Container Image: Revisit Rust file type detection libraries

[yveszoundi]

Background

Entrusted has implemented its own file type detection business logic

• This is based on magic bytes and doesn't rely on file name extensions or whatsoever
• It is not a robust implementation, but an acceptable one based on the time spent and the "value delivered to the people"
• No "great" libraries were found at the time (some libmagic bindings, few pure Rust libraries, etc.)
  • infer was used in early versions of the applications
    • it was not reliable for Office documents detection (OpenDocument, Microsoft Office 365 or legacy versions).
    • See also Does not detect old Office formats bojand/infer#46
  • tree_magic_mini looked promissing but doesn't support apparently Office documents and zip files generally speaking. It was previously experimented with.
  • There are several other libraries that need to be re-assessed (relevance, capabilities)

The libraries that we care about need to perform mime detection based on file bytes rather than relying on file extensions.

Objectives

• Assess if we can use a more robust mime type detection library in the sandbox container image
• See if we can detect many more file types
  • In theory we can support at least all documents that LibreOffice can open
  • There are also few more image formats that could be supported