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From Luke Kenneth Casson Leighton <l...@samba-tng.org>
Subject Re: [PATCH/CONTRIB] Shared Mem Hash Table
Date Sat, 07 Jul 2001 11:20:20 GMT
On Sat, Jul 07, 2001 at 08:33:54AM +0100, David Reid wrote:

> I'd be interested to know of other tools that people use that are available
> for others here * on the list to use improving the code.  So far when pools

insure-lite may help _if_ you use the following trick.
insure-lite is availabe in the non-free section of
redhat 6 cds.  insure itself is about $4,000 USD and
no, they have never heard of open source projects
so they are not interested in providing licenses as
a promotional loss-leader [in complete contrast to
vmware who are very supportive of open source].

these code fragments come from samba source (GPL):

close the low 3 fd's and open /dev/null in their place
void close_low_fds(void)
	int fd;
	int i;
#ifndef __INSURE__
	/* try and use up these file descriptors, so silly
	   library routines writing to stdout etc won't cause havoc */
	for (i = 0; i < 3; i++)
		fd = open("/dev/null", O_RDWR, 0);


[except that insure writes out to stderr, so you can't close
that one]

#ifdef __INSURE__

This routine is a trick to immediately catch errors when debugging
with insure. A xterm with a gdb is popped up when insure catches
a error. It is Linux specific.
int _Insure_trapr_error(int a1, int a2, int a3, int a4, int a5, int a6)
	static int (*fn) ();
	int ret;
	char pidstr[10];
	pstring cmd =
		"/usr/X11R6/bin/xterm -display :0 -T Panic -n Panic -e /bin/sh -c 'cat /tmp/ierrs.*.%d ;
gdb /proc/%d/exe %d'";

	slprintf(pidstr, sizeof(pidstr), "%d", sys_getpid());
	pstring_sub(cmd, "%d", pidstr);

	if (!fn)
		static void *h;
		h =
		fn = dlsym(h, "_Insure_trapr_error");

	ret = fn(a1, a2, a3, a4, a5, a6);


	return ret;

[this little trick _is_ actually documented in the insure
documentation.  insure-lite strips out stack-debugging
info, making it almost completely useless... _unless_
you use the above little trick.]

insure is *extremely* good.  if you have used purify, you will
be laughing at it.

insure detects at *run-time*:

- pointer overwriting:

a = malloc(20);
a = b;

(but it doesn,t detect this:

struct foo
	void *a;

f->a = malloc(20);
memset(f, 0, sizeof(struct foo));

or, it _does_, it detects it as a loss of memory f->a
but not _why_.

but _does_ detect this:

struct foo fa;
struct foo fb;

fa.a = malloc(20);
fa = fb;

cool, huh? :)

- underwriting and overwriting of memory regions and strings

- not freed, freed more than once memory

so, when you do an apr_pool_destroy, it will let you
know immediately if there are any problems AND, get this:
it tells you the stack at the point where the memory

etc.  there's lots more.  it does a little bit of
compile-time checking, too.

the down-side: a normal 3mb executable compiles up at
80mb.  a 30-times increment in binary  size....

> One of the things we really need to improve is our test suite.  

yespleasetestsuitesmakeforeasycuttingandpastingtogetrealliveworkingcoderealquick :)


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