LiangKam
61e9f1312a
Parse the P6 header explicitly, keep every raster byte, and reject non-positive dimensions, maxval other than 255, and mismatched raster lengths. Add scripts/test-qemu-ppm.py.
62 lines
2.6 KiB
Python
Executable File
62 lines
2.6 KiB
Python
Executable File
#!/usr/bin/env python3
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"""Check that ppm_to_png keeps every raster byte and rejects malformed PPM files."""
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import importlib.util
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from pathlib import Path
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import struct
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import sys
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import tempfile
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import zlib
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source = Path(__file__).resolve().parents[1] / 'package' / 'Scripts' / 'qemu-run.py'
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spec = importlib.util.spec_from_file_location('qemu_run', source)
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module = importlib.util.module_from_spec(spec)
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spec.loader.exec_module(module)
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valid = [
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(b'P6\n1 1\n255\n', b'\x01\x02\x03', 1, 1),
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(b'P6\n2 1\n255\n', b'\x09\x0a\x0b\x0c\x0d\x20', 2, 1),
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(b'P6\n1 1\n255\n', b'#\x00\xff', 1, 1),
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(b'P6\n# size\n1 1\n255\n', b'abc', 1, 1),
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(b'P6 # magic\n1 1\n255\n', b'abc', 1, 1),
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(b'P6\n1 # width\n1\n255\n', b'abc', 1, 1),
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(b'P6\n1 2\n255\n', b'abcdef', 1, 2),
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]
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invalid = [b'', b'P3\n1 1\n255\nabc', b'P6\n0 1\n255\n',
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b'P6\n-1 1\n255\nabc', b'P6\n1 1\n65535\nabcdef',
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b'P6\n1 1\n255\nab', b'P6\n1 1\n255\nabcd']
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passed = rejected = 0
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with tempfile.TemporaryDirectory() as work:
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ppm, png = Path(work) / 'in.ppm', Path(work) / 'out.png'
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for index, (header, pixels, width, height) in enumerate(valid):
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ppm.write_bytes(header + pixels)
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try:
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module.ppm_to_png(ppm, png)
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data = png.read_bytes()
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assert data[:8] == b'\x89PNG\r\n\x1a\n'
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offset, compressed = 8, b''
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while offset < len(data):
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size = struct.unpack_from('>I', data, offset)[0]
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tag = data[offset + 4:offset + 8]
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body = data[offset + 8:offset + 8 + size]
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crc = struct.unpack_from('>I', data, offset + 8 + size)[0]
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assert crc == zlib.crc32(tag + body) & 0xffffffff
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if tag == b'IHDR':
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assert struct.unpack('>IIBBBBB', body) == (width, height, 8, 2, 0, 0, 0)
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if tag == b'IDAT':
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compressed += body
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offset += size + 12
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expected = b''.join(b'\0' + pixels[y*width*3:(y+1)*width*3] for y in range(height))
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assert zlib.decompress(compressed) == expected
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passed += 1
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except Exception as error:
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print('valid case', index + 1, 'FAIL', type(error).__name__)
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for index, data in enumerate(invalid):
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ppm.write_bytes(data)
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try:
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module.ppm_to_png(ppm, png)
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except ValueError:
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rejected += 1
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except Exception as error:
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print('invalid case', index + 1, 'wrong error', type(error).__name__)
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print(f'valid={passed}/{len(valid)} invalid_rejected={rejected}/{len(invalid)}')
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sys.exit(0 if passed == len(valid) and rejected == len(invalid) else 1)
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