update bài 2, bài 1

Bài 1: Xóa phần debug
Bài 2: Tạo 2 tiến trình con, xử lý semaphore

Author: GitHubCodeForLife

bai1.c

@@ -7,19 +7,13 @@
 int x=0;
 void* thread(void* arg) 
 { 
-	
-	printf("\n Entered..\n"); 
-
 	//critical section 
 	do{
 		x=x+1;	
 		if(x==20)
 		   x=0;
 		usleep(100);
 	}while(1);
-	
-	//signal 
-	printf("\nJust Exiting...\n"); 
 } 
 
 int main() 

bai1_sem.c

@@ -6,11 +6,8 @@
 sem_t mutex; 
 int x=0;
 void* thread(void* arg) 
-{ 
-	//wait 
-	sem_wait(&mutex); 
-	printf("\nP1: Entered..\n"); 
-
+{  
+	sem_wait(&mutex);
 	//critical section 
 	do{
 		//printf("\n%d",x);
@@ -19,10 +16,7 @@ void* thread(void* arg)
 		   x=0;
 		//usleep(100);
 	}while(1);
-	
-	//signal 
-	printf("\nJust Exiting...\n"); 
-	sem_post(&mutex); 
+	sem_post(&mutex); 	
 } 
 
 

bai2

@@ -1,51 +1,71 @@
-#include <sys/types.h>
-#include <unistd.h>
-#include <stdio.h>
 #include <pthread.h> 
-#include <semaphore.h> 
-#include <time.h>
+#include <sys/stat.h>
+#include <stdio.h>          /* printf()                 */
+#include <stdlib.h>         /* exit(), malloc(), free() */
+#include <unistd.h>
+#include <sys/types.h>      /* key_t, sem_t, pid_t      */
+#include <sys/wait.h>
+#include <sys/shm.h>        /* shmat(), IPC_RMID        */
+#include <errno.h>          /* errno, ECHILD            */
+#include <semaphore.h>      /* sem_open(), sem_destroy(), sem_wait().. */
+#include <fcntl.h>          /* O_CREAT, O_EXEC          */
+
 void* A1(void* arg) 
 { 
-  	printf("A1"); 
+  	printf("A1\n"); 
 } 
 void* A2(void* arg) 
 { 
- 	printf("A2"); 
+ 	printf("A2\n"); 
 } 
 void* B1(void* arg) 
 { 
- 	printf("B1"); 	
+ 	printf("B1\n"); 	
 } 
 void* B2(void* arg) 
 { 
- 	printf("B2");
+ 	printf("B2\n");
 } 
 int main()
 {
-	 printf("\n");
+	 int i;
 	 pthread_t t1, t2;
 	 pid_t pid;
-	 pid = fork();// duplicates process
-	 switch (pid)
-	{
- 	case -1:
-	 	printf( "Khong the tao tien trinh con !" );
-	 	exit(1);
- 	case 0:
-		pthread_create(&t1,NULL,A1,NULL); 
-		pthread_create(&t2,NULL,A2,NULL); 
-		pthread_join(t1, NULL);
-		pthread_join(t2, NULL);
-		break;
- 	default:
-		pthread_create(&t1,NULL,B1,NULL); 
-		pthread_create(&t2,NULL,B2,NULL);
-		pthread_join(t1, NULL);
-		pthread_join(t2, NULL); 
-		break;
- 	}
- 	printf("\n");
-	exit(0);
-	//return 0;
+
+	  /* create 2 child processes */
+	   for (i = 0; i < 2; i++){
+		pid = fork ();
+		if (pid < 0)              /* check for error      */
+		    printf ("Fork error.\n");
+		else if (pid == 0)
+		    break;                  /* child processes */
+	   }
+
+	 if (pid != 0){
+		/* wait for all children to exit */
+		while (pid = waitpid (-1, NULL, 0)){
+		    if (errno == ECHILD)
+		        break;
+		}
+
+		printf ("\nParent: All children have exited.\n");
+		exit (0);
+   	 }
+    else{
+		if(i==0){
+			pthread_create(&t1,NULL,A1,NULL); 
+			pthread_create(&t2,NULL,A2,NULL); 
+			pthread_join(t1, NULL);	
+			pthread_join(t2, NULL);		
+			
+		} else{
+			pthread_create(&t1,NULL,B1,NULL); 
+			pthread_create(&t2,NULL,B2,NULL); 
+			pthread_join(t1, NULL);
+			pthread_join(t2, NULL);
+		}
+			exit (0);		
+		
+   }
 }
 

bai2.c

@@ -1,92 +1,93 @@
-#include <sys/types.h>
-#include <unistd.h>
-#include <stdio.h>
 #include <pthread.h> 
-#include <semaphore.h> 
-#include <sys/types.h>
 #include <sys/stat.h>
-#include <fcntl.h>
+#include <stdio.h>          /* printf()                 */
+#include <stdlib.h>         /* exit(), malloc(), free() */
+#include <unistd.h>
+#include <sys/types.h>      /* key_t, sem_t, pid_t      */
+#include <sys/wait.h>
+#include <sys/shm.h>        /* shmat(), IPC_RMID        */
+#include <errno.h>          /* errno, ECHILD            */
+#include <semaphore.h>      /* sem_open(), sem_destroy(), sem_wait().. */
+#include <fcntl.h>          /* O_CREAT, O_EXEC          */
 
-#define SNAME1 "/mysem1"
-#define SNAME2 "/mysem2"
-sem_t mutex1, mutex2;
 void* A1(void* arg) 
 { 
-  	printf("A1");
-	//post A2
-	sem_post(&mutex1);
-	//Post B2
-	sem_t* sem1 = (sem_t*) arg;
-	sem_post(sem1);
+  	printf("A1\n");
 } 
 void* A2(void* arg) 
 { 	
-	//Wait A1
-        sem_wait(&mutex1);
-	//Wait B1
-        sem_t* sem2 = (sem_t*) arg;
-	sem_wait(sem2);
-			
- 	printf("A2"); 
+ 	printf("A2\n"); 
 } 
 void* B1(void* arg) 
 { 
- 	printf("B1");
-	//Post B2
-	sem_post(&mutex2);
-	//Post A2
-	sem_t* sem2 = (sem_t*) arg;
-	sem_post(sem2);
-			
+ 	printf("B1\n");		
 } 
 void* B2(void* arg) 
 { 
-	//Wait B1
-	sem_wait(&mutex2);
-	//Wait A1
-	sem_t* sem1 = (sem_t*) arg;
-	sem_wait(sem1);
- 	printf("B2"); 
+ 	printf("B2\n"); 
 } 
 int main()
-{
-	 printf("\n");
-	 sem_init(&mutex1, 0, 0);
-	 sem_init(&mutex1, 0, 0);
+{	
+	 unsigned int value = 0;
+	 int i;
 	 sem_t *sem1, *sem2;
-	 //sem_init(sem1, 1, 0);
-	 //sem_init(sem2, 1, 0);
-	 pthread_t t1, t2, t3, t4;
+	 sem1 = sem_open ("pSem1", O_CREAT | O_EXCL, 0644, value); 
+	 sem2 = sem_open ("pSem2", O_CREAT | O_EXCL, 0644, value);
+   	 /* name of semaphore is "pSem", semaphore is reached using this name */
+   	 sem_unlink ("pSem1");
+	 sem_unlink ("pSem2");    
+	 pthread_t t1, t2;
 	 pid_t pid;
-	 pid = fork();
-	 switch (pid)
-	{
- 	case -1:
-	 	printf( "Khong the tao tien trinh con !" );
-	 	exit(1);
- 	case 0:
-		printf("\n");
-		sem1 = sem_open(SNAME1, 0);
-	 	sem2 = sem_open(SNAME2, 0);
-		pthread_create(&t1,NULL,A1,(void*)&sem1); 
-		pthread_create(&t2,NULL,A2,(void*)&sem2); 
-		pthread_join(t2, NULL);
+
+	  /* fork child processes */
+	   for (i = 0; i < 2; i++){
+		pid = fork ();
+		if (pid < 0)              /* check for error      */
+		    printf ("Fork error.\n");
+		else if (pid == 0)
+		    break;                  /* child processes */
+	   }
+
+	 if (pid != 0){
+		/* wait for all children to exit */
+		while (pid = waitpid (-1, NULL, 0)){
+		    if (errno == ECHILD)
+		        break;
+		}
+
+		printf ("\nParent: All children have exited.\n");
+		
+		/* cleanup semaphores */
+		printf("sem_destroy return value:%d\n",sem_destroy (sem1));
+		printf("sem_destroy return value:%d\n",sem_destroy (sem2));
+		exit (0);
+   	 }
+    else{
+	printf("Hello from process %d\n",i);
+	if(i%2==0){
+		//wait 
+		printf("P %d is waiting...\n",i);
+		pthread_create(&t1,NULL,A1,NULL); 
 		pthread_join(t1, NULL);
-		break;
- 	default:
-		printf("\n");
-		sem1 = sem_open(SNAME1, 0);
-	 	sem2 = sem_open(SNAME2, 0);
-		pthread_create(&t3,NULL,B1,(void*)&sem2);
-		pthread_create(&t4,NULL,B2,(void*)&sem1);
-		pthread_join(t4, NULL); 
-		pthread_join(t3, NULL);
-		break;
- 	}
- 	printf("\n");
-	sem_destroy(&mutex1);
-	sem_destroy(&mutex2);
-	exit(0);
-	//return 0;
+		sem_post(sem1);	
+		sem_wait(sem2);			
+		pthread_create(&t2,NULL,A2,NULL); 
+		pthread_join(t2, NULL);		
+		
+       		//sleep (1);
+	} else{
+		pthread_create(&t1,NULL,B1,NULL); 
+		pthread_join(t1, NULL);
+		
+		sem_post(sem2);
+		sem_wait(sem1);
+		pthread_create(&t2,NULL,B2,NULL); 
+		pthread_join(t2, NULL);
+				
+	}
+        exit (0);		
+       
+   }
+	
 }