *obj, H5VL_subclass_t cls, int opt_type, hbool_t *supported);
414 } H5VL_introspect_class_t;
415 
416 /* Async request operation routines */
417 typedef struct H5VL_request_class_t {
418     herr_t (*wait)(void *req, uint64_t timeout, H5ES_status_t *status);
419     herr_t (*notify)(void *req, H5VL_request_notify_t cb, void *ctx);
420     herr_t (*cancel)(void *req);
421     herr_t (*specific)(void *req, H5VL_request_specific_t specific_type, va_list arguments);
422     herr_t (*optional)(void *req, H5VL_request_optional_t opt_type, va_list arguments);
423     herr_t (*free)(void *req);
424 } H5VL_request_class_t;
425 
426 /* 'blob' routines */
427 typedef struct H5VL_blob_class_t {
428     herr_t (*put)(void *obj, const void *buf, size_t size, void *blob_id, void *ctx);
429     herr_t (*get)(void *obj, const void *blob_id, void *buf, size_t size, void *ctx);
430     herr_t (*specific)(void *obj, void *blob_id, H5VL_blob_specific_t specific_type, va_list arguments);
431     herr_t (*optional)(void *obj, void *blob_id, H5VL_blob_optional_t opt_type, va_list arguments);
432 } H5VL_blob_class_t;
433 
434 /* Object token routines */
435 typedef struct H5VL_token_class_t {
436     herr_t (*cmp)(void *obj, const H5O_token_t *token1, const H5O_token_t *token2, int *cmp_value);
437     herr_t (*to_str)(void *obj, H5I_type_t obj_type, const H5O_token_t *token, char **token_str);
438     herr_t (*from_str)(void *obj, H5I_type_t obj_type, const char *token_str, H5O_token_t *token);
439 } H5VL_token_class_t;
440 
441 /**
442  * \ingroup H5VLDEV
443  * Class information for each VOL connector
444  */
445 //! <!-- [H5VL_class_t_snip] -->
446 typedef struct H5VL_class_t {
447     /* Overall connector fields & callbacks */
448     unsigned           version;          /**< VOL connector class struct version #     */
449     H5VL_class_value_t value;            /**< Value to identify connector              */
450     const char *       name;             /**< Connector name (MUST be unique!)         */
451     unsigned           cap_flags;        /**< Capability flags for connector           */
452     herr_t (*initialize)(hid_t vipl_id); /**< Connector initialization callback        */
453     herr_t (*terminate)(void);           /**< Connector termination callback           */
454 
455     /* VOL framework */
456     H5VL_info_class_t info_cls; /**< VOL info fields & callbacks  */
457     H5VL_wrap_class_t wrap_cls; /**< VOL object wrap / retrieval callbacks */
458 
459     /* Data Model */
460     H5VL_attr_class_t     attr_cls;     /**< Attribute (H5A*) class callbacks */
461     H5VL_dataset_class_t  dataset_cls;  /**< Dataset (H5D*) class callbacks   */
462     H5VL_datatype_class_t datatype_cls; /**< Datatype (H5T*) class callbacks  */
463     H5VL_file_class_t     file_cls;     /**< File (H5F*) class callbacks      */
464     H5VL_group_class_t    group_cls;    /**< Group (H5G*) class callbacks     */
465     H5VL_link_class_t     link_cls;     /**< Link (H5L*) class callbacks      */
466     H5VL_object_class_t   object_cls;   /**< Object (H5O*) class callbacks    */
467 
468     /* Infrastructure / Services */
469     H5VL_introspect_class_t introspect_cls; /**< Container/connector introspection class callbacks */
470     H5VL_request_class_t    request_cls;    /**< Asynchronous request class callbacks */
471     H5VL_blob_class_t       blob_cls;       /**< 'Blob' class callbacks */
472     H5VL_token_class_t      token_cls;      /**< VOL connector object token class callbacks */
473 
474     /* Catch-all */
475     herr_t (*optional)(void *obj, int op_type, hid_t dxpl_id, void **req,
476                        va_list arguments); /**< Optional callback */
477 } H5VL_class_t;
478 //! <!-- [H5VL_class_t_snip] -->
479 
480 /********************/
481 /* Public Variables */
482 /********************/
483 
484 /*********************/
485 /* Public Prototypes */
486 /*********************/
487 
488 #ifdef __cplusplus
489 extern "C" {
490 #endif
491 
492 /* Helper routines for VOL connector authors */
493 /**
494  * \ingroup H5VLDEV
495  * \brief Registers a new VOL connector
496  *
497  * \param[in] cls A pointer to the plugin structure to register
498  * \vipl_id
499  * \return \hid_t{VOL connector}
500  *
501  * \details H5VLregister_connector() registers a new VOL connector as a member
502  *          of the virtual object layer class. This VOL connector identifier is
503  *          good until the library is closed or the connector is unregistered.
504  *
505  *          \p vipl_id is either #H5P_DEFAULT or the identifier of a VOL
506  *          initialization property list of class #H5P_VOL_INITIALIZE created
507  *          with H5Pcreate(). When created, this property list contains no
508  *          library properties. If a VOL connector author decides that
509  *          initialization-specific data are needed, they can be added to the
510  *          empty list and retrieved by the connector in the VOL connector's
511  *          initialize callback. Use of the VOL initialization property list is
512  *          uncommon, as most VOL-specific properties are added to the file
513  *          access property list via the connector's API calls which set the
514  *          VOL connector for the file open/create. For more information, see
515  *          the \ref_vol_doc.
516  *
517  *          H5VL_class_t is defined in H5VLconnector.h in the source code. It
518  *          contains class information for each VOL connector:
519  *          \snippet this H5VL_class_t_snip
520  *
521  * \since 1.12.0
522  *
523  */
524 H5_DLL hid_t H5VLregister_connector(const H5VL_class_t *cls, hid_t vipl_id);
525 /**
526  * \ingroup H5VLDEV
527  */
528 H5_DLL void *H5VLobject(hid_t obj_id);
529 /**
530  * \ingroup H5VLDEV
531  */
532 H5_DLL hid_t H5VLget_file_type(void *file_obj, hid_t connector_id, hid_t dtype_id);
533 /**
534  * \ingroup H5VLDEV
535  */
536 H5_DLL hid_t H5VLpeek_connector_id_by_name(const char *name);
537 /**
538  * \ingroup H5VLDEV
539  */
540 H5_DLL hid_t H5VLpeek_connector_id_by_value(H5VL_class_value_t value);
541 
542 #ifdef __cplusplus
543 }
544 #endif
545 
546 #endif /* H5VLconnector_H */
547