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1"""Recognize image file formats based on their first few bytes."""2 3from os import PathLike4 5__all__ = ["what"]6 7#-------------------------#8# Recognize image headers #9#-------------------------#10 11def what(file, h=None):12    f = None13    try:14        if h is None:15            if isinstance(file, (str, PathLike)):16                f = open(file, 'rb')17                h = f.read(32)18            else:19                location = file.tell()20                h = file.read(32)21                file.seek(location)22        for tf in tests:23            res = tf(h, f)24            if res:25                return res26    finally:27        if f: f.close()28    return None29 30 31#---------------------------------#32# Subroutines per image file type #33#---------------------------------#34 35tests = []36 37def test_jpeg(h, f):38    """JPEG data in JFIF or Exif format"""39    if h[6:10] in (b'JFIF', b'Exif'):40        return 'jpeg'41 42tests.append(test_jpeg)43 44def test_png(h, f):45    if h.startswith(b'\211PNG\r\n\032\n'):46        return 'png'47 48tests.append(test_png)49 50def test_gif(h, f):51    """GIF ('87 and '89 variants)"""52    if h[:6] in (b'GIF87a', b'GIF89a'):53        return 'gif'54 55tests.append(test_gif)56 57def test_tiff(h, f):58    """TIFF (can be in Motorola or Intel byte order)"""59    if h[:2] in (b'MM', b'II'):60        return 'tiff'61 62tests.append(test_tiff)63 64def test_rgb(h, f):65    """SGI image library"""66    if h.startswith(b'\001\332'):67        return 'rgb'68 69tests.append(test_rgb)70 71def test_pbm(h, f):72    """PBM (portable bitmap)"""73    if len(h) >= 3 and \74        h[0] == ord(b'P') and h[1] in b'14' and h[2] in b' \t\n\r':75        return 'pbm'76 77tests.append(test_pbm)78 79def test_pgm(h, f):80    """PGM (portable graymap)"""81    if len(h) >= 3 and \82        h[0] == ord(b'P') and h[1] in b'25' and h[2] in b' \t\n\r':83        return 'pgm'84 85tests.append(test_pgm)86 87def test_ppm(h, f):88    """PPM (portable pixmap)"""89    if len(h) >= 3 and \90        h[0] == ord(b'P') and h[1] in b'36' and h[2] in b' \t\n\r':91        return 'ppm'92 93tests.append(test_ppm)94 95def test_rast(h, f):96    """Sun raster file"""97    if h.startswith(b'\x59\xA6\x6A\x95'):98        return 'rast'99 100tests.append(test_rast)101 102def test_xbm(h, f):103    """X bitmap (X10 or X11)"""104    if h.startswith(b'#define '):105        return 'xbm'106 107tests.append(test_xbm)108 109def test_bmp(h, f):110    if h.startswith(b'BM'):111        return 'bmp'112 113tests.append(test_bmp)114 115def test_webp(h, f):116    if h.startswith(b'RIFF') and h[8:12] == b'WEBP':117        return 'webp'118 119tests.append(test_webp)120 121def test_exr(h, f):122    if h.startswith(b'\x76\x2f\x31\x01'):123        return 'exr'124 125tests.append(test_exr)126 127#--------------------#128# Small test program #129#--------------------#130 131def test():132    import sys133    recursive = 0134    if sys.argv[1:] and sys.argv[1] == '-r':135        del sys.argv[1:2]136        recursive = 1137    try:138        if sys.argv[1:]:139            testall(sys.argv[1:], recursive, 1)140        else:141            testall(['.'], recursive, 1)142    except KeyboardInterrupt:143        sys.stderr.write('\n[Interrupted]\n')144        sys.exit(1)145 146def testall(list, recursive, toplevel):147    import sys148    import os149    for filename in list:150        if os.path.isdir(filename):151            print(filename + '/:', end=' ')152            if recursive or toplevel:153                print('recursing down:')154                import glob155                names = glob.glob(os.path.join(glob.escape(filename), '*'))156                testall(names, recursive, 0)157            else:158                print('*** directory (use -r) ***')159        else:160            print(filename + ':', end=' ')161            sys.stdout.flush()162            try:163                print(what(filename))164            except OSError:165                print('*** not found ***')166 167if __name__ == '__main__':168    test()169