/usr/lib/python2.7/imghdr.py is in libpython2.7-stdlib 2.7.15~rc1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 | """Recognize image file formats based on their first few bytes."""
__all__ = ["what"]
#-------------------------#
# Recognize image headers #
#-------------------------#
def what(file, h=None):
f = None
try:
if h is None:
if isinstance(file, basestring):
f = open(file, 'rb')
h = f.read(32)
else:
location = file.tell()
h = file.read(32)
file.seek(location)
for tf in tests:
res = tf(h, f)
if res:
return res
finally:
if f: f.close()
return None
#---------------------------------#
# Subroutines per image file type #
#---------------------------------#
tests = []
def test_jpeg(h, f):
"""JPEG data in JFIF format"""
if h[6:10] == 'JFIF':
return 'jpeg'
tests.append(test_jpeg)
def test_exif(h, f):
"""JPEG data in Exif format"""
if h[6:10] == 'Exif':
return 'jpeg'
tests.append(test_exif)
def test_png(h, f):
if h[:8] == "\211PNG\r\n\032\n":
return 'png'
tests.append(test_png)
def test_gif(h, f):
"""GIF ('87 and '89 variants)"""
if h[:6] in ('GIF87a', 'GIF89a'):
return 'gif'
tests.append(test_gif)
def test_tiff(h, f):
"""TIFF (can be in Motorola or Intel byte order)"""
if h[:2] in ('MM', 'II'):
return 'tiff'
tests.append(test_tiff)
def test_rgb(h, f):
"""SGI image library"""
if h[:2] == '\001\332':
return 'rgb'
tests.append(test_rgb)
def test_pbm(h, f):
"""PBM (portable bitmap)"""
if len(h) >= 3 and \
h[0] == 'P' and h[1] in '14' and h[2] in ' \t\n\r':
return 'pbm'
tests.append(test_pbm)
def test_pgm(h, f):
"""PGM (portable graymap)"""
if len(h) >= 3 and \
h[0] == 'P' and h[1] in '25' and h[2] in ' \t\n\r':
return 'pgm'
tests.append(test_pgm)
def test_ppm(h, f):
"""PPM (portable pixmap)"""
if len(h) >= 3 and \
h[0] == 'P' and h[1] in '36' and h[2] in ' \t\n\r':
return 'ppm'
tests.append(test_ppm)
def test_rast(h, f):
"""Sun raster file"""
if h[:4] == '\x59\xA6\x6A\x95':
return 'rast'
tests.append(test_rast)
def test_xbm(h, f):
"""X bitmap (X10 or X11)"""
s = '#define '
if h[:len(s)] == s:
return 'xbm'
tests.append(test_xbm)
def test_bmp(h, f):
if h[:2] == 'BM':
return 'bmp'
tests.append(test_bmp)
#--------------------#
# Small test program #
#--------------------#
def test():
import sys
recursive = 0
if sys.argv[1:] and sys.argv[1] == '-r':
del sys.argv[1:2]
recursive = 1
try:
if sys.argv[1:]:
testall(sys.argv[1:], recursive, 1)
else:
testall(['.'], recursive, 1)
except KeyboardInterrupt:
sys.stderr.write('\n[Interrupted]\n')
sys.exit(1)
def testall(list, recursive, toplevel):
import sys
import os
for filename in list:
if os.path.isdir(filename):
print filename + '/:',
if recursive or toplevel:
print 'recursing down:'
import glob
names = glob.glob(os.path.join(filename, '*'))
testall(names, recursive, 0)
else:
print '*** directory (use -r) ***'
else:
print filename + ':',
sys.stdout.flush()
try:
print what(filename)
except IOError:
print '*** not found ***'
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