X-Git-Url: https://gapil.gnulinux.it/gitweb/?p=gapil.git;a=blobdiff_plain;f=listati%2Fmessage_getter.c;fp=listati%2Fmessage_getter.c;h=4b19bef3018ac30abf7b270aaf8f534055c34cc6;hp=0000000000000000000000000000000000000000;hb=9fc37da8fe691ce7ca6222773aace47c5edef3d1;hpb=5b56553e2294af812321ffaea6b296d2ad068f41

diff --git a/listati/message_getter.c b/listati/message_getter.c
new file mode 100644
index 0000000..4b19bef
--- /dev/null
+++ b/listati/message_getter.c
@@ -0,0 +1,49 @@
+void HandSigInt(int sig);
+#define MSGMAXSIZE 256
+char *shmname = "messages";
+char *semname = "messages";
+
+int main(int argc, char *argv[]) 
+{
+    sem_t * sem, void * shm_ptr, time_t t;
+    ...
+    Signal(SIGINT, HandSigInt);
+    // get a shared memory segment
+    if ((shm_ptr = CreateShm(shmname, MSGMAXSIZE, 0666, 0)) == NULL) {
+	perror("Cannot find shared memory");
+	exit(1);
+    }
+    // get a locked semaphore
+    if ((sem = sem_open(semname, O_CREAT|O_EXCL, 0666, 0)) == SEM_FAILED) {
+	perror("Cannot open semaphore");
+	exit(1);
+    }
+    // set initial string
+    strncpy((char *) shm_ptr, argv[optind], MSGMAXSIZE);
+    // do initial release
+    if (sem_post(sem) != 0) {
+	perror("cannot do semaphore initial release");
+	exit(1);
+    }
+    // main loop
+    while(1) {
+	if (sem_getvalue(sem, &i) !=0) {             // get sem values
+	    perror("cannot get semaphore value");
+	    exit(1);
+	}
+	printf("sem=%i, ", i);                       // print sem values
+	t = time(NULL);                              // get time
+	printf("%s", ctime(&t));                     // print time
+	if (sem_wait(sem) != 0) {                    // acquire semaphore
+	    perror("cannot use semaphore");
+	    exit(1);
+	}
+	printf("message: %s\n", (char *) shm_ptr );  // print message
+	if (sem_post(sem) != 0) {                    // release semaphore
+	    perror("cannot release semaphore");
+	    exit(1);
+	}
+	sleep(1);
+   }
+exit(0);    
+}