When a local workspace root uses a FileSystemProvider where authority element of uri is significant, the SimpleFileDialog presented by File\Open File cannot navigate into subfolders

[gjsjohnmurray]

Issue Type: Bug

The problem seems to lie in this code:

vscode/src/vs/workbench/services/dialogs/browser/simpleFileDialog.ts

Lines 213 to 224 in 79e9194

	private remoteUriFrom(path: string): URI {
	if (!path.startsWith('\\\\')) {
	path = path.replace(/\\/g, '/');
	}
	const uri: URI = this.scheme === Schemas.file ? URI.file(path) : URI.from({ scheme: this.scheme, path });
	// If the default scheme is file, then we don't care about the remote authority
	const authority = uri.scheme === Schemas.file ? undefined : this.remoteAuthority;
	return resources.toLocalResource(uri, authority,
	// If there is a remote authority, then we should use the system's default URI as the local scheme.
	// If there is *no* remote authority, then we should use the default scheme for this dialog as that is already local.
	authority ? this.pathService.defaultUriScheme : uri.scheme);
	}

When the workspace is a local one, this.remoteAuthority is undefined, so the returned uri has authority: ''

I intend to prepare a variant of the MemFS sample to demonstrate the problem.

VS Code version: Code - Insiders 1.59.0-insider (0448522, 2021-07-23T19:21:12.120Z)
OS version: Windows_NT x64 10.0.19043
Restricted Mode: No

[gjsjohnmurray]

https://github.com/gjsjohnmurray/vscode-extension-samples/tree/show-129296 contains a modified fsprovider-sample in which the MemFS files are generated with uris of the form memfs://dummyauthority/... instead of the usual memfs:/...

To reproduce the issue:

1. Clone https://github.com/gjsjohnmurray/vscode-extension-samples/tree/show-129296

2. Open the fsprovider-sample folder

3. Build and run the extension

4. Run the command MemFS: Setup Workspace

5. Run MemFS: Create Files

6. Expand the root folder to confirm files are present:
   

7. Use Ctrl/Cmd+O to open the simple file dialog, which correctly shows the same folders and files:
   

8. Select any of the three folders and observe the error message:
   

This arises because of the following check in the modified sample:

    private _lookup(uri: vscode.Uri, silent: boolean): Entry | undefined {
        if (uri.authority !== 'dummyauthority') {
            throw vscode.FileSystemError.FileNotFound(uri);
        }

(https://github.com/gjsjohnmurray/vscode-extension-samples/blob/fb27d812ee30ce44ba413a60b0b58ee5ef59ae13/fsprovider-sample/src/fileSystemProvider.ts#L158-L161)

In the case of my own FSP extension, only the loss of the authority element of the uri is significant, but it is conceivable that other FSPs rely on query or fragment. I think SimpleFileDialog loses those elements too.

[gjsjohnmurray]

it is conceivable that other FSPs rely on query or fragment. I think SimpleFileDialog loses those elements too.

An example of one relying on query is referenced in #128151, which is about how the Explorer tree mishandles query, so pinging @bpasero here too.