C# to C IPC with memory mapped file

REAMDE.md

MappedMemory: C# to C

1. From console create file: dd if=/dev/zero of=/tmp/sharedfile bs=12288 count=1
2. The C# program
3. The C program

usage

mcs Sender.cs
mono Sender.exe
Start.
End.
# another terminal
gcc -o receiver receiver.c
./receiver
Test

ref

• https://stackoverflow.com/questions/27842300/c-to-c-sharp-mono-memory-mapped-files-shared-memory-in-linux

receiver.c

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

int main(int argc, char *argv[])
{
    int fd;
    int index;
    char *data;
    const char *filepath = "/tmp/sharedfile";

    if ((fd = open(filepath, O_CREAT|O_RDWR, (mode_t)00700)) == -1) {
        perror("open");
        exit(EXIT_FAILURE);
    }

    data = mmap(NULL, 12288, PROT_WRITE|PROT_READ, MAP_SHARED, fd, 0);
    if (data == MAP_FAILED) {
        perror("mmap");
        exit(EXIT_FAILURE);
    }

    for (index= 0; index < 4; index++) {
        fprintf(stdout, "%c", data[index]);
    }

    sleep(10);

    if (msync(data, 12288, MS_SYNC) == -1) {
        perror("Error sync to disk");
    }

    if (munmap(data, 12288) == -1) {
        close(fd);
        perror("Error un-mmapping");
        exit(EXIT_FAILURE);
    }

    close(fd);

    return 0;
}

Sender.cs

using System;
using System.IO;
using System.IO.MemoryMappedFiles;
using System.Threading;

namespace FileSharedMemory
{
    class MainClass
    {
        public static void Main (string[] args)
        {

            using (var mmf = MemoryMappedFile.CreateFromFile("/tmp/sharedfile", FileMode.OpenOrCreate, "/tmp/sharedfile"))
            {
                using (var stream = mmf.CreateViewStream ()) {
                    Console.WriteLine("Start.");
                    // writing "Test" at the beginning of memory-mapped file.
                    stream.Position = 0;
                    var buffer = new byte[] { 0x54, 0x65, 0x73, 0x74 }; // Test
                    stream.Write (buffer, 0, 4);
                    Thread.Sleep (20000);
                    Console.WriteLine("End.");
                }
            }
        }
    }
}