Makes checking fstat for file optional.

[dhermes]

In storage, file upload will now fail if no size is passed in and if the file object does not have a fileno
which can be stat'ed.

Fixes #900.

[dhermes]

@jonparrott This doesn't quite go all the way to fix what you wanted. It still requires size if the file object is not a file.

[jgeewax]

@Capstan : There's no way for GCS to just "not care about the size, we'll tell you when we're done piping data into it", right?

[dhermes]

It's an HTTP header thing.

[jgeewax]

Code LGTM.

The comment to @Capstan is in the hopes that we can send chunks until we're done sending chunks, and GCS counts the total bytes then... done and done. (That way, a stream that doesn't have a size up front, would be uploadable... right?)

[Capstan]

re: @jgeewax

On the contrary, there are two published ways to send without knowing a final size.

The first works with single-POST / single-PUT (simple and multipart) and just uses Transfer-Encoding: chunked. Logically, we should even be able to handle trailing headers with digests (e.g., Content-MD5). We don't support the Digest header yet. Multipart requires doing the transfer encoding twice since you know neither the whole body nor the second body of the multipart's size.

The second works with resumable uploads. You omit the X-Upload-Content-Length header, and then use Content-Range: x-y/* (the star at the end to show you don't know the length) on the PUTs to the resumable session.

[jgeewax]

OK so then the question becomes: if I can send chunks until I'm done sending chunks, what's stopping us from uploading an arbitrary stream?

(I think this conversation is deviating from the topic of this PR though, so maybe best to discuss in a separate issue? The original maybe?)

[theacodes]

This at least helps from a user perspective (way better error message) so this LGTM. However, I agree with @jgeewax - we should just be able to upload an arbitrary stream.

[tseaver]

LGTM

[dhermes]

Opened #931 to capture @Capstan feedback and try to loop support for it into the library.