s3transfer/upload.py
def _read(self, fileobj, amount, truncate=True):
        """
        Reads a specific amount of data from a stream and returns it. If there
        is any data in initial_data, that will be popped out first.

        :type fileobj: A file-like object that implements read
        :param fileobj: The stream to read from.

        :type amount: int
        :param amount: The number of bytes to read from the stream.

        :type truncate: bool
        :param truncate: Whether or not to truncate initial_data after
            reading from it.

        :return: Generator which generates part bodies from the initial data.
        """
        # If the the initial data is empty, we simply read from the fileobj
        if len(self._initial_data) == 0:
            return fileobj.read(amount)

        # If the requested number of bytes is less than the amount of
        # initial data, pull entirely from initial data.
        if amount <= len(self._initial_data):
            data = self._initial_data[:amount]
            # Truncate initial data so we don't hang onto the data longer
            # than we need.
            if truncate:
                self._initial_data = self._initial_data[amount:]
            return data

        # At this point there is some initial data left, but not enough to
        # satisfy the number of bytes requested. Pull out the remaining
        # initial data and read the rest from the fileobj.
        amount_to_read = amount - len(self._initial_data)
        data = self._initial_data + fileobj.read(amount_to_read)

        # Zero out initial data so we don't hang onto the data any more.
        if truncate:
            self._initial_data = b''
        return data
def _read(self, fileobj, amount, truncate=True):
        """
        Reads a specific amount of data from a stream and returns it. If there
        is any data in initial_data, that will be popped out first.

        :type fileobj: A file-like object that implements read
        :param fileobj: The stream to read from.

        :type amount: int
        :param amount: The number of bytes to read from the stream.

        :type truncate: bool
        :param truncate: Whether or not to truncate initial_data after
            reading from it.

        :return: Generator which generates part bodies from the initial data.
        """
        # If the the initial data is empty, we simply read from the fileobj
        if len(self._initial_data) == 0:
            return fileobj.read(amount)

        # If the requested number of bytes is less than the amount of
        # initial data, pull entirely from initial data.
        if amount <= len(self._initial_data):
            data = self._initial_data[:amount]
            # Truncate initial data so we don't hang onto the data longer
            # than we need.
            if truncate:
                self._initial_data = self._initial_data[amount:]
            return data

        # At this point there is some initial data left, but not enough to
        # satisfy the number of bytes requested. Pull out the remaining
        # initial data and read the rest from the fileobj.
        amount_to_read = amount - len(self._initial_data)
        data = self._initial_data + fileobj.read(amount_to_read)

        # Zero out initial data so we don't hang onto the data any more.
        if truncate:
            self._initial_data = b''
        return data
Reads a specific amount of data from a stream and returns it. If there
        is any data in initial_data, that will be popped out first.

        :type fileobj: A file-like object that implements read
        :param fileobj: The stream to read from.

        :type amount: int
        :param amount: The number of bytes to read from the stream.

        :type truncate: bool
        :param truncate: Whether or not to truncate initial_data after
            reading from it.

        :return: Generator which generates part bodies from the initial data.