QFSFileEngine: Implement memory mapped files

[Dmitry A. Kuminov]

Adding support for memory mapped files (QAbstractFileEngine::map() and unmap() methods of QFSFileEngine) includes implementing QFSFileEnginePrivate::map() and unmap() methods in qfsfileengine_os2.cpp.

A good article on implementing memory mapped files on OS/2 can be found in EDM: ​http://www.edm2.com/0610/memorymap.html

[Silvan Scherrer]

i'm not sure if it helps or not, but Yuri did also a implementation of map(). see ​http://web.os2power.com/yuri/MemoryMappedFiles

[Dmitry A. Kuminov]

Aha, as Yuri says, it's a wrapper around WPSTK mmf functions. I may guess that WPSTK uses the approach described in the above EDM article. Anyway, thank you for the link, I'll check the sources when it's time to implement this.

[Silvan Scherrer]

the memory mapped files implementation is since longer at netlabs svn. see ​http://svn.netlabs.org/ports for the source. we should try to use that. and if stuff is missing is should be implemented there. so we have a good and usable map() unmap() implemantation.

[Silvan Scherrer]

all the above comments are mostly obsolete now. we should definitely use libcx for it.

[Silvan Scherrer]

This is done in Qt5. No plans to resolve it for Qt4