Valid Linux custom PBA filename is invalid on Windows Island.

[mssalvatore]

Description

Rules about valid Linux file names are much more permissive than Windows file names. When a custom Linux PBA file is submitted to a Windows Island, the file may not be able to be written to disk if it violates Windows file naming rules.

Proposed solution

Convert PBA file names to base64url

Caveats

Some filenames could potentially resolve to reserved Windows files. For example, 5B encodes to NUL, which is reserved. This could be easily remedied by applying a prefix to all base64url encoded file names.

If possible, let's delay this work until we refactor Custom PBAs as a payload.

Alternative solutions

1. Only allow Linux custom PBA files to use Windows-safe filenames
2. Store files in MongoDB instead of on disk

[cakekoa]

PBAs are being removed in #2442