[boost] [iostreams] mapped_file trouble

From: Dylan Trotter (trotterdylan_at_[hidden])
Date: 2005-08-24 23:05:14

Hi,

I just wanted to point out a fairly major flaw with the Windows 
implementation of memory mapped files. In memory_mapped.cpp on line 
205-207 a file mapping is created as follows:

         ::CreateFileMappingA( pimpl_->handle_, NULL,
                               readonly ? PAGE_READONLY : PAGE_READWRITE,
                               0, 0, p.path.c_str() );

The problem with this is that if p.path.c_str() has any backslashes in 
it (very likely given that it's Windows), the call fails. From the MS 
documentation:

"Windows NT:  The name can contain any character except the backslash 
character.
Windows Me/98/95:  The name can contain any character except the 
backslash character. The empty string ("") is a valid object name."

Also from the documentation:

"If this parameter is NULL, the mapping object is created without a name."

Given that there's no way to access named memory maps from the boost 
interface anyway, it seems pointless to name the mapping. My suggestion 
is to pass in NULL and avoid naming difficulties altogether.

Thanks,

Dylan Trotter