[Ace-users] [ace-users] WIN32_Asynch_IO.cpp : error in iovec construction fromchain of message blocks

[Johnny Willemsen]

Hi,
 
In the writev method there are two ++iovcnt increments. Do we need to have
both, I think the last one needs to be removed. Can you have a look.
 
Regards,
Johnny Willemsen
Remedy IT
Postbus 101
2650 AC  Berkel en Rodenrijs
The Netherlands
www.theaceorb.nl / www.remedy.nl 

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________________________________

	From: ace-users-bounces at cse.wustl.edu
[mailto:ace-users-bounces at cse.wustl.edu] On Behalf Of Alexander Libman
	Sent: Friday, November 02, 2007 5:56 AM
	To: ace-bugs at cs.wustl.edu
	Cc: ace-users at cs.wustl.edu
	Subject: [ace-users] WIN32_Asynch_IO.cpp : error in iovec
construction fromchain of message blocks
	
	
	    ACE VERSION: 5.6.1
	 
	    HOST MACHINE and OPERATING SYSTEM:
	        WINDOWS - any 
	 
	    TARGET MACHINE and OPERATING SYSTEM, if different from HOST:
	    COMPILER NAME AND VERSION (AND PATCHLEVEL):
	        WINDOWS - any
	 
	    THE $ACE_ROOT/ace/config.h FILE [if you use a link to a
platform-
	    specific file, simply state which one]:
	 
	    THE $ACE_ROOT/include/makeinclude/platform_macros.GNU FILE [if
you
	    use a link to a platform-specific file, simply state which one
	    (unless this isn't used in this case, e.g., with Microsoft
Visual
	    C++)]:
	 
	    CONTENTS OF
$ACE_ROOT/bin/MakeProjectCreator/config/default.features
	    (used by MPC when you generate your own makefiles):
	 
	    AREA/CLASS/EXAMPLE AFFECTED:
	
	    DOES THE PROBLEM AFFECT:
	        COMPILATION?
	            no
	        LINKING?
	            no
	        EXECUTION?
	            yes
	        OTHER (please specify)?
	            no
	    SYNOPSIS:
	Error in construction iovec from the chain of message blocks.
	
	    DESCRIPTION:
	If any message block in chain has empty space (readv) or zero length
(writev),
	iovec constructed with extra uninitialized element. We have this
error for 6 years,
	I need glasses:)
	    REPEAT BY:
	
	    SAMPLE FIX/WORKAROUND:
	 
	Here is fix for readv, same for writev
	WIN32_Asynch_IO.cpp

	00439 #if (defined (ACE_HAS_WINSOCK2) && (ACE_HAS_WINSOCK2 != 0))
	00440   iovec  iov[ACE_IOV_MAX
<http://www.dre.vanderbilt.edu/Doxygen/Current/html/ace/a01287.html#f2a34d22
026b6e2899992232d24da22b> ];
	00441   int    iovcnt = 0;
	00442 
	00443   // We should not read more than user requested,
	00444   // but it is allowed to read less
	00445 
	00446   for (const ACE_Message_Block
<http://www.dre.vanderbilt.edu/Doxygen/Current/html/ace/a00324.html> * msg =
&message_block;
	00447        msg != 0 && bytes_to_read > 0 && iovcnt < ACE_IOV_MAX
<http://www.dre.vanderbilt.edu/Doxygen/Current/html/ace/a01287.html#f2a34d22
026b6e2899992232d24da22b> ;
	******  Replace here
	00448---      msg = msg->cont () , ++iovcnt )
	00448+++      msg = msg->cont ())
	00449   {
	00450     size_t msg_space = msg->space ();
	00451 
	*****     This comment can be removed
	00452     // OS should correctly process zero length buffers
	00453     // if ( msg_space == 0 )
	00454     //   ACE_ERROR_RETURN ((LM_ERROR,
	00455     //                      ACE_TEXT
("ACE_WIN32_Asynch_Read_Stream::readv:")
	00456     //                      ACE_TEXT ("No space in the message
block\n")),
	00457     //                     -1);
	00458 
	*****    End of comment to be removed
	00459     if (msg_space > bytes_to_read)
	00460       msg_space = bytes_to_read;
	00461     bytes_to_read -= msg_space;
	00462 
	00463     // Make as many iovec as needed to fit all of msg_space.
	00464     size_t wr_ptr_offset = 0;
	00465     while (msg_space > 0 && iovcnt < ACE_IOV_MAX)
	00466       {
	00467         u_long this_chunk_length;
	00468         if (msg_space > ULONG_MAX)
	00469           this_chunk_length = ULONG_MAX;
	00470         else
	00471           this_chunk_length = static_cast<u_long> (msg_space);
	00472         // Collect the data in the iovec.
	00473         iov[iovcnt].iov_base = msg->wr_ptr () + wr_ptr_offset;
	00474         iov[iovcnt].iov_len  = this_chunk_length;
	00475         msg_space -= this_chunk_length;
	00476         wr_ptr_offset += this_chunk_length;
	00477 
	00478         // Increment iovec counter if there's more to do.
	******** The following if should be removed
	00479---     if (msg_space > 0)
	******* This should be preserved
	00480           ++iovcnt;
	00481       }
	00482     if (msg_space > 0)       // Ran out of iovecs before
msg_space exhausted
	00483       {
	00484         errno = ERANGE;
	00485         return -1;
	00486       }
	00487   }
	00488 
	00489   // Re-calculate number bytes to read
	00490   bytes_to_read = 0;
	00491 
	00492   for (int i = 0; i < iovcnt ; ++i)
	00493     bytes_to_read += iov[i].iov_len;
	00494 
	....