[ILUG] memory leaks...

[Caolan McNamara]

>>>>>>>>>>>>>>>>>> Original Message <<<<<<<<<<<<<<<<<<

On 01.03.00, 02:18:36, Sean <sean at binky.net> wrote regarding Re: [ILUG] 
memory leaks...:


> 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.

The bees knees when it comes to this stuff though is purify from 
rational rose, no version for linux unfortunately, but has one for 
solaris. At it seriously kicks ass, I have to say I love it. Memory 
leak tracing plus electric fence style bounds error flagging for 
dynamic and static arrays. Uninitialized reads as well, reads from 
past the end of a file etc etc. Great stuff altogether. One of the few 
pieces of development software which I would recommend that you buy, a 
killer app in favour of solaris :-)


C.