C++ regex program not working as expected on Raspberry Pi - c++

Question

I'm having a confusing situation.
I wrote a program in C++11 which searches timestamps within an email file and replaces them with another one that is x hours older. It receives the amout of hours via localhost UDP packets.
If i compile (using CLion and the c++ compiler) and run my program on my x86_64 ubuntu machine, everything works just fine. But when i compile (tested c++ and g++ compiler) and run my file on my Raspberry Pi (running raspbian), it doesn't find any regex matches to be altered in the email file.
It doesn't work when i pass an email file as parameter on raspberry pi, whilst on my ubuntu machine, it worked fine. I used the same email file on both machines.
Here's the significant code (all of main.cpp)
#include <iostream>
#include <cstdio>
#include <cstring>
#include <regex>
#include <fstream>
#include <vector>
#include <exception>
#include <string>
#include <ctime>
#include <iomanip>
#include <sstream>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <stdexcept>
#include<arpa/inet.h>
#include "func.h"
using namespace std;
int main(int argc, char* argv[]) {
string filename = "/SOME/TEST/EMAIL.EML";
string StampPat = "[MTWFS][ouehra][neduit]\\x2C(\\s+|\\S)[0-9]+\\s[A-S][a-z][a-z]((\\s)|(\\r\\s))[0-2][0-9][0-9][0-9]((\\s)|(\\r\\s))[0-2][0-9]\\x3A[0-5][0-9]\\x3A[0-5][0-9]";
regex DatePat(StampPat,regex_constants::ECMAScript);
if (argc == 2)
{
filename=argv[1];
}
string currentline ="Hello world";
string previousline = "";
string memoryForFileLines="";
smatch results;
fstream email_file;
email_file.open(filename,fstream::in | fstream::out);
long long int oldreadpos = 0;
long long int readpos = 0;
long long int newWritePos = 0;
int matches = 0;
int setbackHours = 0;
bool previousmatch = false;
string stimestamp;
cout << stimestamp << "\n";
int sockfd = socket(AF_INET,SOCK_DGRAM,0);
struct sockaddr_in serv, client;
serv.sin_family = AF_INET;
serv.sin_port = htons(1337);
serv.sin_addr.s_addr = inet_addr("127.0.0.1");
socklen_t l = sizeof(client);
socklen_t m = sizeof(serv);
char buffer[10] = "REQTO";
char buffer2[5]="0000";
int sent = sendto(sockfd,buffer,5,0,(struct sockaddr *)&serv,m);
recvfrom(sockfd,buffer,10,0,(struct sockaddr *)&client,&l);
char *ptr;
if (strncmp(buffer,"RCVTO",5) == 0)
{
cout << "RECEIVED OFFSET INFO\n";
char *endOfBuffer = &buffer[10];
setbackHours = (int)strtol(buffer+6,&endOfBuffer,10);
}
while (getline(email_file,currentline) && currentline.find("Content-Type"))
{
//tm dateMod;
memoryForFileLines = "";
memoryForFileLines.append(currentline);
bool match = regex_search(memoryForFileLines,results,DatePat,regex_constants::match_any);
if (match) {
cout << "Found on position " << results.position(0) << " " << memoryForFileLines << "\n";
newWritePos = readpos + results.position(0);
email_file.seekp(newWritePos);
stimestamp = modTimestamp(setbackHours,results.str(),true, false);
cout <<"new timestamp: "<< stimestamp << std::endl;
email_file << stimestamp;
email_file.seekg(readpos+currentline.length());
matches++;
previousmatch = true;
}
else if (!previousmatch)
{
memoryForFileLines = "";
memoryForFileLines.append(previousline);
memoryForFileLines.append(currentline);
match = regex_search(memoryForFileLines,results,DatePat);
if(match)
{
cout << "Found on position " << results.position(0) << " " << memoryForFileLines << "\n";
newWritePos = oldreadpos + results.position(0);
email_file.seekp(newWritePos);
unsigned long oldsize = results.str().size();
stimestamp = modTimestamp(setbackHours,results.str(),true,true);
cout <<"new timestamp: "<< stimestamp << std::endl;
email_file << stimestamp;
matches++;
}
} else
{
previousmatch=false;
}
previousline="";
previousline.append(currentline);
oldreadpos = readpos;
readpos = email_file.tellg();
}
cout << matches << std::endl;
email_file.close();
sent = sendto(sockfd,"MAILD",5,0,(struct sockaddr *)&serv,m);
return 0;
}