[Python-bugs-list] [Bug #115919] Integer multiplication overflow
noreply@sourceforge.net
noreply@sourceforge.net
Tue, 3 Oct 2000 10:30:58 -0700
Bug #115919, was updated on 2000-Oct-03 08:01
Here is a current snapshot of the bug.
Project: Python
Category: Core
Status: Open
Resolution: None
Bug Group: Platform-specific
Priority: 6
Summary: Integer multiplication overflow
Details: roland@cachemir ~ $ python2.0
Python 2.0b2 (#3, Oct 3 2000, 16:30:25)
[GCC 2.95.2 20000220 (Debian GNU/Linux)] on linux2
Type "copyright", "credits" or "license" for more information.
>>> 1+1
2
>>> 1*1
Traceback (most recent call last):
File "<stdin>", line 1, in ?
OverflowError: integer multiplication
>>>
Last CVS update 2000-10-03 around 14:00 UTC. Last before that was some weeks ago, sorry for not being precise. Compiled with ./configure --prefix=/usr/local/ && make, su and make install. Only personal change is the use of readline in Modules/Setup.local. Did I do something wrong?
Follow-Ups:
Date: 2000-Oct-03 08:25
By: jhylton
Comment:
What happens when you run "make test"? It looks like there is something fundamentally broken, but I can't tell what it is. If 1*1 fails, I expect the rest of the test suite to also report errors.
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Date: 2000-Oct-03 08:38
By: lo-lan-do
Comment:
make test shows me plenty of lines looking like this one (except the name of the test changes):
test_grammar
test test_grammar crashed -- exceptions.OverflowError: integer multiplication
I also get messages along the lines of 'test test_dbm skipped -- No module named dbm', but I guess these ones are OK.
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Date: 2000-Oct-03 08:40
By: jhylton
Comment:
Can you include the complete output?
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Date: 2000-Oct-03 09:02
By: lo-lan-do
Comment:
[In case the bug would be caused by a recent upgrade to a beta glibc, I tried the '1*1' test with Python 1.5.2. No bug visible there.]
$ make distclean && ./configure --prefix=/usr/local/ && make
$ make test &> test.log
It seems that 'make test' somehow hangs when testing threads, so I cut at that point. I hope the relevant info is shown before that point.
Here goes...
PYTHONPATH= ./python -tt ./Lib/test/regrtest.py -l
Unhandled exception in thread:
test_grammar
test test_grammar crashed -- exceptions.OverflowError: integer multiplication
test_opcodes
test_operations
test_builtin
test test_builtin crashed -- exceptions.OverflowError: integer multiplication
test_exceptions
test_types
test test_types crashed -- exceptions.OverflowError: integer multiplication
test_MimeWriter
test_StringIO
test_al
test test_al skipped -- No module named al
test_array
test test_array crashed -- exceptions.OverflowError: integer multiplication
test_atexit
test_audioop
test test_audioop skipped -- No module named audioop
test_augassign
test test_augassign crashed -- exceptions.OverflowError: integer multiplication
test_binascii
test_binhex
test test_binhex crashed -- exceptions.OverflowError: integer multiplication
test_bsddb
test_cd
test test_cd skipped -- No module named cd
test_cfgparser
test test_cfgparser crashed -- exceptions.OverflowError: integer multiplication
test_cgi
test test_cgi crashed -- exceptions.OverflowError: integer multiplication
test_cl
test test_cl skipped -- No module named cl
test_class
test_cmath
test_compile
test_contains
test_cookie
test test_cookie crashed -- exceptions.OverflowError: integer multiplication
test_cpickle
test_crypt
test test_crypt skipped -- No module named crypt
test_dbm
test test_dbm skipped -- No module named dbm
test_dl
test test_dl skipped -- No module named dl
test_dospath
test_errno
test_extcall
test_fcntl
test_file
test_fork1
test_format
test_gc
test_gdbm
test test_gdbm skipped -- No module named gdbm
test_getopt
test_gettext
test test_gettext crashed -- exceptions.OverflowError: integer multiplication
test_gl
test test_gl skipped -- No module named gl
test_grp
test_gzip
test test_gzip skipped -- No module named zlib
test_hash
test_imageop
test test_imageop skipped -- No module named imageop
test_imgfile
test test_imgfile skipped -- No module named imgfile
test_largefile
test test_largefile skipped -- platform does not have largefile support
test_linuxaudiodev
test test_linuxaudiodev skipped -- No module named linuxaudiodev
test_long
test test_long crashed -- exceptions.OverflowError: integer multiplication
test_longexp
test_math
test_md5
test_mimetools
test test_mimetools crashed -- exceptions.AttributeError: encode
test_minidom
test test_minidom skipped -- No module named pyexpat
test_mmap
test test_mmap crashed -- exceptions.OverflowError: integer multiplication
test_new
test_nis
test test_nis skipped -- No module named nis
test_ntpath
test_openpty
test_operator
test test_operator failed -- Writing: 'mul(5, 2) = <class exceptions.OverflowError at 0x818f41c>: 10 expected', expected: 'testing:
neg\012testing: or_\012testing: pos\012testing: repeat\012testing: rshift'
test_parser
test_pickle
test_pkg
test_poll
test test_poll crashed -- exceptions.OverflowError: integer multiplication
test_popen2
test_posixpath
test_pow
test test_pow crashed -- exceptions.OverflowError: integer multiplication
test_pty
test test_pty skipped -- No module named termios
test_pwd
test_pyexpat
test test_pyexpat skipped -- cannot import name expat
test_re
test test_re crashed -- exceptions.OverflowError: integer multiplication
test_regex
test_rfc822
test test_rfc822 crashed -- exceptions.OverflowError: integer multiplication
test_rgbimg
test test_rgbimg skipped -- No module named rgbimg
test_rotor
test_sax
test test_sax skipped -- cannot import name expat
test_select
test_sha
test_signal
test_socket
test_sre
test test_sre failed -- Writing: "sre.match(r'(a)|(b)', 'b').start(1)", expected: ''
test_strftime
test test_strftime crashed -- exceptions.OverflowError: integer multiplication
test_string
test_strop
test_struct
test test_struct crashed -- exceptions.OverflowError: integer multiplication
test_sunaudiodev
test test_sunaudiodev skipped -- No module named sunaudiodev
test_thread
Traceback (most recent call last):
File "./Lib/test/test_thread.py", line 21, in task
delay = random.random() * numtasks
File "/home/roland/perso/src/sourceforge/python/dist/src/Lib/whrandom.py", line 71, in random
x = (171 * x) % 30269
OverflowError: integer multiplication
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Date: 2000-Oct-03 09:03
By: jhylton
Comment:
Two more questions:
1) What platform? Is this a 64-bit machine? A regular x86?
2) Could you run this under gdb and report where exactly the error is being generated? The exception is raised in Objects/intobject.c. I would set a breakpoint at the top of int_mul() and step through the function.
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Date: 2000-Oct-03 09:32
By: lo-lan-do
Comment:
1) Regular i686 (sez uname).
2) It seems that ah and bh are 1 and not 0 like they should.
A bit of printf-debugging shows me that LONG_BIT/2 is 32,
so somehow 1 >> 32 != 0, which seems most strange and
bizarre to me. On the other hand, gcc tells me the following
when I compile:
intobject.c: In function `int_mul':
intobject.c:327: warning: right shift count >= width of type
I hope he [gcc] still does the rshift, but I'm no gcc guru.
Hope this helps...
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Date: 2000-Oct-03 10:01
By: jhylton
Comment:
This does help. The compiler warning is a bad sign. I notice that you're using a more recent version of gcc than I have installed. I'll try building with a newer gcc, but in the interim it may help if you compile the following test program:
#include <stdio.h>
#include <ctype.h>
#ifndef CHAR_BIT
#define CHAR_BIT 8
#endif
#ifndef LONG_BIT
#define LONG_BIT (CHAR_BIT * sizeof(long))
#endif
int main()
{
int a, b;
a = 1;
b = a;
a = a >> (LONG_BIT / 2);
printf("CHAR_BIT = %d, LONG_BIT = %d\n", CHAR_BIT, LONG_BIT);
printf("%d >> %d == %d\n", b, LONG_BIT/2, a);
return 0;
}
On my system it compiles without warning using gcc -Wall and produces the following output:
CHAR_BIT = 8, LONG_BIT = 32
1 >> 16 == 0
What output do you get? What is sizeof(long) on your platform? Does ctype.h define CHAR_BIT or LONG_BIT?
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Date: 2000-Oct-03 10:23
By: lo-lan-do
Comment:
Your test program compiles without warning and
gives the same results as yours here.
sizeof(long) is 4, limits.h defines CHAR_BIT to be 8.
LONG_BIT is defined in bits/xopen_lim.h to be 32.
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Date: 2000-Oct-03 10:30
By: lo-lan-do
Comment:
Now if I replace LONG_BIT/2 by LONG_BIT in your test program:
roland@cachemir /tmp $ gcc -Wall test.c && ./a.out
test.c: In function `main':
test.c:20: warning: right shift count >= width of type
CHAR_BIT = 8, LONG_BIT = 32
1 >> 32 == 1
roland@cachemir /tmp $
So I guess it's really something to do with gcc. Drat.
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http://sourceforge.net/bugs/?func=detailbug&bug_id=115919&group_id=5470