Linux--mmap实现进程间通信_linux mmap 跨进程通信代码-优快云博客

本文通过一个服务端和客户端程序示例介绍了如何使用内存映射文件进行进程间通信。服务端不断更新共享内存区域的数据，而客户端则读取这些更新并打印出来。该方法适用于需要频繁小数据量交换的场景。

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服务端程序

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/types.h>


int main(int argc, char **argv)
{
	static int couter = 0;
	if (argc != 2)
	{
		printf("usage: %s file_name\n", argv[0]);
		return -1;
	}

	int fd = open(argv[1], O_CREAT | O_RDWR, 0744);
	if (fd < 0)
	{
		perror("open");
		return -1;
	}

	lseek(fd, 0x1000, SEEK_SET);
	write(fd, "\0", 1);

	char *mm = (char *)mmap(NULL, 0x1000, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
	if (mm == MAP_FAILED)
	{
		perror("mmap");
		return -1;
	}

	close(fd);
	while(1)
	{
		sprintf(mm, "%d[gzhang]", couter++);
	//	*mm = 'G';
		sleep(1);
	}

	munmap(mm, 0x1000);

	return 0;
}

客户端程序

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <string.h>
#include <sys/types.h>
#include <errno.h>

int main(int argc, char **argv)
{
	if (argc != 2)
	{
		printf("usage: %s file_name\n", argv[0]);
		return -1;
	}

	int fd = open(argv[1], O_RDWR);
	if (fd < 0)
	{
		perror("open");
		return -1;
	}

	//lseek(fd, 0x1000, SEEK_SET);
	//write(fd, "\0", 1);

	char *mm = mmap(NULL, 0x1000, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
	if (!mm)
	{
		printf("mmap error\n");
		return -1;
	}

	close(fd);
	while(1)
	{
		printf("get [%s]\n", mm);
		sleep(1);
	}

	munmap(mm, 0x1000);

	return 0;
}