[新增] 信号量测试Demo

test_sem.c

@@ -0,0 +1,86 @@
+#include<unistd.h>
+#include<signal.h>
+#include<stdio.h>
+#include<string.h>
+#include<stdlib.h>
+#include<sys/wait.h>
+#include<semaphore.h>
+#include<sys/sem.h>
+#include <sys/stat.h>
+
+#include<fcntl.h>
+
+int main(){
+	int pid1,pid2;
+	sem_t *resource1; 
+	sem_t *resource2; 
+	char inpipe[200],outpipe1[100],outpipe2[100];
+	int fd[2];				//0为读出段,1为写入端    
+	pipe(fd);				//建立一个无名管道
+
+	pid1 = fork();
+	if(pid1<0){
+		printf("error in the first fork!");
+	}
+	else if(pid1==0){	//子进程1
+		printf("[%s|%u]Current: %u\n", __FUNCTION__, __LINE__, getpid());
+		printf("Pid of PID[1]: %u\n", getpid());
+
+		resource1=sem_open("name_sem1",O_CREAT,0666,0);		// 有名信号量打开，name_sem1
+		close(fd[0]);		//关掉读出端
+		lockf(fd[1],1,0);	// 管道持锁, 锁定从当前偏移量到文件结尾的区域
+		sprintf(outpipe1,"Child process 1 is sending a message!\n");
+		write(fd[1],outpipe1, strlen(outpipe1));
+		lockf(fd[1],0,0);	// 管道解锁
+		sem_post(resource1);			// 信号量开锁，name_sem1
+		sem_close(resource1);								// 有名信号量关闭，name_sem1
+		exit(0);			// 线程退出
+	}
+	
+	pid2 = fork();
+	if(pid2<0){
+		printf("error in the second fork!\n");
+	}else if(pid2==0){	// 子进程2
+		printf("[%s|%u]Current: %u\n", __FUNCTION__, __LINE__, getpid());
+		resource1=sem_open("name_sem1",O_CREAT,0666,0);
+		resource2=sem_open("name_sem2",O_CREAT,0666,0);
+
+		sem_wait(resource1);
+		printf("Pid of PID[2]: %u\n", getpid());
+		close(fd[0]);
+		lockf(fd[1],1,0);	
+		sprintf(outpipe2,"Child process 2 is sending a message!\n");
+		write(fd[1],outpipe2, strlen(outpipe2));
+		lockf(fd[1],0,0);		
+		sem_post(resource2);	
+
+		sem_close(resource1);
+		sem_close(resource2);
+
+		exit(0);
+	}
+
+	if(pid1 > 0 && pid2 >0){
+		printf("[%s|%u]Current: %u\n", __FUNCTION__, __LINE__, getpid());
+		resource2=sem_open("name_sem2",O_CREAT,0666,0);
+
+		sem_wait(resource2);	// 信号量持锁，source2
+		printf("Current: %u\n", getpid());
+
+		waitpid(pid1,NULL,0);	// 等待子线程1状态变化(退出)；
+		waitpid(pid2,NULL,0);	// 等待子线程2状态变化(退出)；
+
+		close(fd[1]);		//关掉写端
+		read(fd[0],inpipe,200);
+		printf("%s\n",inpipe);
+
+		sem_close(resource2);
+
+		exit(0);		// 进程退出，正常
+	}
+
+	sem_unlink("name_sem1");	// 信号量销毁，
+	sem_unlink("name_sem2");
+
+	return 0;
+}