[新增] 信号量测试Demo

.editorconfig

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+# EditorConfig helps developers define and maintain consistent
+# EditorConfig帮助开发人员定义和维护一致性
+# coding styles between different editors and IDEs
+# 不同编辑器和ide之间的编码样式
+# 打开需要格式化的文件并手动格式化代码（Mac OS ：shift+option+f  Windows ：shift+alt+f）
+# editorconfig.org
+# editorconfig顶级配置文件,停止向上寻找配置文件
+root = true
+
+[*]
+# change these settings to your own preference
+# 将这些设置更改为您自己的首选项
+# 缩进样式=空格
+indent_style = tab
+# 缩进大小=2
+indent_size = 8
+
+# we recommend you to keep these unchanged
+# 我们建议你保持这些不变
+# 换行符类型 = lf
+end_of_line = lf
+# 字符集=utf-8
+charset = utf-8
+# 删除行尾空格 = 是
+trim_trailing_whitespace = true
+# 插入最后一行=真
+insert_final_newline = true
+
+[*.md]
+# 删除行尾空格 = 否
+trim_trailing_whitespace = false
+
+[package.json]
+# 缩进样式=空格
+indent_style = space
+# 缩进大小=2
+indent_size = 2

.gitignore

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+
+output/

CMakeLists.txt

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+cmake_minimum_required(VERSION 3.18)
+
+set(TARGET_EXE demo_sem)
+
+project(${TARGET_EXE})
+
+add_executable(${TARGET_EXE})
+
+target_sources(${TARGET_EXE}
+    PRIVATE
+        test_sem.c
+)
+
+target_link_libraries(${TARGET_EXE} pthread)

ReadMe.md

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+
+
+## Install
+
+
+```shell
+# Top 
+cmake -S . -B output -G "Unix Makefiles"
+```

test_sem.c

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+#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;
+}