cc [ flag... ] file... -lsysevent [ library... ] #include <libsysevent.h> int sysevent_subscribe_event(sysevent_handle_t *sysevent_hdl, char *event_class, char **event_subclass_list, int num_subclasses);
void sysevent_unsubscribe_event(sysevent_handle_t *sysevent_hdl,
char *event_class);
event_class
event_subclass_list
num_subclasses
sysevent_hdl
The sysevent_subscribe_event() function registers the caller's interest in event notifications belonging to the class event_class and the subclasses contained in event_subclass_list. The subscriber handle sysevent_hdl is updated with the new subscription and the calling process receives event notifications from the event handler specified in sysevent_bind_handle.
System events matching event_class and a subclass contained in event_subclass_list published after the caller returns from sysevent_subscribe_event() are guaranteed to be delivered to the calling process. Matching system events published and queued prior to a call to sysevent_subscribe_event() may be delivered to the process's event handler.
The num_subclasses argument provides the number of subclass string elements in event_subclass_list.
A caller can use the event class EC_ALL to subscribe to all event classes and subclasses. The event class EC_SUB_ALL can be used to subscribe to all subclasses within a given event class.
Subsequent calls to sysevent_subscribe_event() are allowed to add additional classes or subclasses. To remove an existing subscription, sysevent_unsubscribe_event() must be used to remove the subscription.
The sysevent_unsubscribe_event() function removes the subscription described by event_class for sysevent_hdl. Event notifications matching event_class will not be delivered to the calling process upon return.
A caller can use the event class EC_ALL to remove all subscriptions for sysevent_hdl.
The library manages all subscription resources.
The sysevent_subscribe_event() function returns 0 if the subscription is successful. Otherwise, -1 is returned and errno is set to indicate the error.
The sysevent_unsubscribe_event() function returns no value.
The sysevent_subscribe_event() function will fail if:
EACCES
EINVAL
ENOMEM
Example 1 Subscribing for environmental events
#include <libsysevent.h> #include <sys/nvpair.h> static int32_t attr_int32; #define CLASS1 "class1" #define CLASS2 "class2" #define SUBCLASS_1 "subclass_1" #define SUBCLASS_2 "subclass_2" #define SUBCLASS_3 "subclass_3" #define MAX_SUBCLASS 3 static void event_handler(sysevent_t *ev) { nvlist_t *nvlist; /* * Special processing for events (CLASS1, SUBCLASS_1) and * (CLASS2, SUBCLASS_3) */ if ((strcmp(CLASS1, sysevent_get_class_name(ev)) == 0 && strcmp(SUBCLASS_1, sysevent_get_subclass_name(ev)) == 0) || (strcmp(CLASS2, sysevent_get_subclass_name(ev) == 0) && strcmp(SUBCLASS_3, sysevent_get_subclass(ev)) == 0)) { if (sysevent_get_attr_list(ev, &nvlist) != 0) return; if (nvlist_lookup_int32(nvlist, "my_int32_attr", &attr_int32) != 0) return; /* Event Processing */ } else { /* Event Processing */ } } int main(int argc, char **argv) { sysevent_handle_t *shp; const char *subclass_list[MAX_SUBCLASS]; /* Bind event handler and create subscriber handle */ shp = sysevent_bind_handle(event_handler); if (shp == NULL) exit(1); /* Subscribe to all CLASS1 event notifications */ subclass_list[0] = EC_SUB_ALL; if (sysevent_subscribe_event(shp, CLASS1, subclass_list, 1) != 0) { sysevent_unbind_handle(shp); exit(1); } /* Subscribe to CLASS2 events for subclasses: SUBCLASS_1, * SUBCLASS_2 and SUBCLASS_3 */ subclass_list[0] = SUBCLASS_1; subclass_list[1] = SUBCLASS_2; subclass_list[2] = SUBCLASS_3; if (sysevent_subscribe_event(shp, CLASS2, subclass_list, MAX_SUBCLASS) != 0) { sysevent_unbind_handle(shp); exit(1); } for (;;) { (void) pause(); } }
See attributes(5) for descriptions of the following attributes:
| |||||||||
syseventd(1M), sysevent_bind_handle(3SYSEVENT), sysevent_get_attr_list(3SYSEVENT), sysevent_get_class_name(3SYSEVENT), sysevent_get_vendor_name(3SYSEVENT), attributes(5)