Saving parameters after shut down

component paramhelper;

pin in float invalue                "Receives value to save";
pin out float outvalue              "Sends value";
pin in bit readtrigger = 0          "signal to read from file";
pin in bit writetrigger = 0         "signal to write to file";

option singleton yes;               
option userspace yes;

author "ArcEye";
license "GPL";
;;

#include <stdio.h>    /* Standard input/output definitions */
#include <stdlib.h> 
#include <stdint.h>   /* Standard types */
#include <string.h>   /* String function definitions */
#include <unistd.h>   /* UNIX standard function definitions */
#include <fcntl.h>    /* File control definitions */
#include <errno.h>    /* Error number definitions */
#include <signal.h>
int done = 0;


void adios(int sig)
{
    done = 1;
}


void user_mainloop(void)
{
char filepath[] = "~/emc2/param.sav";
int read = 0;

    signal(SIGINT, adios);
    signal(SIGTERM, adios);
        
    while(!done)
        {
        usleep(500000);
        
        FOR_ALL_INSTS()  
            { 
            if(readtrigger && !read) // only want to read once
                {
                FILE *fp;
                fp = fopen(filepath, "r");
                fscanf(fp, "%f", (float*)&outvalue);
                read = 1;  
                }
            else if(writetrigger)
                {
                FILE *fp;
                fp = fopen(filepath, "w");
                fprintf(fp, "%f", invalue);
                }           
            }
        }

    exit(0);
}