ham_condition_state()

Attach a condition associated with a state transition

Synopsis:

#include <ha/ham.h>

ham_condition_t *ham_condition_state(
                         ham_entity_t *ehdl,
                         const char *cname,
                         unsigned fromstate,
                         unsigned tostate,
                         unsigned flags );

Library:

libham

Description:

This condition is triggered when the specified entity changes from a state matching fromstate to a state matching tostate. CONDSTATEANY can be used to specify a wild card signifying any STATE. The matching of states is based on either an explicit match or special conditions explained in the Flags section below.

The ehdl argument is an entity handle obtained either:

• from a ham_attach*() call or a ham_entity*() call

  or:

• by calling ham_entity_handle*() with an existing entity name. Since conditions are associated with entities, the entity handle (ehdl) must be available before you can add conditions.

Flags

Standard flags that are applicable for conditions are also valid here. (See ham_condition() for more details). In addition, the following flags are also defined:

/* special condition flags */

HCONDSTATEFROMSET /* from state is a set */
HCONDSTATETOSET /* to state is a set */
HCONDSTATEFROMINV /* invert from state set */
HCONDSTATETOINV /* invert to state set */

States can be given using:

• individual values
• the wild card CONDSTATEANY
• bitmaps that allow several states to be referred to collectively as sets.

If fromstate or tostate refers to a set, the corresponding flag HCONDSTATEFROMSET or HCONDSTATETOSET must be set.

If you want fromstate or tostate to refer to the logical negation of a set of states define HCONDSTATEFROMINV or HCONDSTATETOINV in flags. This would logically invert the set of states specified (equivalent to saying “any state other than this set”).

Returns:

a condition handle

Success.

NULL

Failure (errno is set).

Errors:

EBADF

Couldn't connect to the HAM.

EEXIST

The name provided for the condition already exists.

EINVAL

The handle, type, or name given is invalid (e.g. it contains the “/” character) or is NULL.

The connection to the HAM is invalid. This happens when the process that opened the connection (using ham_connect()) and the process that's calling ham_condition() aren't the same.

ENAMETOOLONG

The name given (in aname) is too long, i.e. it exceeds _POSIX_PATH_MAX (defined in <limits.h>). Note that the combined length of an entity/condition/action name is also limited by _POSIX_PATH_MAX.

ENOMEM

Not enough memory to create a new handle.

In addition to the above errors, the HAM returns any error it encounters while servicing this request.

Classification:

QNX Neutrino

See also:

ham_condition(), ham_condition_raise(), ham_attach() ham_attach_self() ham_entity() ham_entity_control() ham_entity_handle() ham_entity_handle_free() ham_entity_node()