[modules] Add kconfig module

Add a kconfig module to allow meson to integrate with existing projects
that use kconfig.

docs/markdown/Kconfig-module.md

@@ -0,0 +1,41 @@
+---
+short-description: Kconfig module
+authors:
+    - name: Mark Schulte, Paolo Bonzini
+      years: [2017, 2019]
+      has-copyright: false
+...
+
+# Kconfig module
+
+This module parses Kconfig output files to allow use of kconfig
+configurations in meson projects.
+
+**Note**: this does not provide kconfig frontend tooling to generate a
+configuration. You still need something such as kconfig frontends (see
+link below) to parse your Kconfig files, and then (after you've
+choosen the configuration options), output a ".config" file.
+
+  [kconfig-frontends]: http://ymorin.is-a-geek.org/projects/kconfig-frontends
+
+## Usage
+
+To use this module, just do: **`kconfig = import('unstable-kconfig')`**.
+The following functions will then be available as methods on the object
+with the name `kconfig`. You can, of course, replace the name
+`kconfig` with anything else.
+
+### kconfig.load()
+
+This function loads an output file, usually ".config", (the file path
+must be specified as the first and only argument) to load a configuration
+from. The configuration is returned as a dictionary object.
+
+Note that `kconfig.load()` makes no attempt at parsing the values in the
+file.  Therefore, true boolean values will be represented as the string "y"
+and integer values will have to be converted with `.to_int()`.
+
+* The first (and only) argument is the path to the configuration file to
+  load (usually ".config").
+
+**Returns**: a [dictionary object](Reference-manual.md#dictionary-object).

docs/markdown/Release-notes-for-0.50.0.md

@@ -23,3 +23,8 @@ always be built by default.
 Now if `build_by_default` is explicitly set to false it will no longer be
 overridden. If `build_by_default` is not set, its default will still be
 determined by the value of `install` for greater backward compatibility.
+
+## Adding module to parse kconfig output files
+
+Adds the ability to load and use kconfig output files as part of the
+`meson.build` files be loading the kconfig module.

docs/sitemap.txt

@@ -45,6 +45,7 @@ index.md
 			Simd-module.md
 			Windows-module.md
 			Cuda-module.md
+			Kconfig-module.md
 		Java.md
 		Vala.md
 		D.md

mesonbuild/modules/unstable_kconfig.py

@@ -0,0 +1,72 @@
+# Copyright 2017, 2019 The Meson development team
+
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+
+#     http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from . import ExtensionModule
+
+from .. import mesonlib
+from ..mesonlib import typeslistify
+from ..interpreterbase import FeatureNew, noKwargs
+from ..interpreter import InvalidCode
+
+import os
+
+class KconfigModule(ExtensionModule):
+
+    @FeatureNew('Kconfig Module', '0.50.0')
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self.snippets.add('load')
+
+    def _load_file(self, path_to_config):
+        result = dict()
+        try:
+            with open(path_to_config) as f:
+                for line in f:
+                    if '#' in line:
+                        comment_idx = line.index('#')
+                        line = line[:comment_idx]
+                    line = line.strip()
+                    try:
+                        name, val = line.split('=', 1)
+                    except ValueError:
+                        continue
+                    result[name.strip()] = val.strip()
+        except IOError as e:
+            raise mesonlib.MesonException('Failed to load {}: {}'.format(path_to_config, e))
+
+        return result
+
+    @noKwargs
+    def load(self, interpreter, state, args, kwargs):
+        sources = typeslistify(args, (str, mesonlib.File))
+        if len(sources) != 1:
+            raise InvalidCode('load takes only one file input.')
+
+        s = sources[0]
+        if isinstance(s, mesonlib.File):
+            # kconfig input is processed at "meson setup" time, not during
+            # the build, so it cannot reside in the build directory.
+            if s.is_built:
+                raise InvalidCode('kconfig input must be a source file.')
+            s = s.relative_name()
+
+        s = os.path.join(interpreter.environment.source_dir, s)
+        if s not in interpreter.build_def_files:
+            interpreter.build_def_files.append(s)
+
+        return self._load_file(s)
+
+
+def initialize(*args, **kwargs):
+    return KconfigModule(*args, **kwargs)

run_project_tests.py

@@ -550,6 +550,7 @@ def detect_tests_to_run():
         ('failing-meson', 'failing', False),
         ('failing-build', 'failing build', False),
         ('failing-test',  'failing test', False),
+        ('kconfig', 'kconfig', False),
 
         ('platform-osx', 'osx', not mesonlib.is_osx()),
         ('platform-windows', 'windows', not mesonlib.is_windows() and not mesonlib.is_cygwin()),

test cases/kconfig/1 basic/.config

@@ -0,0 +1,3 @@
+CONFIG_VAL1=y
+# CONFIG_VAL2 is not set
+CONFIG_VAL_VAL=4

test cases/kconfig/1 basic/meson.build

@@ -0,0 +1,16 @@
+project('kconfig basic test')
+
+k = import('unstable-kconfig')
+conf = k.load('.config')
+
+if not conf.has_key('CONFIG_VAL1')
+  error('Expected CONFIG_VAL1 to be set, but it wasn\'t')
+endif
+
+if conf.has_key('CONFIG_VAL2')
+  error('Expected CONFIG_VAL2 not be set, but it was')
+endif
+
+if conf.get('CONFIG_VAL_VAL').to_int() != 4
+  error('Expected CONFIG_VAL_VAL to be 4')
+endif

test cases/kconfig/2 subdir/.config

@@ -0,0 +1,2 @@
+CONFIG_IS_SET=y
+# CONFIG_NOT_IS_SET is not set

test cases/kconfig/2 subdir/dir/meson.build

@@ -0,0 +1,13 @@
+
+k = import('unstable-kconfig')
+
+conf = k.load(meson.source_root() / '.config')
+
+if not conf.has_key('CONFIG_IS_SET')
+  error('Expected CONFIG_IS_SET to be set, but it wasn\'t')
+endif
+
+if conf.has_key('CONFIG_NOT_IS_SET')
+  error('Expected CONFIG_NOT_IS_SET not be set, but it was')
+endif
+

test cases/kconfig/2 subdir/meson.build

@@ -0,0 +1,4 @@
+project('kconfig subdir test')
+
+# Test into sub directory
+subdir('dir')

test cases/kconfig/3 load_config files/dir/config

@@ -0,0 +1,2 @@
+CONFIG_IS_SET=y
+# CONFIG_NOT_IS_SET is not set

test cases/kconfig/3 load_config files/dir/meson.build

@@ -0,0 +1,13 @@
+
+k = import('unstable-kconfig')
+
+conf = k.load(files('config'))
+
+if not conf.has_key('CONFIG_IS_SET')
+  error('Expected CONFIG_IS_SET to be set, but it wasn\'t')
+endif
+
+if conf.has_key('CONFIG_NOT_IS_SET')
+  error('Expected CONFIG_NOT_IS_SET not be set, but it was')
+endif
+

test cases/kconfig/3 load_config files/meson.build

@@ -0,0 +1,4 @@
+project('kconfig subdir test')
+
+# Test into sub directory
+subdir('dir')