Determine file type (binary or text)

[Trent Mick]

[Sami Viitanen wrote]
> Hello,
> 
> How can I check if a file is binary or text?
> 
> There was some easy way but I forgot it..

Generally I define a text file as "it has no null bytes". I think this
is a pretty safe definition (I would be interested to hear practical
experience to the contrary). Assuming that, then:

    def is_binary(filename):
        """Return true iff the given filename is binary.

        Raises an EnvironmentError if the file does not exist or cannot be
        accessed.
        """
        fin = open(filename, 'rb')
        try:
            CHUNKSIZE = 1024
            while 1:
                chunk = fin.read(CHUNKSIZE)
                if '\0' in chunk: # found null byte
                    return 1
                if len(chunk) < CHUNKSIZE:
                    break # done
        finally:
            fin.close()

        return 0

Cheers,
Trent


-- 
Trent Mick
TrentM at ActiveState.com