At present this method assumes that the parent section does not need
to recalculate its position or adjust any metadata it may contain. But
when the entry changes size this may not be true. Also if the parent
section is more than just a container (e.g. it is a CBFS) then the
section may need to regenerate its output.

Add a new WriteChildData() method to sections and call this from the
WriteData() method, to handle this situation.

Signed-off-by: Simon Glass <sjg@chromium.org>

At present we simply extract the data directly from entries using the
image_pos information. This happens to work on current entry types, but
cannot work if the entry type encodes the data in some way. Update the
ReadData() method to provide the data by calling a new ReadChildData()
method in the parent. This allows the entry_Section class, or possibly
any other container class, to return the correct data in all cases.

Signed-off-by: Simon Glass <sjg@chromium.org>

Sometimes an entry may shrink after it has already been packed. In that
case we must repack the items. Of course it is always possible to just
leave the entry at its original size and waste space at the end. This is
what binman does by default, since there is the possibility of the entry
changing size every time binman calculates its contents, thus causing a
loop.

Signed-off-by: Simon Glass <sjg@chromium.org>

The positioning does not currently work correctly if at the end of an
image with no fixed size. Also if the header is in the middle of an image
it can cause a gap in the image since the header position is normally at
the image end, so entries after it are placed after the end of the image.

Fix these problems and add more tests to cover these cases.

Signed-off-by: Simon Glass <sjg@chromium.org>

At present it is not possible to discover the contraints to repacking an
image (e.g. maximum section size) since this information is not preserved
from the original image description.

Add new 'orig-offset' and 'orig-size' properties to hold this. Add them to
the main device tree in the image.

Signed-off-by: Simon Glass <sjg@chromium.org>

While it is useful and efficient to build images in a single pass from a
unified description, it is sometimes desirable to update the image later.

Add support for replace an existing file with one of the same size. This
avoids needing to repack the file. Support for more advanced updates will
come in future patches.

Signed-off-by: Simon Glass <sjg@chromium.org>

At present we have an 'image' property in the entry for this purpose, but
this is not necessary and seems error-prone in the presence of
inheritance. Add a function instead. The Entry_section class overrides
this with a special version, since top-level sections are in fact images,
since Image inherits Entry_section.

Signed-off-by: Simon Glass <sjg@chromium.org>

At present the Entry constructor sets up the object and then immediately
reads its device-tree node to obtain its properties.

This breaks a convention that constructors should not do any processing.
A consequence is that we must pass all arguments to the constructor and
cannot have the node-reading proceed in a different way unless we pass
flags to that constructor. We already have a 'test' flag in a few cases,
and now need to control whether the 'orig_offset' and 'orig_size'
properties are set or not.

Adjust the code to require a separate call to ReadNode() after
construction. The Image class remains as it was.

Signed-off-by: Simon Glass <sjg@chromium.org>

When modifying an image it is convenient to load the data from the file
into each entry so that it can be reprocessed. Add a new LoadData() method
to handle this.

Signed-off-by: Simon Glass <sjg@chromium.org>

Use the new logging feature to log information about progress with
packing. This is useful to see how binman is figuring things out.

Also update elf.py to use the same feature.

Signed-off-by: Simon Glass <sjg@chromium.org>