Heap Corruption in C++

[Gajananh999]

Hello Everyone,
I have one socket client c++ program it has some heap corruption in that. i m not understanding where this is happening

#include <stdio.h>
#include <stdlib.h>
#include <winsock2.h>
#include <string.h>
#include <windows.h>
#include <stdlib.h>
#include <string.h>
#include <conio.h>
#include <process.h>
#include <dos.h>
#include <clocale>
#include <cstdio>
#include <locale>

#include "dirent.h"

#define DEFAULT_PROTO SOCK_STREAM

char *server_name = (char*) malloc (256); 
char *portasstring = (char*) malloc (64); 
char *formatasstring = (char*) malloc (64);
char *storefilename=(char*) malloc (2048);
char *speedline=(char *) malloc (64);
char *sleeptime=(char *) malloc (64);
char *nooflineattime=(char *) malloc (64);
char basePath[MAX_PATH];



void handlefile(char* filepath)
{
	try 
	{
			FILE *fsetup;
			FILE *fHIST, *hist;
			char ch, hch;
			char *line;
			char *readLineNumber; 
			int hcnt, cnt, linecnt, totallinecnt;	
			char *filetemp;
			char *histPath;
			char *path = (char*) malloc (255);
			char *drive = (char*) malloc (255);
			char *dir = (char*) malloc (255);
			char *fname =(char*) malloc (255);
			char *ext = (char*) malloc (255);
			int i;
			int sentLines;
			SYSTEMTIME str_t;
			GetSystemTime(&str_t);
			_splitpath(filepath,drive,dir,fname,ext);

			sentLines=0;
			cnt=0;
			hcnt=0;
			linecnt=0;
			totallinecnt = 0;
			histPath = (char*) malloc (255);
			filetemp = (char*) malloc (255);
			readLineNumber = (char*) malloc (255);
			readLineNumber[0] = '\0';
			line = (char*) malloc (51200);
			line[0] = '\0';

	
			fsetup = fopen(filepath,"r");
	
			if(fsetup != NULL)
			{
				sprintf(histPath,"%sHIST\\%s.HIST", basePath,fname);
				/* open a hist file which is created now */
				hist = fopen(histPath,"r");
				if(hist != NULL)
				{

					while(1)
					{
						hch = fgetc(hist);
						if(hch == EOF) break;
						readLineNumber[hcnt++] = hch;
						readLineNumber[hcnt] = '\0';

					}
					fclose(hist);
				}
		
				i=0;
				while(i < strlen(formatasstring))
				{
					line[cnt++] = formatasstring[i++];
				}
				line[cnt] = '\0';
		
				while(1)
				{
					ch = fgetc(fsetup);
					if(feof(fsetup))
					{
						//printf("feof\n");
						break;
					}
					else if(ch=='\n')
					{
						linecnt ++;
						totallinecnt ++;
						if(linecnt ==atoi(nooflineattime))
						{
							line[cnt++] = ch;
							line[cnt]='\0';
							if(totallinecnt > atoi(readLineNumber))
							{
								if(sendline(line)==0)// check for socket connection is open or no.
								{
										sentLines++;
									//	printf("sentlines--> %d\n\n",sentLines);
										sprintf(filetemp,"%d\0", totallinecnt);
										fHIST = fopen(histPath,"w");
										fwrite(filetemp, strlen(filetemp),1,fHIST);
										fclose(fHIST);
								}else
								{
									printf("socket no t open\n");
									break;
								}
								if(sentLines > atoi(speedline))
								{
									break;
								}
							}
							else
							{

								Sleep(atoi(sleeptime));
							}
							//free(line);
							//line= (char*) malloc (51200);
							line[0] = '\0';
							cnt = 0;
							i=0;
							while(i < strlen(formatasstring))
							{
								line[cnt++] = formatasstring[i++];
							}
							line[cnt] = '\0';
							linecnt = 0;
						}
						else
						{
							line[cnt++] = ch;
							i=0;
							while(i < strlen(formatasstring))
							{
								line[cnt++] = formatasstring[i++];
							}
							line[cnt] = '\0';

						}
					}
					else
					{
						line[cnt++] = ch;
						line[cnt] = '\0';
					}
				}	
			}
			else
			{
		
			}
			free(path); 
			free(drive); 
			free(dir); 
			free(fname);
			free(ext); 
			free(histPath);
			free(filetemp);
			free(readLineNumber); 
			free(line); 
			fsetup=NULL;
			fHIST=NULL;
			hist=NULL;
	}catch(char * str)
	{
			WriteError(str);
	}
	
	}

unsigned _stdcall createthreadtohandlefile(void* pfilename)
{
	try
	{
		char *filename = (char*)pfilename;
		char *createtemp;
		createtemp = (char*) malloc (255);
		createtemp[0] = '\0';
		sprintf(createtemp,"%s",filename);
	
		handlefile(createtemp);
	
		free(createtemp);
     	_endthreadex(0);	
	}catch(char * str)
	{
			WriteError(str);
	}
	return 0;
}

void handlefolder(char* dirpath)
{
	try {
		DIR *dir;
		struct dirent *ent;
		char* foldertemp;
		HANDLE handle[100];
		int i,n,nooffiles=0;
		dir = opendir (dirpath);
		if (dir != NULL) 
		{

			while ((ent = readdir (dir)) != NULL) 
			{
					switch (ent->d_type) 
					{
						case DT_REG:
				
							foldertemp = (char*) malloc (255);
							foldertemp[0] = '\0';
							sprintf(foldertemp,"%s\\%s",dirpath,ent->d_name);
							if(strstr(foldertemp,".log"))
							{
							handle[nooffiles] =  (HANDLE)_beginthreadex( NULL, 0, &createthreadtohandlefile, foldertemp, 0, NULL);
							//	handle= (HANDLE) _beginthread(createthreadtohandlefile,0,foldertemp);// create thread
								nooffiles++;
								Sleep(1000L);
							}
							break;

						case DT_DIR:
							break;

						default:
							break;
					}
			}	
			
			closedir (dir);
		} 
		else 
		{
			perror ("no dir");
		}
	//	Sleep(200);
		//WaitForSingleObject(handle,INFINITE);
	    WaitForMultipleObjects(nooffiles,handle, TRUE, INFINITE);
	    CloseHandle( handle );
		
		dir = NULL;
		free(foldertemp);	
	}catch(char * str)
	{
		WriteError(str);
	}
}

int main()
{

	FILE *fsetup;
	char ch;
	char *path, *setupFileName;
	int cnt, linecnt;

	char *drive = (char*) malloc (255);
	char *dir = (char*) malloc (255);
	char *fname =(char*) malloc (255);
	char *ext = (char*) malloc (255);
	int i;
	TCHAR szPath[MAX_PATH];
	GetModuleFileName( NULL, szPath, MAX_PATH );
	
	wcstombs(basePath, szPath, sizeof(basePath));
	

	_splitpath(basePath,drive,dir,fname,ext);
	sprintf(basePath,"%s%s",drive,dir);

	try{
		cnt=0;
		linecnt=0;
		path = (char*) malloc (160);
		setupFileName = (char*) malloc (256);
		path[0] = '\0';
		storefilename[0] = '\0';
		sprintf(setupFileName,"%ssetup.ini",basePath);
		fsetup = fopen(setupFileName,"r");
		if(fsetup != NULL)
		{

			while(1)
			{
				ch = fgetc(fsetup);
				if(ch==EOF)
				{
					handlefolder(path);
					break;
				}
				else if(ch=='\n')
				{
					linecnt++;
					if(linecnt == 1) 
					{
						sprintf(server_name,"%s",path);
					}
					else if(linecnt == 2) 
					{
						sprintf(portasstring,"%s",path);
					}
					else if(linecnt == 3) 
					{
						sprintf(formatasstring,"%s ",path);
					}	
					else if(linecnt == 4) 
					{
						sprintf(nooflineattime,"%s ",path);	
					}
					else if(linecnt == 5) 
					{
						sprintf(speedline,"%s ",path);
					}
					else if(linecnt == 6) 
					{
						sprintf(sleeptime,"%s ",path);
					}
					else
					{
						handlefolder(path);
					}
					path[0] = '\0';
					cnt = 0;
				}
				else
				{
					path[cnt++] = ch;
					path[cnt] = '\0';
				}
			}	
		}
		
	}catch(char * str)
	{
			WriteError(str);
	}
	fsetup = NULL;
	free(path);
	free(server_name);
	free(portasstring);
	free(formatasstring);
	free(storefilename);	
	return 0;
	
}

this is the error

Faulting application name: CollationaAgent1.exe, version: 0.0.0.0, time stamp: 0x506c10be
Faulting module name: CollationaAgent1.exe, version: 0.0.0.0, time stamp: 0x506c10be
Exception code: 0xc0000417
Fault offset: 0x0000409e
Faulting process id: 0x2234
Faulting application start time: 0x01cda15071db8dce
Faulting application path: E:\00ISAC\03Projects\Client\Carwale\Code\CollationAgent\server1\CollationaAgent1.exe
Faulting module path: E:\00ISAC\03Projects\Client\Carwale\Code\CollationAgent\server1\CollationaAgent1.exe
Report Id: bbc0d896-0d43-11e2-b40e-001fe2129807

[zb0S216C]

You're freeing memory that does not exists. Before attempting to free a block of memory, always check the pointer for "NULL", and always set a freed pointer to null.

_Wazzak

[kbw]

In main():
- you never close fsetup
- you never free:
setupFileName
drive
dir
fname
ext

There's a lot of bad practice going on regarding memory mangement. Clearly, you can't write code this way.

[Gajananh999]

Dear Framework,

where exactly you are talking about.?

[Gajananh999]

Dear KBW,

Thanks for your reply

I m beginner C++ so please excuse my code and where were i m wrong please correct me.

I want your more help to make this code perfect

[kbw]

Clearly, you're using C++ and not C. So:
1. use std::string when you need strings
2. declare variables where they're used
3. if the buffers are small, declare them on the stack
4. if the buffers are large, wrap them in a class that releases them. Minimally, there's std:auto_ptr<>, but there are newer and better newer standard ones
5. use the C++ stream library to handle files rather than ANSI C file functions
6. use C++ casts rather than C casts

Think more about your program logic and system limits.
1. What happens if your directory has more than 100 files?
2. How many objects can you wait for with WaitForMultipleObjects?
4. You don't close thread handles after the wait.
3. You catch const char*, but never throw one.

I hope that helps.

[Gajananh999]

Dear Kbw,

Thank for your reply.