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From: paolo@gcc.gnu.org
To: bkoz@redhat.com, gcc-bugs@gcc.gnu.org, gcc-prs@gcc.gnu.org,
	ncm@cantrip.org, nobody@gcc.gnu.org, paolo@gcc.gnu.org,
	peturr02@ru.is
Subject: Re: libstdc++/9424: i/ostream::operator>>/<<(streambuf*) drops characters
Date: Wed, 26 Feb 2003 00:34:00 -0000	[thread overview]
Message-ID: <20030226003454.28510.qmail@sources.redhat.com> (raw)

Synopsis: i/ostream::operator>>/<<(streambuf*) drops characters

Responsible-Changed-From-To: unassigned->paolo
Responsible-Changed-By: paolo
Responsible-Changed-When: Wed Feb 26 00:34:53 2003
Responsible-Changed-Why:
    Analyzed.
State-Changed-From-To: open->analyzed
State-Changed-By: paolo
State-Changed-When: Wed Feb 26 00:34:53 2003
State-Changed-Why:
    The issue is the following: when a setg(buf, buf, buf + 10)
    is missing, __copy_streambufs, called by operator>>, ends up
    using sgetn to fill an internal temporary buffer.
    
    The latter, in turn, calls unavoidably the custom uflow,
    which moves 'current' past the end of the buffer, and 
    underflow, called by sgetc, does not return the expected
    '1'.
    
    Now, everything boild down to the following general 
    question: is an implementation of operator>> allowed to
    call (indirectly) sgetn?
    
    If so, the PR seems "only" a QoI issue, otherwise, a real 
    bug, which can be fixed in many ways. For example, avoiding
    the call in __copy_streambufs (with a wrapper?)
    
    Nathan? Benjamin?
    
    Paolo.

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=9424


             reply	other threads:[~2003-02-26  0:34 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-02-26  0:34 paolo [this message]
  -- strict thread matches above, loose matches on Subject: below --
2003-03-09 11:27 paolo
2003-03-07 21:26 Paolo Carlini
2003-03-07 19:56 Nathan Myers
2003-02-26  9:36 Pétur Runólfsson
2003-01-23 19:06 peturr02

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