Updating to new OTS repo from https://github.com/khaledhosny/ots.git

third_party/ots/tools/ttf-checksum.py

+import struct
+import sys
+
+def readU32(contents, offset):
+  wordBytes = contents[offset:offset + 4]
+  return struct.unpack('>I', wordBytes)[0]
+
+def readU16(contents, offset):
+  wordBytes = contents[offset:offset + 2]
+  return struct.unpack('>H', wordBytes)[0]
+
+def checkChecksum(infile):
+  contents = infile.read()
+  if len(contents) % 4:
+    print 'File length is not a multiple of 4'
+
+  sum = 0
+  for offset in range(0, len(contents), 4):
+    sum += readU32(contents, offset)
+    while sum >= 2**32:
+      sum -= 2**32
+  print 'Sum of whole file: %x' % sum
+
+  numTables = readU16(contents, 4)
+
+  for offset in range(12, 12 + numTables * 16, 16):
+    tag = contents[offset:offset + 4]
+    chksum = readU32(contents, offset + 4)
+    toffset = readU32(contents, offset + 8)
+    tlength = readU32(contents, offset + 12)
+
+    sum = 0
+    for offset2 in range(toffset, toffset + tlength, 4):
+      sum += readU32(contents, offset2)
+      while sum >= 2**32:
+        sum -= 2**32
+    if sum != chksum:
+      print 'Bad chksum: %s' % tag
+
+if __name__ == '__main__':
+  if len(sys.argv) != 2:
+    print 'Usage: %s <ttf filename>' % sys.argv[0]
+  else:
+    checkChecksum(file(sys.argv[1], 'r'))