As a consequence of a heavy discussion in another thread,
I wrote this program:
#include <stdlib.h>
int main(void)
{
char *p=calloc(65521 ,65552);
if (p)
printf("BUG!!!! \n");
}
The multiplication will give an erroneus result
in 32 bit size_t systems. I have tested this
in several systems with several compilers.
Maybe people with other compilers/implementations
would compile this program and send the results?
The results I have so far are:
LINUX
GCC 2.95
HAS THE BUG
GCC-4.02
NO BUGS
GCC-3.x
NO BUGS
WINDOWS
cygwin gcc 3.4.4
NO bugs
pelles c:
HAS THE BUG
Microsoft
Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 14.00.50727.42
for 80x86
NO BUGS (If the multiplication overflows it will trap. Very good
behavior)
AIX
IBM-cc (compiling in 32 bit mode)
NO BUGS
gcc 4.0.0 (compiling in 32 bit mode)
NO BUGS
Thanks in advance for your cooperation
Jan 2 '07
149  4313 
"CBFalconer " <cb********@yah oo.comwrote in message
news:45******** *******@yahoo.c om...
alex bodnaru wrote:
CBFalconer wrote:
"David T. Ashley" wrote:
... snip ...
54135^2 is going to be on the order of 2.5G. That is a pretty
fair hunk of memory.
---------
[nouser@pamc ~]$ cat test3.c
#include <stdio.h>
#include <stdlib.h>
int main(void)
{
char *p;
int i;
for (i=65535; i>0; i--)
{
if (p = calloc(i,i))
{
printf("%d is apparently the largest integer that will
succeed.\n",
>i);
break;
}
}
}
[nouser@pamc ~]$ gcc test3.c
[nouser@pamc ~]$ ./a.out
54135 is apparently the largest integer that will succeed.
[nouser@pamc ~]$
With DJGPP 2.03 (specifies the library) that crashes immediately in
memset. With nmalloc linked in in place of the library it yields
23093.
Advisory cross-post to comp.os.msdos.d jgpp, f'ups set to clc.
even the first malloc is 4gb, and i doubt you have more ;-)
Which should simply fail. The code is looking for the largest
assignable value and for foulups in the calloc multiply operation.
It shouldn't crash. nmalloc fails and returns NULL. DJGPP malloc
claims to succeed, but doesn't, and the memset crashes. This also
shows the need to include calloc in the nmalloc package, to ensure
the same limits are observed.
Why did you override the follow-up I had set? And top-post.
Please go to comp.lang.c for further general discussion of this.
Meanwhile, be aware of the DJGPP bug.
http://groups.google.com/group/comp....f8224d28?hl=en
Chuck,
1) you've encourage DJGPP (and c.l.c) users to use nmalloc for a few years
with little response
2) you never built DJGPP demand for nmalloc by submitting it to the DJGPP
archives
3) since you've said your health isn't good, you could've asked if someone
on comp.os.msdos.d jgpp was willing to prepare and submit nmalloc to the
DJGPP archives for you, but you haven't
4) DJ has never publicly responded to your posts on nmalloc...
5) although you believe in nmalloc, you've never bothered to ask DJ why he's
shown zero interest in nmalloc... Without asking, you'll never know if it
was something simple holding back nmalloc.
Just how serious are you about getting nmalloc into the DJGPP archives or
the DJGPP C library?
Rod Pemberton
PS. Sent to both groups...
"Rod Pemberton" <do*********@bi tfoad.cmmwrites :
2) you never built DJGPP demand for nmalloc by submitting it to the DJGPP
archives
He did, there were some buglets that needed tweaking long ago, it's
probably just waiting for someone with write access to review it and
put it in place. Plus backward compatibility (the malloc debug
interface) and all that.
4) DJ has never publicly responded to your posts on nmalloc...
Dude, go WAY back in the djgpp-workers mail archives.
Ben Pfaff wrote:
Mark McIntyre <ma**********@s pamcop.netwrite s:
.... snip ...
>>
It still doesn't follow. The pointer returned by malloc need not
be a complete absolute reference. Magic can go on behind the
scenes, much as it did with 16-bit pointers used to reference
20-bit memory.
I assume you're speaking of the segmented 16-bit x86 architecture
as featured in MS-DOS compilers. The object pointers used by
these compilers in some modes were 16 bits wide, and they could
only address 64 kB worth of data. You could use
implementation-specific extensions to address more than 16 kB of
memory, or you could switch your compiler to a mode where
pointers were 32 bits long, but there was no way to address more
than 64 kB of objects with 16-bit pointers and without using C
extensions.
Turbo C 2.01 says the following. In that mode (with some other
options set) I can simply compile virtually any standard C source.
Things will be unwell if the object code exceeds 64 k, but I can
put up with that. near and far are just things the compiler does
internally.
"Compact model: This model has 64K for code, 64K
for stack and static data, and up to 1 MB for
the heap. All functions are near by default and
all data pointers are far by default."
I suspect that this may blow up if function pointer are converted
to void * and back again. However that is standard conforming.
--
Chuck F (cbfalconer at maineline dot net)
Available for consulting/temporary embedded and systems.
<http://cbfalconer.home .att.net>
jacob navia wrote:
>
.... snip ...
>
Obviously each 16 bit pointer could address only 64K!!!
Mr McIntyre has strong hallucinations when he supposes that
you can have more than 64K with 16 bit pointers!
Emulating Dan Pops tact again?
--
Chuck F (cbfalconer at maineline dot net)
Available for consulting/temporary embedded and systems.
<http://cbfalconer.home .att.net>
Richard Heathfield wrote:
>
.... snip ...
>
Many people were oppressed by King Henry VII. More suffered under
King Henry VIII.
<OT>
That may also reflect the world population at the time, and the
available oppression methods. The shrubish leader has exceeded
both, IMO. I suspect Adolph Schickelgruber holds the record.
Record candidates should include Genghis Khan, Napoleon,
Robespierre, Stalin, Cromwell, Queen Mary I, Mao, all spammers,
various Czars, Popes, and Roman Emperors. Maybe the results should
be normallized to world population at the time of oppression.
</OT>
--
Chuck F (cbfalconer at maineline dot net)
Available for consulting/temporary embedded and systems.
<http://cbfalconer.home .att.net>
in 713360 20070105 054050 CBFalconer <cb********@yah oo.comwrote:
>Richard Heathfield wrote:
>>
.... snip ...
>>
Many people were oppressed by King Henry VII. More suffered under
King Henry VIII.
<OT>
That may also reflect the world population at the time, and the
available oppression methods. The shrubish leader has exceeded
both, IMO. I suspect Adolph Schickelgruber holds the record.
Record candidates should include Genghis Khan, Napoleon,
Robespierre, Stalin, Cromwell, Queen Mary I, Mao, all spammers,
various Czars, Popes, and Roman Emperors. Maybe the results should
be normallized to world population at the time of oppression.
</OT>
So Adam pushing Eve around would be top of the list?
Bob Martin said:
in 713360 20070105 054050 CBFalconer <cb********@yah oo.comwrote:
>>Richard Heathfield wrote:
>>>
.... snip ...
>>>
Many people were oppressed by King Henry VII. More suffered under
King Henry VIII.
<OT>
That may also reflect the world population at the time, and the
available oppression methods. The shrubish leader has exceeded
both, IMO. I suspect Adolph Schickelgruber holds the record.
Record candidates should include Genghis Khan, Napoleon,
Robespierre , Stalin, Cromwell, Queen Mary I, Mao, all spammers,
various Czars, Popes, and Roman Emperors. Maybe the results should
be normallized to world population at the time of oppression.
</OT>
So Adam pushing Eve around would be top of the list?
Other way round. :-)
--
Richard Heathfield
"Usenet is a strange place" - dmr 29/7/1999 http://www.cpax.org.uk
email: rjh at the above domain, - www.
Richard Heathfield wrote:
Bob Martin said:
>CBFalconer <cb********@yah oo.comwrote:
>>Richard Heathfield wrote:
.... snip ...
Many people were oppressed by King Henry VII. More suffered under
King Henry VIII.
<OT>
That may also reflect the world population at the time, and the
available oppression methods. The shrubish leader has exceeded
both, IMO. I suspect Adolph Schickelgruber holds the record.
Record candidates should include Genghis Khan, Napoleon,
Robespierre , Stalin, Cromwell, Queen Mary I, Mao, all spammers,
various Czars, Popes, and Roman Emperors. Maybe the results should
be normallized to world population at the time of oppression.
</OT>
So Adam pushing Eve around would be top of the list?
Other way round. :-)
If we count Cain and Abel in either case they achieved a NOL
(normallized oppression level) of 25%. And they are tied by Cain.
Maybe we should limit the field to recorded history. Bible
thumpers can opt-out. Or, if we include a factor for the QOO
(quality of oppression) Cain 'wins' since his QOO is 1.0.
--
Chuck F (cbfalconer at maineline dot net)
Available for consulting/temporary embedded and systems.
<http://cbfalconer.home .att.net>
CBFalconer <cb********@yah oo.comwrites:
Ben Pfaff wrote:
>Mark McIntyre <ma**********@s pamcop.netwrite s:
... snip ...
>>>
It still doesn't follow. The pointer returned by malloc need not
be a complete absolute reference. Magic can go on behind the
scenes, much as it did with 16-bit pointers used to reference
20-bit memory.
I assume you're speaking of the segmented 16-bit x86 architecture
as featured in MS-DOS compilers. The object pointers used by
these compilers in some modes were 16 bits wide, and they could
only address 64 kB worth of data. You could use
implementati on-specific extensions to address more than 16 kB of
memory, or you could switch your compiler to a mode where
pointers were 32 bits long, but there was no way to address more
than 64 kB of objects with 16-bit pointers and without using C
extensions.
Turbo C 2.01 says the following. In that mode (with some other
options set) I can simply compile virtually any standard C source.
Things will be unwell if the object code exceeds 64 k, but I can
put up with that. near and far are just things the compiler does
internally.
"Compact model: This model has 64K for code, 64K
for stack and static data, and up to 1 MB for
the heap. All functions are near by default and
all data pointers are far by default."
I suspect that this may blow up if function pointer are converted
to void * and back again. However that is standard conforming.
I don't think this contradicts anything I wrote. The compact
model uses 32-bit object pointers, like I said. Function
pointers are different and need not have the same form.
--
"When in doubt, treat ``feature'' as a pejorative.
(Think of a hundred-bladed Swiss army knife.)"
--Kernighan and Plauger, _Software Tools_
Ben Pfaff wrote:
CBFalconer <cb********@yah oo.comwrites:>
>Ben Pfaff wrote:
>>Mark McIntyre <ma**********@s pamcop.netwrite s:
... snip ...
>>>>
It still doesn't follow. The pointer returned by malloc need not
be a complete absolute reference. Magic can go on behind the
scenes, much as it did with 16-bit pointers used to reference
20-bit memory.
I assume you're speaking of the segmented 16-bit x86 architecture
as featured in MS-DOS compilers. The object pointers used by
these compilers in some modes were 16 bits wide, and they could
only address 64 kB worth of data. You could use
implementatio n-specific extensions to address more than 16 kB of
memory, or you could switch your compiler to a mode where
pointers were 32 bits long, but there was no way to address more
than 64 kB of objects with 16-bit pointers and without using C
^^^^^^^^^^^^^^^
>>extensions.
^^^^^^^^^^
>>
Turbo C 2.01 says the following. In that mode (with some other
options set) I can simply compile virtually any standard C source.
Things will be unwell if the object code exceeds 64 k, but I can
put up with that. near and far are just things the compiler does
internally.
"Compact model: This model has 64K for code, 64K
for stack and static data, and up to 1 MB for
the heap. All functions are near by default and
all data pointers are far by default."
I suspect that this may blow up if function pointer are converted
to void * and back again. However that is standard conforming.
I don't think this contradicts anything I wrote. The compact
model uses 32-bit object pointers, like I said. Function
pointers are different and need not have the same form.
And my point is that no C extensions are needed. Just feed it
portable standard code. I primarily use it to check I haven't
inadverdently relied on an int size larger than 16 bits.
--
Chuck F (cbfalconer at maineline dot net)
Available for consulting/temporary embedded and systems.
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