sourcemap-extractor

#!/usr/bin/env python3
#    sourcemap-extractor: a simple script for extracting source code from js sourcemap files
#
#    Copyright (C) 2024 mini_bomba
#
#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation, either version 3 of the License, or
#    (at your option) any later version.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program.  If not, see <https://www.gnu.org/licenses/>.

import json
import base64
import sys
from pathlib import Path

IGNORED_PATH_PREFIXES = ["webpack://"]

# Read all available input from stdin
input_data = sys.stdin.read()

# Try to parse it as json
try:
    parsed_data = json.loads(input_data)
except json.JSONDecodeError:
    try:
        decoded_data = base64.b64decode(input_data)
        parsed_data = json.loads(decoded_data)
    except Exception:
        print("Failed to load input sourcemap", file=sys.stderr)
        raise

if 'sources' not in parsed_data or 'sourcesContent' not in parsed_data:
    print("Sources do not include source code", file=sys.stderr)
    exit(1)

cwd = Path.cwd()
for i, path in enumerate(parsed_data['sources']):
    for prefix in IGNORED_PATH_PREFIXES:
        if path.startswith(prefix):
            path = path[len(prefix):]
            break

    try:
        parsed_path = Path(path)
    except Exception:
        print(f"Failed to parse path: {path}, skipping", file=sys.stderr)
        continue

    while parsed_path.anchor != '':
        parsed_path = Path(*parsed_path.parts[:1])
    if parsed_path.suffix == '':
        parsed_path = parsed_path.with_suffix('.js')

    # write file
    full_path = cwd / parsed_path
    full_path.parent.mkdir(parents=True, exist_ok=True)
    with full_path.open('w') as f:
        f.write(parsed_data['sourcesContent'][i])

    print(f"File extracted: {path}", file=sys.stderr)