c - 通过管道从一个进程发送到另一个进程的缓冲区大小

Question

我创建了两个子进程，它们之间有管道连接。

进程A中的代码:

char *buf;
size_t size;

buf = "some string";
size = strlen(buf);
printf("size in process A:%zu\n", size);
write(pfds[3][1], &size, sizeof (size_t));
write(pfds[3][1], buf, sizeof (buf));


buf="other string";
size = strlen(buf);
printf("size in process A:%zu\n", size);
write(pfds[3][1], &size, sizeof (size_t));
write(pfds[3][1], buf, sizeof (buf));

进程B中的代码:

size_t size;
/*read in size from Process A*/
read(pfds[3][0], &size, sizeof (size_t));
printf("READ size in process B: %zu\n", size);

/*allocate memory space for the line*/
char *buf = malloc(size);

/*read in line from process A*/
read(pfds[3][0], buf, size);
printf("READ buf in process B: %s.\n", buf);

/*read in size from readProcess*/
read(pfds[3][0], &size, sizeof (size_t));
printf("READ size in process B:%zu\n", size);

/*free the allocated memory*/
free(buf);

输出看起来像这样:

size in process A:11
size in process A:12
READ size in process B: 11
READ buf in process B: some
                            .
READ size in process B:101

我想用大小来控制一个while循环，不断地从A发送行到B，直到大小变成0。但是我做错了什么？第一次发送大小合适，第二次发送就不行了。

Answer 1

sizof(buf) 会返回4，一个指针的大小，你需要的是strlen(buf)所以

write(pfds[3][1], buf, sizeof (buf));

应该是

write(pfds[3][1], buf, strlen(buf));