提交带有电子邮件附件的表单

Question

我的代码是：

<form action="#" method="POST" enctype="multipart/form-data"  >
 <input type="file" name="csv_file[]" />
 <br/>

 <input type="file" name="csv_file[]" />
 <br/>

 <input type="file" name="csv_file[]" />
 <br/>

 <input type="submit" name="upload" value="Upload" />
 <br/>

</form> 

<?php

if($_POST) {

    for($i=0; $i < count($_FILES['csv_file']['name']); $i++){

        $ftype[]       = $_FILES['csv_file']['type'][$i];
        $fname[]       = $_FILES['csv_file']['name'][$i];

    }


    // array with filenames to be sent as attachment
    $files = $fname;

    // email fields: to, from, subject, and so on
    $to = "example@gmail.com";
    $from = "example@gmail.com"; 
    $subject ="My subject"; 
    $message = "My message";
    $headers = "From: $from";

    // boundary 
    $semi_rand = md5(time()); 
    $mime_boundary = "==Multipart_Boundary_x{$semi_rand}x"; 

    // headers for attachment 
    $headers .= "\nMIME-Version: 1.0\n" . "Content-Type: multipart/mixed;\n" . " boundary=\"{$mime_boundary}\""; 

    // multipart boundary 
    $message = "This is a multi-part message in MIME format.\n\n" . "--{$mime_boundary}\n" . "Content-Type: text/plain; charset=\"iso-8859-1\"\n" . "Content-Transfer-Encoding: 7bit\n\n" . $message . "\n\n"; 
    $message .= "--{$mime_boundary}\n";

    // preparing attachments
    for($x=0;$x<count($files);$x++){
        $file = fopen($files[$x],"rb");
        $data = fread($file,filesize($files[$x]));
        fclose($file);
        $data = chunk_split(base64_encode($data));
        $message .= "Content-Type: {\"application/octet-stream\"};\n" . " name=\"$files[$x]\"\n" . 
        "Content-Disposition: attachment;\n" . " filename=\"$files[$x]\"\n" . 
        "Content-Transfer-Encoding: base64\n\n" . $data . "\n\n";
        $message .= "--{$mime_boundary}\n";
    }

    // send

    $ok = @mail($to, $subject, $message, $headers); 
    if ($ok) { 
        echo "<p>mail sent to $to!</p>"; 
    } else { 
        echo "<p>mail could not be sent!</p>"; 
    } 



}

?>

我从这里得到了代码：https://stackoverflow.com/a/27565430/4357238

表单成功发送电子邮件，当我收到电子邮件时，文件名显示，但文件为空文件（0字节）。

例如，我发送一个名为car.jpg的文件，当它到达我的电子邮件时，它会在我的电子邮件中显示为car.jpg，但是当我下载文件并打开文件时，它说该文件是因为文件是空的而无法打开它。

出了什么问题，我该如何解决？