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"""A very strange "hash" that uses the magic module (python3-magic) to guess
the file type."""
import magic
# It changed API a few times...
try:
_magic_identify = magic.from_buffer
except AttributeError:
_magic_identify = magic.none_magic.buffer
class FileDigester:
"""A hashlib-like class to guess a filetype using the magic module."""
FILE_BYTES_MAX = 1024 * 1024 # copied from file source
def __init__(self):
self.buff = b""
self.identification = None
def _compute_identification(self):
try:
return _magic_identify(self.buff)
except UnicodeDecodeError:
return "magic identification is not valid UTF-8"
def update(self, buff):
if self.identification:
return
self.buff += buff
if len(self.buff) >= self.FILE_BYTES_MAX:
self.identification = self._compute_identification()
self.buff = None
def identify(self):
"""Return the guessed file magic identification."""
if self.identification:
return self.identification
return self._compute_identification()
def hexdigest(self):
"""Compatibility with hashlib. An alias of identify. Doesn't return
hex."""
return self.identify()
def copy(self):
new = FileDigester()
new.buff = self.buff
new.identification = self.identification
return new
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