?

創建fifo管道的時候，open會阻塞？
還是我的代碼有問題？

#include <stdio.h>

#include <unistd.h>

#include <fcntl.h>

#include <errno.h>

#include <sys/types.h>

#Include <sys/stat.h>

#define FIFO1 "/tmp/fifo.1"

#define FIFO2 "/tmp/fifo.2"

#define FILE_MODE (S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH)

int main()

{

? ? int rfd, wfd;

? ? if ((mkfifo(FIFO1, FILE_MODE) < 0) && errno != EEXIST)

? ? {//error

? ?? ???exit(0);

? ? }

? ? if ((mkfifo(FIFO2, FILE_MODE) < 0) && errno != EEXIST)

? ? {//error

? ?? ???exit(0);

? ? }

fprintf(stderr, "before open\n");

? ? rfd = open(FIFO1, O_RDONLY, 0);

? ? wfd = open(FIFO2, O_WRONLY, 0);

fprintf(stderr, "after open\n");

//到這里出現問題，after open一直沒有打印出來。

}

?

?

?

man 3 open.一般3的解釋較2的解釋詳細.

O_NONBLOCK

? ?? ?When opening a FIFO with O_RDONLY or O_WRONLY set:

? ?? ?* If??O_NONBLOCK??is set, an open() for reading-only shall return without delay. An open() for writing-only shall return an error if no process currently has the file open for reading.

? ?? ? * If O_NONBLOCK is clear, an open() for reading-only shall block the calling thread until??a??thread??opens??the??file for writing. An open() for writing-only shall block the calling thread until a thread opens the??file for reading.

復制代碼

轉載于:https://www.cnblogs.com/YL450606975/p/4427238.html

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