Thread: What's up with this strcpy?

I'm having some problem with the strcpy function. Hopefully some of you can point out what I'm doing wrong please.

Basically, I'm calling a function to read a file and put something in an output buffer. The function is something like this.

Code:

int PutSthInBuffer (unsigned char *Buffer, int length) {
     unsigned char *Path;
     unsigned char *Type;
     unsigned char *Line;

     // Memory is first allocated for all three local pointers.
     
     //
     // read a line, then call strtok and assign one of the tokens to     
     // Path. The reading line part can be safely assumed to be taken
     // care of (don't want to post extra code).
     //

     Type = strtok (Line, " ");
     Path = strtok (NULL, " ");     

     Buffer = strcpy (Buffer, Path);
     FreeMem (Path, Type, Line); // this free memory from whatever 
                                                  // pointers it's passed.

     return 0;
}

void FreeMem (unsigned char *ptr1, unsigned char* ptr2, unsigned 
                         char *ptr3) {
        free (ptr1);
        free (ptr2);
        free (ptr3);
}

The problem I'm having is, before I call FreeMem, the content of Buffer is what it should be. After I call FreeMem, the content of Buffer is no longer valid. So the thing that the calling function gets in the Buffer is not a valid string.

I checked the addresses of Buffer and Path, and they point to different addresses. So how come when I free Path, the content of Buffer is messed too? Hopefully I've included sufficient snippets of code to understand this problem. Let me know if you think other piece of code may be helpful.

>>Buffer = strcpy (Buffer, Path);

strcpy (Buffer, Path); would suffice here. For me, strcpy is
returning the address of the Buffer parameter, but perhaps it is
returning the address of the Path parameter, in which case,
explains your problem - maybe check that the addresses of Buffer
and Path are different after this line of code? If they are not,
then just use strcpy (Buffer, Path);

>>Hopefully I've included sufficient snippets of code

Not in my opinion, please post the code for FreeMem, and also
code involving the declaration of Path in the code as well, since
in your snippet, Path is declared as unsigned char - not a pointer.
Try my above suggestion first though.

[EDIT]
OP has updated his code, so the above is out of context i guess...
[/EDIT]

[UPDATE]
you shouldn't call free on a pointer that was not allocated with
malloc.
[/UPDATE]

>>I didn't assign Line to Buffer anywhere.

Check the addresses before and after the line:

Buffer = strcpy (Buffer, Path);

If it's not happening there, then I don't know where it is
happening - nonetheless I don't see the point in assigning the
return value of strcpy to Buffer - just doesn't sit well with me.

//
// read a line, then call strtok and assign one of the tokens to
// Path. The reading line part can be safely assumed to be taken
// care of (don't want to post extra code).
//

Typical isn't it? The part that you think is working ok ends up
biting back!