This is a tree implementation with elements with primary and secondary
key. The code is a cleaned up version of ramfs's implementation. ramfs
doesn't use this version yet.
The modules code uses gBootDevice as an indicator that modules can be
loaded from the boot volume. This is not the case until packagefs has
been mounted, though, so we postpone setting gBootDevice.
* Don't only look up the entry attribute when the entry is implicit.
Look it up, when it is a directory instead. This aligns it the logic
with _UpdateCheckEntryCollisions().
* When the entry attribute exits and the entry is not implicit, add file
attributes, but not stat data. This also aligns the logic with
_UpdateCheckEntryCollisions(), which removes colliding attributes, but
keeps stat data.
Directories are added implicitly when entries are added, so there's no
need to add those directories. Directories without content don't need to
be added either, since due to the read-only nature of packages they will
remain empty.
* Add global HAIKU_PACKAGES_UPDATE_ONLY build system variable, which is
set for the "update" and "update-all" build profile actions.
* Change the HAIKU_INCLUDE_IN_CONTAINER_VAR variable on packages to
HAIKU_INCLUDE_IN_PACKAGES for all packages. The variable is also
set for the "update" and "update-all" build profile actions.
* Introduce HAIKU_CONTAINER_INHERIT_UPDATE_VARIABLE on container
variable. If set, the contained variable will be set on the container
when one or more files in it are updated. It is set on packages so an
update of a file in a package causes the package to be updated in the
image.
* Introduce HAIKU_CONTAINER_ALWAYS_CREATE_DIRECTORIES on container
variable. If set, directories will be created also in update mode. It
is set on packages.
Add flags parameter to BPackageWriter::Init() (and the private
implementation classes) to indicate that an existing package file shall
be updated instead of created. Currently that always happens in-place.
When compression doesn't save space, using it nonetheless results in a
file that the reader complains about. So we fall back to writing an
uncompressed package attributes section in such a case.
The same still needs to be done for the TOC section.
* Add hooks HandleSectionStart() and HandleSectionEnd(). They are
invoked to bracket package file section, so the handler can
discriminate which section the attributes belong to.
HandleSectionStart() features a return parameter _handleSection, which
allows to handler to pick which sections it wants to handle.
* "package dump" does now print the section names.
