Device.cpp

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#include <iostream>
#include <string>
#include <unistd.h>
#include <signal.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <Device.h>

using namespace std;

int Device::pythonPid;
unsigned char Device::buffer[BUFFER_SIZE];

static void initPython()
{
    int parentPid = getpid();

    // Creates a whole new process
    Device::pythonPid = fork();
    if(Device::pythonPid == -1)
    {
        cout << "Problems while initiazing a new process!!!" << endl;
        perror("Reason");
        exit(-1);
    }

    // pid > 0 means this is still parent process
    if(Device::pythonPid > 0)
    {
        cout << "Initiating python program with pid: " << Device::pythonPid << endl;
        return; // so we just keep doing our amazing job
    }

    // If we got here, from the line bellow until exit(0) means totaly the child process
    cout << "$ " << PYTHON_PROGRAM << " " << parentPid << endl;
    char strPid[16]; // Gotta convert pid into a string
    sprintf(strPid, "%i", parentPid);
    int rc = execl(PYTHON_PROGRAM, "main.py", strPid, NULL);
    if(rc == -1)
    {
        cout << "Error while initiating python program: " << rc << endl;
        perror("Reason");
    }
    exit(0);
}

void Device::init()
{
    Device::pythonPid = 0;
    initPython();
}

void Device::destroy()
{
    if(Device::pythonPid > 0)
    {
        cout << "Killing python process: " << Device::pythonPid << endl;
        kill(Device::pythonPid, SIGTERM);
    }
}