jyapayne/glymur
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Refactored filetype box to use struct.unpack_from. #130

Browse source
This commit is contained in:
John Evans 2014-03-02 07:58:48 -05:00
commit c01079d677
1 changed files with 8 additions and 10 deletions
Download patch file Download diff file Expand all files Collapse all files

18
glymur/jp2box.py
View file

@ -994,7 +994,7 @@ class DataReferenceBox(Jp2kBox):
@staticmethod @staticmethod
def parse(fptr, offset, length): def parse(fptr, offset, length):
"""Parse Label box. """Parse data reference box.
Parameters Parameters
---------- ----------
@ -1124,19 +1124,17 @@ class FileTypeBox(Jp2kBox):
------- -------
FileTypeBox instance FileTypeBox instance
""" """
# Read the brand, minor version. read_buffer = fptr.read(length - 8)
read_buffer = fptr.read(8) # Extract the brand, minor version.
(brand, minor_version) = struct.unpack('>4sI', read_buffer) (brand, minor_version) = struct.unpack_from('>4sI', read_buffer, 0)
if sys.hexversion >= 0x030000: if sys.hexversion >= 0x030000:
brand = brand.decode('utf-8') brand = brand.decode('utf-8')
# Read the compatibility list. Each entry has 4 bytes. # Extract the compatibility list. Each entry has 4 bytes.
current_pos = fptr.tell() num_entries = int((length - 16)/ 4)
num_bytes = (offset + length - current_pos) / 4
read_buffer = fptr.read(int(num_bytes) * 4)
compatibility_list = [] compatibility_list = []
for j in range(int(num_bytes)): for j in range(int(num_entries)):
entry, = struct.unpack('>4s', read_buffer[4*j:4*(j+1)]) entry, = struct.unpack_from('>4s', read_buffer, 8 + j * 4)
if sys.hexversion >= 0x03000000: if sys.hexversion >= 0x03000000:
entry = entry.decode('utf-8') entry = entry.decode('utf-8')
compatibility_list.append(entry) compatibility_list.append(entry)