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* Re: libstdc++/6746: ifstream::readsome() always returns zero
@ 2002-05-20 13:39 paolo
0 siblings, 0 replies; 8+ messages in thread
From: paolo @ 2002-05-20 13:39 UTC (permalink / raw)
To: gcc-bugs, gcc-prs, nobody, tony.oliver
Synopsis: ifstream::readsome() always returns zero
State-Changed-From-To: feedback->analyzed
State-Changed-By: paolo
State-Changed-When: Mon May 20 13:39:25 2002
State-Changed-Why:
Confirmed. The following is a minimal testcase (6746.cc):
#include <fstream>
#include <cassert>
int main()
{
char str[50];
std::streamsize count;
std::ifstream file("6746.cc");
count = file.readsome(str, 50);
assert( count == 50 );
}
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=6746
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: libstdc++/6746: ifstream::readsome() always returns zero
@ 2002-11-23 6:06 bkoz
0 siblings, 0 replies; 8+ messages in thread
From: bkoz @ 2002-11-23 6:06 UTC (permalink / raw)
To: bkoz, gcc-bugs, gcc-prs, tony.oliver
Synopsis: ifstream::readsome() always returns zero
State-Changed-From-To: feedback->closed
State-Changed-By: bkoz
State-Changed-When: Mon Nov 18 12:24:13 2002
State-Changed-Why:
Fixed.
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=6746
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: libstdc++/6746: ifstream::readsome() always returns zero
@ 2002-11-19 12:32 bkoz
0 siblings, 0 replies; 8+ messages in thread
From: bkoz @ 2002-11-19 12:32 UTC (permalink / raw)
To: bkoz, gcc-bugs, gcc-prs, tony.oliver
Synopsis: ifstream::readsome() always returns zero
State-Changed-From-To: open->feedback
State-Changed-By: bkoz
State-Changed-When: Mon Nov 11 15:13:36 2002
State-Changed-Why:
Fixed. Sorry about the delay.
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=6746
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: libstdc++/6746: ifstream::readsome() always returns zero
@ 2002-07-04 17:39 bkoz
0 siblings, 0 replies; 8+ messages in thread
From: bkoz @ 2002-07-04 17:39 UTC (permalink / raw)
To: bkoz, gcc-bugs, gcc-prs, tony.oliver
Synopsis: ifstream::readsome() always returns zero
State-Changed-From-To: analyzed->open
State-Changed-By: bkoz
State-Changed-When: Thu Jul 4 17:39:53 2002
State-Changed-Why:
It looks like I am not going to be able to fix this before I leave. I'll resume looking at it after I get back, say July 23 rd ish...
In sum, it looks like the patch to libstdc++/3647 was wrong. At this point, rdbuf()->in_avail() is returning 0 for newly opened istreams (that are not empty.). This is incorrect.
I suspect that the way to solve this is to set _M_buf and friends to real values instead of indeterminate values in filebuf's ctors. I did work up a partial solution to this based on this approach, but cannot find it at the moment.
Here's another testcase for this
#include <fstream>
#include <sstream>
#include <iostream>
void test01()
{
using namespace std;
streamsize sum = 0;
istringstream iss("shamma shamma");
// test01
size_t i = iss.rdbuf()->in_avail();
cout << i << endl;
// test02
size_t max = 0;
while (iss.good() && max < 10)
{
char buf[1024];
streamsize gotten = iss.readsome(buf, sizeof buf);
sum += gotten;
cout << gotten << " (" << sum << ")" << endl;
++max;
}
}
void test02()
{
using namespace std;
streamsize sum = 0;
ifstream ifs(__FILE__);
// test01
size_t i = ifs.rdbuf()->in_avail();
cout << i << endl;
// test02
size_t max = 0;
while (ifs.good() && max < 10)
{
char buf[1024];
streamsize gotten = ifs.readsome(buf, sizeof buf);
sum += gotten;
cout << gotten << " (" << sum << ")" << endl;
++max;
}
}
int main()
{
test01();
test02();
return 0;
}
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=6746
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: libstdc++/6746: ifstream::readsome() always returns zero
@ 2002-05-29 8:56 bkoz
0 siblings, 0 replies; 8+ messages in thread
From: bkoz @ 2002-05-29 8:56 UTC (permalink / raw)
To: bkoz, gcc-bugs, gcc-prs, nobody, tony.oliver
Synopsis: ifstream::readsome() always returns zero
Responsible-Changed-From-To: unassigned->bkoz
Responsible-Changed-By: bkoz
Responsible-Changed-When: Wed May 29 08:09:45 2002
Responsible-Changed-Why:
Mine.
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=6746
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: libstdc++/6746: ifstream::readsome() always returns zero
@ 2002-05-26 4:16 Paolo Carlini
0 siblings, 0 replies; 8+ messages in thread
From: Paolo Carlini @ 2002-05-26 4:16 UTC (permalink / raw)
To: nobody; +Cc: gcc-prs
The following reply was made to PR libstdc++/6746; it has been noted by GNATS.
From: Paolo Carlini <pcarlini@unitus.it>
To: tony.oliver@mci.co.uk, gcc-gnats@gcc.gnu.org, gcc-prs@gcc.gnu.org,
gcc-bugs@gcc.gnu.org
Cc:
Subject: Re: libstdc++/6746: ifstream::readsome() always returns zero
Date: Sun, 26 May 2002 10:58:07 +0200
The following is the testcase mentioned by submitter in the PR:
#include <fstream>
#include <iostream>
using namespace std;
int main(int, char**)
{
streamsize sum = 0;
ifstream ifs(__FILE__);
while (ifs.good())
{
char buf[1024];
streamsize gotten = ifs.readsome(buf, sizeof buf);
sum += gotten;
cout << gotten << " (" << sum << ")" << endl;
}
return 0;
}
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=6746
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: libstdc++/6746: ifstream::readsome() always returns zero
@ 2002-05-20 10:57 paolo
0 siblings, 0 replies; 8+ messages in thread
From: paolo @ 2002-05-20 10:57 UTC (permalink / raw)
To: gcc-bugs, gcc-prs, nobody, tony.oliver
Synopsis: ifstream::readsome() always returns zero
State-Changed-From-To: open->feedback
State-Changed-By: paolo
State-Changed-When: Mon May 20 10:57:07 2002
State-Changed-Why:
For some reason, the source code is missing from your PR. Could you possibly provide it?
Thanks, Paolo.
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=6746
^ permalink raw reply [flat|nested] 8+ messages in thread
* libstdc++/6746: ifstream::readsome() always returns zero
@ 2002-05-20 10:16 tony.oliver
0 siblings, 0 replies; 8+ messages in thread
From: tony.oliver @ 2002-05-20 10:16 UTC (permalink / raw)
To: gcc-gnats
>Number: 6746
>Category: libstdc++
>Synopsis: ifstream::readsome() always returns zero
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: unassigned
>State: open
>Class: sw-bug
>Submitter-Id: net
>Arrival-Date: Mon May 20 10:16:01 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator: Tony Oliver
>Release: gcc-3.1
>Organization:
>Environment:
sparc-sun-solaris2.8
Thread model: posix
>Description:
Calling ifstream::readsome() always yields a return value of zero (no bytes read). No stream error flags are set. This behaviour has been introduced in release gcc-3.1: it worked fine in gcc-3.0.4.
The problem appears to be confined to the filebuf part of ifstream, not the istream part, since (for instance) istringstream::readsome() does not suffer from this problem.
My installation of gcc-3.1 was configured with the following options (/home/to0001/ is my networked home directory):
--prefix=/home/to0001/app/gcc-3.1
--enable-languages=c,c++
--disable-shared
--verbose
Trivial test program source code attached.
Expected output (as output by gcc-3.0.4 version):
308 (308)
0 (308)
Actual output:
0 (0)
0 (0)
0 (0)
... [forever]
>How-To-Repeat:
g++ -ansi -pedantic -Wall -o gcc-test gcc-test.c++
gcc-test
>Fix:
>Release-Note:
>Audit-Trail:
>Unformatted:
^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2002-11-18 20:24 UTC | newest]
Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
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2002-05-20 13:39 libstdc++/6746: ifstream::readsome() always returns zero paolo
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2002-11-23 6:06 bkoz
2002-11-19 12:32 bkoz
2002-07-04 17:39 bkoz
2002-05-29 8:56 bkoz
2002-05-26 4:16 Paolo Carlini
2002-05-20 10:57 paolo
2002-05-20 10:16 tony.oliver
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