1 /*
2  * timer_create.c - create a per-process timer.
3  */
4 
5 #include <stddef.h>
6 #include <errno.h>
7 #include <signal.h>
8 #include <stdlib.h>
9 #include <string.h>
10 #include <time.h>
11 #include <sys/syscall.h>
12 
13 #include "kernel-posix-timers.h"
14 
15 #ifdef __NR_timer_create
16 
17 #define __NR___syscall_timer_create __NR_timer_create
18 static __inline__ _syscall3(int, __syscall_timer_create, clockid_t, clock_id,
19 			struct sigevent *, evp, kernel_timer_t *, ktimerid);
20 
21 /* Create a per-process timer */
timer_create(clockid_t clock_id,struct sigevent * evp,timer_t * timerid)22 int timer_create(clockid_t clock_id, struct sigevent *evp, timer_t * timerid)
23 {
24 	int retval;
25 	kernel_timer_t ktimerid;
26 	struct sigevent default_evp;
27 	struct timer *newp;
28 
29 	if (evp == NULL) {
30 		/*
31 		 * The kernel has to pass up the timer ID which is a userlevel object.
32 		 * Therefore we cannot leave it up to the kernel to determine it.
33 		 */
34 		default_evp.sigev_notify = SIGEV_SIGNAL;
35 		default_evp.sigev_signo = SIGALRM;
36 		evp = &default_evp;
37 	}
38 
39 	/* Notification via a thread is not supported yet */
40 	if (__builtin_expect(evp->sigev_notify == SIGEV_THREAD, 1))
41 		return -1;
42 
43 	/*
44 	 * We avoid allocating too much memory by basically using
45 	 * struct timer as a derived class with the first two elements
46 	 * being in the superclass. We only need these two elements here.
47 	 */
48 	newp = malloc(offsetof(struct timer, thrfunc));
49 	if (newp == NULL)
50 		return -1;	/* No memory */
51 	default_evp.sigev_value.sival_ptr = newp;
52 
53 	retval = __syscall_timer_create(clock_id, evp, &ktimerid);
54 	if (retval != -1) {
55 		newp->sigev_notify = evp->sigev_notify;
56 		newp->ktimerid = ktimerid;
57 
58 		*timerid = (timer_t) newp;
59 	} else {
60 		/* Cannot allocate the timer, fail */
61 		free(newp);
62 		retval = -1;
63 	}
64 
65 	return retval;
66 }
67 
68 #endif
69