info.c

#include <sys/sysinfo.h> // for sysinfo
#include <unistd.h> //for usleep
#include <stdio.h>  // standard i/o
#include <stdlib.h> //standard library
#include <string.h> //for strcmp and other string fxn

#include "info.h" //to get fxn headers

float getTotalMemory()
{
    struct sysinfo info; // define sysinfo struct

    if (sysinfo(&info) != 0) //call sysinfo and check error
    {
        perror("total memory issue");
        return -1;
    }

    return (info.totalram * info.mem_unit) / (1024.0 * 1024.0 * 1024.0); //convert from bytes to GB as stated on manpage
}

float getUsedMemory()
{
    struct sysinfo info; // define sysinfo struct

    if (sysinfo(&info) != 0) //call sysinfo and check error
    {
        perror("used memory issue");
        return -1;
    }
    float usedMemory = (info.totalram * info.mem_unit) / (1024.0 * 1024.0 * 1024.0) - (info.freeram * info.mem_unit) / (1024.0 * 1024.0 * 1024.0);
    return usedMemory; //above is the total - free ram converted into GB
}

CpuStats parseCpuStats()
{
    CpuStats stats; // define a stats struct
    FILE *file = fopen("/proc/stat", "r"); //use fopen to open into proc/stat for reading
    if (file == NULL) //error check if it is null, return null struct
    {
        perror("File is null");
        return stats;
    }
    fscanf(file, "cpu %ld %ld %ld %ld %ld %ld %ld", &stats.user, &stats.nice, &stats.system, &stats.idle, &stats.iowait, &stats.irq, &stats.softirq); // read the values in the file and save it in the struct
    fclose(file); //close file
    return stats; //return struct with values
}

int parseCpuCore() {
    FILE *file = fopen("/proc/cpuinfo", "r"); // use fopen to open into proc/cpuinfo for reading

    char lines[512]; //define a lines buffer with 512
    int cores = 0; //define cores

    while (fgets(lines, 512, file) != NULL) // loop through file 
    {
        if (strncmp(lines, "processor", 9) == 0) //every time processor is seen, add a core
        {
            cores++;
        }
    }
    fclose(file); //close file
    return cores; //return cores
}

float parseCpuFreq() {
    int frequency; //frequency integer
    FILE *freq_file = fopen("/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq", "r"); //open the file where cpu info is, reference #8
    fscanf(freq_file, "%d", &frequency); // read the integer frequency value in hertz
    fclose(freq_file); //close file
    return frequency / 1000000.0; //typecast to float and convert hertz to Ghz
}

long addTotalTime(CpuStats stats)
{ //just add all va;ues in the struct as long and return
    return stats.user + stats.system + stats.softirq + stats.nice + stats.irq + stats.iowait + stats.idle;
}

float getCpuUsage(int tdelay)
{
    CpuStats stats_prev = parseCpuStats(); //get cpu stats
    usleep(tdelay); //sleep
    CpuStats stats_curr = parseCpuStats(); // get cpu stats after sleeping
    long total_time = addTotalTime(stats_curr) - addTotalTime(stats_prev); // subtract time
    long idle_time = stats_curr.idle - stats_prev.idle; //subtract idle time
    if (total_time <= 0) //check if time is invalid
    {
        return 0.0;
    }
    float cpu_usage = (1.0 - ((double)idle_time / total_time)) * 100; // do calculation as said in a3 description
    if (cpu_usage <= 0) return 0.0; //error check
    return cpu_usage; //return usage
}