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168 lines
3.7 KiB
Python
168 lines
3.7 KiB
Python
"""Recognize image file formats based on their first few bytes."""
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from os import PathLike
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__all__ = ["what"]
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#-------------------------#
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# Recognize image headers #
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#-------------------------#
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def what(file, h=None):
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f = None
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try:
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if h is None:
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if isinstance(file, (str, PathLike)):
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f = open(file, 'rb')
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h = f.read(32)
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else:
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location = file.tell()
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h = file.read(32)
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file.seek(location)
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for tf in tests:
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res = tf(h, f)
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if res:
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return res
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finally:
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if f: f.close()
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return None
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#---------------------------------#
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# Subroutines per image file type #
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#---------------------------------#
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tests = []
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def test_jpeg(h, f):
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"""JPEG data in JFIF or Exif format"""
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if h[6:10] in (b'JFIF', b'Exif'):
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return 'jpeg'
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tests.append(test_jpeg)
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def test_png(h, f):
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if h.startswith(b'\211PNG\r\n\032\n'):
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return 'png'
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tests.append(test_png)
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def test_gif(h, f):
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"""GIF ('87 and '89 variants)"""
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if h[:6] in (b'GIF87a', b'GIF89a'):
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return 'gif'
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tests.append(test_gif)
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def test_tiff(h, f):
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"""TIFF (can be in Motorola or Intel byte order)"""
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if h[:2] in (b'MM', b'II'):
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return 'tiff'
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tests.append(test_tiff)
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def test_rgb(h, f):
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"""SGI image library"""
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if h.startswith(b'\001\332'):
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return 'rgb'
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tests.append(test_rgb)
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def test_pbm(h, f):
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"""PBM (portable bitmap)"""
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if len(h) >= 3 and \
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h[0] == ord(b'P') and h[1] in b'14' and h[2] in b' \t\n\r':
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return 'pbm'
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tests.append(test_pbm)
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def test_pgm(h, f):
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"""PGM (portable graymap)"""
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if len(h) >= 3 and \
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h[0] == ord(b'P') and h[1] in b'25' and h[2] in b' \t\n\r':
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return 'pgm'
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tests.append(test_pgm)
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def test_ppm(h, f):
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"""PPM (portable pixmap)"""
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if len(h) >= 3 and \
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h[0] == ord(b'P') and h[1] in b'36' and h[2] in b' \t\n\r':
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return 'ppm'
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tests.append(test_ppm)
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def test_rast(h, f):
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"""Sun raster file"""
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if h.startswith(b'\x59\xA6\x6A\x95'):
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return 'rast'
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tests.append(test_rast)
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def test_xbm(h, f):
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"""X bitmap (X10 or X11)"""
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if h.startswith(b'#define '):
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return 'xbm'
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tests.append(test_xbm)
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def test_bmp(h, f):
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if h.startswith(b'BM'):
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return 'bmp'
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tests.append(test_bmp)
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def test_webp(h, f):
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if h.startswith(b'RIFF') and h[8:12] == b'WEBP':
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return 'webp'
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tests.append(test_webp)
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def test_exr(h, f):
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if h.startswith(b'\x76\x2f\x31\x01'):
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return 'exr'
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tests.append(test_exr)
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#--------------------#
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# Small test program #
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#--------------------#
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def test():
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import sys
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recursive = 0
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if sys.argv[1:] and sys.argv[1] == '-r':
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del sys.argv[1:2]
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recursive = 1
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try:
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if sys.argv[1:]:
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testall(sys.argv[1:], recursive, 1)
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else:
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testall(['.'], recursive, 1)
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except KeyboardInterrupt:
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sys.stderr.write('\n[Interrupted]\n')
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sys.exit(1)
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def testall(list, recursive, toplevel):
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import sys
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import os
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for filename in list:
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if os.path.isdir(filename):
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print(filename + '/:', end=' ')
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if recursive or toplevel:
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print('recursing down:')
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import glob
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names = glob.glob(os.path.join(filename, '*'))
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testall(names, recursive, 0)
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else:
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print('*** directory (use -r) ***')
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else:
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print(filename + ':', end=' ')
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sys.stdout.flush()
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try:
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print(what(filename))
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except OSError:
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print('*** not found ***')
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if __name__ == '__main__':
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test()
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