Add gclient parser. (flutter/engine#32135)

* Add gclient parser.

* pin python-installation version.

* Update documentation.

* Add license header.

engine/src/flutter/.github/workflows/scorecards-analysis.yml

@@ -4,6 +4,9 @@ on:
   branch_protection_rule:
   push:
     branches: [ main ]
+  pull_request:
+    branches:
+      - main
 
 # Declare default permissions as read only.
 permissions: read-all
@@ -21,12 +24,20 @@ jobs:
 
     steps:
       - name: "Checkout code"
-        uses: actions/checkout@ec3a7ce113134d7a93b817d10a8272cb61118579 # v2.4.0
+        uses: actions/checkout@ec3a7ce113134d7a93b817d10a8272cb61118579
         with:
           persist-credentials: false
 
+      - name: setup python
+        uses: actions/setup-python@0ebf233433c08fb9061af664d501c3f3ff0e9e20
+        with:
+          python-version: '3.7.7' # install the python version needed
+
+      - name: execute py script
+        run: python ci/deps_parser.py
+
       - name: "Run analysis"
-        uses: ossf/scorecard-action@c8416b0b2bf627c349ca92fc8e3de51a64b005cf # v1.0.2
+        uses: ossf/scorecard-action@c8416b0b2bf627c349ca92fc8e3de51a64b005cf
         with:
           results_file: results.sarif
           results_format: sarif
@@ -41,7 +52,7 @@ jobs:
 
       # Upload the results as artifacts (optional).
       - name: "Upload artifact"
-        uses: actions/upload-artifact@82c141cc518b40d92cc801eee768e7aafc9c2fa2 # v2.3.1
+        uses: actions/upload-artifact@82c141cc518b40d92cc801eee768e7aafc9c2fa2
         with:
           name: SARIF file
           path: results.sarif
@@ -49,6 +60,6 @@ jobs:
 
       # Upload the results to GitHub's code scanning dashboard.
       - name: "Upload to code-scanning"
-        uses: github/codeql-action/upload-sarif@5f532563584d71fdef14ee64d17bafb34f751ce5 # v1.0.26
+        uses: github/codeql-action/upload-sarif@5f532563584d71fdef14ee64d17bafb34f751ce5
         with:
           sarif_file: results.sarif

engine/src/flutter/ci/deps_parser.py

@@ -0,0 +1,102 @@
+#!/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.
+
+# Usage: deps_parser.py --deps <DEPS file> --output <flattened deps>
+#
+# This script parses the DEPS file, extracts the fully qualified dependencies
+# and writes the to a file. This file will be later used to validate the dependencies
+# are pinned to a hash.
+
+import argparse
+import os
+import sys
+
+SCRIPT_DIR = os.path.dirname(sys.argv[0])
+CHECKOUT_ROOT = os.path.realpath(os.path.join(SCRIPT_DIR, '..'))
+
+
+# Used in parsing the DEPS file.
+class VarImpl(object):
+    _env_vars = {
+        "host_cpu": "x64",
+        "host_os": "linux",
+    }
+
+    def __init__(self, local_scope):
+        self._local_scope = local_scope
+
+    def Lookup(self, var_name):
+        """Implements the Var syntax."""
+        if var_name in self._local_scope.get("vars", {}):
+            return self._local_scope["vars"][var_name]
+        # Inject default values for env variables
+        if var_name in self._env_vars:
+            return self._env_vars[var_name]
+        raise Exception("Var is not defined: %s" % var_name)
+
+
+def ParseDepsFile(deps_file):
+    local_scope = {}
+    var = VarImpl(local_scope)
+    global_scope = {
+        'Var': var.Lookup,
+        'deps_os': {},
+    }
+    # Read the content.
+    with open(deps_file, 'r') as fp:
+        deps_content = fp.read()
+
+    # Eval the content.
+    exec (deps_content, global_scope, local_scope)
+
+    # Extract the deps and filter.
+    deps = local_scope.get('deps', {})
+    filtered_deps = []
+    for k, v in deps.items():
+        # We currently do not support packages or cipd which are represented
+        # as dictionaries.
+        if isinstance(v, str):
+            filtered_deps.append(v)
+
+    return filtered_deps
+
+
+def WriteManifest(deps, manifest_file):
+    print('\n'.join(sorted(deps)))
+    with open(manifest_file, 'w') as manifest:
+        manifest.write('\n'.join(sorted(deps)))
+
+
+def ParseArgs(args):
+    args = args[1:]
+    parser = argparse.ArgumentParser(
+        description='A script to flatten a gclient DEPS file.')
+
+    parser.add_argument(
+        '--deps',
+        '-d',
+        type=str,
+        help='Input DEPS file.',
+        default=os.path.join(CHECKOUT_ROOT, 'DEPS'))
+    parser.add_argument(
+        '--output',
+        '-o',
+        type=str,
+        help='Output flattened deps file.',
+        default=os.path.join(CHECKOUT_ROOT, 'deps_flatten.txt'))
+
+    return parser.parse_args(args)
+
+
+def Main(argv):
+    args = ParseArgs(argv)
+    deps = ParseDepsFile(args.deps)
+    WriteManifest(deps, args.output)
+    return 0
+
+
+if __name__ == '__main__':
+    sys.exit(Main(sys.argv))