Variable Update from Config File in C

Today's problem is related with update of variables from the configuration file.  The variables and their corresponding user values are saved in a config file and when a program is run, these variables are updated with user define values.  The complete code regarding this problem is given below:

#include <stdio.h>

/*Create structure of variable with default initial values*/

struct variables {

    int DATA_SIZE;

    int ATTEN_DATES;

    int MAX_LINE_CHAR;

} config_var = {30, 31, 1024};

char *cleanTxt(char *str) {

    char *txt = malloc(config_var.DATA_SIZE);

    int i = 0, j = 0, lf = 0, rf = 0;

    while (str[i] != '\0') {

        /*If string starts with space, do   *

         *not copy space characters into txt*/

        if (str[i] == ' ' && lf == 0) {

        } else {/*Otherwise copy the character*/

            txt[j] = str[i];

            lf = 1;

            j++;

        }

        i++;

    }

    txt[i] = '\0';

    i = strlen(txt);

    /*Remove trailing spaces, string terminating, new*

     *line or return carriage symbols. Do it till    *

     *alpha numeric character is not found.          */

    while (i >= 0) {

        if (txt[i] == ' ' \

                || txt[i] == '\0' \

                || txt[i] == '\n' \

                || txt[i] == '\r') {

            txt[i] = '\0';

        } else {

            break;

        }

        i--;

    }

    return txt;

    free(txt);

}

void setKeyValue(char *k, char * v) {

    if (strcmp(k, "DATA_SIZE") == 0) {

        config_var.DATA_SIZE = atoi(v);

    }

    if (strcmp(k, "ATTEN_DATES") == 0) {

        config_var.ATTEN_DATES = atoi(v);

    }

}

int main(void) {

    FILE *fconfig;

    char *line = malloc(config_var.MAX_LINE_CHAR);

    char key[config_var.MAX_LINE_CHAR];

    char value[config_var.MAX_LINE_CHAR];

    fconfig = fopen("config.f", "r");

    if (!fconfig) {

        printf("Unable to load configuration file???\n");

        return 0;

    }

    int i = 0, l = 0;

    if (fconfig) {

        while (fgets(line, config_var.MAX_LINE_CHAR, fconfig)) {

            if (line[0] != '#' && strlen(cleanTxt(line)) > 0) {

                i = 0, l = 0;

                while (line[l] != '=') {

                    key[i] = line[l];

                    l++;

                    i++;

                }

                key[i] = '\0';

                i = 0;

                l++;

                while (line[l] != '\0') {

                    value[i] = line[l];

                    l++;

                    i++;

                }

                value[i] = '\0';

                setKeyValue(key, value);

            }

        }

        free(line);

    }

    fclose(fconfig);

    printf("%d\n", config_var.DATA_SIZE);

    printf("%d\n", config_var.ATTEN_DATES);

    return 0;

}

............config.f file data............

DATA_SIZE=30

#ATTEN_DATES=30

ATTEN_DATES=33