Method read

Lib/_pyio.py:1676–1696

Read at most size bytes, returned as bytes. If size is less than 0, read all bytes in the file making multiple read calls. See ``FileIO.readall``. Attempts to make only one system call, retrying only per PEP 475 (EINTR). This means less data may be returned than

(self, size=None)

            raise UnsupportedOperation('File not open for writing')

    def read(self, size=None):
        """Read at most size bytes, returned as bytes.

        If size is less than 0, read all bytes in the file making
        multiple read calls. See ``FileIO.readall``.

        Attempts to make only one system call, retrying only per
        PEP 475 (EINTR). This means less data may be returned than
        requested.

        In non-blocking mode, returns None if no data is available.
        Return an empty bytes object at EOF.
        """
        self._checkClosed()
        self._checkReadable()
        if size is None or size < 0:
            return self.readall()
        try:
            return os.read(self._fd, size)
        except BlockingIOError:
            return None

    def readall(self):
        """Read all data from the file, returned as bytes.