bson_file_split.cc

#include <iostream>
#include <fstream>
#include <sstream>

using namespace std;

#define SPLIT_SIZE 1024 * 1024 * 1024

int main (int argc, char *argv[]) {
    if (argc<2) {
        cout << "Usage : " << argv[0] << " [filename]" << endl;
        return 0;
    }
    
    streampos size;
    char * memblock;
    
    int filenumber = 0;
    
    ifstream file (argv[1], ios::in|ios::binary);
    if (file.is_open())
    {
        long long position = 0;
        long long current_size = 0;
        
        std::ostringstream out_filename;
        out_filename << filenumber << "." << argv[1];
        ofstream outfile(out_filename.str().c_str(),ios::out|ios::binary);
        
        while (true) {
            int size;
            file.read((char*)&size,sizeof(int));
            if (file.eof()) {
                if (current_size > 0)
                    cout << current_size << endl;
                return 0;
            }
            if (current_size + size > SPLIT_SIZE) {
                cout << current_size << endl;
                current_size = 0;
                filenumber++;
                out_filename.str("");
                out_filename.clear();
                out_filename << filenumber << "." << argv[1];
                outfile.close();
                outfile.open(out_filename.str().c_str(),ios::out|ios::binary);
            }
            outfile.write((char*)&size,4);
            char* buffer = new char[size-4];
            file.read(buffer,size-4);
            outfile.write(buffer,size-4);
            delete buffer;
            position += size;
            current_size += size;
        }
        file.close();
    } else cout << "Unable to open file";
    return 0;
}