Created
August 26, 2024 09:27
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Quick and dirty parse PDF file and extract objects/images
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| import re | |
| import zlib | |
| import argparse | |
| from PIL import Image | |
| def parse_args(): | |
| parser = argparse.ArgumentParser(description='Decompress data using zlib') | |
| parser.add_argument('pdf_file', help='The PDF file to analyze') | |
| return parser.parse_args() | |
| def get_objects(pdf_data): | |
| """Get objects offset from the beginning of the file""" | |
| rx = rb'(\d+) (\d+) obj\b' | |
| objects = [] | |
| for match in re.finditer(rx, pdf_data): | |
| obj_idx = match.start() | |
| endobj_idx = pdf_data[obj_idx:].find(b'endobj') + obj_idx +7 | |
| obj_data = pdf_data[obj_idx:endobj_idx] | |
| definition, arguments, *others = obj_data.splitlines() | |
| if not others: | |
| print('No data', definition, arguments) | |
| continue | |
| if others[0] == b'endobj': | |
| objects.append((definition, arguments, b'')) | |
| elif others[0] == b'stream': | |
| stream_idx = obj_data.find(b'\nstream\n') +8 | |
| endstream_idx = obj_data.find(b'\nendstream\n') | |
| objects.append((definition, arguments, obj_data[stream_idx:endstream_idx])) | |
| else: | |
| raise ValueError('Unknown object type') | |
| return objects | |
| def parse_pdf(pdf_data): | |
| objects = get_objects(pdf_data) | |
| for definition, arguments, stream in objects: | |
| # Check if the stream is compressed | |
| if not stream: | |
| pass | |
| elif b'/FlateDecode' in arguments: | |
| stream = zlib.decompress(stream) | |
| elif b'/LZWDecode' in arguments: | |
| stream = zlib.decompress(stream, -15) | |
| else: | |
| print('Unknown compression method') | |
| # Check if the stream is an image | |
| if b'/Image' in arguments: | |
| s_arguments = arguments.decode() | |
| filename = re.sub(r'\W', '_', definition) + '.bmp' | |
| width = int(re.search(r'/Width (\d+)', s_arguments).group(1)) | |
| height = int(re.search(r'/Height (\d+)', s_arguments).group(1)) | |
| bits_per_component = int(re.search(r'/BitsPerComponent (\d+)', s_arguments).group(1)) | |
| color_space = re.search(r'/ColorSpace/(\w+)', s_arguments).group(1).replace('Device', '') | |
| image = Image.frombytes(color_space, (width, height), stream) | |
| image.save(filename) | |
| print('Image saved as', filename) | |
| print(definition, arguments, stream[:50]) | |
| def main(): | |
| args = parse_args() | |
| with open(args.pdf_file, 'rb') as f: | |
| pdf_data = f.read() | |
| assert pdf_data[:4] == b'%PDF', 'Not a PDF file' | |
| parse_pdf(pdf_data) | |
| if __name__ == '__main__': | |
| main() |
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