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From: kimr@eiffel.UUCP (Kim Rochat)
Newsgroups: comp.lang.eiffel
Subject: Patch for Eiffel version 2.3.4 garbage collector.
Message-ID: <572@eiffel.UUCP>
Date: 18 May 91 00:19:53 GMT
Organization: Interactive Software Engineering, Santa Barbara CA
Lines: 107

A defect has been found and fixed in the garbage collector of Interactive 
Software's release of Eiffel version 2.3.4.

This defect results in a segmentation fault in some Eiffel applications
using both garbage collection and class ARRAY.  It most commonly occurs
if the "force" routine of class ARRAY is used to dynamically grow an
array, but other ARRAY operations which result in an ARRAY object being
copied may also cause the problem.  The segmentation fault is a
consequence of the array operation, but may occur later in the system
execution when the ARRAY object is scanned by the garbage collector.

The context diff for the fix is included at the end of this article.  

Use the following instructions to apply to fix to your Eiffel installation.
Assume that $EIFFEL contains the full pathname of the "Eiffel" subdirectory
in the Eiffel installation directory.

1) Extract the context diff from the end of this message, placing it in 
   /tmp/diffs.

2) cd $EIFFEL/files

3) make a backup copy of _basic.c

4) Apply the patch to _basic.c using the "patch" utility:

		patch < /tmp/diffs

   or apply the diffs to _basic.c by hand.

Recompile _basic.c and recreate the runtime library _run_time.a:

5) After making a backup copy of "_makeD", Edit "_makeD" and make 
   certain that the CFLAGS macro includes either "-DBSD" or "-DSYSTEMV", 
   as appropriate for your platform. (CFLAGS is usually 

	CFLAGS = -O -DBSD -DDARRAY

   but should be set to 

	CFLAGS = -O -DSYSTEM -DDARRAY

    for Unix System V and other non-BSD Unix systems).

6) Move _run_time.a to a backup file.

7) rebuild the run_time_library:
	
	make -f _makeD

    This will take a few minutes while the run time files recompile.

8) Rebuild your Eiffel system using the new runtime:

	rm <root_class_name>; es

9) If you have a C package for your application, the files in
   the C package directory can be updated by removing the files 
   "_run_time.a" and "_basic.c" from the
   C package directory and re-running the "es" command that
   originally generated the C package directory.

Kim Rochat
Interactive Software Engineering
Responses to: eiffel@eiffel.com

-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
*** _basic.c.old	Fri May 17 15:57:56 1991
--- _basic.c	Fri May 17 15:58:22 1991
***************
*** 9,15 ****
  #include "_mem.h"
  extern	int16	str_DT;	 
  extern	int16	gac_flag, gac_option;  
- extern	void	strcpy ();	 
  extern	void	str_lower ();  
  extern int16 db_DT, int_DT, real_DT, bool_DT, char_DT;
  extern uint32 _rt_40a, _rt_40d;
--- 9,14 ----
***************
*** 117,122 ****
--- 116,123 ----
  int range, start, nbelem;
  {
  	OBJPTR new_area;
+ 	register OBJPTR element;
+ 	register int32 i;
  	new_area = spAllocate (range, gentest (oldarea, 0));
  #ifdef SYSTEMV
     memcpy((char *) (Access (new_area)+start),(char *) (Access (oldarea)),nbelem*_rt_40d);
***************
*** 124,129 ****
--- 125,137 ----
  #ifdef BSD
     bcopy((char *) (Access (oldarea)),(char *) (Access (new_area)+start),nbelem*_rt_40d);
  #endif
+ 	if (gac_option &&  gentest (new_area, 0) &&
+ 			ISBLACK(new_area) && !ISBLACK(oldarea)) {
+ 		for (i=0;i<nbelem;i++) {
+ 			if (element=(OBJPTR)(*(Access (new_area)+start+i)))
+ 				SHADE (element);
+ 		}
+ 	}
  	return (new_area);
  }
  OBJPTR	MakeStr(s)