Clarification needed for the amount of memory unmapped during imagefile closure.

[Jini George]

Hello!

I needed a clarification regarding the amount of memory unmapped during 
imagefile closure in src/java.base/share/native/libjimage/imageFile.cpp.

I noticed that when the "modules" file is opened in 
ImageFileReader::open(), and the contents are mmap()-ed, the size to be 
mmap()-ed is derived from map_size().

399     // Memory map image (minimally the index.)
400     _index_data = (u1*)osSupport::map_memory(_fd, _name, 0, 
(size_t)map_size());

Which could be _file_size or _index_size, and for 64 bit processes, it 
would be _file_size. (about 140 MB)

488     // Retrieve the size of the mapped image.
489     inline u8 map_size() const {
490         return (u8)(memory_map_image ? _file_size : _index_size);
491     }

But when the contents are unmapped in ImageFileReader::close(), the 
amount of memory unmapped is only _index_size (which is considerably 
lesser than _file_size).

427 // Close image file.
428 void ImageFileReader::close() {
429     // Deallocate the index.
430     if (_index_data) {
431         osSupport::unmap_memory((char*)_index_data, _index_size);
432         _index_data = NULL;
433     }

Wanted to check if this is an oversight, or if there is a reason behind 
this and I am missing something. Shouldn't the amount of memory unmapped 
be map_size() too ?

Any help would be appreciated !

Thanks in advance,
Jini.