OSMemoryNotification.c [plain text]
#include <errno.h>
#include <libkern/OSMemoryNotification.h>
#include <mach/mach.h>
#include <notify.h>
#include <stdlib.h>
#include <sys/time.h>
const char *kOSMemoryNotificationName = "com.apple.system.memorystatus";
struct _OSMemoryNotification {
int token;
mach_port_t port;
};
int
OSMemoryNotificationCreate(OSMemoryNotificationRef *note)
{
OSMemoryNotificationRef ref = malloc(sizeof(struct _OSMemoryNotification));
if (NULL == ref) {
return ENOMEM;
}
if (NOTIFY_STATUS_OK != notify_register_mach_port(kOSMemoryNotificationName, &ref->port, 0, &ref->token))
return ENOMEM;
*note = ref;
return 0;
}
int
OSMemoryNotificationDestroy(OSMemoryNotificationRef note)
{
if (NOTIFY_STATUS_OK != notify_cancel(note->token))
return EINVAL;
if (KERN_SUCCESS != mach_port_deallocate(mach_task_self(), note->port))
return EINVAL;
free(note);
return 0;
}
int
OSMemoryNotificationWait(OSMemoryNotificationRef note, OSMemoryNotificationLevel *level)
{
return OSMemoryNotificationTimedWait(note, level, NULL);
}
static mach_msg_timeout_t
abs_to_timeout(const struct timeval *abstime)
{
struct timeval rel, now;
gettimeofday(&now, NULL);
rel.tv_usec = abstime->tv_usec - now.tv_usec;
rel.tv_sec = abstime->tv_sec - now.tv_sec;
if (rel.tv_usec < 0) {
rel.tv_usec += 1000000;
rel.tv_sec--;
}
if (((int)rel.tv_sec < 0) || ((rel.tv_sec == 0) && (rel.tv_usec == 0))) {
return 0;
}
return rel.tv_sec * 1000 + rel.tv_usec / 1000;
}
int
OSMemoryNotificationTimedWait(OSMemoryNotificationRef note, OSMemoryNotificationLevel *level, const struct timeval *abstime)
{
mach_msg_empty_rcv_t msg = {{0}};
mach_msg_return_t ret;
uint64_t val;
if (abstime) {
mach_msg_timeout_t timeout = abs_to_timeout(abstime);
if (0 == timeout)
return ETIMEDOUT;
ret = mach_msg(&msg.header, MACH_RCV_MSG | MACH_RCV_TIMEOUT, 0, sizeof msg, note->port, timeout, MACH_PORT_NULL);
if (MACH_RCV_TIMED_OUT == ret) {
return ETIMEDOUT;
}
} else {
ret = mach_msg(&msg.header, MACH_RCV_MSG, 0, sizeof msg, note->port, MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL);
}
if (MACH_MSG_SUCCESS != ret)
return EINVAL;
if (NOTIFY_STATUS_OK != notify_get_state(note->token, &val))
return EINVAL;
*level = (OSMemoryNotificationLevel)val;
return 0;
}
OSMemoryNotificationLevel OSMemoryNotificationCurrentLevel(void)
{
uint64_t val;
int token;
if (NOTIFY_STATUS_OK != notify_register_check(kOSMemoryNotificationName, &token))
return OSMemoryNotificationLevelAny;
if (NOTIFY_STATUS_OK != notify_get_state(token, &val))
return OSMemoryNotificationLevelAny;
if (NOTIFY_STATUS_OK != notify_cancel(token))
return OSMemoryNotificationLevelAny;
return (OSMemoryNotificationLevel)val;
}