* descriptors.cc: New file.
* descriptors.h: New file.
* gold-threads.h (class Hold_optional_lock): New class.
* fileread.cc: Include "descriptors.h".
(File_read::~File_read): Release descriptor rather than closing
it.
(File_read::open) [file]: Call open_descriptor rather than open.
Set is_descriptor_opened_.
(File_read::open) [memory]: Assert that descriptor is not open.
(File_read::reopen_descriptor): New function.
(File_read::release): Release descriptor.
(File_read::do_read): Make non-const. Reopen descriptor.
(File_read::read): Make non-const.
(File_read::make_view): Reopen descriptor.
(File_read::do_readv): Likewise.
* fileread.h (class File_read): Add is_descriptor_opened_ field.
Update declarations.
* layout.cc: Include "descriptors.h".
(Layout::create_build_id): Use open_descriptor rather than open.
* output.cc: Include "descriptors.h".
(Output_file::open): Use open_descriptor rather than open.
* archive.cc (Archive::const_iterator): Change Archive to be
non-const.
(Archive::begin, Archive::end): Make non-const.
(Archive::count_members): Likewise.
* archive.h (class Archive): Update declarations.
* object.h (Object::read): Make non-const.
* Makefile.am (CCFILES): Add descriptors.cc.
(HFILES): Add descriptors.h.
* Makefile.in: Rebuild.
parameters. Update for new key type to views_. Change all
callers.
(File_read::read): Adjust for byteshift in returned view.
(File_read::add_view): New function, broken out of
find_and_make_view.
(File_read::make_view): New function, broken out of
find_and_make_view.
(File_read::find_or_make_view): Add offset and aligned
parameters. Rewrite accordingly. Change all callers.
(File_read::get_view): Add offset and aligned parameters. Adjust
for byteshift in return value.
(File_read::get_lasting_view): Likewise.
* fileread.h (class File_read): Update declarations.
(class File_read::View): Add byteshift_ field. Add byteshift to
constructor. Add byteshift method.
* archive.h (Archive::clear_uncached_views): New function.
(Archive::get_view): Add aligned parameter. Change all callers.
* object.h (Object::get_view): Add aligned parameter. Change all
callers.
(Object::get_lasting_view): Likewise.
* fileread.cc (File_read::release): Don't call clear_views if
there are multiple objects.
* fileread.h (File_read::clear_uncached_views): New function.
* archive.cc (Add_archive_symbols::run): Call clear_uncached_views
on the archive.
