+ * Calculates and compares the MD5 of a file to it's expected value.
+ *
+ * @since 3.7.0
+ *
+ * @param string $filename The filename to check the MD5 of.
+ * @param string $expected_md5 The expected MD5 of the file, either a base64 encoded raw md5, or a hex-encoded md5
+ * @return bool|object WP_Error on failure, true on success, false when the MD5 format is unknown/unexpected
+ */
+function verify_file_md5( $filename, $expected_md5 ) {
+ if ( 32 == strlen( $expected_md5 ) )
+ $expected_raw_md5 = pack( 'H*', $expected_md5 );
+ elseif ( 24 == strlen( $expected_md5 ) )
+ $expected_raw_md5 = base64_decode( $expected_md5 );
+ else
+ return false; // unknown format
+
+ $file_md5 = md5_file( $filename, true );
+
+ if ( $file_md5 === $expected_raw_md5 )
+ return true;
+
+ return new WP_Error( 'md5_mismatch', sprintf( __( 'The checksum of the file (%1$s) does not match the expected checksum value (%2$s).' ), bin2hex( $file_md5 ), bin2hex( $expected_raw_md5 ) ) );
+}
+
+/**
+ * Unzips a specified ZIP file to a location on the Filesystem via the WordPress Filesystem Abstraction.