Formatting: Expand sanitize_file_name to have better support for utf8…

… characters.

Brings the changes in [47638] to the 5.4 branch.

Props: xknown, peterwilsoncc.


git-svn-id: https://develop.svn.wordpress.org/branches/5.4@47643 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/formatting.php

@@ -2005,6 +2005,24 @@ function remove_accents( $string ) {
 function sanitize_file_name( $filename ) {
 	$filename_raw  = $filename;
 	$special_chars = array( '?', '[', ']', '/', '\\', '=', '<', '>', ':', ';', ',', "'", '"', '&', '$', '#', '*', '(', ')', '|', '~', '`', '!', '{', '}', '%', '+', chr( 0 ) );
+
+	// Check for support for utf8 in the installed PCRE library once and store the result in a static.
+	static $utf8_pcre = null;
+	if ( ! isset( $utf8_pcre ) ) {
+		// phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged
+		$utf8_pcre = @preg_match( '/^./u', 'a' );
+	}
+
+	if ( ! seems_utf8( $filename ) ) {
+		$_ext     = pathinfo( $filename, PATHINFO_EXTENSION );
+		$_name    = pathinfo( $filename, PATHINFO_FILENAME );
+		$filename = sanitize_title_with_dashes( $_name ) . '.' . $_ext;
+	}
+
+	if ( $utf8_pcre ) {
+		$filename = preg_replace( "#\x{00a0}#siu", ' ', $filename );
+	}
+
 	/**
 	 * Filters the list of characters to remove from a filename.
 	 *
@@ -2014,7 +2032,6 @@ function sanitize_file_name( $filename ) {
 	 * @param string   $filename_raw  The original filename to be sanitized.
 	 */
 	$special_chars = apply_filters( 'sanitize_file_name_chars', $special_chars, $filename_raw );
-	$filename      = preg_replace( "#\x{00a0}#siu", ' ', $filename );
 	$filename      = str_replace( $special_chars, '', $filename );
 	$filename      = str_replace( array( '%20', '+' ), '-', $filename );
 	$filename      = preg_replace( '/[\r\n\t -]+/', '-', $filename );

tests/phpunit/tests/formatting/SanitizeFileName.php

@@ -68,4 +68,20 @@ function test_replaces_unnammed_file_extensionless() {
 		// Test a filenames that becomes extensionless.
 		$this->assertEquals( 'no-extension', sanitize_file_name( '_.no-extension' ) );
 	}
+
+	/**
+	 * @dataProvider data_wp_filenames
+	 */
+	function test_replaces_invalid_utf8_characters( $input, $expected ) {
+		$this->assertEquals( $expected, sanitize_file_name( $input ) );
+	}
+
+	function data_wp_filenames() {
+		return array(
+			[ urldecode( '%B1myfile.png' ), 'myfile.png' ],
+			[ urldecode( '%B1myfile' ), 'myfile' ],
+			[ 'demo bar.png', 'demo-bar.png' ],
+			[ 'demo' . json_decode( '"\u00a0"' ) . 'bar.png', 'demo-bar.png' ],
+		);
+	}
 }