RE: ost::String class release 1.1.1

[erik_ohrnberger]

David,
 635 char *String::getSpace(unsigned size)
 636 {
 637     unsigned        slot;
 638     char*           text = NULL;
 639     char**          next;
 640 
 641     if(size > slotlimit)
 642         return new char[size];
 643 
 644     slot = size / slotsize;
 645     mutex.enterMutex();
 646     if(!pager)
 647     {
 648         pager = new MemPager(pagesize);
 649         idx = (char **)pager->alloc(sizeof(char *) * slots);
 650         memset(idx, 0, sizeof(char *) * slots);
 651     }
 652     text = idx[slot];
 653     if(text)
 654     {
 655         next = (char **)text;
 656         idx[slot] = *next;
 657     }
 658     else
 659         text = (char *)pager->alloc(++slot * slotsize);
 660     mutex.leaveMutex();
 661     return text;
 662 }

Right on line 656.  
slot = 1
text = 0x32353964 <Address 0x32353964 out of bounds>
size = 1076041732

I think that size must be way off (duh).  OK, so where'd that come from?

 407 void String::copy(const String &original)
 408 {
 409     char *ptr;
 410     content = original.content;
 411 
 412     if(!isBig())
 413         return;
 414 
 415     if(getLength() < minsize)
 416     {
 417         content.ministring.length = getLength();
 418         memcpy(content.ministring.text, getText(), getLength() + 1);
 419         content.ministring.big = false;
 420         return;
 421     }
 422 
 423     ptr = getText();
 424     content.bigstring.size = setSize(content.bigstring.length + 1);
 425     content.bigstring.text = getSpace(getSize());
 426     memcpy(content.bigstring.text, ptr, getLength() + 1);
 427 }

at line 425
getLength() = 8
ptr is pointing to a valid string of text.
content.bigstring.size = 32

Hmm.  Hope that this helps, I'm afraid that I've not studied this String
class sufficiently to diagnose this at the moment.  Perhaps you'l ahve some
insights?

        Thanks,
                Erik.

> -----Original Message-----
> From: David Sugar [mailto:address@hidden
> Sent: Monday, April 05, 2004 1:27 AM
> To: Ohrnberger, Erik; address@hidden
> Subject: Re: ost::String class release 1.1.1
> 
> 
> Hmm...
> 
> text is either assigned from a slot list (linked list) or 
> from mempager 
> alloc'd memory.  If the linked list is messed up, that is one 
> possibility.  
> However, the other option is if the string is too large, a 
> simple new is 
> used, and text is never modified.  Text is not initialized 
> because it does 
> not need a value until it needs to be assigned from the list or from 
> mempager.  Hence, it would help to know more about where 
> precisely this 
> segfault occurs.  One thing you can do is initially set text 
> to NULL at the 
> start of getSpace, as that would make it easier to determine 
> what the real 
> state of text is at the time it happens; whether its before 
> or after it has 
> been assigned by something.
> 
> On Monday 05 April 2004 12:15 pm, address@hidden wrote:
> > Everyone,
> >     I'm noticing instances of seg faults in the 
> ost::String::getSpace()
> > method, where the *text variable is assigned what appears 
> to be random
> > garbage, and is yet used as a pointer into some data structure.
> >
> >     Has anyone else experienced a similar failure?
> >
> >     Is there a patch to the ost::String class that needs to 
> be applied?
> >
> >     Thanks,
> >             Erik.
> >
> >
> > _______________________________________________
> > Bug-commoncpp mailing list
> > address@hidden
> > http://mail.gnu.org/mailman/listinfo/bug-commoncpp
> 
>