[boost] [IOStreams] patch for "seek" bug in file descriptor device

From: Frank Birbacher (bloodymir.crap_at_[hidden])
Date: 2007-08-23 16:18:06

Hi!

I have had a hard time trying to figure out why my windows port of a
file transfer program would not write anything to its files. I'm using
boost svn, msvc 8 express, platform sdk from msvc 2003, and windows xp
(SP2).

I discovered that the file_descriptor device of the IOStreams library
does not check for SetFilePointer failure as Microsoft recommands. This
led to always throwing bad_seek. But the write function on the
std::ostream& does neither return with the failbit set nor does it
propagate the exception.

Anyway the attached patch on the boost svn should fix this problem. I
added a second check for failure as the MSDN (
http://msdn.microsoft.com/library/en-us/fileio/fs/setfilepointer.asp ,
see "Return Value") suggests. It works for me. Here is where I started:

$LC_ALL=C svn info
Path: .
URL: http://svn.boost.org/svn/boost/trunk
Repository Root: http://svn.boost.org/svn/boost
Repository UUID: b8fc166d-592f-0410-95f2-cb63ce0dd405
Revision: 38755
Node Kind: directory
Schedule: normal
Last Changed Author: grafik
Last Changed Rev: 38755
Last Changed Date: 2007-08-18 19:11:07 +0200 (Sat, 18 Aug 2007)

$LC_ALL=C svn st
?      bin.v2
?      stage
?      libs/mpi/doc/mpi_autodoc.xml
?      libs/intrusive/doc/autodoc.xml
?      libs/logic/doc/reference.xml
?      libs/program_options/doc/autodoc.xml
?      libs/xpressive/doc/autodoc.xml
?      libs/interprocess/doc/autodoc.xml
?      libs/function/doc/html
?      libs/algorithm/string/doc/autodoc.xml
M      libs/iostreams/src/file_descriptor.cpp

"svn diff" in attached file.

Frank

Index: libs/iostreams/src/file_descriptor.cpp
===================================================================
--- libs/iostreams/src/file_descriptor.cpp	(revision 38755)
+++ libs/iostreams/src/file_descriptor.cpp	(working copy)
@@ -159,8 +159,10 @@
 #ifdef BOOST_IOSTREAMS_WINDOWS
     if (pimpl_->flags_ & impl::has_handle) {
         if (pimpl_->flags_ & impl::append) {
-            ::SetFilePointer(pimpl_->handle_, 0, NULL, FILE_END);
-            if (::GetLastError() != NO_ERROR)
+            DWORD const dwResult =
+                ::SetFilePointer(pimpl_->handle_, 0, NULL, FILE_END);
+            if (dwResult == INVALID_SET_FILE_POINTER
+                    && ::GetLastError() != NO_ERROR)
                 throw detail::bad_seek();
         }
         DWORD ignore;
@@ -192,10 +194,12 @@
                                   way == BOOST_IOS::cur ?
                                     FILE_CURRENT :
                                     FILE_END );
-        if (::GetLastError() != NO_ERROR) {
+        if (dwResultLow == INVALID_SET_FILE_POINTER
+                && ::GetLastError() != NO_ERROR) {
             throw detail::bad_seek();
         } else {
-           return offset_to_position((lDistanceToMoveHigh << 32) + dwResultLow);
+           return offset_to_position(
+               (stream_offset(lDistanceToMoveHigh) << 32) + dwResultLow);
         }
     }
 #endif // #ifdef BOOST_IOSTREAMS_WINDOWS