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Controls the loading of dynamic plugin types


H5PL_SET_LOADING_STATE (plugin_control_mask)


herr_t H5PLset_loading_state( unsigned int plugin_control_mask )

unsigned int plugin_control_mask   IN: The list of dynamic plugin types to enable or disable. 
A plugin bit set to 0 (zero) prevents use of that dynamic plugin. 
A plugin bit set to 1 (one) enables use of that dynamic plugin.

Setting plugin_control_mask to a negative value enables all dynamic plugins. 
Setting plugin_control_mask to 0 (zero) disables all dynamic plugins.



The loading of external dynamic plugins can be controlled during runtime with an environment variable, HDF5_PLUGIN_PRELOAD. The environment variable can control the loading of dynamic filters at runtime, but it will disable it for all running programs that access that variable using the library.

 H5PL_SET_LOADING_STATE controls the loading of external dynamic plugins during program execution.


 H5PL_SET_LOADING_STATE uses one argument to enable or disable individual plugins.

The plugin_control_mask parameter is an encoded integer in which each bit controls a specific plugin or class of plugins. Bit positions allocated to date are listed in the “Plugin Type/Bit Position” table below.

A plugin bit set to 0 (zero) prevents the use of the dynamic plugin corresponding to that bit position. A plugin bit set to 1 (one) allows the use of that dynamic plugin.

All dynamic plugins can be enabled by setting plugin_control_mask to a negative value. A value of 0 (zero) will disable all dynamic plugins.

H5PL_SET_LOADING_STATE inspects the HDF5_PLUGIN_PRELOAD environment variable every time it is called. If the environment variable is set to the special :: string, all dynamic plugins will be disabled.


The classes of plugins subject to programmatic control are specified in the H5PL_type_t ENUM. Since only dynamically loaded filter plugins are currently subject to programmatic control, only one plugin type is defined:

Plugin TypeBit Position

Additional values may be added to the H5PL_type_t ENUM as programmatic control is implemented for other plugin types.


Returns a non-negative value if successful; otherwise returns a negative value.

/* Disable plugin X: Requires user to negate the state 
 * with a 0 in bit position X and AND it with the result 
 * from an H5PLget_loading_state call. */

int new_setting = curr_setting & ~H5PL_FILTER_PLUGIN ;
H5PLset_loading_state (new_setting);

Release    Change
1.8.15Function introduced in this release.

--- Last Modified: May 03, 2019 | 01:18 PM