Bug 1870059 - Add a moz.build hook. r=firefox-build-system-reviewers,sergesanspaille

Differential Revision: https://phabricator.services.mozilla.com/D211105

moz.configure

@@ -48,6 +48,25 @@ def imply_disable_compile_environment(value):
         return False
 
 
+option(
+    env="MOZ_BUILD_HOOK",
+    nargs=1,
+    help="moz.build file that will be executed as if it were appended to"
+    " every moz.build in the tree.",
+)
+
+
+@depends_if("MOZ_BUILD_HOOK")
+@imports("os")
+def moz_build_hook(value):
+    if not os.path.exists(value[0]):
+        die(f"MOZ_BUILD_HOOK set to {value[0]} but the file doesn't exist")
+    return os.path.abspath(value[0])
+
+
+set_config("MOZ_BUILD_HOOK", moz_build_hook)
+
+
 option(
     env="MOZ_COPY_PDBS",
     help="For builds that do not support symbols in the normal fashion,"

python/mozbuild/mozbuild/frontend/reader.py

@@ -125,6 +125,10 @@ def is_read_allowed(path, config):
     if mozpath.basedir(path, [topsrcdir]):
         return True
 
+    hook = config.substs.get("MOZ_BUILD_HOOK")
+    if hook and path == hook:
+        return True
+
     return False
 
 
@@ -206,7 +210,7 @@ class MozbuildSandbox(Sandbox):
             return
         Sandbox.__setitem__(self, key, value)
 
-    def exec_file(self, path):
+    def exec_file(self, path, becomes_current_path=True):
         """Override exec_file to normalize paths and restrict file loading.
 
         Paths will be rejected if they do not fall under topsrcdir or one of
@@ -220,7 +224,7 @@ class MozbuildSandbox(Sandbox):
                 self._context.source_stack, sys.exc_info()[2], illegal_path=path
             )
 
-        Sandbox.exec_file(self, path)
+        Sandbox.exec_file(self, path, becomes_current_path)
 
     def _export(self, varname):
         """Export the variable to all subdirectories of the current path."""
@@ -1145,6 +1149,9 @@ class BuildReader(object):
         context = Context(VARIABLES, config, self.finder)
         sandbox = MozbuildSandbox(context, metadata=metadata, finder=self.finder)
         sandbox.exec_file(path)
+        hook = config.substs.get("MOZ_BUILD_HOOK")
+        if hook:
+            sandbox.exec_file(hook, becomes_current_path=False)
         self._execution_time += time.monotonic() - time_start
         self._file_count += len(context.all_paths)
 

python/mozbuild/mozbuild/frontend/sandbox.py

@@ -144,7 +144,7 @@ class Sandbox(dict):
     def _context(self):
         return self._active_contexts[-1]
 
-    def exec_file(self, path):
+    def exec_file(self, path, becomes_current_path=True):
         """Execute code at a path in the sandbox.
 
         The path must be absolute.
@@ -158,9 +158,9 @@ class Sandbox(dict):
                 self._context.source_stack, sys.exc_info()[2], read_error=path
             )
 
-        self.exec_source(source, path)
+        self.exec_source(source, path, becomes_current_path)
 
-    def exec_source(self, source, path=""):
+    def exec_source(self, source, path="", becomes_current_path=True):
         """Execute Python code within a string.
 
         The passed string should contain Python code to be executed. The string
@@ -185,7 +185,9 @@ class Sandbox(dict):
             finally:
                 self._current_source = old_source
 
-        self.exec_function(execute, path=path)
+        self.exec_function(
+            execute, path=path, becomes_current_path=becomes_current_path
+        )
 
     def exec_function(
         self, func, args=(), kwargs={}, path="", becomes_current_path=True

python/mozbuild/mozbuild/test/frontend/data/mozbuild.hook

@@ -0,0 +1,10 @@
+DEFINES["ALL"] = True
+
+if RELATIVEDIR == "foo":
+    DEFINES["FOO_ONLY"] = True
+
+if RELATIVEDIR.startswith("foo"):
+    DEFINES["FOO"] = True
+
+if RELATIVEDIR == "bar":
+    DEFINES["BAR_ONLY"] = True

python/mozbuild/mozbuild/test/frontend/test_reader.py

@@ -534,6 +534,26 @@ class TestBuildReader(unittest.TestCase):
             set(info["win.and.osx"]["SCHEDULES"].exclusive), set(["macosx", "windows"])
         )
 
+    def test_hook(self):
+        extra = {
+            "MOZ_BUILD_HOOK": mozpath.abspath(self.file_path("mozbuild.hook")),
+        }
+        config = self.config(
+            "traversal-simple", extra_substs=extra, error_is_fatal=True
+        )
+
+        reader = BuildReader(config)
+
+        contexts = {ctx.relsrcdir: ctx for ctx in reader.read_topsrcdir()}
+
+        self.assertEqual(len(contexts), 4)
+        self.assertEqual(contexts[""]["DEFINES"], {"ALL": True})
+        self.assertEqual(
+            contexts["foo"]["DEFINES"], {"ALL": True, "FOO": True, "FOO_ONLY": True}
+        )
+        self.assertEqual(contexts["foo/biz"]["DEFINES"], {"ALL": True, "FOO": True})
+        self.assertEqual(contexts["bar"]["DEFINES"], {"ALL": True, "BAR_ONLY": True})
+
 
 if __name__ == "__main__":
     main()

python/mozbuild/mozbuild/test/frontend/test_sandbox.py

@@ -124,12 +124,14 @@ class TestedSandbox(MozbuildSandbox):
     def source_path(self, path):
         return SourcePath(self._context, path)
 
-    def exec_file(self, path):
-        super(TestedSandbox, self).exec_file(self.normalize_path(path))
+    def exec_file(self, path, becomes_current_path=True):
+        super(TestedSandbox, self).exec_file(
+            self.normalize_path(path), becomes_current_path
+        )
 
-    def exec_source(self, source, path=""):
+    def exec_source(self, source, path="", becomes_current_path=True):
         super(TestedSandbox, self).exec_source(
-            source, self.normalize_path(path) if path else ""
+            source, self.normalize_path(path) if path else "", becomes_current_path
         )