read a named socket

Makefile

.PHONY: test
test: f read_c read_go
	bash -c 'while true; do echo yaddda | head -2 >> f; echo written; done' & \
		./read_c f; \
		./read_go f; \
		./read.py f; \
		pkill -f "echo yaddda"

f:
	mkfifo f

read_c: read.c
	$(CC) -Wall -O2 $< -o $@

read_go: read.go
	go build -o $@ $<

read.c

#include <stdio.h>

int main(int argc, char **argv) {
    FILE *fp = fopen(argv[1], "r");
    char str[0xff];

    if(fp == NULL) {
        perror("Error opening file");
        return(-1);
    }

    if(fgets(str, 0xff, fp) != NULL) {
        printf("from c: %s", str);
    }
    fclose(fp);
}

read.go

package main

import (
	"bufio"
	"fmt"
	"log"
	"os"
)

func main() {
	fn := os.Args[1]
	f, err := os.Open(fn)
	if err != nil {
		log.Fatalf("failed to open %s: %s", fn, err)
	}

	read1(f)
}

func read1(f *os.File) {
	rd := bufio.NewReader(f)

	line, _, err := rd.ReadLine()
	if err != nil {
		log.Fatalf("failed to read line: %s", err)
	}

	fmt.Printf("from go: %s\n", line)
}

read.py

#!/usr/bin/env python3

import sys

line = None
with open(sys.argv[1], "r") as f:
    line = f.readline()

print("from py: %s" % line)

motiejus ~/x $ make test
bash -c 'while true; do echo yaddda | head -2 >> f; echo written; done' & \
                ./read_c f; \
                ./read_go f; \
                ./read.py f; \
                pkill -f "echo yaddda"
from c: yaddda
written
from go: yaddda
written
from py: yaddda

written
: