Linux FIFO 文件和读/写
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FIFO files and read/write
提问by Kreweta
I've been trying to get some insight on FIFO and this low level I/O before my laboratories on monday and I came to this situation I don't quite understand.
我一直试图在周一的实验室之前对 FIFO 和这种低级 I/O 有所了解，但我遇到了这种情况，我不太明白。
The program should:
该计划应：
Server:
服务器：
- creates FIFOs,
- sends 5 messages: "Message #i", with interval of 5 sec,
- deletes FIFOs,
- 创建 FIFO，
- 发送 5 条消息：“Message #i”，间隔为 5 秒，
- 删除 FIFO，
Client:
客户：
- reads from FIFO and displays the message,
- terminates if there was no msg for 6 seconds,
- 从 FIFO 读取并显示消息，
- 如果 6 秒内没有 msg 则终止，
And it does communicate however, client is displaying not exactly what I did send him, and more importantly, seems to be reading from the beginning every time a new msg arrives. I've been trying to figure out, for quite a while, and it just doesn't seem to match what the documentation said... Please help! :(
并且它确实进行了通信，但是客户端显示的并不是我发送给他的内容，更重要的是，每次新消息到达时，它似乎都从头开始阅读。我一直试图弄清楚，很长一段时间，它似乎与文档所说的不符......请帮忙！:(
server
服务器
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <string.h>
#include <sys/stat.h>
#include <unistd.h>
int main(int argc, char* argv[])
{
int s2c, c2s, i;
char fifo_name1[] = "/tmp/fifo1";
char fifo_name2[] = "/tmp/fifo2";
char msg[80], buf[10];
struct stat st;
// if no fifos, create 'em
if (stat(fifo_name1, &st) != 0)
mkfifo(fifo_name1, 0666);
if (stat(fifo_name2, &st) != 0)
mkfifo(fifo_name2, 0666);
s2c= open(fifo_name1, O_WRONLY);
c2s= open(fifo_name2, O_RDONLY);
// start sending messages, with 5s interval
for (i=0; i<5; i++)
{
printf("Message #%d \n", i);
strcat(msg, "Message #");
strcat(msg, itoa(i, buf, 10));
strcat(msg, "#include <stdio.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
int main(int argc, char* argv[])
{
int c2s, s2c, c=0;
char buf[10];
char fifo_name1[] = "/tmp/fifo1";
char fifo_name2[] = "/tmp/fifo2";
s2c= open(fifo_name1, O_RDONLY);
c2s= open(fifo_name2, O_WRONLY);
// receive messages
while (1)
{
if (read(s2c, &buf, sizeof(char)*10) > 0)
{
printf("%s \n", buf);
c=0;
}
sleep(1);
c++;
if (c>6)
break;
}
printf("client exit successfully");
return EXIT_SUCCESS;
}
");
write(s2c, msg, strlen(msg)+1);
sleep(5);
}
// delete fifos
unlink(fifo_name1);
unlink(fifo_name2);
printf("server exit successfully");
return EXIT_SUCCESS;
}
client
客户
##代码##采纳答案by Anton Kovalenko
strcat(msg, "Message #");always appends to the end of the string already in msg, and the string is never reset during the loop. Replace it with strcpy(msg, "Message #");to start each new message from scratch.
strcat(msg, "Message #");总是附加到已经在 中的字符串的末尾msg，并且字符串在循环期间永远不会被重置。将其替换strcpy(msg, "Message #");为从头开始每条新消息。
