LinuxC进程编程

nsops指出要操作的信号个数;sops指向一个sembuf结构体数组;这个结构体的三个成员变量如下;

通过信号量实现共享内存读写同步
send.c

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <sys/sem.h>
#include <unistd.h>
#include <errno.h>
#include <wait.h>

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define FILE ;./;
#define MAX_SIZE 100

int main() {
    int sem_id, shm_id;
    struct sembuf sem_buf;
    char buffer[MAX_SIZE];

    /* 创建键值 */
    key_t sem_key = ftok(FILE, 1);
    printf(;The sem_key is 0x%x.
;, sem_key);
    key_t shm_key = ftok(FILE, 2);
    printf(;The shm_key is 0x%x.
;, shm_key);
    
    /* 获取描述符 */
    if ((sem_id = semget(sem_key, 2, 0644 | IPC_CREAT)) < 0) {
        perror(;Semget error;);
        exit(1);
    }
    printf(;The sem_id is %d.
;, sem_id);
    if ((shm_id = shmget(shm_key, 2, 0644 | IPC_CREAT)) < 0) {
        perror(;Shmget error;);
        exit(1);
    }
    printf(;The shm_id is %d.
;, shm_id);

    /* 初始化信号量 */
    semctl(sem_id, 0, SETVAL, 1);//0-1
    semctl(sem_id, 1, SETVAL, 0);//1-0
    printf(;Sem-0 = %d.
;, semctl(sem_id, 0, GETVAL, 0));
    printf(;Sem-1 = %d.
;, semctl(sem_id, 1, GETVAL, 0));

    sem_buf.sem_flg = SEM_UNDO;

    /* 映射共享内存 */
    void *shm = shmat(shm_id, NULL, 0);
    if (shm == (void *)-1) {
        perror(;Shmat error;);
        exit(1);
    }

    /* 发送消息 */
    while (1) {
        /* P-0 */
        sem_buf.sem_num = 0;
        sem_buf.sem_op = -1;
        semop(sem_id, &sem_buf, 1);

        /* 发送 */
        memset(buffer, 0, sizeof(buffer));
        printf(;Send message>>>;);
        scanf(%[^
]%*c;, buffer);
        memcpy(shm, buffer, strlen(buffer));

        /* V-1 */
        sem_buf.sem_num = 1;
        sem_buf.sem_op = 1;
        semop(sem_id, &sem_buf, 1);

        if (strcmp(buffer, ;end;) == 0) break;
    }

    /* 解除共享内存映射 */
    shmdt(buffer);

    return 0;
}

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <sys/sem.h>
#include <unistd.h>
#include <errno.h>
#include <wait.h>

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define FILE ;./;
#define MAX_SIZE 100

int main() {
    int sem_id, shm_id;
    struct sembuf sem_buf;
    char buffer[MAX_SIZE];

    /* 创建键值 */
    key_t sem_key = ftok(FILE, 1);
    printf(;The sem_key is 0x%x.
;, sem_key);
    key_t shm_key = ftok(FILE, 2);
    printf(;The shm_key is 0x%x.
;, shm_key);
    
    /* 获取描述符 */
    if ((sem_id = semget(sem_key, 2, 0644 | IPC_CREAT)) < 0) {
        perror(;Semget error;);
        exit(1);
    }
    printf(;The sem_id is %d.
;, sem_id);
    if ((shm_id = shmget(shm_key, 2, 0644 | IPC_CREAT)) < 0) {
        perror(;Shmget error;);
        exit(1);
    }
    printf(;The shm_id is %d.
;, shm_id);

    sem_buf.sem_flg = SEM_UNDO;

    /* 映射共享内存 */
    void *shm = shmat(shm_id, NULL, 0);
    if (shm == (void *)-1) {
        perror(;Shmat error;);
        exit(1);
    }

    /* 接收消息 */
    while (1) {
        /* P-1 */
        sem_buf.sem_num = 1;
        sem_buf.sem_op = -1;
        semop(sem_id, &sem_buf, 1);

        /* 接收 */
        memset(buffer, 0, sizeof(buffer));
        memcpy(buffer, shm, sizeof(buffer));
        memset(shm, 0, sizeof(buffer));
        printf(;Receive message:%s.
;, buffer);

        /* V-0 */
        sem_buf.sem_num = 0;
        sem_buf.sem_op = 1;
        semop(sem_id, &sem_buf, 1);

        if (strcmp(buffer, ;end;) == 0) break;
    }

    /* 解除共享内存映射 */
    shmdt(buffer);

    /* 删除 */
    if(semctl(sem_id, IPC_RMID, 0) == -1) {
		perror(;Semctl error;);
		exit(1);
	}
    if(shmctl(shm_id, IPC_RMID, 0) == -1) {
		perror(;Shmctl error;);
		exit(1);
	}

    return 0;
}

#include <sys/types.h>
#include <signal.h>

int kill(pid_t pid, int sig);

#include <signal.h>

typedef void (*sighandler_t)(int);

sighandler_t signal(int signum, sighandler_t handler);

#include <sys/types.h>
#include <signal.h>
#include <unistd.h>

#include <stdio.h>

void handle(int sig) {
    if (sig == SIGINT) {
        printf(;
SIGINT.
;);
    }
    if (sig == SIGALRM) {
        printf(;
SIGALRM.
;);
    }
}

int main() {
    signal(SIGINT, handle);
    signal(SIGALRM, handle);
    
    alarm(10);//十秒后向本进程发送SIGALRM信号
    pause();//等待一个已经被用户处理的信号

    return 0;
}

atreus;atreus-virtual-machine:~/code/220317$ make
gcc -Wall main.c -o m
atreus;atreus-virtual-machine:~/code/220317$ ./m
^C
SIGINT.
atreus;atreus-virtual-machine:~/code/220317$ ./m

SIGALRM.
atreus;atreus-virtual-machine:~/code/220317$