Get Lines/Chars/Word from a file (teste on Ubuntu)

#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define exit_on_null(s,m) if(s == NULL) { perror(m); exit(1); }

int linhas(FILE *f)
{
    char *line = NULL;
    ssize_t n=0;
    int l=0;
        while((n = getline(&line, &n, f)) != -1)
        {
        l++;
        }
    if(line) free(line);
    return l;
}

int words(FILE *f)
{
        char *line = NULL;
        ssize_t n=0;
        int w=0, i;
    char flag=0;
        while((n = getline(&line, &n, f)) != -1)
        {
        i=0;
        while(line[i] != '\0')
        {
            if(line[i] == ' ' && flag)
            {
                w++;
                flag=0;
            }
            else if(line[i] != ' ' && !flag)
                flag = 1;
            i++;
        }
        if(flag)
        {
            w++;
            flag = 0;
        }
        }
        if(line) free(line);
        return w;
}

int chars(FILE *f)
{
        char *line = NULL;
        ssize_t n=0;
        int c=0;
        while((n = getline(&line, &n, fp)) != -1)
            count+=strlen(line)-1;
        if(line) free(line);
        return c;
}


int main (int argc, char *argv[])
{
    FILE *fp;
    int c;
    /* Usage */
    if (argc<=2)
    {
        printf("Usage: %s <file name>\n",argv[0]);
        exit(1);
    }
    fp=fopen(argv[1],"r");/*Abre ficheiro para leitura*/
    exit_on_null(fp,"Erro na abertura");
    /*Leitura linha a linha*/
    while((c=getopt(argc,argv,":lwc"))!=-1)
    switch(c)
    {
        case 'l': printf("%d\n",linhas(fp));
            break;
        case 'w': printf("%d\n",words(fp));
            break;
        case 'c': printf("%d\n",chars(fp));
            break;
        default: printf("not c l or w\nwill use -c as default:\n"); printf("%d\n",chars(fp)); break;
    }
    fclose(fp);
    return 0;
}