Path: utzoo!telly!attcan!uunet!tut.cis.ohio-state.edu!YAHI.STANFORD.EDU!mdt
From: mdt@YAHI.STANFORD.EDU (Michael Tiemann)
Newsgroups: gnu.g++.bug
Subject: alloca's in ld.c cause seg-faults
Message-ID: <8903201714.AA24798@yahi>
Date: 20 Mar 89 17:14:22 GMT
References: <8903200402.AA26265@maui.cs.ucla.edu>
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Reply-To: tiemann@lurch.stanford.edu
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   Date: Sun, 19 Mar 89 20:02:45 PST
   From: othar@cs.ucla.edu (Othar Hansson)
   Reply-To: othar@cs.ucla.edu
   Organization: Weapons Division, Pepperidge Farm
   Physical-Address: 3436 Boelter Hall



   In "GNU C++ version 1.34.1 (68k, MIT Syntax) 
   compiled by GNU C version 1.34" on a SUN 3, ...

   ld++ exits with a segmentation fault when fed source files with large
   data segments.  The fault is caused by an attempt to 'alloca' a large
   chunk of memory in 'copy_data()' in ld.c

	   bytes = (char *) alloca (entry->header.a_data);

   if a_data is too big (e.g. 950k) to fit on the call stack, then alloca
   returns garbage, apparently.  Allocating using malloc() (with a
   corresponding 'free(bytes)') fixes the problem, but alloca is used in
   similarly dangerous contexts elsewhere.

   Please don't ask how ugly my program must be 
   to have a data segment of 950k :-)


   Othar Hansson

   ( othar@cs.ucla.edu
   ..!{ucbvax|rutgers}!ucla-cs!othar )

This problem may be fixable by doing this:

	unlimit stacksize

Or, do this:

	limit

see what the limit of stacksize is (say 2048K), multiply it by 4, and
set a new limit:

	limit stacksize 8192

Michael