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# Recognizing image files based on their first few bytes.
#-------------------------#
# Recognize sound headers #
#-------------------------#
def what(filename, h=None):
if h is None:
f = open(filename, 'r')
h = f.read(32)
else:
f = None
try:
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_rgb(h, f):
# SGI image library
if h[:2] == '\001\332':
return 'rgb'
tests.append(test_rgb)
def test_gif(h, f):
# GIF ('87 and '89 variants)
if h[:6] in ('GIF87a', 'GIF89a'):
return 'gif'
tests.append(test_gif)
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_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_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_jpeg(h, f):
# JPEG data in JFIF format
if h[6:10] == 'JFIF':
return 'jpeg'
tests.append(test_jpeg)
def test_bmp(h, f):
if h[:2] == 'BM':
return 'bmp'
tests.append(test_bmp)
def test_png(h, f):
if h[:8] == "\211PNG\r\n\032\n":
return 'png'
tests.append(test_png)
#--------------------#
# 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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