VFD plugins (#602)

* Implement support for loading of Virtual File Drivers as plugins

Fix plugin caching for VOL connector and VFD plugins

Fix plugin iteration to skip paths that can't be opened

* Enable dynamic loading of VFDs with HDF5_DRIVER environment variable

* Temporarily disable error reporting during H5F_open double file open

* Default to using HDstat in h5_get_file_size for unknown VFDs

* Use macros for some environment variables that HDF5 interprets

* Update "null" and "ctl testing" VFDs

1 files changed, 18 insertions, 3 deletions

diff --git a/src/H5FDprivate.h b/src/H5FDprivate.h
index 6dbd483..fa562f9 100644
--- a/src/H5FDprivate.h
+++ b/src/H5FDprivate.h
@@ -81,12 +81,19 @@ typedef struct {
         }                                                                                                    \
     }
 
-/* Define structure to hold driver ID & info for FAPLs */
+/* Define structure to hold driver ID, info & configuration string for FAPLs */
 typedef struct {
-    hid_t       driver_id;   /* Driver's ID */
-    const void *driver_info; /* Driver info, for open callbacks */
+    hid_t       driver_id;         /* Driver's ID */
+    const void *driver_info;       /* Driver info, for open callbacks */
+    const char *driver_config_str; /* Driver configuration string */
 } H5FD_driver_prop_t;
 
+/* Which kind of VFD field to use for searching */
+typedef enum H5FD_get_driver_kind_t {
+    H5FD_GET_DRIVER_BY_NAME, /* Name field is set */
+    H5FD_GET_DRIVER_BY_VALUE /* Value field is set */
+} H5FD_get_driver_kind_t;
+
 /*****************************/
 /* Library Private Variables */
 /*****************************/
@@ -97,6 +104,7 @@ typedef struct {
 
 /* Forward declarations for prototype arguments */
 struct H5F_t;
+union H5PL_key_t;
 
 H5_DLL int    H5FD_term_interface(void);
 H5_DLL herr_t H5FD_locate_signature(H5FD_t *file, haddr_t *sig_addr);
@@ -107,10 +115,17 @@ H5_DLL herr_t        H5FD_sb_load(H5FD_t *file, const char *name, const uint8_t
 H5_DLL void *        H5FD_fapl_get(H5FD_t *file);
 H5_DLL herr_t        H5FD_free_driver_info(hid_t driver_id, const void *driver_info);
 H5_DLL hid_t         H5FD_register(const void *cls, size_t size, hbool_t app_ref);
+H5_DLL hid_t         H5FD_register_driver_by_name(const char *name, hbool_t app_ref);
+H5_DLL hid_t         H5FD_register_driver_by_value(H5FD_class_value_t value, hbool_t app_ref);
+H5_DLL htri_t        H5FD_is_driver_registered_by_name(const char *driver_name, hid_t *registered_id);
+H5_DLL htri_t H5FD_is_driver_registered_by_value(H5FD_class_value_t driver_value, hid_t *registered_id);
+H5_DLL hid_t  H5FD_get_driver_id_by_name(const char *name, hbool_t is_api);
+H5_DLL hid_t  H5FD_get_driver_id_by_value(H5FD_class_value_t value, hbool_t is_api);
 H5_DLL H5FD_t *H5FD_open(const char *name, unsigned flags, hid_t fapl_id, haddr_t maxaddr);
 H5_DLL herr_t  H5FD_close(H5FD_t *file);
 H5_DLL int     H5FD_cmp(const H5FD_t *f1, const H5FD_t *f2);
 H5_DLL herr_t  H5FD_driver_query(const H5FD_class_t *driver, unsigned long *flags /*out*/);
+H5_DLL herr_t  H5FD_check_plugin_load(const H5FD_class_t *cls, const union H5PL_key_t *key, hbool_t *success);
 H5_DLL haddr_t H5FD_alloc(H5FD_t *file, H5FD_mem_t type, struct H5F_t *f, hsize_t size, haddr_t *frag_addr,
                           hsize_t *frag_size);
 H5_DLL herr_t  H5FD_free(H5FD_t *file, H5FD_mem_t type, struct H5F_t *f, haddr_t addr, hsize_t size);