Little tool to run setuid that can be called from ~/.xinitrc

magic-mouse-scrolling-speed.c

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

int main(int argc, const char *argv[])
{
    if(geteuid() != 0)
    {
        fprintf(stderr, "This program should be setuid or run as root.\n");
        return 1;
    }
    
    if(argc != 2)
    {
        return 2;
    }

    int value = atoi(argv[1]);

    if(value < 0 || value > 63)
    {
        fprintf(stderr, "Value is out of range.\n");
        return 3;
    }

    FILE *param_file = fopen("/sys/module/hid_magicmouse/parameters/scroll_speed", "w");

    if(!param_file)
    {
        fprintf(stderr, "Magic Mouse not connected.\n");
        return 4;
    }

    if(fprintf(param_file, "%i\n", value) <= 0)
    {
        fprintf(stderr, "Couldn't write parameter.\n");
        fclose(param_file);
        return 5;
    }

    fclose(param_file);

    return 0;
}