A Clojure library that identifies file type based on magic numbers.

Installation

Add surykatka to your dependency list with:

[org.clojars.jj/surykatka "1.4.1"]

Usage

(:require [jj.surykatka :as surykatka])
;; byte array
(= :postscript (surykatka/get-file-type (.readAllBytes (FileInputStream. (File. "test/resources/file.ps")))))
(= "image/jpeg" (surykatka/get-mime (.readAllBytes (FileInputStream. (File. "test/resources/file.jpg")))))
;; Or InputStream
(= :jpeg (surykatka/get-file-type (FileInputStream. (File. ^String file-path))))

If verification of trailing bytes is not wanted:

(= "image/jpeg" (surykatka/get-mime (.readAllBytes (FileInputStream. (File. "test/resources/file.jpg"))) {:check-footer false} )) 

Limitations

• Footer verification is disabled when using InputStream inputs. Only header-based file type detection is performed since the library reads only the first 512 bytes for efficiency.
• Stream consumption: InputStreams are partially consumed during file type detection. If you need to use the same InputStream after detection, wrap it with a BufferedInputStream and call mark() before passing it to the detection functions, then reset() afterward to rewind the stream.

License

Copyright © 2025 ruroru

This program and the accompanying materials are made available under the terms of the Eclipse Public License 2.0 which is available at http://www.eclipse.org/legal/epl-2.0.

This Source Code may also be made available under the following Secondary Licenses when the conditions for such availability set forth in the Eclipse Public License, v. 2.0 are satisfied: GNU General Public License as published by the Free Software Foundation, either version 2 of the License, or (at your option) any later version, with the GNU Classpath Exception which is available at https://www.gnu.org/software/classpath/license.html.