bazel_rules_fuchsia_experimental/tools/package_manifest_creator.py

# Copyright 2021 The Fuchsia Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
"""Generate a package_manifest.json file based on meta.far and blob directory."""

import argparse
import json
import os
import subprocess
import sys

CONTENTS_FILE_RELATIVE_PATH = 'meta/contents'
PACKAGE_FILE_RELATIVE_PATH = 'meta/package'


def read_file_from_meta_far(far_tool, meta_far_path, file):
    """Invokes the far tool to extract the meta_far."""
    args = [far_tool, 'cat', '--archive=' + meta_far_path, '--file=' + file]
    return subprocess.run(
        args, check=True, capture_output=True, text=True).stdout


def parse_args():
    """Parses arguments."""
    parser = argparse.ArgumentParser()
    parser.add_argument('--far-tool', help='Path to far tool', required=True)
    parser.add_argument(
        '--meta-far-file', help='Path to meta.far file', required=True)
    parser.add_argument(
        '--blob-manifest', help='Path to blob manifest file', required=True)
    parser.add_argument(
        '--output-file', help='Path to output manifest file', required=True)
    return parser.parse_args()


def generate_manifest(source_map, args):
    package_manifest = {'version': '1'}
    meta_package = read_file_from_meta_far(args.far_tool, args.meta_far_file,
                                           PACKAGE_FILE_RELATIVE_PATH)
    package = json.loads(meta_package)
    package_manifest['package'] = package
    blobs = []
    meta_content = read_file_from_meta_far(args.far_tool, args.meta_far_file,
                                           CONTENTS_FILE_RELATIVE_PATH)

    # Include the meta.far file at the 'meta/' path
    meta_far_merkle = None
    for k in source_map:
        if source_map[k] == args.meta_far_file:
            meta_far_merkle = k
    if not meta_far_merkle:
        raise ValueError('meta far merkle not found in blob manifest')
    blobs.append({
        'source_path': args.meta_far_file,
        'path': 'meta/',
        'merkle': meta_far_merkle,
        'size': os.path.getsize(args.meta_far_file),
    })

    # Add the rest of the blobs to the manifest.
    for content in meta_content.split('\n'):
        content = content.strip()
        if not len(content):
            continue
        blob_entry = content.split('=')
        blob_path = blob_entry[0]
        merkle = blob_entry[1]
        if merkle not in source_map:
            raise ValueError(
                'No matching merkle in blob manifest file,'
                ' blob_path = {}, merkle = {}', blob_path, merkle)
        source_path = source_map[merkle]
        size = os.path.getsize(source_path)
        blob_map = {
            'source_path': source_path,
            'path': blob_path,
            'merkle': merkle,
            'size': size,
        }
        blobs.append(blob_map)

    package_manifest['blobs'] = blobs
    with open(args.output_file, 'w') as manifest_file:
        json.dump(package_manifest, manifest_file, indent=4)


def generate_source_map(blob_manifest):
    source_map = {}
    with open(blob_manifest, 'r') as blob_manifest:
        for content in blob_manifest.readlines():
            blob_entry = content.strip().split('=')
            merkle = blob_entry[0]
            source_path = blob_entry[1]
            source_map[merkle] = source_path
    return source_map


def main():
    """Main for the package_manifest generation tool."""
    args = parse_args()
    outdir = os.path.dirname(args.output_file)
    os.makedirs(outdir, exist_ok=True)
    source_map = generate_source_map(args.blob_manifest)
    generate_manifest(source_map, args)


if __name__ == '__main__':
    sys.exit(main())