FreeBSD/sharedmemory/main.c

#include <unistd.h>
#include <err.h>                                                                                          
#include <errno.h>
#include <pthread.h>
#include <pthread_np.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/socket.h>
#include <netinet/in.h>		/* bind */
#include <fcntl.h> // O_xxxx
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>  //bzero

const char* pathname="/rats";

static void *udpController(void *dummy)
{
	/* 
	 *
	 * block SIGINT 
	 * to make sure this signal
	 * will be handled by the main thread
	 * because this is this thread's way to terminate
	 * the process
	 *
	 */

	sigset_t sigmask;
	sigemptyset(&sigmask);
	sigaddset(&sigmask,SIGINT);
	if(sigprocmask(SIG_BLOCK,&sigmask,NULL))
		perror("sigprocmask");

	/* 
	 *
	 * create share memory segment
	 *
	 */

	// may use SHM_ANON running FreeBSD while called by the same process
	int fd=shm_open(pathname,O_RDWR,0600);
	if (fd < 0){
		warn("%s: shm_open", __func__);
		pthread_exit(NULL);
	}
	if (ftruncate(fd, getpagesize()) < 0){
		warn("%s: ftruncate", __func__);
		pthread_exit(NULL);
	}

	/* 
	 *
	 * open an UDP socket
	 *
	 */

	int s=socket(PF_INET,SOCK_DGRAM,0);
	if(-1==s){
		warn("socket");
		pthread_exit(NULL);
	}

	/*
	 * Socket address, internet style.
	 */

	struct sockaddr_in sa;
	bzero(&sa,sizeof sa);
	sa.sin_len=sizeof sa;
	sa.sin_family=AF_INET;
	sa.sin_port=htons(5514);
	//sa.sin_addr.s_addr = htonl((((((127 << 8) | 0) << 8) | 0) << 8) | 1);
	sa.sin_addr.s_addr = INADDR_ANY;
	uint32_t cursor;
	if(!bind(s,(struct sockaddr*)&sa,sizeof sa)){

		for(;;){
			char buffer[getpagesize()];
			int n=read(s,&buffer[4],getpagesize()-4);
			if(n==-1){
				break;
			}

			if(n>0){
				if(!bcmp((char*)&buffer[4],"quit",4)){
					printf("kill request\n");
					/* bye */
					kill(getpid(),SIGINT);
					break;
				}

				/* prepend length into the buffer */
				cursor=n+4;		
				buffer[0]= (n>> 24);
				buffer[1]= (n>> 16);
				buffer[2]= (n>> 8);
				buffer[3]= (n);

				ssize_t len = pwrite(fd, buffer, cursor, 0);	

				if(len<0){
					warn("%s: pwrite failure", __func__);
				}
				if(len!=cursor){
					warn("%zu vs %du, %s: pwrite length mismatch",len,cursor, __func__);
				}

			}
		}

	}else
		warn("bind failure");

	close (s);
	pthread_exit(NULL);
}

static void showmem()
{
	int fd = shm_open(pathname, O_RDONLY, 0600);

	if (fd < 0) {
		warn("%s: shm_open", __func__);
		return;
	}

	/* extract length */
	uint8_t curbuf[4];
	ssize_t len=pread(fd, &curbuf, 4, 0);
	if (len == 4) {
		uint32_t l = (uint32_t)curbuf[0] << 24 |
			(uint32_t)curbuf[1] << 16 |
			(uint32_t)curbuf[2] << 8  |
			(uint32_t)curbuf[3];
		if (l > 0) {
			uint8_t* buf = malloc(l);
			if (buf) {
				/* data */
				ssize_t total=pread(fd,buf,l,4);
				printf("%zu:\t %s",total,buf);
				free(buf);
			} else {
				warn("malloc");
			}

		}
	} else {
		printf("nothing.\n");
	}
}

void
sigHandler(int signo, siginfo_t *si, void * /* ucontext_t */ uap)
{
	switch (signo) {
		case SIGINFO:
			printf("no need to panic.\n");
			  __attribute__((fallthrough));
		case SIGALRM:
			showmem();
			break;
		default:
			printf("sig:%d received.", signo);
			break;
	}

}

int main(int argc, char* argv[])
{
	timer_t		timerid;
	int fd = shm_open(pathname, O_CREAT | O_RDWR, 0600);

	if (fd < 0)
		err(EPERM, "%s: shm_open", __func__);
	if (ftruncate(fd, getpagesize()) < 0)
		err(EIO, "%s: ftruncate", __func__);

	pthread_t pidudp;
	pthread_create(&pidudp, NULL, &udpController, NULL);
	/* signal */
	struct sigaction sa;
	sa.sa_handler = NULL;
	sa.sa_sigaction = &sigHandler;
	sa.sa_flags = SA_SIGINFO;
	sigemptyset(&sa.sa_mask);
	// Block every signal during the handler
	sigfillset(&sa.sa_mask);
	if (sigaction(SIGINFO, &sa, NULL)) {
		warn("SIGNFO not caught.");
	}
	if (sigaction(SIGALRM, &sa, NULL)) {
		err(2, "sigaction:ALARM");
	}

	/* timer */
	if (timer_create(CLOCK_REALTIME, NULL, &timerid)) {
		err(2,"timer_create failed.");
	}
	/* 3 -> TIMER_MAX stored into timerid->oshandle */
	printf("Timer #%d now created at address %p.\n", timer_oshandle_np(timerid), timerid);
	/* Set values and start timer */
	struct itimerspec its;
	its.it_interval.tv_sec = 2;
	its.it_interval.tv_nsec = 0;
	its.it_value.tv_sec = its.it_interval.tv_sec;
	its.it_value.tv_nsec = 0;

	if (timer_settime(timerid, 0, &its, NULL)) {
		warn("timer_settime failed.");
	}

	printf("waiting...\n");
	sigset_t sigmask;
	sigemptyset(&sigmask);
	sigaddset(&sigmask,SIGINT);
	sigprocmask(SIG_BLOCK,&sigmask,NULL);

	int sigpending;
	if(sigwait(&sigmask,&sigpending))
		warn("sigwait failure.\n");
	//brutal thread killing, I know it s bad. but I 'm punk btw.
	printf("bye\n");
	timer_delete(timerid);
	struct timespec t;
	if (!clock_gettime(CLOCK_REALTIME, &t)) {
		t.tv_sec += 5;
		if (pthread_timedjoin_np(pidudp, NULL, &t)) {
			pthread_cancel(pidudp);
		}
	} else {
		warn("clock_gettime");
	}

	// required until SHM_ANON is used, or shm remains (persistent until reboot)
	shm_unlink(pathname); 
}