[boost] [Boost-bugs] [ boost-Patches-1452698 ] iostreams // file_descriptor::seek BUG on files > 4 GB

From: SourceForge.net (noreply_at_[hidden])
Date: 2007-01-31 11:27:00

Patches item #1452698, was opened at 2006-03-17 20:08
Message generated for change (Comment added) made by gmsb
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=307586&aid=1452698&group_id=7586

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Category: None
Group: None
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Nobody/Anonymous (nobody)
Assigned to: Jonathan Turkanis (turkanis)
Summary: iostreams // file_descriptor::seek  BUG on files > 4 GB

Initial Comment:

Boost 1.33.1
iostreams library
file_descriptor::seek() method
file_descriptor.cpp, line 198
Win32, Visual C++ 2005

The method seek() can return a wrong value of a newly 
set offset when the offset is further than 4 GB.

//---------------
return offset_to_position((lDistanceToMoveHigh << 32) 
+ dwResultLow);
//---------------

The code above has a bug. On 32-bit systems the 
expression (lDistanceToMoveHigh << 32) equals to 
lDistanceToMoveHigh.

The correct code should first cast the 
lDistanceToMoveHigh variable to 64-bit and then shift 
it.

//---------------
return (static_cast<boost::intmax_t> 
lDistanceToMoveHigh) << 32) + dwResultLow;
//---------------

Sergey Kolodkin

----------------------------------------------------------------------

Comment By: Gareth Sylvester-Bradley (gmsb)
Date: 2007-01-31 16:27

Message:
Logged In: YES 
user_id=271167
Originator: NO

There's also a bug 3 lines earlier. Windows GetLastError() shouldn't be
checked unless dwResultLow is INVALID_SET_FILE_POINTER.

Replace:

  195   if (::GetLastError() != NO_ERROR) {
  196             throw detail::bad_seek();
  197         } else {
  198            return offset_to_position((lDistanceToMoveHigh << 32) +
dwResultLow);
  199         }
  200     }

With:

  195   if (INVALID_SET_FILE_POINTER == dwResultLow && ::GetLastError() !=
NO_ERROR) {
  196             throw detail::bad_seek();
  197         } else {
  198            return
offset_to_position((static_cast<stream_offset>(lDistanceToMoveHigh) << 32)
+ dwResultLow);
  199         }
  200     }

----------------------------------------------------------------------

You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=307586&aid=1452698&group_id=7586

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