Add presubmit check to //mojo/{public, edk} for BUILD.gn file flexibility.

mojo/PRESUBMIT.py

Index: mojo/PRESUBMIT.py
diff --git a/mojo/PRESUBMIT.py b/mojo/PRESUBMIT.py
index 557883e17bfd0f6f8ef16c54b80b2d7131c27854..3d85422260f36eaa0dedbc8672ff20417c7836be 100644
--- a/mojo/PRESUBMIT.py
+++ b/mojo/PRESUBMIT.py
@@ -9,8 +9,170 @@ for more details about the presubmit API built into depot_tools.
 """
 
 import os.path
+import re
 
-def CheckChangeOnUpload(input_api, output_api):
+_SDK_WHITELISTED_EXTERNAL_PATHS = [
+  "//testing/gtest",
+  "//third_party/cython",
+  "//third_party/khronos",
+]
+
+_PACKAGE_PATH_PREFIXES = {"SDK": "mojo/public/",
+                          "EDK": "mojo/edk/"}
+
+_PACKAGE_SOURCE_SET_TYPES = {"SDK": "mojo_sdk_source_set",
+                             "EDK": "mojo_edk_source_set"}
+
+_ILLEGAL_EXTERNAL_PATH_WARNING_MESSAGE = \
+    "Found disallowed external paths within SDK buildfiles."
+
+_ILLEGAL_EDK_ABSOLUTE_PATH_WARNING_MESSAGE = \
+    "Found references to the EDK via absolute paths within EDK buildfiles.",
+
+_ILLEGAL_SDK_ABSOLUTE_PATH_WARNING_MESSAGE_TEMPLATE = \
+    "Found references to the SDK via absolute paths within %s buildfiles."
+
+_ILLEGAL_SDK_ABSOLUTE_PATH_WARNING_MESSAGES = {
+  "SDK": _ILLEGAL_SDK_ABSOLUTE_PATH_WARNING_MESSAGE_TEMPLATE % "SDK",
+  "EDK": _ILLEGAL_SDK_ABSOLUTE_PATH_WARNING_MESSAGE_TEMPLATE % "EDK",
+}
+
+_INCORRECT_SOURCE_SET_TYPE_WARNING_MESSAGE_TEMPLATE = \
+    "All source sets in the %s must be constructed via %s."
+
+_INCORRECT_SOURCE_SET_TYPE_WARNING_MESSAGES = {
+  "SDK": _INCORRECT_SOURCE_SET_TYPE_WARNING_MESSAGE_TEMPLATE
+      % ("SDK", _PACKAGE_SOURCE_SET_TYPES["SDK"]),
+  "EDK": _INCORRECT_SOURCE_SET_TYPE_WARNING_MESSAGE_TEMPLATE
+      % ("EDK", _PACKAGE_SOURCE_SET_TYPES["EDK"]),
+}
+
+def _IsBuildFileWithinPackage(f, package):
+  """Returns whether |f| specifies a GN build file within |package| ("SDK" or
+  "EDK")."""
+  assert package in _PACKAGE_PATH_PREFIXES
+  package_path_prefix = _PACKAGE_PATH_PREFIXES[package]
+
+  if not f.LocalPath().startswith(package_path_prefix):
+    return False
+  if (not f.LocalPath().endswith("/BUILD.gn") and
+      not f.LocalPath().endswith(".gni")):
+    return False
+  return True
+
+def _AffectedBuildFilesWithinPackage(input_api, package):
+  """Returns all the affected build files within |package| ("SDK" or "EDK")."""
+  return [f for f in input_api.AffectedFiles()
+      if _IsBuildFileWithinPackage(f, package)]
+
+def _FindIllegalAbsolutePathsInBuildFiles(input_api, package):
+  """Finds illegal absolute paths within the build files in
+  |input_api.AffectedFiles()| that are within |package| ("SDK" or "EDK").
+  An illegal absolute path within the SDK is one that is to the SDK itself
+  or a non-whitelisted external path. An illegal absolute path within the
+  EDK is one that is to the SDK or the EDK.
+  Returns any such references in a list of (file_path, line_number,
+  referenced_path) tuples."""
+  illegal_references = []
+  for f in _AffectedBuildFilesWithinPackage(input_api, package):
+    for line_num, line in f.ChangedContents():
+      # Determine if this is a reference to an absolute path.
+      m = re.search(r'"(//[^"]*)"', line)
+      if not m:
+        continue
+      referenced_path = m.group(1)
+
+      # In the EDK, all external absolute paths are allowed.
+      if package == "EDK" and not referenced_path.startswith("//mojo"):
+        continue
+
+      # Determine if this is a whitelisted external path.
+      if referenced_path in _SDK_WHITELISTED_EXTERNAL_PATHS:
+        continue
+
+      illegal_references.append((f.LocalPath(), line_num, referenced_path))
+
+  return illegal_references
+
+def _PathReferenceInBuildFileWarningItem(build_file, line_num, referenced_path):
+  """Returns a string expressing a warning item that |referenced_path| is
+  referenced at |line_num| in |build_file|."""
+  return "%s, line %d (%s)" % (build_file, line_num, referenced_path)
+
+def _IncorrectSourceSetTypeWarningItem(build_file, line_num):
+  """Returns a string expressing that the error occurs at |line_num| in
+  |build_file|."""
+  return "%s, line %d" % (build_file, line_num)
+
+def _CheckNoIllegalAbsolutePathsInBuildFiles(input_api, output_api, package):
+  """Makes sure that the BUILD.gn files within |package| ("SDK" or "EDK") do not
+  reference the SDK/EDK via absolute paths, and do not reference disallowed
+  external dependencies."""
+  sdk_references = []
+  edk_references = []
+  external_deps_references = []
+
+  # Categorize any illegal references.
+  illegal_references = _FindIllegalAbsolutePathsInBuildFiles(input_api, package)
+  for build_file, line_num, referenced_path in illegal_references:
+    reference_string = _PathReferenceInBuildFileWarningItem(build_file,
+                                                            line_num,
+                                                            referenced_path)
+    if referenced_path.startswith("//mojo/public"):
+      sdk_references.append(reference_string)
+    elif package == "SDK":
+      external_deps_references.append(reference_string)
+    else:
+      assert referenced_path.startswith("//mojo/edk")
+      edk_references.append(reference_string)
+
+  # Package up categorized illegal references into results.
+  results = []
+  if sdk_references:
+    results.extend([output_api.PresubmitError(
+        _ILLEGAL_SDK_ABSOLUTE_PATH_WARNING_MESSAGES[package],
+        items=sdk_references)])
+
+  if external_deps_references:
+    assert package == "SDK"
+    results.extend([output_api.PresubmitError(
+        _ILLEGAL_EXTERNAL_PATH_WARNING_MESSAGE,
+        items=external_deps_references)])
+
+  if edk_references:
+    assert package == "EDK"
+    results.extend([output_api.PresubmitError(
+        _ILLEGAL_EDK_ABSOLUTE_PATH_WARNING_MESSAGE,
+        items=edk_references)])
+
+  return results
+
+def _CheckSourceSetsAreOfCorrectType(input_api, output_api, package):
+  """Makes sure that the BUILD.gn files always use the correct wrapper type for
+  |package|, which can be one of ["SDK", "EDK"], to construct source_set
+  targets."""
+  assert package in _PACKAGE_SOURCE_SET_TYPES
+  required_source_set_type = _PACKAGE_SOURCE_SET_TYPES[package]
+
+  problems = []
+  for f in _AffectedBuildFilesWithinPackage(input_api, package):
+    for line_num, line in f.ChangedContents():
+      m = re.search(r"[a-z_]*source_set\(", line)
+      if not m:
+        continue
+      source_set_type = m.group(0)[:-1]
+      if source_set_type == required_source_set_type:
+        continue
+      problems.append(_IncorrectSourceSetTypeWarningItem(f.LocalPath(),
+                                                         line_num))
+
+  if not problems:
+    return []
+  return [output_api.PresubmitError(
+      _INCORRECT_SOURCE_SET_TYPE_WARNING_MESSAGES[package],
+      items=problems)]
+
+def _CheckChangePylintsClean(input_api, output_api):
   # Additional python module paths (we're in src/mojo/); not everyone needs
   # them, but it's easiest to add them to everyone's path.
   # For ply and jinja2:
@@ -47,7 +209,36 @@ def CheckChangeOnUpload(input_api, output_api):
       mojo_roll_tools_path,
       mopy_path,
   ]
-  results += input_api.canned_checks.RunPylint(
+  results.extend(input_api.canned_checks.RunPylint(
       input_api, output_api, extra_paths_list=pylint_extra_paths,
-      black_list=temporary_black_list)
+      black_list=temporary_black_list))
+  return results
+
+def _BuildFileChecks(input_api, output_api):
+  """Performs checks on SDK and EDK buildfiles."""
+  results = []
+  for package in ["SDK", "EDK"]:
+    results.extend(_CheckNoIllegalAbsolutePathsInBuildFiles(input_api,
+                                                            output_api,
+                                                            package))
+    results.extend(_CheckSourceSetsAreOfCorrectType(input_api,
+                                                    output_api,
+                                                    package))
+  return results
+
+def _CommonChecks(input_api, output_api):
+  """Checks common to both upload and commit."""
+  results = []
+  results.extend(_BuildFileChecks(input_api, output_api))
+  return results
+
+def CheckChangeOnUpload(input_api, output_api):
+  results = []
+  results.extend(_CommonChecks(input_api, output_api))
+  results.extend(_CheckChangePylintsClean(input_api, output_api))
+  return results
+
+def CheckChangeOnCommit(input_api, output_api):
+  results = []
+  results.extend(_CommonChecks(input_api, output_api))
   return results