Add ninja determinism test

To make sure the ninja files aren't non-deterministic.

I will add this to CI after it's checked in.

Test: Manually
Change-Id: I071562885a1652fbfe2374916f5de017597f770a
diff --git a/scripts/ninja_determinism_test.py b/scripts/ninja_determinism_test.py
new file mode 100755
index 0000000..e207b96
--- /dev/null
+++ b/scripts/ninja_determinism_test.py
@@ -0,0 +1,210 @@
+#!/usr/bin/env python3
+
+import asyncio
+import argparse
+import dataclasses
+import hashlib
+import os
+import re
+import socket
+import subprocess
+import sys
+import zipfile
+
+from typing import List
+
+def get_top() -> str:
+  path = '.'
+  while not os.path.isfile(os.path.join(path, 'build/soong/soong_ui.bash')):
+    if os.path.abspath(path) == '/':
+      sys.exit('Could not find android source tree root.')
+    path = os.path.join(path, '..')
+  return os.path.abspath(path)
+
+
+_PRODUCT_REGEX = re.compile(r'([a-zA-Z_][a-zA-Z0-9_]*)(?:(?:-([a-zA-Z_][a-zA-Z0-9_]*))?-(user|userdebug|eng))?')
+
+
+@dataclasses.dataclass(frozen=True)
+class Product:
+  """Represents a TARGET_PRODUCT and TARGET_BUILD_VARIANT."""
+  product: str
+  release: str
+  variant: str
+
+  def __post_init__(self):
+    if not _PRODUCT_REGEX.match(str(self)):
+      raise ValueError(f'Invalid product name: {self}')
+
+  def __str__(self):
+    return self.product + '-' + self.release + '-' + self.variant
+
+
+async def run_make_nothing(product: Product, out_dir: str) -> bool:
+  """Runs a build and returns if it succeeded or not."""
+  with open(os.path.join(out_dir, 'build.log'), 'wb') as f:
+    result = await asyncio.create_subprocess_exec(
+        'prebuilts/build-tools/linux-x86/bin/nsjail',
+        '-q',
+        '--cwd',
+        os.getcwd(),
+        '-e',
+        '-B',
+        '/',
+        '-B',
+        f'{os.path.abspath(out_dir)}:{os.path.join(os.getcwd(), "out")}',
+        '--time_limit',
+        '0',
+        '--skip_setsid',
+        '--keep_caps',
+        '--disable_clone_newcgroup',
+        '--disable_clone_newnet',
+        '--rlimit_as',
+        'soft',
+        '--rlimit_core',
+        'soft',
+        '--rlimit_cpu',
+        'soft',
+        '--rlimit_fsize',
+        'soft',
+        '--rlimit_nofile',
+        'soft',
+        '--proc_rw',
+        '--hostname',
+        socket.gethostname(),
+        '--',
+        'build/soong/soong_ui.bash',
+        '--make-mode',
+        f'TARGET_PRODUCT={product.product}',
+        f'TARGET_RELEASE={product.release}',
+        f'TARGET_BUILD_VARIANT={product.variant}',
+        '--skip-ninja',
+        'nothing', stdout=f, stderr=subprocess.STDOUT)
+    return await result.wait() == 0
+
+SUBNINJA_OR_INCLUDE_REGEX = re.compile(rb'\n(?:include|subninja) ')
+
+def find_subninjas_and_includes(contents) -> List[str]:
+  results = []
+  def get_path_from_directive(i):
+    j = contents.find(b'\n', i)
+    if j < 0:
+      path_bytes = contents[i:]
+    else:
+      path_bytes = contents[i:j]
+    path_bytes = path_bytes.removesuffix(b'\r')
+    path = path_bytes.decode()
+    if '$' in path:
+      sys.exit('includes/subninjas with variables are unsupported: '+path)
+    return path
+
+  if contents.startswith(b"include "):
+    results.append(get_path_from_directive(len(b"include ")))
+  elif contents.startswith(b"subninja "):
+    results.append(get_path_from_directive(len(b"subninja ")))
+
+  for match in SUBNINJA_OR_INCLUDE_REGEX.finditer(contents):
+    results.append(get_path_from_directive(match.end()))
+
+  return results
+
+
+def transitively_included_ninja_files(out_dir: str, ninja_file: str, seen):
+  with open(ninja_file, 'rb') as f:
+    contents = f.read()
+
+  results = [ninja_file]
+  seen[ninja_file] = True
+  sub_files = find_subninjas_and_includes(contents)
+  for sub_file in sub_files:
+    sub_file = os.path.join(out_dir, sub_file.removeprefix('out/'))
+    if sub_file not in seen:
+      results.extend(transitively_included_ninja_files(out_dir, sub_file, seen))
+
+  return results
+
+
+def hash_ninja_file(out_dir: str, ninja_file: str, hasher):
+  with open(ninja_file, 'rb') as f:
+    contents = f.read()
+
+  sub_files = find_subninjas_and_includes(contents)
+
+  hasher.update(contents)
+
+  for sub_file in sub_files:
+    hash_ninja_file(out_dir, os.path.join(out_dir, sub_file.removeprefix('out/')), hasher)
+
+
+def hash_files(files: List[str]) -> str:
+  hasher = hashlib.md5()
+  for file in files:
+    with open(file, 'rb') as f:
+      hasher.update(f.read())
+  return hasher.hexdigest()
+
+
+def dist_ninja_files(out_dir: str, zip_name: str, ninja_files: List[str]):
+  dist_dir = os.getenv('DIST_DIR', os.path.join(os.getenv('OUT_DIR', 'out'), 'dist'))
+  os.makedirs(dist_dir, exist_ok=True)
+
+  with open(os.path.join(dist_dir, zip_name), 'wb') as f:
+    with zipfile.ZipFile(f, mode='w') as zf:
+      for ninja_file in ninja_files:
+        zf.write(ninja_file, arcname=os.path.basename(out_dir)+'/out/' + os.path.relpath(ninja_file, out_dir))
+
+
+async def main():
+    parser = argparse.ArgumentParser()
+    args = parser.parse_args()
+
+    os.chdir(get_top())
+    subprocess.check_call(['touch', 'build/soong/Android.bp'])
+
+    product = Product(
+      'aosp_cf_x86_64_phone',
+      'trunk_staging',
+      'userdebug',
+    )
+    os.environ['TARGET_PRODUCT'] = 'aosp_cf_x86_64_phone'
+    os.environ['TARGET_RELEASE'] = 'trunk_staging'
+    os.environ['TARGET_BUILD_VARIANT'] = 'userdebug'
+
+    out_dir1 = os.path.join(os.getenv('OUT_DIR', 'out'), 'determinism_test_out1')
+    out_dir2 = os.path.join(os.getenv('OUT_DIR', 'out'), 'determinism_test_out2')
+
+    os.makedirs(out_dir1, exist_ok=True)
+    os.makedirs(out_dir2, exist_ok=True)
+
+    success1, success2 = await asyncio.gather(
+      run_make_nothing(product, out_dir1),
+      run_make_nothing(product, out_dir2))
+
+    if not success1:
+      with open(os.path.join(out_dir1, 'build.log'), 'r') as f:
+        print(f.read(), file=sys.stderr)
+      sys.exit('build failed')
+    if not success2:
+      with open(os.path.join(out_dir2, 'build.log'), 'r') as f:
+        print(f.read(), file=sys.stderr)
+      sys.exit('build failed')
+
+    ninja_files1 = transitively_included_ninja_files(out_dir1, os.path.join(out_dir1, f'combined-{product.product}.ninja'), {})
+    ninja_files2 = transitively_included_ninja_files(out_dir2, os.path.join(out_dir2, f'combined-{product.product}.ninja'), {})
+
+    dist_ninja_files(out_dir1, 'determinism_test_files_1.zip', ninja_files1)
+    dist_ninja_files(out_dir2, 'determinism_test_files_2.zip', ninja_files2)
+
+    hash1 = hash_files(ninja_files1)
+    hash2 = hash_files(ninja_files2)
+
+    if hash1 != hash2:
+        sys.exit("ninja files were not deterministic! See disted determinism_test_files_1/2.zip")
+
+    print("Success, ninja files were deterministic")
+
+
+if __name__ == "__main__":
+    asyncio.run(main())
+
+