Extend simple file with extension getter

Signed-off-by: Christopher Ng <chrng8@gmail.com>

lib/private/Files/SimpleFS/NewSimpleFile.php

@@ -190,6 +190,17 @@ class NewSimpleFile implements ISimpleFile {
 		}
 	}
 
+	/**
+	 * {@inheritDoc}
+	 */
+	public function getExtension(): string {
+		if ($this->file) {
+			return $this->file->getExtension();
+		} else {
+			return \pathinfo($this->name, PATHINFO_EXTENSION);
+		}
+	}
+
 	/**
 	 * Open the file as stream for reading, resulting resource can be operated as stream like the result from php's own fopen
 	 *

lib/private/Files/SimpleFS/SimpleFile.php

@@ -158,6 +158,13 @@ class SimpleFile implements ISimpleFile {
 		return $this->file->getMimeType();
 	}
 
+	/**
+	 * {@inheritDoc}
+	 */
+	public function getExtension(): string {
+		return $this->file->getExtension();
+	}
+
 	/**
 	 * Open the file as stream for reading, resulting resource can be operated as stream like the result from php's own fopen
 	 *

lib/public/Files/SimpleFS/ISimpleFile.php

@@ -102,6 +102,11 @@ interface ISimpleFile {
 	 */
 	public function getMimeType();
 
+	/**
+	 * @since 24.0.0
+	 */
+	public function getExtension(): string;
+
 	/**
 	 * Open the file as stream for reading, resulting resource can be operated as stream like the result from php's own fopen
 	 *

lib/public/Files/SimpleFS/InMemoryFile.php

@@ -126,6 +126,13 @@ class InMemoryFile implements ISimpleFile {
 		return $fileInfo->buffer($this->contents);
 	}
 
+	/**
+	 * {@inheritDoc}
+	 */
+	public function getExtension(): string {
+		return \pathinfo($this->name, PATHINFO_EXTENSION);
+	}
+
 	/**
 	 * Stream reading is unsupported for in memory files.
 	 *