How to map and r/w to a fifo file?

[yayuwang0624]

I am trying to use a pipe to achieve IPC in wasm. However, it seems like fifo is not mapped as a fifo, and I failed to open it.

I am not sure if the fifo type is supported or if I did it wrong.

Here is how I run it:

mkfifo /tmp/fifo

ls /tmp/fifo
> |rw-r--r-- - x  2 May 11:42 /tmp/fifo

clang --target=wasm32-wasi --sysroot=/usr/share/wasi-sysroot -o test_fifo.wasm test_fifo.c

wasmer run --mapdir /tmp:/tmp test_fifo.wasm
> /tmp/fifo is not a FIFO

// test_fifo.c

#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>

int main()
{
        const char *fifo_path = "/tmp/fifo";
        struct stat st;

        if (stat(fifo_path, &st) == -1) {
                perror("stat");
                exit(EXIT_FAILURE);
        }

        if (S_ISFIFO(st.st_mode)) {
                printf("%s is a FIFO\n", fifo_path);

                int fd = open(fifo_path, O_RDONLY);
                if (fd == -1) {
                        perror("open");
                        exit(EXIT_FAILURE);
                }

                char buffer[128];
                ssize_t bytes_read;
                while ((bytes_read = read(fd, buffer, sizeof(buffer) - 1)) > 0) {
                        buffer[bytes_read] = '\0';
                        printf("Received: %s\n", buffer);
                }

                if (bytes_read == -1) {
                        perror("read");
                }

                close(fd);
        } else {
                printf("%s is not a FIFO\n", fifo_path);
        }

        return 0;
}