waf: px4: define dynamic environment

We get the flags used by PX4Firmware build system so that we can use foreign
headers properly. Also, we add some defines used by PX4.

Tools/ardupilotwaf/px4.py

@@ -5,13 +5,45 @@
 Waf tool for PX4 build
 """
 
+from waflib.TaskGen import before_method, feature
+
 import os
 
+_dynamic_env_data = {}
+def _load_dynamic_env_data(bld):
+    bldnode = bld.bldnode.make_node('modules/PX4Firmware')
+    for name in ('cxx_flags', 'include_dirs', 'definitions'):
+        _dynamic_env_data[name] = bldnode.find_node(name).read().split(';')
+
+    _dynamic_env_data['DEFINES'] = [
+        'NUTTX_GIT_VERSION="%s"' % bld.git_submodule_head_hash('PX4NuttX')[:8],
+        'PX4_GIT_VERSION="%s"' % bld.git_submodule_head_hash('PX4Firmware')[:8],
+    ]
+
+@feature('px4_ap_stlib', 'px4_ap_program')
+@before_method('process_source')
+def px4_dynamic_env(self):
+    # The generated files from configuration possibly don't exist if it's just
+    # a list command (TODO: figure out a better way to address that).
+    if self.bld.cmd == 'list':
+        return
+
+    if not _dynamic_env_data:
+        _load_dynamic_env_data(self.bld)
+
+    self.env.append_value('INCLUDES', _dynamic_env_data['include_dirs'])
+    self.env.prepend_value('CXXFLAGS', _dynamic_env_data['cxx_flags'])
+    self.env.prepend_value('CXXFLAGS', _dynamic_env_data['definitions'])
+    self.env.append_value('DEFINES', _dynamic_env_data['DEFINES'])
+
 def configure(cfg):
     cfg.load('cmake')
 
     env = cfg.env
 
+    env.AP_PROGRAM_FEATURES += ['px4_ap_program']
+    env.AP_STLIB_FEATURES += ['px4_ap_stlib']
+
     def srcpath(path):
         return cfg.srcnode.make_node(path).abspath()