[ILUG] memory leaks...

[Sean]

kevin lyda wrote something:
{ i had a question here but i seem to have answered it, so i thought i'd
{ share...

  He's back ;-)  Wheres me t-shirt ?/??

{ 
{ memory leaks are really annoying.  and they're also tough to spot. 
{ glibc provides a method to spot them:
{ 
{ #include <mcheck.h>
{ 
{ and then call mtrace() at the start of main().  compile the program with
{ -g for debugging, and set the environment variable MALLOC_TRACE to a
{ file to log memory allocation and freeing.  once you've run the program
{ run this:
{ 
{ mtrace <program> $MALLOC_TRACE
{ 
  follow up:

  I've tried this before with the following prog:
--BEGIN
#include <mcheck.h>
#include <stdio.h>
#include <stdlib.h>

int main(int argc, char *argv[])
{
   int i;
   char *buff;

   mtrace(); /* for mtrace */
   for (i = 0; i < 10; i++) buff = malloc(i * i * sizeof(char));

   free(buff);

   return 0;
}
--END
  (stupid I know, but an example)

  mtrace does:
Memory not freed:
-----------------
   Address     Size     Caller
0x08049690      0x1  at /home/sean/c/mem.c:13
0x080496a0      0x2  at /home/sean/c/mem.c:13
0x080496b0      0x3  at /home/sean/c/mem.c:13
0x080496c0      0x4  at /home/sean/c/mem.c:13
0x080496d0      0x5  at /home/sean/c/mem.c:13
0x080496e0      0x6  at /home/sean/c/mem.c:13
0x080496f0      0x7  at /home/sean/c/mem.c:13
0x08049700      0x8  at /home/sean/c/mem.c:13
0x08049710      0x9  at /home/sean/c/mem.c:13

  Electric fence brings an error up:
       ElectricFence Aborting: Allocating 0 bytes, probably a bug.

{ voila, it lists all the memory leaks and the lines where the memory was
{ allocated.

  Not bad.  This together with other tools could lead to entensive debugging...
   Still not totally an excuse for remembering the [m|c]allocs ones does
   while programming, but a help.  Its better than most.

{ 
{ dunno if this works from c++, but then c++ programs are supposed to leak
{ like a sieve anyway so does it really matter?

  Not if the compiler is ok and the program is programed correctly.
  C++ is just about mature enough not to blame the tools.  Some other OO
  languages... 

{ 
{ kevin
{ -- 
{ kevin at suberic.net       "we were goin' for breakfast.  in canada.  we
{ fork()'ed on 37058400    made a deal: if she'd stop hookin', i'd stop
{ meatspace place: home    shootin' people.  maybe we were aiming high."
{                                                    --porter, "payback"
{ 

Sean.
.