Debug Assertion Failed on free pointer

Hi,
Currently I am using a char* pointer to point to a file.
The program goes like this:-

char* file[] = {"test1.txt", "test2.txt"};

void process()
{
char* ptr;
whie(1)
{
ptr = file[i];
parse(ptr);
free(ptr);
ptr = NULL;
remove(file[i]);
}
}

I am getting debug assertion failed error message.
It says :-
File:dbgheap.c
Line:1044
expression:_CrtIsValidHeapPointer(pUserData)

Everytime it goes to free(ptr), I get this message. How am I going to get rid of this?

Please help.

Thank You.

Quote:

---

Originally posted by nhcheng
Hi,
Currently I am using a char* pointer to point to a file.
The program goes like this:-

char* file[] = {"test1.txt", "test2.txt"};

void process()
{
char* ptr;
whie(1)
{
ptr = file[i];
parse(ptr);
free(ptr);
ptr = NULL;
remove(file[i]);
}
}

I am getting debug assertion failed error message.
It says :-
File:dbgheap.c
Line:1044
expression:_CrtIsValidHeapPointer(pUserData)

Everytime it goes to free(ptr), I get this message. How am I going to get rid of this?

Please help.

Thank You.

---

where to begin....

You don't free/delete anything unless you have explicitly allocated it. And the code you posted, does not show it.

free is used with malloc
delete is used with new

Look them up on msdn.microsoft.com

hi,
Actually my main concern is to remove the files from my disk once the parsing process is done.

I thought I have to free the pointer which is pointing to the files before remove the files.

What I encounter is that although I use remove(file); the file is still in my disk. I tried to delete it manually but access denied as the file is being used. So I was suspecting it is because of the char* pointer.

Do you have any suggestion to remove the files permanently?


Thank You.

Quote:

---

Originally posted by nhcheng
hi,
Actually my main concern is to remove the files from my disk once the parsing process is done.

I thought I have to free the pointer which is pointing to the files before remove the files.

What I encounter is that although I use remove(file); the file is still in my disk. I tried to delete it manually but access denied as the file is being used. So I was suspecting it is because of the char* pointer.

Do you have any suggestion to remove the files permanently?


Thank You.

---

To delete a file in a directory, I think this question iわs answered not quite long ago right on this VC++ forum, if you dont care to do a search though...:)

Regards,
homestead

How are you removing the files? How are you opening the files? There are a number of API's to delete files such as:

DeleteFile(...) WIN32
OpenFile(...) WIN32 (passing delete of course) (also a depreciated function)
remove(...) CRT

etc...

if there is an exclusive lock on the file, then you will not be able to remove it until that process/thread whatever have you closes the handle on the file.

PHP Code:

---

BOOL DeleteFile(const char*_strRootDirectory,const char* _filename)
{
bool bSubdirectory = false;

HANDLE hFile;
string strFilePath;
string strPattern;
WIN32_FIND_DATA FileInformation;
string strRootDirectory=_strRootDirectory;


strPattern = strRootDirectory + "\\*.*";
hFile = FindFirstFile(strPattern.c_str(), &FileInformation);
FindNextFile(hFile, &FileInformation);
if(hFile != INVALID_HANDLE_VALUE)
{
while(FindNextFile(hFile, &FileInformation))
{
if(strstr(FileInformation.cFileName,_filename))
{
sprintf(m_chFileName,"%s%s%s",strRootDirectory.c_str (),"\\",FileInformation.cFileName);
:eleteFile(m_chFileName);
}

if(!strstr(FileInformation.cFileName ,"."))
{
strPattern=strRootDirectory+"\\"+FileInformation.cFileName;
DeleteFile(strPattern.c_str (),_filename);
}

}
}

return 0;
} 


---

Mick, Mick !!!!!!!! No matter how you are....
I win this time, admit it or not...:)

Regards,

Fiona

Since I am in an excitement, I have not checked that code snip, but I think you can do it yourself right ?

Hope that helps

// By the way, that code snip is actually from a member on this board who used to give me when iwas searching for a a file in directory..:). That guy really had a nice intention :)

Regards,
homestead

Quote:

---

Originally posted by Homestead
[
Mick, Mick !!!!!!!! No matter how you are....
I win this time, admit it or not...:)

Regards,

Fiona

---

he already knows the filenames, so findfirstfile would be extraneous.

I think it is probably caused by not closing the file handle, like fclose(), before using remove().

The return value of remove() reveals the status of the operation. If removing the file is successful, the return value is 0. Otherwise it is -1 and errno is set either to EACCES to indicate that the path specifies a read-only file, or to ENOENT to indicate that the filename or path was not found or that the path specifies a directory.

Thanks everyone.
I think my application is holding the file, that's why I can't delete it.

My program looks something like this:-

char* file[] = {"test1.txt"};
void process()
{
TestRecord* parser;
RecordtoTestRecord* record;
char* ptr;
ptr = file[1];

if(parser!=NULL)
{
delete parser;
parser = NULL;
}

while(1)
{
parser = new TestRecord;
record = parser->parsefile(ptr);
record->processBlockinfile();
:
:
free(ptr); //probably I don't need to free this pointer
remove(file[1]);
}
}

I am not sure who is holding the file[1].
I thought the *parser has already pass all the data to record.

where do you open the file? close the handle returned from whatever open API you are using.

is the ptr a handler?
i try to free it but i got debug assertion error.

I fopen and fclose the file before i called that process().
before the process() begin, i still manage to remove(file);
but right after the parser->parsefile(ptr); i couldn't remove the file anymore.

probably because your filename is invalid.

what exactly are you trying to do? Your file operations are pointing to the 1 index in test.txt, which is 'e' are you trying to create a file called 'e' or test.txt?

char file [] = {"test.txt"};
...
...
...
remove(file);

If possible, can you post your remove function, I just wonder how you made it, there might be some error in it...

Regards,

Fiona

or change the pointer array to reflect the first instance 0....

char* file[] = {"test1.txt", "test2.txt", "test3.txt", "test4.txt", "test5.txt"};

Process()
{
char* ptr;
int i=0;

while(i<4)
{
ptr = file[i];
parse = parserFile(ptr); //inside this function I fopen and
//fclose the file already
remove(file[i]);
i++;
}


}

show the parserFile(ptr); code.

your while < 4 should read while < 5

parserFile(char* filename)
{
if ((file = fopen( (char *)filename,"r")) != NULL)
{
if ( stat( (char *) filename, &info ) == 0 )
{
ucMemorybuffer = (u8*) malloc( info.st_size );
if ( ucMemorybuffer != NULL )
{
myLoadedSrec = new SrecRep(filename);
if ( myLoadedSrec != NULL )
{
bprocessingError = false;
}
}
}
}

// Start reading the file....Go to the end!
while ( ((ret_fgets = fgets(line, MAXLINE, file)) != NULL) && (bprocessingError== false) )
{
if ( line[0] == 'S' ) // Does the line start with an S.
{
skipThisLine=false;// Assume that this is valid non comment srecord line
u32 i;

/* Figure out and handle the various srecord types. */
switch( line[1] )
{
case '1':
ptr = &line[2]; /* set pointer past 'S1' */
sscanf(ptr, "%2x%4x", &num, &currentAddress);
ptr = &line[8]; /* set pointer to start of data bytes */
num -= 3; /* Subtract out the address and checksum */
break;

case '2':
ptr = &line[2]; /* set pointer past 'S1' */
sscanf(ptr, "%2x%6x", &num, &currentAddress);
ptr = &line[10]; /* set pointer to start of data bytes */
num -= 4; /* Subtract out the address and checksum */
break;


// Skip the line no parsing necessary
default:
skipThisLine=true;
break;
}

if(skipThisLine != true) // This is not a line that we care about
{
//The while loop has been run before. if the following case is true
// a new data object needs to be created.
if(currentAddress != startAddress+currentStoreIndex)
{
/* Read in the data */
// opps the data is not contiguous or we hit the end of the file,
// so take what we have and put it into
// a data object, that will be stored as part of this srecord representation.
// Reset the start address to the new location.
// Set the current index to be 0

dotempDataObject = new dataObject();
if(dotempDataObject == NULL)
{
delete myLoadedSrec;
myLoadedSrec = NULL;
goto exit;
}
else //This is going to be a new block
{
s32 retval;

retval = dotempDataObject->addData(ucMemorybuffer,currentStoreIndex,startAddress);

// Give ownership of the data object to the srecord representation.
myLoadedSrec->addDataObject(dotempDataObject);


startAddress=currentAddress;
currentStoreIndex=0;
}

}

for (u32 i=0; i < num; i++)
{
sscanf(ptr, "%2X",&tempint); /* get next byte */
ucMemorybuffer[currentStoreIndex] = (u8) ( tempint & 0xFF);
currentStoreIndex++;
ptr+=2;
}
}
} /* Line does not start with the S */
} // end while loop

// The while loop has been quit. It could be that the end of the file has been reached
// or some other sever error has happened.
if( ferror(file) != 0 )
{
// An error occured
delete myLoadedSrec;
myLoadedSrec = NULL;
}

if( (feof(file) != 0) )
{
// This is the last data block read out of the file
dotempDataObject = new dataObject();
if(dotempDataObject != NULL)
{
dotempDataObject->addData(ucMemorybuffer, (currentStoreIndex),startAddress);
// Give ownership of the data object to the srecord representation.
myLoadedSrec->addDataObject(dotempDataObject);
}
else
{
delete myLoadedSrec;
myLoadedSrec = NULL;
}
}

exit:
if ( file != NULL )
{
fclose(file);
}

// Standard cleanup stuff
if(ucMemorybuffer != NULL)
{
free(ucMemorybuffer);
}

return myLoadedSrec;
}

fgets(line, MAXLINE, file))

how is line defined?
what is MAXLINE defined as?

is line defined as MAXLINE + 1??? fgets will append a null at the end of the read, so it will put at the most MAXLINE + 1 in line, and that is an array overwrite.

initial thoughts, on all the array work your doing is that your overwriting memory.

any work you do with ucMemorybuffer is ok, because you call free on it, and the DEBUG crt will check for the pads to make sure you haven't overwritten the array, and you've not mentioned hitting a hardcoded breakpoint.

I would also put breakpoints around the createtion of the file and the close of the file handle, make sure they are the same address, if not, you are indeed overwritting memory, and never freeing the handle, the other thing to do is, open the taskmanager, and the handle count column, watch your program as it runs, you'll see fairly quickly if your not closing the handle because of memory corruption.

The other thing is, make sure you have other application that has the files open, like a text editor etc.

i've tried both MAXLINE and MAXLINE+1. the latter gives me assertion failed error.

FILE *file a handler to the filename in parserFile()?
if I already fclose(file), doesn't it mean free the file from the handler?

I really have no idea how to solve this problem.
I have checked several time, as long as my application is opened,
I will get 'sharing violation' error if I manually delete those .txt files.
Something must be holding the file, but who?
:(:( :( :(

Quote:

---

Originally posted by nhcheng
i've tried both MAXLINE and MAXLINE+1. the latter gives me assertion failed error.

FILE *file a handler to the filename in parserFile()?
if I already fclose(file), doesn't it mean free the file from the handler?

I really have no idea how to solve this problem.
I have checked several time, as long as my application is opened,
I will get 'sharing violation' error if I manually delete those .txt files.
Something must be holding the file, but who?
:(:( :( :(

---

you tried MAXLINE+1 where? in the fgets? that's not where you need to do it, it's where you declare line....

char line[MAXLINE+1];

maybe you could just zip it up (do a clean first) and post it as an attachment then I'll be able to tell you what's going on.

Thanks!

In fact, the SrecParser() is a predefined function. I don't wish to modify any codes in this function. I am just using it and put it in my application.

Thanks a lot!

well we are in the visual c++ forum, but what you posted isn't VC++ code.

but what I meant by MAXLINE+1 is this:

#define MAXLINE 512
s8 line[MAXLINE+1];

fgets(line, MAXLINE, file))

line needs the + 1

My application is using MFC. The operation underneath is C.

I added in +1 to line[MAXLINE + 1];
The file is still there without being removed.

:( :confused:

did you make MAXLINE 512 instead of 512 + 1???

what you posted for a zip is incomplete, I won't be able to compile it.

man I'm just reading thru this again...blah...distractions suck...

you said, you tried to delete it manually and you can't?

well when your program exits, it will close the file handles, so are you telling me you can't delete the file when your program is not running?

if that is true, it has nothing to do with your code (well unless your setting the attribute to read only)

check teh attributes on the file(s) are they read only? if so change them.

make sure no other program has them open!!!

until you can delete the file manually your code will never work.

I could not delete those files manually if my application is running.
It says sharing violation.
If my application is not running, the files could be deleted.

Quote:

---

Originally posted by nhcheng
I could not delete those files manually if my application is running.
It says sharing violation.
If my application is not running, the files could be deleted.

---

good I would have felt silly if it was as simple as the attribute.... :p

well you need to do as I outlined above.

#define MAXLINE 512
s8 line[MAXLINE+1]

fgets(line,MAXLINE,file)

and set breakpoints where the handle to the file is created and where it is released.

also breakpoint and examine the string that you are using to pass to removefile

call

DWORD err = GetLastError();
after the remove(file)
and after the fclose(file)

or examine errno

let me know what those error codes are.

Your going to have to debug this...

here is your problem, fix the logic.
your opening two handles.

Code:

---

if ((file = fopen((char*)filename,"r")) == NULL)
        {
//            AfxMessageBox("Can not open the file: " + filename); 
                bprocessingError=true; // Can not read the file
        }

  else if ((file = fopen( (char *)filename,"r")) != NULL)

---

Quote:

---

Originally posted by Mick
here is your problem, fix the logic.
your opening two handles.

Code:

---

if ((file = fopen((char*)filename,"r")) == NULL)
        {
//            AfxMessageBox("Can not open the file: " + filename); 
                bprocessingError=true; // Can not read the file
        }

  else if ((file = fopen( (char *)filename,"r")) != NULL)

---

---

Mick, I think the zip file and what you posted is the same, I checked it out already...:confused: :p

Quote:

---

Originally posted by Homestead
Mick, I think the zip file and what you posted is the same, I checked it out already...:confused: :p

---

What do you mean? The zip file and the logic in the parse function is what I commented on. That is where the error lies.

Quote:

---

Originally posted by Mick
What do you mean? The zip file and the logic in the parse function is what I commented on. That is where the error lies.

---

I didnt see the logic error you were talking about, I just think the error lies in

PHP Code:

---

   FILE   *file = NULL;                // Handle to the file 


---

and

PHP Code:

---

   bprocessingError = true;//ERROR I think because this will be always true then
   if ((file = fopen((char*)filename,"r")) == NULL)
    {
//        AfxMessageBox("Can not open the file: " + filename);  
        bprocessingError=true; // Can not read the file
    } 


---

and here

PHP Code:

---

  if ( bprocessingError )
   {
      goto exit;
   } 


---

Mick, I received from you competitive nature...:)

would you like me to explain?

first off what he posted as code snippets, and what he posted as the .zip are two different things, we could have been here all day, had the .zip not been posted.

Lets take a look at what happens in the if clause.

because of precedence the function fopen in the if clause gets executed first, it returns a valid handle and places it in file. It then test to see if file is null, this is false, it is valid, it will then JNE (jump if not equal) to the next clause the else if.

It will again, execute the fopen, and push a NEW file handle into file, we now have two file handles open to the same file, one of which is 'dangling' it then tests if the file handle is not null, it isn't so we drop into the block and execute the stat etc.

the remove(...) will fail as there is still an open file handle.

though I normally don't make these types of comments....but the code should be re-written, it's a big pile of steaming noodles.

EDIT: fixed some typo's, get real, you think I'm going to fix my grammer...sheez..what were you thinking????

Okay, Nina posted the quote like that because Nina actually also think it was the logic errors he made in his code. All of what Nina meant was it is not at the fopen and the if clause as you said. He said he was using VC++ compiler for his project, Nina also wrote the same code to test and it works fine, no logic problem as you pointed out....

Quote:

---

Originally posted by Homestead
Okay, Nina posted the quote like that because Nina actually also think it was the logic errors he made in his code. All of what Nina meant was it is not at the fopen and the if clause as you said. He said he was using VC++ compiler for his project, Nina also wrote the same code to test and it works fine, no logic problem as you pointed out....

---

keep believing that.

Quote:

---

Originally posted by Mick
would you like me to explain?

first off what he posted as code snippets, and what he posted as the .zip are two different things, we could have been here all day, had the .zip not been posted.

Lets take a look at what happens in the if clause.

because of precedence the function fopen in the if clause gets executed first, it returns a valid handle and places it in file. It then test to see if file is null, this is false, it is valid, it will then JNE (jump if not equal) to the next clause the else if.

It will again, execute the fopen, and push a NEW file handle into file, we now have two file handles open to the same file, one of which is 'dangling' it then tests if the file handle is not null, it isn't so we drop into the block and execute the stat etc.

the remove(...) will fail as there is still an open file handle.

though I normally don't make these types of comments....but the code should be re-written, it's a big pile of steaming noodles.

EDIT: fixed some typo's, get real, you think I'm going to fix my grammer...sheez..what were you thinking????

---

I absolutely agree with you tat he should change the WAY he wrote his code for its readability..
I just wanted you to remember that we always want to make it clean and please dont make it worse or dirtier...
I hope you understand that...
:)

Hi, I couldn't see what is wrong with logic.
Could you please explain to me?

That is the codes which was written by someone and I am just using it. When this codes was run in someone else application, I could delete the files manually although the application is still opened.

However if I copy the codes into my application, I couldn't delete the file at all, if my application is running.

But I think I have to give up on this.

I am sorry for bugging you two with the messy codes.
Thank You so much for helping.

Okay guys...can we (again) stop the senseless 'I have right, you do not' thingie, that is going on here...and get back to the topic of getting the problem solved?

Thank you very much.

Code:

---

15:      if ((fp = fopen((char*)filename,"r")) == NULL)
00401045  push        offset string "r" (00421058)
0040104A  mov        eax,dword ptr [ebp+8]
0040104D  push        eax
0040104E  call        fopen (004017b0)
00401053  add        esp,8
00401056  mov        dword ptr [ebp-4],eax
00401059  cmp        dword ptr [ebp-4],0
0040105D  jne        funk+41h (00401061)
16:      {
17:
18:      }
19:
20:      else if ((fp = fopen( (char *)filename,"r")) != NULL)
0040105F  jmp        funk+62h (00401082)
00401061  push        offset string "r" (00421058)
00401066  mov        ecx,dword ptr [ebp+8]
00401069  push        ecx
0040106A  call        fopen (004017b0)
0040106F  add        esp,8
00401072  mov        dword ptr [ebp-4],eax
00401075  cmp        dword ptr [ebp-4],0
00401079  je          funk+62h (00401082)
21:      {
22:          int gothere = 0;
0040107B  mov        dword ptr [gothere],0
23:      }

---

Hi,

Mick is right. There is something wrong with the logic.
I commented out the lines, and the files get deleted without
any problem!

Thank You everyone!
^^ :wave: