Linux C编程（二）

1、父进程创建一个新的文本文件，并向文本文件中写入数据，当数据写入完成后，用匿名管道通信的方式将该文件传输给子进程，同时用命名管道文件将该文件传输给另一个进程

#include<unistd.h>
#include<stdio.h>
#include<stdlib.h>
#include<fcntl.h>
#include<string.h>
#include<sys/types.h>
#include<sys/stat.h>
#define BUFSZ 256
#define FIFO_NAME "/home/xianfeng/my_fifo"
#define BUFFER_SIZE PIPE_BUF

int main(void)
{
        FILE *fp;
        char *hello="hello ";
        int res;
        int fd[2];
        char buf[BUFSZ];
        pid_t pid;
        int len;
        if( pipe(fd)<0 )
        {
                perror("管道调用失败");
                exit(1);
        }
        if( (pid = fork())<0 )
        {
                perror("创建进程失败");
                exit(1);
        }
    else if(pid > 0)
        {
                printf("这是父进程\n");
                //fd[1]=open("test,txt");
                printf("父进程写入hello");
                write(fd[1], "hello\n", 25);

        printf("\n");
		if(access(FIFO_NAME,F_OK)==-1){
            res=mkfifo(FIFO_NAME,0777);
            if(res!=0){
                fprintf(stderr,"创建fifo文件失败\n");
                exit(EXIT_FAILURE);
            }
		}
		printf("Process %d opening FIFO\n", getpid());
        res = open(FIFO_NAME, O_WRONLY);
        printf("Process %d result %d\n", getpid(), res);
        sleep(5);
        if (res != -1){
            write(res,"Hello Linux!\n",25);
        }
         (void)close(res);
        printf("Process %d finished\n", getpid());
        exit(EXIT_SUCCESS);
        }
        else
        {
                printf("这是子进程\n");
                read(fd[0], buf, BUFSZ);
                printf("子进程读出结果 %s\n", buf);
        }
                return 0;
}

#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <limits.h>
#include <sys/types.h>
#include <sys/stat.h>

#define FIFO_NAME "/home/xianfeng/my_fifo"
#define BUFFER_SIZE PIPE_BUF
#define TEN_MEG (1024 * 1024 * 10)

int main()
{
    int pipe_fd;
    int res;
    int open_mode = O_RDONLY;
    int bytes_sent = 0;
    char buffer[BUFFER_SIZE + 1];

    printf("Process %d opening FIFO O_RDONLY\n", getpid());
    pipe_fd = open(FIFO_NAME, open_mode);
    read(pipe_fd,buffer,25);
    printf("%s\n",buffer);	

    printf("Process %d finished\n", getpid());
    exit(EXIT_SUCCESS);
}

2、利用套接字分别编写一个简易的服务器端程序和客户端程序，实现基于INTERNET的双向网络通信

/*client.c*/
#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <stdlib.h>
int main()
{
    int sockfd;
    int len;
    struct sockaddr_in address;
    int result;
    char ch = 'A';

    sockfd = socket(AF_INET, SOCK_STREAM, 0);    //创建套接字
    //套接字命名
    address.sin_family = AF_INET;                       
    address.sin_addr.s_addr = inet_addr("127.0.0.1");
    address.sin_port = 9734;
    len = sizeof(address);	
    //连接到服务器套接字
    result = connect(sockfd, (struct sockaddr *)&address, len);

    if(result == -1) {
        perror("oops: client");
        exit(1);
    }
    //通信操作
    write(sockfd, &ch, 1);
    read(sockfd, &ch, 1);
    printf("char from server = %c\n", ch);
    close(sockfd);   
    exit(0);
}

/*server.c*/
#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <stdlib.h>

int main()
{
    int server_sockfd, client_sockfd;
    int server_len, client_len;
    struct sockaddr_in server_address;
    struct sockaddr_in client_address;

    //创建套接字
    server_sockfd = socket(AF_INET, SOCK_STREAM, 0);
    //命名套接字
    server_address.sin_family = AF_INET;
    server_address.sin_addr.s_addr = inet_addr("127.0.0.1");
    server_address.sin_port = 9734;
    server_len = sizeof(server_address);
    bind(server_sockfd, (struct sockaddr *)&server_address, server_len);  //bind命名

    //创建一个连接队列
    listen(server_sockfd, 5);    //创建容量为5的队列
    while(1) {
        char ch;
        printf("server waiting\n");

    //接受一个连接
        client_len = sizeof(client_address);
        client_sockfd = accept(server_sockfd,(struct sockaddr *)&client_address, &client_len);  //accept接受客户连接
    //通信操作
        read(client_sockfd, &ch, 1);
        ch++;
        write(client_sockfd, &ch, 1);
        close(client_sockfd);
    }
}

3、假设有一个整数初值为200，开20个线程，每个线程将这个整数减掉10，最后刚好把这个整数减到0,；要求考虑同步与互斥管理，实现死锁的检测和避免管理

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <pthread.h>
#include <semaphore.h>
#define NUM_THREADS 20

void *thread_function(void *arg);
sem_t bin_sem;

#define WORK_SIZE 1024
char work_area[WORK_SIZE];

int num=200;
int main() {
    int res;
    pthread_t a_thread[NUM_THREADS];
    void *thread_result;
    int lots_of_threads;
    res = sem_init(&bin_sem, 0, 0);
    if (res != 0) {
        perror("信号初始化错误\n");
        exit(EXIT_FAILURE);
    }

    for(lots_of_threads = 0; lots_of_threads < NUM_THREADS; lots_of_threads++) {

        res = pthread_create(&(a_thread[lots_of_threads]), NULL, thread_function, (void *)&lots_of_threads);//创建进程，用数组表示
        if (res != 0) {
            perror("线程创建失败\n");
            exit(EXIT_FAILURE);
        }
        sleep(1);
    }
    for(lots_of_threads = NUM_THREADS - 1; lots_of_threads >= 0; lots_of_threads--) {
        res = pthread_join(a_thread[lots_of_threads], &thread_result/*指向线程返回值*/);  //以阻塞的方式等待线程结束，进程同步操作
        if (res == 0) {
            printf("Picked up a thread\n");
        }
        else {
            perror("pthread_join failed");
        }
    }
    printf("All done\n");
    exit(EXIT_SUCCESS);
}

void *thread_function(void *arg) {
    sem_post(&bin_sem);
    int my_number = *(int *)arg;
    int rand_num;
    num-=10;
    printf("%d\n",num);
    printf("thread_function is running. Argument was %d\n", my_number);
    rand_num=1+(int)(9.0*rand()/(RAND_MAX+1.0));
    sleep(rand_num);
    printf("Bye from %d\n", my_number);
    sem_post(&bin_sem);
    pthread_exit(NULL);
}