libstdc++/3720: Problems with num_get

[Peter Schmid <schmid at snake dot iap dot physik dot tu-darmstadt dot de>]

>Number:         3720
>Category:       libstdc++
>Synopsis:       Problems with num_get
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Jul 17 15:06:00 PDT 2001
>Closed-Date:
>Last-Modified:
>Originator:     Peter Schmid
>Release:        3.1 20010716 (experimental)
>Organization:
TU Darmstadt
>Environment:
System: Linux kiste 2.4.6 #6 Wed Jul 11 02:21:23 CEST 2001 i686 unknown
Architecture: i686
SuSE 7.1
GNU ld version 2.11.90.0.23 (with BFD 2.11.90.0.23)
host: i686-pc-linux-gnu
build: i686-pc-linux-gnu
target: i686-pc-linux-gnu
configured with: ../gcc/configure --enable-shared --disable-nls --enable-threads=posix --enable-clocale=gnu --enable-languages=c,c++,f77,objc
>Description:
According to the book "The C++ Standard Library" by Josuttis on page
707 the facet num_get is used to parse the textual representation of
numbers. This works, unless I enter more than 56 decimals. Somehow a
segmentation fault occurs. I believe libstdc++ should handle this gracefully. 
  
>How-To-Repeat:
Source code n1.C

#include <locale>
#include <iostream>
#include <iterator>

int main()
{

    std::locale loc;
    typedef std::istreambuf_iterator<char> ist_it;
    ist_it beg = ist_it(std::cin);
    ist_it end = ist_it();
    std::ios_base& fmt = std::cin;
    std::ios_base::iostate err = std::ios_base::goodbit;
    double value;
    std::num_get<char, ist_it> const& ng
        = std::use_facet<std::num_get<char, ist_it> >(loc);
    ng.get(beg, end, fmt, err, value);
    std::cout << "value: " << value << std::endl;
}
Compiling n1.C
g++ -v -o n1 n1.C -W -Wall -g
Reading specs from /usr/local/lib/gcc-lib/i686-pc-linux-gnu/3.1/specs
Configured with: ../gcc/configure --enable-shared --disable-nls --enable-threads=posix --enable-clocale=gnu --enable-languages=c,c++,f77,objc
Thread model: posix
gcc version 3.1 20010716 (experimental)
 /usr/local/lib/gcc-lib/i686-pc-linux-gnu/3.1/cc1plus -v -D__GNUC__=3 -D__GNUC_MINOR__=1 -D__GNUC_PATCHLEVEL__=0 -D__ELF__ -Dunix -Dlinux -D__ELF__ -D__unix__ -D__linux__ -D__unix -D__linux -Asystem=posix -D__NO_INLINE__ -D__STDC_HOSTED__=1 -W -Wall -D_GNU_SOURCE -Acpu=i386 -Amachine=i386 -Di386 -D__i386 -D__i386__ -D__tune_i686__ -D__tune_pentiumpro__ n1.C -D__GNUG__=3 -D__DEPRECATED -D__EXCEPTIONS -D__GXX_ABI_VERSION=100 -quiet -dumpbase n1.C -g -W -Wall -version -o /tmp/ccUe5GLI.s
GNU CPP version 3.1 20010716 (experimental) (cpplib) (i386 Linux/ELF)
GNU C++ version 3.1 20010716 (experimental) (i686-pc-linux-gnu)
	compiled by GNU C version 3.1 20010716 (experimental).
ignoring nonexistent directory "/usr/local/i686-pc-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/local/include/g++-v3
 /usr/local/include/g++-v3/i686-pc-linux-gnu
 /usr/local/include/g++-v3/backward
 /usr/local/include
 /usr/local/lib/gcc-lib/i686-pc-linux-gnu/3.1/include
 /usr/include
End of search list.
 /usr/local/lib/gcc-lib/i686-pc-linux-gnu/3.1/../../../../i686-pc-linux-gnu/bin/as -V -Qy -o /tmp/ccp9xNWy.o /tmp/ccUe5GLI.s
GNU assembler version 2.11.90.0.23 (i686-pc-linux-gnu) using BFD version 2.11.90.0.23
 /usr/local/lib/gcc-lib/i686-pc-linux-gnu/3.1/collect2 -m elf_i386 -dynamic-linker /lib/ld-linux.so.2 -o n1 /usr/lib/crt1.o /usr/lib/crti.o /usr/local/lib/gcc-lib/i686-pc-linux-gnu/3.1/crtbegin.o -L/usr/local/lib/gcc-lib/i686-pc-linux-gnu/3.1 -L/usr/local/lib/gcc-lib/i686-pc-linux-gnu/3.1/../../../../i686-pc-linux-gnu/lib -L/usr/local/lib/gcc-lib/i686-pc-linux-gnu/3.1/../../.. /tmp/ccp9xNWy.o -lstdc++ -lm -lgcc_s -lgcc -lc -lgcc_s -lgcc /usr/local/lib/gcc-lib/i686-pc-linux-gnu/3.1/crtend.o /usr/lib/crtn.o

Running n1
./n1
1.2345678901234567890123456789012345678901234567890123456
Segmentation fault (core dumped)

Debugging n1
GNU gdb 5.0
Copyright 2001 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "i686-pc-linux-gnu"...
(gdb) r
Starting program: /home/peter/trans/vergleich/mein_stlport/i18n/n1 
1.2345678901234567890123456789012345678901234567890123456

Program received signal SIGSEGV, Segmentation fault.
0x0804a861 in std::num_get<char, std::istreambuf_iterator<char, std::char_traits<char> > >::get(std::istreambuf_iterator<char, std::char_traits<char> >, std::istreambuf_iterator<char, std::char_traits<char> >, std::ios_base&, std::_Ios_Iostate&, double&) const (this=0x0, __in=
      {<iterator<std::input_iterator_tag,char,long int,char*,char&>> = {<No data fields>}, _M_sbuf = 0x0, _M_c = 0}, __end=
      {<iterator<std::input_iterator_tag,char,long int,char*,char&>> = {<No data fields>}, _M_sbuf = 0x0, _M_c = 0}, __io=@0x0, __err=@0x0, __v=@0x0)
    at /usr/local/include/g++-v3/bits/locale_facets.h:637
(gdb) l
632	      { return do_get(__in, __end, __io, __err, __v); }
633	
634	      iter_type 
635	      get(iter_type __in, iter_type __end, ios_base& __io,
636		  ios_base::iostate& __err, double& __v) const
637	      { return do_get(__in, __end, __io, __err, __v); }
638	
639	      iter_type 
640	      get(iter_type __in, iter_type __end, ios_base& __io,
641		  ios_base::iostate& __err, long double& __v) const
(gdb) bt
#0  0x0804a861 in std::num_get<char, std::istreambuf_iterator<char, std::char_traits<char> > >::get(std::istreambuf_iterator<char, std::char_traits<char> >, std::istreambuf_iterator<char, std::char_traits<char> >, std::ios_base&, std::_Ios_Iostate&, double&) const (this=0x0, __in=
      {<iterator<std::input_iterator_tag,char,long int,char*,char&>> = {<No data fields>}, _M_sbuf = 0x0, _M_c = 0}, __end=
      {<iterator<std::input_iterator_tag,char,long int,char*,char&>> = {<No data fields>}, _M_sbuf = 0x0, _M_c = 0}, __io=@0x0, __err=@0x0, __v=@0x0)
    at /usr/local/include/g++-v3/bits/locale_facets.h:637
(gdb) 
>Fix:
	
>Release-Note:
>Audit-Trail:
>Unformatted: