Hq9eFuck interpreter source in C

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


/*I know this code ain't good, but the main thing is idea for you to do it better.*/
void run_99_bottles_of_beer()
{
    char i = 99;
    while (i >= 3)
    {
        printf("%i bottles of beer on the wall, %i bottles of beer!\n", i, i);
        printf("Take one down, pass it around, %i bottles of beer on the wall.\n\n", --i);
    }
    printf("2 bottles of beer on the wall, 2 bottles of beer.\n");
    printf("Take one down, pass it around, 1 bottle of beer on the wall.\n\n");
    printf("1 bottle of beer on the wall, 1 bottle of beer.\n");
    printf("Take one down, pass it around, no more bottles of beer on the wall.\n\n");
    printf("No more bottles of beer on the wall, no more bottles of beer.\n");
    printf("Go to the store and buy some more, 99 bottles of beer on the wall.\n\n");
}

int main(int argc, char **argv)
{

    FILE* source_file;
    long size;

    if (argc <= 1)
    {
        puts("No source.");
        return 0;
    }

    source_file = fopen(argv[1], "r");

    if (source_file == NULL)
    {
        puts("Can't open file.");
        return 0;
    }

    fseek(source_file, 0, SEEK_END);
    size = ftell(source_file);
    fseek(source_file, 0, SEEK_SET);

    char* tape = calloc(60000, 1);
    char* source = malloc(size);

    long i = 0;
    while (size-- > 0)
    {
        char ch = getc(source_file);
        source[i] = ch;
        ++i;
    }

    int tape_pointer = 0;
    int src_pointer = 0;
    int src_length = strlen(source);
    int loop = 0;

    while (src_pointer < src_length)
    {
        char src_op = source[src_pointer];

        /*Brainfuck extension*/
        if (src_op == '<') tape_pointer--; else
        if (src_op == '>') tape_pointer++; else
        if (src_op == '+') tape[tape_pointer]++; else
        if (src_op == '-') tape[tape_pointer]--; else
        if (src_op == ',') tape[tape_pointer] = getchar(); else
        if (src_op == '.') putchar(tape[tape_pointer]); else
        if (src_op == ']')
        {
            if (tape[tape_pointer] != 0)
            {
                loop = 1;
                while (loop != 0)
                {
                    --src_pointer;
                    if (source[src_pointer] == '[') loop--; else
                    if (source[src_pointer] == ']') loop++;
                }
            }
        } else
        if (src_op == '[')
        {
            if (tape[tape_pointer] == 0)
            {
                loop = 1;
                while (loop != 0)
                {
                    ++src_pointer;
                    if (source[src_pointer] == ']') loop--; else
                    if (source[src_pointer] == '[') loop++;
                }
            }
        }

        /*HQ9+ extension (command '+' taken by brainfuck)*/
        if (src_op == 'H') puts("Hello world!"); else
        if (src_op == 'Q') puts(source); else
        if (src_op == '9') run_99_bottles_of_beer();

        /*Deep Thought extension, you write 'DT' in code, it prints '42'*/
        if (src_op == 'D' && source[src_pointer + 1] == 'T')
        {
            ++src_pointer;
            printf("%i\n", 42);
        }
        src_pointer++;
    }

    return 0;
}