Re: Question

[Laurent Michel]

David,

I recompiled and here is the trace:

Program received signal SIGSEGV, Segmentation fault.
0xb7a55695 in isEmptyProtocol (aProto=0xb7736f90) at protocol.c:62
62                      isEmpty &= (p2->properties->count == 0);
(gdb) where
#0  0xb7a55695 in isEmptyProtocol (aProto=0xb7736f90) at protocol.c:62
#1  0xb7a5553e in unique_protocol (aProto=0xb7736f90) at protocol.c:118
#2  0xb7a534eb in init_protocols (protocols=0xb7736fb0) at protocol.c:189
#3  0xb7a534da in init_protocols (protocols=0xb773a0c0) at protocol.c:186
#4  0xb7a5328a in objc_init_protocols (protocols=0xb773a0c0) at protocol.c:196
#5  0xb7a48264 in load_category (cat=0xb773a2c0, class=0xb7a64340) at 
category_loader.c:38
#6  0xb7a47f02 in try_load_category (cat=0xb773a2c0) at category_loader.c:50
#7  0xb7a47e6a in objc_try_load_category (cat=0xb773a2c0) at 
category_loader.c:63
#8  0xb7a5143f in __objc_exec_class (module=0xb773a398) at loader.c:89
#9  0xb76c55a4 in .objc_load_function () from 
/home/ldm/work/platform/Clo/queens2/../ORFoundation/libORFoundation.so
#10 0xb7fece9b in ?? () from /lib/ld-linux.so.2
#11 0xb7fecf84 in ?? () from /lib/ld-linux.so.2
#12 0xb7fdf20f in ?? () from /lib/ld-linux.so.2


So line 62. 

It won't show the variables though:

(gdb) p *p2
$3 = {
  isa = 0xb7a642f0, 
  name = 0xb771df54 "ORExpr", 
  protocol_list = 0xb7795a18, 
  instance_methods = 0xb7795a20, 
  class_methods = 0xb7795a20, 
  optional_instance_methods = 0xb7795a20, 
  optional_class_methods = 0xb7795a20, 
  properties = 0x0, 
  optional_properties = 0x0
}
(gdb) l
57              if (aProto->isa == ObjC2ProtocolClass)
58              {
59                      struct objc_protocol2 *p2 = (struct 
objc_protocol2*)aProto;
60                      isEmpty &= (p2->optional_instance_methods->count == 0);
61                      isEmpty &= (p2->optional_class_methods->count == 0);
62                      isEmpty &= (p2->properties->count == 0);
63                      isEmpty &= (p2->optional_properties->count == 0);
64              }
65              return isEmpty;
66      }

So p2->properties is NULL and trying to access the count attribute crashes. 
This is happening on a protocol
of mine (ORExpr) which inherits from other protocols:

@protocol ORExpr <ORConstraint,NSObject,NSCoding>
-(id<ORTracker>) tracker;
-(ORInt) min;
-(ORInt) max;
-(BOOL) isConstant;
-(BOOL) isVariable;

....

@end

Any ideas?


On Mar 5, 2013, at 7:20 AM, Laurent Michel <address@hidden> wrote:

> 
> On Mar 5, 2013, at 4:10 AM, David Chisnall <address@hidden> wrote:
> 
>> Hi,
>> 
>> How old is your runtime?  Without debugging symbols, this looks like it 
>> might be a bug that was fixed in May last year.  It would really help if you 
>> could do a debug build of the runtime and let me know exactly what is 
>> failing.  If you do ccmake . in your libobjc2 build directory, and change 
>> the build type to Debug, you should get the symbols.
> 
> libobjc2 was 1.6.1
> 
> 
> address@hidden:/usr/local/src/old$ sha1sum libobjc2-1.6.tar.gz 
> 348ab64899b25ecb2bfdfd13ebeeab2d6a2c8988  libobjc2-1.6.tar.gz
> 
> 
> total 9196
> drwxr-xr-x 4 root root     4096 Mar  4 08:37 GNUstep
> lrwxrwxrwx 1 root root       23 Mar  4 08:37 libgnustep-base.so -> 
> libgnustep-base.so.1.24
> lrwxrwxrwx 1 root root       25 Mar  4 08:37 libgnustep-base.so.1.24 -> 
> libgnustep-base.so.1.24.3
> -rwxr-xr-x 1 root root  9105637 Mar  4 08:36 libgnustep-base.so.1.24.3
> -r--r--r-- 1 root root   136452 May 18  2012 libobjc.a
> lrwxrwxrwx 1 root root       31 May 18  2012 libobjc.so -> 
> /usr/local/lib/libobjc.so.4.6.0
> lrwxrwxrwx 1 root root       31 May 18  2012 libobjc.so.4 -> 
> /usr/local/lib/libobjc.so.4.6.0
> lrwxrwxrwx 1 root root       31 May 18  2012 libobjc.so.4.6 -> 
> /usr/local/lib/libobjc.so.4.6.0
> -r--r--r-- 1 root root   140820 May 18  2012 libobjc.so.4.6.0
> lrwxrwxrwx 1 root root       33 May 18  2012 libobjcxx.so -> 
> /usr/local/lib/libobjcxx.so.4.6.0
> lrwxrwxrwx 1 root root       33 May 18  2012 libobjcxx.so.4 -> 
> /usr/local/lib/libobjcxx.so.4.6.0
> lrwxrwxrwx 1 root root       33 May 18  2012 libobjcxx.so.4.6 -> 
> /usr/local/lib/libobjcxx.so.4.6.0
> -r--r--r-- 1 root root    13002 May 18  2012 libobjcxx.so.4.6.0
> drwxrwsr-x 4 root staff    4096 Mar  3 13:33 python2.7
> address@hidden:/usr/local/lib$ 
> 
> I was looking yesterday night for a more recent tar ball, but couldn't locate 
> one. 
> 
> I'll recompile libobjc2 in debug and will update you. Thanks for the info 
> David!
> 
> --
>  Laurent
> 
> 
>> 
>> David
>> 
>> On 5 Mar 2013, at 01:37, Laurent Michel <address@hidden> wrote:
>> 
>>> PS/ I decided to recompile GNUstep simply because I was experiencing a 
>>> crash with my compiled binary during the 
>>> library initializations of GNUstep/libobjc. Namely, here is the backtrace:
>>> 
>>> [Thread debugging using libthread_db enabled]
>>> Using host libthread_db library "/lib/i386-linux-gnu/libthread_db.so.1".
>>> [New Thread 0xb7021b40 (LWP 8378)]
>>> 
>>> Program received signal SIGSEGV, Segmentation fault.
>>> 0xb7a58d50 in init_protocols () from /usr/local/lib/libobjc.so
>>> (gdb) where
>>> #0  0xb7a58d50 in init_protocols () from /usr/local/lib/libobjc.so
>>> #1  0xb7a58c47 in init_protocols () from /usr/local/lib/libobjc.so
>>> #2  0xb7a588c1 in objc_init_protocols () from /usr/local/lib/libobjc.so
>>> #3  0xb7a517e3 in objc_try_load_category () from /usr/local/lib/libobjc.so
>>> #4  0xb7a57251 in __objc_exec_class () from /usr/local/lib/libobjc.so
>>> #5  0xb76d15d4 in .objc_load_function () from 
>>> /home/ldm/work/platform/Clo/queens2/../ORFoundation/libORFoundation.so
>>> #6  0xb7fece9b in ?? () from /lib/ld-linux.so.2
>>> #7  0xb7fecf84 in ?? () from /lib/ld-linux.so.2
>>> #8  0xb7fdf20f in ?? () from /lib/ld-linux.so.2
>>> (gdb) quit
>>> A debugging session is active.
>> 
>> --
>> This email complies with ISO 3103
>> 
>> 
>> _______________________________________________
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>