[Bug libstdc++/17086] New: IOStreams Large File Support (> 2 GB) not fully implemented.

["scrimr at louisville dot stortek dot com" <gcc-bugzilla at gcc dot gnu dot org>]

Reading specs from /usr/local/lib/gcc/sparc-sun-solaris2.8/3.4.1/specs
Configured with: ../configure --with-as=/usr/ccs/bin/as --with-
ld=/usr/ccs/bin/ld --disable-nls
Thread model: posix
gcc version 3.4.1

Solaris 8 patch level is generic_108528-17 recommended patch cluster

I converted this code from c library functions that did work for 64-bit files.  
Before the 3.4.1 compiler I could not create files >2 GB with this stream code 
but it was completely working properly for files <= 2 GB(-1).

With the same program I can write files larger than 2 GB with the ofstream 
class (e.g. 5 GB), which I could not do before gcc 3.4.1, but now I am unable 
to seekg in files of any size with the ifsteam class. I also cannot 
sequentially read (without seeks) in files larger than 2 GB with the ifstream 
class (e.g. 5 GB).

Code Snippit that fails (throws exception) is as follows:

  inStream.exceptions( ios::failbit | ios::badbit );
  inStream.open( fileToProcess.c_str(), ios::in | ios::binary | ios::ate );

  ...

  int markerLength = (verificationMarker()).size(); // = 5
  inStream.seekg( -(rawSumLength()+markerLength),ios::cur); // 5 + 16

  ...

  SumMarkerFromFile = new char[markerLength+1];
  SumMarkerFromFile[markerLength] = '\0';
  inStream.read( SumMarkerFromFile, markerLength );
  
The code opens the ifstream for a file in binary mode and at the end of the 
file.  Then I try to back up 21 bytes for some data that I need to read.  Then 
I try to read it and the code then throws an exception on the read.  Both seekg 
and open do not seem to be failing.  read is throwing an exception.  The 
problem seems to occurs regardless of file size.  I think the seekg call is 
causing a bad stream state and then the read throws an exception because of the 
bad stream state.  Keep in mind that this does not work even for file less than 
or equal to 2 GB with the 3.4.1 compiler/libraies.

Anyway, seekg may be one of the failing components.  The wierd thing is that if 
I open a file and read it sequentially without seeks for files smaller than 2 
GB it works fine.  For files above 2 GB, the sequential reading does not work 
and does not even throw exceptions.  It appears to work but I know there is no 
way that it read a 5 GB file in less than a second.  So, it does not appear to 
be working here either.

I think this iostreams LFS support needs to be carefully rechecked for 
completeness.  Also, it seems that iostreams support in general seems to be 
broken for files below 2 GB now (e.g. seekg).

If you have any questions or suggestions I would love to hear them.  If you 
think I am doing something wrong I would love to hear that too.

-- 
           Summary: IOStreams Large File Support (> 2 GB) not fully
                    implemented.
           Product: gcc
           Version: 3.4.1
            Status: UNCONFIRMED
          Severity: critical
          Priority: P1
         Component: libstdc++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: scrimr at louisville dot stortek dot com
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: 3.4.1
  GCC host triplet: 3.4.1
GCC target triplet: 3.4.1


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17086