write.c

一个驱动程序开发 一个系统调用 内附文档 非常详细

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <signal.h>
#include <time.h>

#define BUFSIZE 1024*100
#define MAXDATALEN (sizeof(int))


struct timespec ts;
int end = 0;
void clean_exit(int dummy) {
	end = 1;
}

main() {
	int fd, len, wlen;
	char receive[BUFSIZE];
	char writestr[32*BUFSIZE];
	
	signal(SIGTERM, clean_exit);	
	signal(SIGINT, clean_exit);	

	fd = open("/dev/mpcdevice0", O_RDWR);

	if( fd == -1) {
		printf("open error...\n");
		exit(0);
	}
	wlen = 0;
	while(1) {
			len = read(STDIN_FILENO, receive, 1);
			if(len!=1){
				perror("Sorry,read error!");
				return;
			}
			wlen += sprintf (writestr+wlen, "%c", receive[0]);
			if (receive[0]=='\n') break;
	}
	if ( write(fd,writestr, wlen) < 0) {/*试图从终端输出所读字符*/
		perror("\nSorry,write out error!\n");
      return;
	}else {
			printf("write OK...\n");
	}
	
	close(fd);
}