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Re: find(1) memory leak in cygheap

On Aug 20 18:23, Haojun Bao wrote:
> On Thu, Aug 20, 2009 at 4:39 PM, Corinna
> Vinschen<> wrote:
> > On Aug 20 14:09, Haojun Bao wrote:
> >> I have done some debugging, and the culprit should be dup(2) syscall.
> >> Here's another test case, this time written in C.
> >>
> >> Note that the cygheap_start and cygheap_max value will be very likely
> >> different on your computer, so you should use gdb to take a peek into
> >> cygwin1.dll to get your value. Or else you should remove the reference
> >> to these memory location.
> >>
> >> The test case will show cygheap is always growing, and at the end it will print
> >> ? 1 [main] a 3560 Q:\a.exe: *** fatal error - cmalloc would have returned NULL
> >
> > Thanks for the testcase! ?It was pretty easy to find the culprit with
> > it. ?Deep in dup(), the strings for the filenames of the new file
> > descriptor were allocated twice. ?While I was at it, I also found two
> > other potential memory leaks, which would just show up much less
> > frequent.
> >
> > This fixes your find testcase as well, and probably (hopefully?) also
> > the problem reported in
> >
> > I applied a patch to CVS and will upload a -60 release asap.
> >
> >
> > Thanks again,
> > Corinna
> >
> Great. In fact, I also found this code myself might cause problem in path.h:
> (we should test if path is NULL, and free it before the memcpy, and
> other member pointers should also be checked and free-ed first, is it
> about right?:-)

Yes and no.  It might look cleaner to free the pointers at this point
if they are non-NULL, but in fact the operator= is called after the
path_conv content has been memcpy'ed to another fhandler.  So, if you
free the pointers, you free the pointers of another file descriptor.
SEGV's galore!


Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat

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