Some x86 sections have special offsets which currently result in empty
data being returned from the 'extract' command. Fix this by taking account
of the skip-at-start property.

Add a little more debugging while we are here.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Bin Meng <bmeng.cn@gmail.com>

So far we don't allow entries to change size when repacking. But this is
not very useful since it is common for entries to change size after an
updated binary is built, etc.

Add support for this, respecting the original offset/size/alignment
constraints of the image layout. For this to work the original image
must have been created with the 'allow-repack' property.

This does not support entry types with sub-entries such as files and
CBFS, but it does support sections.

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

Now that an Image is an Entry_section, there is no need for the separate
BuildSection() function. Drop it and add a bit of logging.

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

When reading an image in, write its fdtmap to a file in the output
directory. This is useful for debugging. Update the 'ls' command to set up
the output directory; otherwise it will fail.

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>

This data provides all the information about the position and size of each
entry. Store it for later use when loading an image. It can be reused as
is if the image is modified without changing offsets/sizes.

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

It is useful to be able to extract entry contents from an image to see
what is inside. Add a simple function to read the contents of an entry,
decompressing it by default.

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