iOS,macOS: Clean up create_ios_framework.py

Over time, this script and others in sky/tools have accumulated a lot of
additional and sometimes duplicate code.

This is a first pass cleanup of create_ios_framework.py to extract
common utility code to utils.py and refactor for better readability.

Author: cbracken

ci/licenses_golden/excluded_files

@@ -439,6 +439,7 @@
 ../../../flutter/sky/tools/create_xcframework.py
 ../../../flutter/sky/tools/dist_dart_pkg.py
 ../../../flutter/sky/tools/install_framework_headers.py
+../../../flutter/sky/tools/utils.py
 ../../../flutter/testing
 ../../../flutter/third_party/.clang-tidy
 ../../../flutter/third_party/.gitignore

sky/tools/create_ios_framework.py

@@ -9,20 +9,14 @@
 
 import argparse
 import os
-import platform
-import shutil
-import subprocess
 import sys
 
 from create_xcframework import create_xcframework  # pylint: disable=import-error
-
-ARCH_SUBPATH = 'mac-arm64' if platform.processor() == 'arm' else 'mac-x64'
-DSYMUTIL = os.path.join(
-    os.path.dirname(__file__), '..', '..', 'buildtools', ARCH_SUBPATH, 'clang', 'bin', 'dsymutil'
+from utils import (  # pylint: disable=import-error
+    assert_directory, assert_file, buildroot_relative_path, copy_binary, copy_tree, create_zip,
+    extract_dsym, lipo, strip_binary, write_codesign_config
 )
 
-buildroot_dir = os.path.abspath(os.path.join(os.path.realpath(__file__), '..', '..', '..', '..'))
-
 
 def main():
   parser = argparse.ArgumentParser(
@@ -42,25 +36,25 @@ def main():
 
   args = parser.parse_args()
 
-  dst = (args.dst if os.path.isabs(args.dst) else os.path.join(buildroot_dir, args.dst))
+  dst = (args.dst if os.path.isabs(args.dst) else buildroot_relative_path(args.dst))
 
   arm64_out_dir = (
       args.arm64_out_dir
-      if os.path.isabs(args.arm64_out_dir) else os.path.join(buildroot_dir, args.arm64_out_dir)
+      if os.path.isabs(args.arm64_out_dir) else buildroot_relative_path(args.arm64_out_dir)
   )
 
   x64_out_dir = None
   if args.x64_out_dir:
     x64_out_dir = (
         args.x64_out_dir
-        if os.path.isabs(args.x64_out_dir) else os.path.join(buildroot_dir, args.x64_out_dir)
+        if os.path.isabs(args.x64_out_dir) else buildroot_relative_path(args.x64_out_dir)
     )
 
   simulator_x64_out_dir = None
   if args.simulator_x64_out_dir:
     simulator_x64_out_dir = (
         args.simulator_x64_out_dir if os.path.isabs(args.simulator_x64_out_dir) else
-        os.path.join(buildroot_dir, args.simulator_x64_out_dir)
+        buildroot_relative_path(args.simulator_x64_out_dir)
     )
 
   framework = os.path.join(dst, 'Flutter.framework')
@@ -72,24 +66,15 @@ def main():
   if args.simulator_arm64_out_dir:
     simulator_arm64_out_dir = (
         args.simulator_arm64_out_dir if os.path.isabs(args.simulator_arm64_out_dir) else
-        os.path.join(buildroot_dir, args.simulator_arm64_out_dir)
+        buildroot_relative_path(args.simulator_arm64_out_dir)
     )
 
   if args.simulator_arm64_out_dir is not None:
     simulator_arm64_framework = os.path.join(simulator_arm64_out_dir, 'Flutter.framework')
 
-  if not os.path.isdir(arm64_framework):
-    print('Cannot find iOS arm64 Framework at %s' % arm64_framework)
-    return 1
-
-  if not os.path.isdir(simulator_x64_framework):
-    print('Cannot find iOS x64 simulator Framework at %s' % simulator_framework)
-    return 1
-
-  if not os.path.isfile(DSYMUTIL):
-    print('Cannot find dsymutil at %s' % DSYMUTIL)
-    return 1
-
+  assert_directory(arm64_framework, 'iOS arm64 framework')
+  assert_directory(simulator_arm64_framework, 'iOS arm64 simulator framework')
+  assert_directory(simulator_x64_framework, 'iOS x64 simulator framework')
   create_framework(
       args, dst, framework, arm64_framework, simulator_framework, simulator_x64_framework,
       simulator_arm64_framework
@@ -101,10 +86,18 @@ def main():
       '%s_extension_safe' % simulator_x64_out_dir, '%s_extension_safe' % simulator_arm64_out_dir
   )
 
-  generate_gen_snapshot(dst, x64_out_dir, arm64_out_dir)
+  # Copy gen_snapshot binary to destination directory.
+  if arm64_out_dir:
+    gen_snapshot = os.path.join(arm64_out_dir, 'gen_snapshot_arm64')
+    copy_binary(gen_snapshot, os.path.join(dst, 'gen_snapshot_arm64'))
+  if x64_out_dir:
+    gen_snapshot = os.path.join(x64_out_dir, 'gen_snapshot_x64')
+    copy_binary(gen_snapshot, os.path.join(dst, 'gen_snapshot_x64'))
+
   zip_archive(dst)
   return 0
 
+
 def create_extension_safe_framework( # pylint: disable=too-many-arguments
     args, dst, arm64_out_dir, simulator_x64_out_dir, simulator_arm64_out_dir
 ):
@@ -128,20 +121,17 @@ def create_extension_safe_framework( # pylint: disable=too-many-arguments
   )
   return 0
 
+
 def create_framework(  # pylint: disable=too-many-arguments
     args, dst, framework, arm64_framework, simulator_framework,
     simulator_x64_framework, simulator_arm64_framework
 ):
   arm64_dylib = os.path.join(arm64_framework, 'Flutter')
   simulator_x64_dylib = os.path.join(simulator_x64_framework, 'Flutter')
   simulator_arm64_dylib = os.path.join(simulator_arm64_framework, 'Flutter')
-  if not os.path.isfile(arm64_dylib):
-    print('Cannot find iOS arm64 dylib at %s' % arm64_dylib)
-    return 1
-
-  if not os.path.isfile(simulator_x64_dylib):
-    print('Cannot find iOS simulator dylib at %s' % simulator_x64_dylib)
-    return 1
+  assert_file(arm64_dylib, 'iOS arm64 dylib')
+  assert_file(simulator_arm64_dylib, 'iOS simulator arm64 dylib')
+  assert_file(simulator_x64_dylib, 'iOS simulator x64 dylib')
 
   # Compute dsym output paths, if enabled.
   framework_dsym = None
@@ -151,23 +141,15 @@ def create_framework(  # pylint: disable=too-many-arguments
     simulator_dsym = simulator_framework + '.dSYM'
 
   # Emit the framework for physical devices.
-  shutil.rmtree(framework, True)
-  shutil.copytree(arm64_framework, framework)
+  copy_tree(arm64_framework, framework)
   framework_binary = os.path.join(framework, 'Flutter')
   process_framework(args, dst, framework_binary, framework_dsym)
 
   # Emit the framework for simulators.
   if args.simulator_arm64_out_dir is not None:
-    shutil.rmtree(simulator_framework, True)
-    shutil.copytree(simulator_arm64_framework, simulator_framework)
-
+    copy_tree(simulator_arm64_framework, simulator_framework)
     simulator_framework_binary = os.path.join(simulator_framework, 'Flutter')
-
-    # Create the arm64/x64 simulator fat framework.
-    subprocess.check_call([
-        'lipo', simulator_x64_dylib, simulator_arm64_dylib, '-create', '-output',
-        simulator_framework_binary
-    ])
+    lipo([simulator_x64_dylib, simulator_arm64_dylib], simulator_framework_binary)
     process_framework(args, dst, simulator_framework_binary, simulator_dsym)
   else:
     simulator_framework = simulator_x64_framework
@@ -179,74 +161,41 @@ def create_framework(  # pylint: disable=too-many-arguments
   dsyms = [simulator_dsym, framework_dsym] if args.dsym else None
   create_xcframework(location=dst, name='Flutter', frameworks=xcframeworks, dsyms=dsyms)
 
-  # Add the x64 simulator into the fat framework.
-  subprocess.check_call([
-      'lipo', arm64_dylib, simulator_x64_dylib, '-create', '-output', framework_binary
-  ])
-
+  lipo([arm64_dylib, simulator_x64_dylib], framework_binary)
   process_framework(args, dst, framework_binary, framework_dsym)
   return 0
 
 
-def embed_codesign_configuration(config_path, contents):
-  with open(config_path, 'w') as file:
-    file.write('\n'.join(contents) + '\n')
-
-
 def zip_archive(dst):
-  ios_file_with_entitlements = ['gen_snapshot_arm64']
-  ios_file_without_entitlements = [
-      'Flutter.xcframework/ios-arm64/Flutter.framework/Flutter',
-      'Flutter.xcframework/ios-arm64_x86_64-simulator/Flutter.framework/Flutter',
-      'extension_safe/Flutter.xcframework/ios-arm64/Flutter.framework/Flutter',
-      'extension_safe/Flutter.xcframework/ios-arm64_x86_64-simulator/Flutter.framework/Flutter'
-  ]
-  embed_codesign_configuration(os.path.join(dst, 'entitlements.txt'), ios_file_with_entitlements)
-
-  embed_codesign_configuration(
-      os.path.join(dst, 'without_entitlements.txt'), ios_file_without_entitlements
+  write_codesign_config(os.path.join(dst, 'entitlements.txt'), ['gen_snapshot_arm64'])
+
+  write_codesign_config(
+      os.path.join(dst, 'without_entitlements.txt'), [
+          'Flutter.xcframework/ios-arm64/Flutter.framework/Flutter',
+          'Flutter.xcframework/ios-arm64_x86_64-simulator/Flutter.framework/Flutter',
+          'extension_safe/Flutter.xcframework/ios-arm64/Flutter.framework/Flutter',
+          'extension_safe/Flutter.xcframework/ios-arm64_x86_64-simulator/Flutter.framework/Flutter'
+      ]
   )
 
-  subprocess.check_call([
-      'zip',
-      '-r',
-      'artifacts.zip',
-      'gen_snapshot_arm64',
-      'Flutter.xcframework',
-      'entitlements.txt',
-      'without_entitlements.txt',
-      'extension_safe/Flutter.xcframework',
-  ],
-                        cwd=dst)
+  create_zip(
+      dst, 'artifacts.zip', [
+          'gen_snapshot_arm64',
+          'Flutter.xcframework',
+          'entitlements.txt',
+          'without_entitlements.txt',
+          'extension_safe/Flutter.xcframework',
+      ]
+  )
 
 
 def process_framework(args, dst, framework_binary, dsym):
   if dsym:
-    subprocess.check_call([DSYMUTIL, '-o', dsym, framework_binary])
+    extract_dsym(framework_binary, dsym)
 
   if args.strip:
-    # copy unstripped
     unstripped_out = os.path.join(dst, 'Flutter.unstripped')
-    shutil.copyfile(framework_binary, unstripped_out)
-    subprocess.check_call(['strip', '-x', '-S', framework_binary])
-
-
-def generate_gen_snapshot(dst, x64_out_dir, arm64_out_dir):
-  if x64_out_dir:
-    x64_path = os.path.join(x64_out_dir, 'gen_snapshot_x64')
-    _generate_gen_snapshot(x64_path, os.path.join(dst, 'gen_snapshot_x64'))
-
-  if arm64_out_dir:
-    arm64_path = os.path.join(arm64_out_dir, 'gen_snapshot_arm64')
-    _generate_gen_snapshot(arm64_path, os.path.join(dst, 'gen_snapshot_arm64'))
-
-
-def _generate_gen_snapshot(gen_snapshot_path, destination):
-  if not os.path.isfile(gen_snapshot_path):
-    print('Cannot find gen_snapshot at %s' % gen_snapshot_path)
-    sys.exit(1)
-
-  shutil.copy2(gen_snapshot_path, destination)
+    strip_binary(framework_binary, unstripped_copy_path=unstripped_out)
 
 
 if __name__ == '__main__':

sky/tools/utils.py

@@ -0,0 +1,89 @@
+#!/usr/bin/env python3
+#
+# Copyright 2013 The Flutter Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import os
+import platform
+import shutil
+import subprocess
+import sys
+
+
+def assert_directory(path, what):
+  """Logs an error and exits with EX_NOINPUT if the specified directory doesn't exist."""
+  if not os.path.isdir(path):
+    log_error('Cannot find %s at %s' % (what, path))
+    sys.exit(os.EX_NOINPUT)
+
+
+def assert_file(path, what):
+  """Logs an error and exits with EX_NOINPUT if the specified file doesn't exist."""
+  if not os.path.isfile(path):
+    log_error('Cannot find %s at %s' % (what, path))
+    sys.exit(os.EX_NOINPUT)
+
+
+def buildroot_relative_path(path):
+  """Returns the absolute path to the specified buildroot-relative path."""
+  buildroot_dir = os.path.abspath(os.path.join(os.path.realpath(__file__), '..', '..', '..', '..'))
+  return os.path.join(buildroot_dir, path)
+
+
+def copy_binary(source_path, destination_path):
+  """Copies a binary, preserving POSIX permissions."""
+  assert_file(source_path, 'file to copy')
+  shutil.copy2(source_path, destination_path)
+
+
+def copy_tree(source_path, destination_path):
+  """Performs a recursive copy of a directory.
+  If the destination path is present, it is deleted first."""
+  assert_directory(source_path, 'directory to copy')
+  shutil.rmtree(destination_path, True)
+  shutil.copytree(source_path, destination_path)
+
+
+def create_zip(cwd, zip_filename, paths):
+  """Creates a zip archive in cwd, containing a set of cwd-relative files."""
+  subprocess.check_call(['zip', '-r', zip_filename] + paths, cwd=cwd)
+
+
+def _dsymutil_path():
+  """Returns the path to dsymutil within Flutter's clang toolchain."""
+  arch_subpath = 'mac-arm64' if platform.processor() == 'arm' else 'mac-x64'
+  dsymutil_path = os.path.join('flutter', 'buildtools', arch_subpath, 'clang', 'bin', 'dsymutil')
+  return buildroot_relative_path(dsymutil_path)
+
+
+def extract_dsym(binary_path, dsym_out_path):
+  """Extracts a dSYM bundle from the specified Mach-O binary."""
+  arch_dir = 'mac-arm64' if platform.processor() == 'arm' else 'mac-x64'
+  dsymutil = buildroot_relative_path(
+      os.path.join('flutter', 'buildtools', arch_dir, 'clang', 'bin', 'dsymutil')
+  )
+  subprocess.check_call([dsymutil, '-o', dsym_out_path, binary_path])
+
+
+def lipo(input_binaries, output_binary):
+  """Uses lipo to create a fat binary from a set of input binaries."""
+  subprocess.check_call(['lipo'] + input_binaries + ['-create', '-output', output_binary])
+
+
+def log_error(message):
+  """Writes the message to stderr, followed by a newline."""
+  print(message, file=sys.stderr)
+
+
+def strip_binary(binary_path, unstripped_copy_path):
+  """Makes a copy of an unstripped binary, then strips symbols from the binary."""
+  assert_file(binary_path, 'binary to strip')
+  shutil.copyfile(binary_path, unstripped_copy_path)
+  subprocess.check_call(['strip', '-x', '-S', binary_path])
+
+
+def write_codesign_config(output_path, paths):
+  """Writes an Apple codesign configuration file containing the specified paths."""
+  with open(output_path, mode='w', encoding='utf-8') as file:
+    file.write('\n'.join(paths) + '\n')