File attachments: function "fileIsAccessible" does not exclude directories, produces Notice

[JayEn84]

Problem description

I used a (previously errorneous) script that should attach all files within a directory to a PHPMailer object using addAttachment. The script did unfortunately not exclude paths to (sub) directories. Here is what happens:

If you use the addAttachment function and pass a directory path rather than a file path, then

• the file_get_contents function produces a Notice file_get_contents(): Read of 8192 bytes failed with errno=21 Is a directory in ...
• A zero byte attachment with the directory's name as file name is added to the email.

Code to reproduce

$mail->addAttachment('/some/path');

Suggestion

The function fileIsAccessible uses file_exists to check whether a file path is valid. But this function returns true if the given path is a file or a directory (https://www.php.net/manual/en/function.file-exists.php). The problem could be solved by using is_file instead.