Bounds check - out of bounds - c++

Question

I'm in need of a little debugging. The code is 100% compile-ready. However, it crashes if given either a small fragment of a document to compress, and when it decompresses it gives a error about bounds checking. I'm a little afraid of running it as well. It's not dangerous, but this is my masterpiece as of now. It is right in the sweet spot of compression techniques. This is one I made up. It uses a calculus derivation algorithm to get millions of unique keys to use. These are all predictable. And because they're unique, I can't screw it up by taking a key more than one time in the hashing. The aim of this code is to generate a hash which is perfectly regenerative and gives no loss in the compression. Thank you.
#include <iostream>
#include <bitset>
#include <vector>
#include <cmath>
#include <fstream>
#include <algorithm>
using namespace std;
class S_Rend {
private:
const bitset<8> beta=0xad;
protected:
bitset<8> alpha, lambda, gamma, omega;
bitset<8> delta, eta, theta, ghost, spec;
vector<long> cred;
public:
unsigned int integral;
S_Rend() { delta=0x00; eta=0x00; theta=0x00; lambda=0x00; alpha=0x00; delta=0x00; };
~S_Rend() { };
int s_render(ifstream&,ofstream&);
int render(ifstream&,ofstream&);
long s_nop(long t, int set);
} n;
/*+**- Project::Sailwinds -**+*/
long S_Rend::s_nop(long t,int set) {
if (set) {
integral=0;
t=(long&)beta;
}
integral++;
if (abs(round((t*1.618)*t-(integral+0.618))-1) <= 4294967296)
return (abs(round((t*1.618)*t-(integral+0.618))-1));
else
return (abs(round(sqrt(t))+(round(sqrt(t))*round(sqrt(integral))+1)));
}
int S_Rend::render(ifstream& in, ofstream& out) {
long bn;
long size=0;
long t;
if (!(in.is_open()))
{ return -1; }
else {
t=(long&)beta;
for_each (std::istreambuf_iterator<char>(in), \
std::istreambuf_iterator<char>(), \
[&] (int x) {
t=s_nop((long&)t,0);
cred.push_back(t);
alpha = (long&)cred[size];
delta = (long&)x;
lambda ^= (alpha ^ delta);
lambda ^= beta;
lambda = (int&)lambda + 1;
size++;
});
printf("*");
}
if (out.is_open())
{ out << lambda << endl;
out << size << endl;
out << delta << endl;
out << cred[size-1] << endl; }
else { return -1; }
in.close();
out.close();
return 0;
}
int S_Rend::s_render(ifstream& in, ofstream& out) {
long i, n;
long size;
long t;
long chk;
in >> lambda;
in >> size;
in >> delta;
in >> chk;
t=(long&)beta;
long bn=0;
while (size-1>=bn) {
t=s_nop((long&)t,0);
cred.push_back(t);
bn++;
}
if (cred[bn-1]==chk)
cout << "\nValidity Pass... Success!" << endl;
else {
printf("\nValidity Pass...Fail! %u != %u",cred[cred.size()-1],chk);
return 1;
}
cout << "\nWriting to Buffer..." << endl;
vector<long> btrace;
vector<long> ltr;
bn=1;
while (size-1>=bn) {
ltr.push_back(1);
btrace.push_back(1);
ltr[0]=(long&)lambda;
for (i=1;i<=btrace.size()-1;i++) {
alpha = (long&)cred[size-bn];
ghost = (long&)btrace[i-1];
spec = (long&)ltr[bn] - 1;
spec ^= (int&)beta;
eta = spec | alpha;
theta = spec & alpha;
omega = spec | eta;
gamma = spec & eta;
if ((eta ^ gamma) == (theta ^ omega)) {
printf(".");
ghost = (eta ^ gamma);
btrace[i-1] = (long&)ghost;
}
}
bn++;
}
cout << "One more second..\n";
bn=0;
while (bn<=btrace.size()-1) {
bn++;
delta = (long&)btrace[bn];
out << (const char)(long&)delta;
}
cout << "\nBuffer Written... Exiting..\n";
in.close();
out.close();
printf("*");
return 0;
}
int main() {
string outfile = "";
string infile = "";
string DC = "1";
printf("Enter <C> or <D> to compress or decompress ");
cin >> DC;
printf("\nInput File: ");
cin >> infile;
ifstream in;
in.open(infile.c_str(), std::ios::in | std::ios::binary);
if (in.fail())
return -1;
printf("\nOutput File: ");
cin >> outfile;
ofstream out;
out.open(outfile.c_str(), std::ios::out);
if (out.fail())
return -1;
if ((DC=="c") || (DC=="C"))
bool f=n.render(in, out);
if ((DC=="d") || (DC=="D"))
bool f=n.s_render(in, out);
printf("\nProgram Execution Done.");
n.~S_Rend();
return 0;
}

Answer 1

This last while-loop is accessing index 1 to (and including!) btrace.size():
bn=0;
while (bn<=btrace.size()-1) {
bn++;
delta = (long&)btrace[bn];
out << (const char)(long&)delta;
}
Move bn++; to the end of the loop, like you did in all your other loops.
And i have to agree with user4581301, using <= size-1 instead of just < size looks weird.

Answer 2

(int &)beta is a mistake. This is a reinterpret_cast which violates the strict aliasing rule. Probably it also accesses out of bounds; e.g. bitset<8> may only be 1 byte big, but (int &)beta will read 4 bytes out of that memory location.
Instead you should use beta.to_ulong(). You make the same mistake in dozens of places.
Remove all the casts from your code. Using a cast (especially a C-style cast) tells the compiler "Don't warn me if this is a mistake, I know what I am doing". But in fact you don't know what you are doing. Mostly, C++ can be written without using casts.
(There may be other mistakes too, just this one stood out to me on first reading. Fix all of these and try again).