Python mmap 模块，ACCESS_COPY 实例源码

def __init__(self, filename):
        self._filename = filename

        self._f = open(filename, "rb")

        # memory-map the file, size 0 means whole file
        self._mapped = mmap.mmap(self._f.fileno(), 0, access=mmap.ACCESS_COPY)

        super(MappedFileDataModel, self).__init__(self._mapped)

def _verify_bmap_checksum(self):
        """
        This is a helper function which verifies the bmap file checksum.
        """

        import mmap

        correct_chksum = self._xml.find(self._bmap_cs_attrib_name).text.strip()

        # Before verifying the shecksum, we have to substitute the checksum
        # value stored in the file with all zeroes. For these purposes we
        # create private memory mapping of the bmap file.
        mapped_bmap = mmap.mmap(self._f_bmap.fileno(), 0,
                                access=mmap.ACCESS_COPY)

        chksum_pos = mapped_bmap.find(correct_chksum.encode())
        assert chksum_pos != -1

        mapped_bmap[chksum_pos:chksum_pos + self._cs_len] = b'0' * self._cs_len

        hash_obj = hashlib.new(self._cs_type)
        hash_obj.update(mapped_bmap)
        calculated_chksum = hash_obj.hexdigest()

        mapped_bmap.close()

        if calculated_chksum != correct_chksum:
            raise Error("checksum mismatch for bmap file '%s': calculated "
                        "'%s', should be '%s'"
                        % (self._bmap_path, calculated_chksum, correct_chksum))

def _verify_bmap_checksum(self):
        """ This is a helper function which verifies SHA1 checksum of the bmap
        file. """

        import mmap

        correct_sha1 = self._xml.find("BmapFileSHA1").text.strip()

        # Before verifying the shecksum, we have to substitute the SHA1 value
        # stored in the file with all zeroes. For these purposes we create
        # private memory mapping of the bmap file.
        mapped_bmap = mmap.mmap(self._f_bmap.fileno(), 0,
                                access = mmap.ACCESS_COPY)

        sha1_pos = mapped_bmap.find(correct_sha1)
        assert sha1_pos != -1

        mapped_bmap[sha1_pos:sha1_pos + 40] = '0' * 40
        calculated_sha1 = hashlib.sha1(mapped_bmap).hexdigest()

        mapped_bmap.close()

        if calculated_sha1 != correct_sha1:
            raise Error("checksum mismatch for bmap file '%s': calculated " \
                        "'%s', should be '%s'" % \
                        (self._bmap_path, calculated_sha1, correct_sha1))

def _verify_bmap_checksum(self):
        """
        This is a helper function which verifies the bmap file checksum.
        """

        import mmap

        if self.bmap_version_minor == 3:
            correct_chksum = self._xml.find("BmapFileSHA1").text.strip()
        else:
            correct_chksum = self._xml.find("BmapFileChecksum").text.strip()

        # Before verifying the shecksum, we have to substitute the checksum
        # value stored in the file with all zeroes. For these purposes we
        # create private memory mapping of the bmap file.
        mapped_bmap = mmap.mmap(self._f_bmap.fileno(), 0,
                                access = mmap.ACCESS_COPY)

        chksum_pos = mapped_bmap.find(correct_chksum)
        assert chksum_pos != -1

        mapped_bmap[chksum_pos:chksum_pos + self._cs_len] = '0' * self._cs_len

        hash_obj = hashlib.new(self._cs_type)
        hash_obj.update(mapped_bmap)
        calculated_chksum = hash_obj.hexdigest()

        mapped_bmap.close()

        if calculated_chksum != correct_chksum:
            raise Error("checksum mismatch for bmap file '%s': calculated "
                        "'%s', should be '%s'"
                        % (self._bmap_path, calculated_chksum, correct_chksum))

def _verify_bmap_checksum(self):
        """
        This is a helper function which verifies SHA1 checksum of the bmap file.
        """

        import mmap

        correct_sha1 = self._xml.find("BmapFileSHA1").text.strip()

        # Before verifying the shecksum, we have to substitute the SHA1 value
        # stored in the file with all zeroes. For these purposes we create
        # private memory mapping of the bmap file.
        mapped_bmap = mmap.mmap(self._f_bmap.fileno(), 0,
                                access = mmap.ACCESS_COPY)

        sha1_pos = mapped_bmap.find(correct_sha1)
        assert sha1_pos != -1

        mapped_bmap[sha1_pos:sha1_pos + 40] = '0' * 40
        calculated_sha1 = hashlib.sha1(mapped_bmap).hexdigest()

        mapped_bmap.close()

        if calculated_sha1 != correct_sha1:
            raise Error("checksum mismatch for bmap file '%s': calculated "
                        "'%s', should be '%s'"
                        % (self._bmap_path, calculated_sha1, correct_sha1))

def _verify_bmap_checksum(self):
        """ This is a helper function which verifies SHA1 checksum of the bmap
        file. """

        import mmap

        correct_sha1 = self._xml.find("BmapFileSHA1").text.strip()

        # Before verifying the shecksum, we have to substitute the SHA1 value
        # stored in the file with all zeroes. For these purposes we create
        # private memory mapping of the bmap file.
        mapped_bmap = mmap.mmap(self._f_bmap.fileno(), 0,
                                access = mmap.ACCESS_COPY)

        sha1_pos = mapped_bmap.find(correct_sha1)
        assert sha1_pos != -1

        mapped_bmap[sha1_pos:sha1_pos + 40] = '0' * 40
        calculated_sha1 = hashlib.sha1(mapped_bmap).hexdigest()

        mapped_bmap.close()

        if calculated_sha1 != correct_sha1:
            raise Error("checksum mismatch for bmap file '%s': calculated " \
                        "'%s', should be '%s'" % \
                        (self._bmap_path, calculated_sha1, correct_sha1))