gdal /vsimem/ file writer. This is compatible with boto s3.Object#put(Body=SimpleVSIMemFile('/vsimem/foo.tif')

SimpleVSIMEMFile.py

class SimpleVSIMemFileError(Exception):
    """Unknown SimpleVSIMemFile error with VSI subsystem."""

class SimpleVSIMEMFile(object):
    def __init__(self, path):
        """Simple file-like object for reading out of a VSIMEM dataset.
        Params:
            path: /vsimem path to use
        """
        self._path = path
        self._size = gdal.VSIStatL(self._path).size
        self._check_error()
        self._pos = 0

    def __len__(self):
        """Length of the file."""
        return self._size

    def read(self, size=-1):
        """Read size bytes from the file.
        Params:
            size: Number of bytes to read.
        """

        length = len(self)
        if self._pos >= length:
            # No more data to read
            return b""

        if size == -1:
            # Set size to remainder of file
            size = length - self._pos
        else:
            # Limit size to remainder of file
            size = min(size, length - self._pos)

        # Open file
        vsif = gdal.VSIFOpenL(self._path, "r")
        self._check_error()
        try:
            # Seek to current position, read data, and update position
            gdal.VSIFSeekL(vsif, self._pos, 0)
            self._check_error()
            buf = gdal.VSIFReadL(1, size, vsif)
            self._check_error()
            self._pos += len(buf)

        finally:
            # Close file
            gdal.VSIFCloseL(vsif)
            self._check_error()

        return buf

    def seek(self, offset, whence=0):
        """Seek to position in file."""
        if whence == 0:
            # Seek from start of file
            self._pos = min(offset, len(self))
        elif whence == 1:
            # Seek from current position
            self._pos = min(max(0, self._pos + offset), len(self))
        elif whence == 2:
            # Seek from end of file
            self._pos = max(0, len(self) - offset)
        return self._pos

    def tell(self):
        """Tell current position in file."""
        return self._pos

    def _check_error(self):
        if gdal.VSIGetLastErrorNo() != 0:
            raise SimpleVSIMemFileError(gdal.VSIGetLastErrorMsg())