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

From: SourceForge.net (noreply_at_[hidden])
Date: 2006-03-17 15:08:36

Patches item #1452698, was opened at 2006-03-17 12:08
Message generated for change (Tracker Item Submitted) made by Item Submitter
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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
Submitted By: Nobody/Anonymous (nobody)
Assigned to: Nobody/Anonymous (nobody)
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

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