add support for MSI files to infer backend

CHANGELOG.md

@@ -5,7 +5,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## Unreleased
-
+### Added
+ - MSI detection to [`infer`] backend
 ## v0.3.7 - 2021-09-25
 ### Added
 - `-j`/`--jobs` flag for specifying the number of threads fif should use for scanning files

src/mime_db.rs

@@ -18,8 +18,6 @@ cfg_if! {
 			db: infer::Infer,
 		}
 
-		// TODO: msi
-
 		fn open_document_check(buf: &[u8], kind: &str) -> bool {
 			let mime = format!("application/vnd.oasis.opendocument.{}", kind);
 			let mime = mime.as_bytes();
@@ -53,6 +51,10 @@ cfg_if! {
 					buf.starts_with(b"\x46\x4f\x52\x4d\x41\x49\x46\x46")
 				});
 
+				info.add("application/x-msi", "msi", |buf| {
+					buf.starts_with(b"\xd0\xcf\x11\xe0\xa1\xb1\x1a\xe1")
+				})
+
 				info.add("image/svg+xml", "svg", |buf| {
 					// before doing the moderately expensive SVG check, we should make sure that the input is actually SGML-ish,
 					// by which i mean, starts with anywhere from zero to ∞-1 whitespace characters, and then a less than sign,