Fwd: The APT problem

[Joel Klecker <jk at espy dot org>]

[ I have been sitting on this for a while because I wasn't sure about 
reporting it. ]

Should this be considered a glibc bug? or even a bug at all?

libstdc++2.9 on Debian systems is linked with glibc 2.0; 
libstdc++2.9-glibc2.1 is linked with glibc 2.1.

>-- begin forwarded message --
>Subject: The APT problem
>To: egcs@packages.debian.org
>Date: Wed, 23 Jun 1999 14:23:29 +0200 (CEST)
>CC: debian-glibc@lists.debian.org, jgg@debian.org
>From: Richard Braakman <dark@xs4all.nl>
>
>When glibc 2.1 was introduced in potato, apt stopped working.  Recompiling
>fixed it, but I figured this indicated a bug in the compat code, so today
>I found time to investigate it.  Jason Gunthorpe had provided me with
>a test case:
>
>#include <iostream>
>#include <fstream>
>
>void die(const char *S)
>{
>   cerr << S << endl;
>   exit(1);
>}
>
>int main(int argc,const char *argv[])
>{
>   ifstream F(argv[1],ios::in | ios::nocreate);
>
>   if (!F != 0)
>      die("!F #1");
>
>   streampos Off = F.tellg();
>   if (!F != 0)
>      die("!F #2");
>
>   return 0;
>}
>
>(This has to be run with the name of an existing file as argument.)
>
>When run on a glibc2.1 system, a version compiled with libstdc++2.9
>will die with "!F #2".  A version compiled with libstdc++2.9-glibc2.1
>will exit successfully.
>
>The problem turns out to be rather simple.  istream:tellg() contains
>this code:
>
>streampos istream::tellg()
>{
>#if 0
>    streampos pos = _strbuf->pubseekoff(0, ios::cur, ios::in);
>#else
>    streampos pos = _IO_seekoff (_strbuf, 0, _IO_seek_cur, _IOS_INPUT);
>#endif
>    if (pos == streampos(EOF))
>        set(ios::badbit);
>    return pos;
>}
>
>(This is taken from egcs 1.1.2/libio, a different version than what
>generated libstdc++2.9, but I can tell from the disassembly that the
>significant part didn't change.)
>
>This code calls _IO_seekoff directly, expecting that it takes a 32-bit
>offset.  But _IO_seekoff in glibc2.1 takes a 64-bit offset, and ends
>up trying to seek to 0x100000000 and failing.
>
>egcs's libio appears to be full of references to glibc's libio.
>I checked some others at random (_IO_proc_open, _IO_file_close,
>_IO_adjust_column), and found that filebuf::seekoff probably
>has the same problem when it calls _IO_file_seekoff, because both
>_IO_old_file_seekoff and _IO_new_file_seekoff now take a 64-bit offset.
>
>Richard Braakman
>-- end forwarded message --
-- 
Joel Klecker (aka Espy)                    Debian GNU/Linux Developer
<URL:mailto:jk@espy.org>                 <URL:mailto:espy@debian.org>
<URL:http://web.espy.org/>               <URL:http://www.debian.org/>