Date: Fri, 26 Oct 2001 11:56:16 -0700 (PDT) From: Jeff Brown <jabrown@ipn.caida.org> To: <FreeBSD-gnats-submit@freebsd.org> Subject: ports/31511: g++30 output SIGBUS-ing Message-ID: <Pine.GSO.4.33.0110261154340.16460-100000@ipn.caida.org>
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>Number: 31511
>Category: ports
>Synopsis: g++30 produces binaries which SIGBUS when trying to use cout/cin/cerr/clog
>Confidential: no
>Severity: serious
>Priority: low
>Responsible: freebsd-ports
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Fri Oct 26 12:00:01 PDT 2001
>Closed-Date:
>Last-Modified:
>Originator: Jeff Brown
>Release: FreeBSD 4.1.1-RELEASE i386
>Organization:
Mildly organized.
>Environment:
FreeBSD 4.1.1-R laptop system, using a ports tree from Oct 25, with the package
"41upgrade-2000.11.01" installed, as well as a "make" binary from a 4.3-R
system.
>Description:
Using gcc-3.0.1 built and installed with the "gcc30" port and its default
options, simple C++ "hello world" programs compile but fail to execute
properly. Any attempted I/O operations on cin/cout/cerr/clog result in
a SIGBUS error, as the library attempts to dereference a NULL-valued pointer
after subtracting 12 from it.
The problem appears to be related to standard input/output/error; I/O
operations on streams backed by files seem to work just fine.
>How-To-Repeat:
test.cc:
-----------------
#include <iostream>
int main()
{
std::cout.flush();
return 0;
}
-----------------
% g++30 -g test.cc -o test
% ./test
Bus error (core dumped)
A quick look in gdb reveals where things go South: the load from
memory at 0x8054acc (which, in this instance, is loading from
address 0x806a440) yields a value of "0". When it is offset
and dereferenced as a pointer, havoc ensues. It would appear that
something is screwing up the second argument to this function, "__os".
(gdb) run
Starting program: /usr/home/jabrown/broken-gcc/test
Program received signal SIGBUS, Bus error.
0x8054ad1 in sentry (this=0xbfbff588, __os=@0x806a440) at ostream.tcc:39
39 : _M_ok(__os.good()), _M_os(__os)
(gdb) disassemble 0x8054abc 0x8054ad3
Dump of assembler code from 0x8054abc to 0x8054ad3:
0x8054abc <sentry>: push %ebp
0x8054abd <sentry+1>: mov %esp,%ebp
0x8054abf <sentry+3>: push %ebx
0x8054ac0 <sentry+4>: sub $0x4,%esp
0x8054ac3 <sentry+7>: mov 0x8(%ebp),%ebx
0x8054ac6 <sentry+10>: sub $0xc,%esp
0x8054ac9 <sentry+13>: mov 0xc(%ebp),%eax
0x8054acc <sentry+16>: mov (%eax),%eax
0x8054ace <sentry+18>: sub $0xc,%eax
0x8054ad1 <sentry+21>: mov (%eax),%eax
End of assembler dump.
(gdb) print/x $eax
$1 = 0xfffffff4
Since I'm pretty much a C++ newbie, and have little/no knowledge of the
inner workings of the I/O libraries, I don't know what to do from here.
>Fix:
Use ifstreams for input, ofstreams for output. (Ouch.)
>Release-Note:
>Audit-Trail:
>Unformatted:
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