[Bug c++/24217] New: filebuf.open call sets the error bits incorrectly

[Bug c++/24217] New: filebuf.open call sets the error bits incorrectly

[hemasai at yahoo dot com]

We are using filebuf.open call to open a file in readonly mode in a
multi-threaded application.  The result of the open call is checked with
is_open.  The truss log shows that the file was opened successfully giving the
file handle.  However, the application log shows that the open call failed and
that fail() was true with rdstate=4.  This behaviour is seen only after a few
minutes of application running (during which time it successfully opens the
same file).


-- 
           Summary: filebuf.open call sets the error bits incorrectly
           Product: gcc
           Version: 3.3.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: hemasai at yahoo dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24217

[Bug libstdc++/24217] filebuf.open call sets the error bits incorrectly

[pcarlini at suse dot de]

------- Comment #1 from pcarlini at suse dot de  2005-10-06 12:27 -------
Hi. Certaintly, we cannot hope to debug further the issue without a proper,
self-contained, piece of code useful to reproduce the problem: this is a
strict requirement for any PR, in particular for very hard to reproduce
issues related to MT. That said, I'm afraid you are assuming a level of MT
safety that we don't (wo don't *want*, I would say, but this is very large
topic and the actual guarantees are also highly dependent on the underlying
libc, which we don't control, unfortunately) provide: for example, if running
your application single-threaded or protecting the filebuf operations with a
mutex avoids the problem, then very likely we would not consider the behavior
a bug.


-- 

pcarlini at suse dot de changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |WAITING


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24217

[Bug libstdc++/24217] filebuf.open call sets the error bits incorrectly

[hemasai at yahoo dot com]

------- Comment #2 from hemasai at yahoo dot com  2005-10-06 18:12 -------
sample code:
fn(const char* fname)
{
   ifstream fstr;

   if (!fname)
      return;

   fstr.clear();
      fstr.open(fname, ios::in | ios::nocreate);
   if (!(fstr.is_open())) {
            cout << "rdstate():" << fstr.rdstate();
            cout << "bad():" << fstr.bad();
            cout << "fail():" << fstr.fail();
            return;
   }
//Read the file contents
}

As you can see, the fstr is a stack variable that is used to access the file. 
The flags were cleared before the open call. When it failed rdstate was set to
4.
This function call successfully opened the file multiple times before the
failure.


-- 

hemasai at yahoo dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |UNCONFIRMED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24217

[Bug libstdc++/24217] filebuf.open call sets the error bits incorrectly

[pcarlini at suse dot de]

------- Comment #3 from pcarlini at suse dot de  2005-10-06 18:32 -------
(In reply to comment #2)
> sample code:

Sorry, but this is not useful. We need a *self-contained* source file, which
we can compile and run as-is, using your very same build options. We need to
exactly reproduce the problem in all its details before taking any further
action.


-- 

pcarlini at suse dot de changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |WAITING


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24217

[Bug libstdc++/24217] filebuf.open call sets the error bits incorrectly

[pcarlini at suse dot de]

------- Comment #4 from pcarlini at suse dot de  2005-12-16 18:43 -------
Feedback not forthcoming.


-- 

pcarlini at suse dot de changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |RESOLVED
         Resolution|                            |INVALID


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24217