HEIC parser reaches EOF inside get32() call

[Guymer]

The attached HEIC image was taken with an iPhone XR and when I try to extract the metadata using exifread.process_file(fobj, details = False) then I get the following Traceback:

Traceback (most recent call last):
  File "create_photo_album_JSON.py", line 83, in <module>
    tags = exifread.process_file(fobj, details = False)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/exifread/__init__.py", line 242, in process_file
    offset, endian = heic.find_exif()
  File "/opt/local/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/exifread/heic.py", line 229, in find_exif
    meta = self.expect_parse('meta')
  File "/opt/local/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/exifread/heic.py", line 122, in expect_parse
    return self.parse_box(box)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/exifread/heic.py", line 133, in parse_box
    probe(box)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/exifread/heic.py", line 155, in parse_meta
    psub(box)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/exifread/heic.py", line 221, in parse_iloc
    extent_length = self.get_int(box.length_size)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/exifread/heic.py", line 74, in get_int
    return self.get32()
  File "/opt/local/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/exifread/heic.py", line 58, in get32
    return struct.unpack('>L', self.get(4))[0]
struct.error: unpack requires a buffer of 4 bytes

The script was run on MacOS Big Sur 11.1 using Python 3.8.6 and ExifRead 2.3.1 from MacPorts.

[nickdimitroff]

Not sure what's going on, but I hit a different error with this file. It didn't like this hdlr thing.

DEBUG HEIC: skipping <box 'hdlr'>

Was able to get past the error with this inside of get_parser in heic.py.

        except (IndexError, KeyError) as err:
            #raise NoParser(box.name) from err
            self.skip(box)

and get exif data out

...
INFO EXIF LensMake (ASCII): Apple
INFO EXIF LensModel (ASCII): iPhone XR back camera 4.25mm f/1.8
INFO EXIF LensSpecification (Ratio): [17/4, 17/4, 9/5, 9/5]
INFO EXIF MakerNote (Undefined): [65, 112, 112, 108, 101, 32, 105, 79, 83, 0, 0, 1, 77, 77, 0, 25, 0, 1, 0, 9, ... ]
INFO EXIF MeteringMode (Short): Pattern
INFO EXIF OffsetTime (ASCII): Z
...

May be a fix to #160