Windows absolute paths with drive letters incorrectly parsed as cloud provider schemes

[tuhlnaa]

Environment

• OS: Windows 10
• Hardware (GPU, or instance type): Local machine
  streaming library version: 0.13.0

To reproduce

Steps to reproduce the behavior:

1. On a Windows system, attempt to create an MDSWriter with an absolute Windows path:

from streaming import MDSWriter

columns = {
    'filename': 'str',
    'data': 'ndarray:float32'
}

# This fails on Windows with absolute paths
output_path = r"D:/test"

with MDSWriter(out=output_path, columns=columns) as writer:
    pass

2. Observe the error:

ValueError: Invalid Cloud provider prefix: d.

Expected behavior

MDSWriter should accept Windows absolute paths (e.g., D:\path\to\dir or D:/path/to/dir) as valid local filesystem paths, similar to how it handles Unix absolute paths (e.g., /path/to/dir).

Root Cause

The issue is in streaming/base/storage/upload.py in the CloudUploader.get() method:

obj = urllib.parse.urlparse(out) if isinstance(out, str) else urllib.parse.urlparse(out[1])
provider_prefix = obj.scheme

When urllib.parse.urlparse() is called on a Windows path like D:/path/to/dir, it incorrectly interprets the drive letter as a URL scheme:

>>> import urllib.parse
>>> urllib.parse.urlparse("D:/test")
ParseResult(scheme='d', netloc='', path='/test', params='', query='', fragment='')

The drive letter D: is parsed as scheme='d', which then fails the validation since 'd' is not in the UPLOADERS dictionary.

[XiaohanZhangCMU]

thanks for bringing this up @tuhlnaa. Currently streaming is in KTLO mode since we don't have resource to add new features. But we welcome contributions from open source community for adding useful features like this.