Create an init routine which loads the environment only once instead
every evaluation.

Signed-off-by: David Bauer <mail@david-bauer.net>

Include the file-extension with the image-customization.lua file. This
will ease work with editors providing syntax highlighting, as they now
properly detect the file-type.

Signed-off-by: David Bauer <mail@david-bauer.net>

Signed-off-by: David Bauer <mail@david-bauer.net>

Signed-off-by: David Bauer <mail@david-bauer.net>

Implement a flexible system for handling site-defined features as well
as packages.

This system is inspired by the existing feature-system and allows for a
more flexible approach for selecting specific packages for devices.

Features are now defined in a `features` file in the site-root. The same
goes for packages.

These files are sequentially evaluated and the device-package list is
evaluated for each device independently.

Signed-off-by: David Bauer <mail@david-bauer.net>

Device-specific package additions could generate `CONFIG_PACKAGE_...=m`
lines, which would override `CONFIG_PACKAGE_...=y` lines inserted by
OpenWrt for default packages (as Gluon did not know about these default
packages). This resulted in the unintended removal of such packages from
other devices that did not contain the same package in their device
package lists.

Avoid this issue by explicitly adding OpenWrt's target default package
list to the front of Gluon's target package list.

OpenWrt's default package list contains the package "nftables", which is
a virtual package provided by "nftables-json" and "nftables-nojson".
Explicitly handle this case, otherwise our config check will fail when
we extend our default package list with the one from OpenWrt.

Another leftover from legacy OpenWrt targets, which we don't support
anymore.

No legacy OpenWrt targets exist anymore which require the .config profile
name to differ from the image name.

With the removal of ramips-rt305x, all targets come with opkg again.

All defined features need to be known at the same time, otherwise handling
a feed-provided feature definition file would add gluon-web-advanced etc.
to the package list when the corresponding feature flags appear in
GLUON_FEATURES.

Fixes: ee5ec5af ("build: rewrite features.sh in Lua")

The `features` file is converted to a Lua-based DSL.

A helper function `_` is used in the DSL; this will return the original
string for enabled features, and nil for disabled features. This allows
to use boolean operations on features without making the code too
verbose.

Besides having more readable and robust code, this also fixes the bug
that all files `packages/*/features` were evaluated instead of only
using the feature definitions of currently active feeds.

Normally, we build all nonshared packages (which includes all kernel
modules) to generate an opkg feed for later package installations by
users. On targets without opkg, this just wastes time - disable it.

(cherry picked from commit b3edfd29)

Normally, we build all nonshared packages (which includes all kernel
modules) to generate an opkg feed for later package installations by
users. On targets without opkg, this just wastes time - disable it.

target_config.lua and target_config_check.lua don't pass a table of
callbacks anymore, so target_config_lib.lua can by simplified by moving
all the code that was in the returned function to the toplevel.

So far, we were using a sort operation on the generated .config to
implement precedence of =y packages over =m, and =m over unset.
Unfortunately, this sort not only used for packages, but for all config
lines. This made it impossible to override settings from targets/generic
in a target config when the new setting was sorted before the generic
setting.

To fix this, track configurations by their keys, so we can properly
override config keys that were set before. Value-based precedence is
only preserved for package configuration.

The config() and try_config() calls always take key and value as
separate arguments now. Strings are quoted automatically; the values
true, nil and false map to y, m and unset for tristate options. config()
can take an optional third argument to override the error message to
display when the setting fails to apply.

All existing target configs generate the same .config with the old and the
new code. The new code is also a bit faster on targets with many devices.

The precedence of different package lists was broken since #1876,
disallowing removal of GLUON_FEATURES packages via GLUON_SITE_PACKAGES.

Including all package selections, both implicit defaults and explicit
handling in Gluon, the order of precedence is now the following:

1.  OpenWrt defaults (including target-specific defaults)
2.  Device-specific packages from OpenWrt
3.  Generic default packages (from target/generic)
4.  Target default packages (target/$(GLUON_TARGET))
5.  Removal of opkg for tiny targets
6.  Packages derived from GLUON_FEATURES + GLUON_FEATURES_$(class)
7.  GLUON_SITE_PACKAGES
8.  GLUON_SITE_PACKAGES_$(class)
9.  Device-specific packages from target/$(GLUON_TARGET)
10. Device-specific packages from GLUON_$(device)_SITE_PACKAGES

This also contains various pieces of cleanup:

- No hardcoded order of device classes for target_config.lua arguments
  anymore (in fact, the Makefile doesn't know anything about device
  classes now)
- target_conifg_lib.lua only hardcodes the fallback class for x86, no
  other occurences of specific class names
- Feature -> package list mapping is moved from Makefile to the Lua code
  as well (still implemented in Shell though)

When adding device classes, targets without devices such as x86 were not
handled. As site and feature packages are included on such a per-device
decision, x86 images ended up without most packages.

Include a class setting for a target and include the class-packages
target-wide when this setting is configured.

Fixes 9c523650 ("build: introduce device classes")

This commit allows to define a device-class flag in the target
definitions. This way, it is possible to distinguish between groups
of devices in the build-process in terms of package or feature
selection.

Fixes: 071cf7b2 ("Switch to Lua for target definitions")