Memory Leaks?

This is a discussion on Memory Leaks? within the C++ Programming forums, part of the General Programming Boards category; Hey I've been working on an SMS sending manager for gnokii in Linux but I feel I am a little ...

  1. #1
    Registered User
    Join Date
    Nov 2007
    Posts
    3

    Memory Leaks?

    Hey I've been working on an SMS sending manager for gnokii in Linux but I feel I am a little bit out of my depth in relation to the memory management side of things... I'm not sure if I'm having any memory leak issues but some things make me a bit suspicious. Could anyone take a glance of my code and see if they can find any?

    Code:
    #include <iostream>
    #include <fstream>
    #include <string>
    #include <vector>
    #include <dirent.h>
    using namespace std;
    
    char* remove(char* const src, char character);
    vector<string> getListOfFiles(const char* directory);
    
    int main()
    {
      string DirIn = "/var/gsm/in/", DirOut = "/var/gsm/out/", DirSent = "/var/gsm/sent/", DirFail = "/var/gsm/fail/";
    
      vector<string> Filenames = getListOfFiles(DirOut.c_str());
    
      for(unsigned int i = 0; i < Filenames.size(); i++)
      {
        fstream SMSFile((DirOut + Filenames.at(i)).c_str());
        if(!SMSFile.fail())
        {
          char NumberLine[64];
          SMSFile.getline(NumberLine, 64);
          string Number = NumberLine;
          Number = Number.substr(8);
          if(Number.length() == 10)
          {
            cout << "Number is OK" << endl;
          }
          else
          {
            cout << "Number is Wrong" << endl;
          }
          cout << Number << endl;
    
          char MsgLine[160];
          SMSFile.getline(MsgLine, 160);
    
          // Remove ", ', carriage returns and new lines
          strcpy(MsgLine, remove(MsgLine, '\n'));
          strcpy(MsgLine, remove(MsgLine, '\r'));
          strcpy(MsgLine, remove(MsgLine, '\''));
          strcpy(MsgLine, remove(MsgLine, '"'));
    
          string Msg = MsgLine;
    
          if(!system(("echo \"" + Msg + "\" | gnokii --sendsms " + Number).c_str()))
          {
            cout <<  "SMS Sent to " << Number << "!" << endl;
            system(("mv " + DirOut + Filenames.at(i) + " " + DirSent).c_str());
          }
          else
          {
            cout <<  "SMS Failed to " << Number << "!" << endl;
            system(("mv " + DirOut + Filenames.at(i) + " " + DirFail).c_str());
          }
        }
        }
        else
        {
          cout << "Unable to open the file" << endl;
        }
      }
      return 0;
    };
    
    vector<string> getListOfFiles(const char* directory)
    {
      vector<string> Filenames;
      DIR* dirHandle;
      struct dirent* dirEntry;
      dirHandle = opendir(directory);
      if(dirHandle != NULL)
      {
        while((dirEntry = readdir(dirHandle)))
        {
          if(dirEntry->d_type != DT_DIR)
          {
            Filenames.push_back(dirEntry->d_name);
          }
        }
      }
      return Filenames;
    }
    
    char* remove(char* const src, char character)
    {
      char* s = src;
      int occurences = 0, length = 0;
      while(*s)
      {
        if(*s == character)
          occurences++;
        length++;
        s++;
      }
    
      char* result = new char[length - occurences + 1];
      char* resultptr = result;
      s = src;
      while(*s)
      {
        if(*s != character)
        {
          *resultptr = *s;
          resultptr++;
        }
        s++;
      }
      *resultptr = '\0';
      return result;
    }
    I think mainly around the passing of variables between functions, some of them are local such as the vector, so if I return it is the memory marked for deletion so that when I try to access it from outside the function it'll stuff up?

    Thanks heaps

  2. #2
    Registered User
    Join Date
    Jun 2006
    Posts
    75
    You're returning the vector by value. There's no problem in that since it's being copied back in the calling function.

  3. #3
    Registered User
    Join Date
    Jun 2006
    Posts
    75
    You're allocating memory (using new) in remove(), but not deleteing it anywhere. That's a memory leak.

  4. #4
    Kernel hacker
    Join Date
    Jul 2007
    Location
    Farncombe, Surrey, England
    Posts
    15,677
    As far as I can see, there's no reason to use "remove" in that fashion. Just remove the characters directly in the input string, rather than allocating a new string. Then you don't leak.

    --
    Mats
    Compilers can produce warnings - make the compiler programmers happy: Use them!
    Please don't PM me for help - and no, I don't do help over instant messengers.

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