只允许图像&PDF类型的图像上传PHP脚本

我有一个脚本，只允许上传一个图像，工作良好。

但是现在它允许任何和所有类型的上传。

如何只允许jpg, jpeg, gif, png &PDF文件是唯一允许上传的文件?

这是我的部分代码。

<?php  
// make a note of the current working directory, relative to root.
$directory_self = str_replace(basename($_SERVER['PHP_SELF']), '', $_SERVER['PHP_SELF']);
// make a note of the directory that will recieve the uploaded files
$uploadsDirectory = $_SERVER['DOCUMENT_ROOT'] . $directory_self . 'uploaded_files/';
// make a note of the location of the upload form in case we need it
$uploadForm = 'http://' . $_SERVER['HTTP_HOST'] . $directory_self . 'multiple.upload.form.php';
// make a note of the location of the success page
$uploadSuccess = 'http://' . $_SERVER['HTTP_HOST'] . $directory_self . 'multiple.upload.success.php';
// name of the fieldname used for the file in the HTML form
$fieldname = 'file';
//echo'<pre>';print_r($_FILES);exit;
// Now let's deal with the uploaded files
// possible PHP upload errors
$errors = array(1 => 'php.ini max file size exceeded', 
                2 => 'html form max file size exceeded', 
                3 => 'file upload was only partial', 
                4 => 'no file was attached');
// check the upload form was actually submitted else print form
isset($_POST['submit'])
or error('the upload form is needed', $uploadForm);
// check if any files were uploaded and if 
// so store the active $_FILES array keys
$active_keys = array();
foreach($_FILES[$fieldname]['name'] as $key => $filename)
{
if(!empty($filename))
{
$active_keys[] = $key;
}
}
// check at least one file was uploaded
if (count($active_keys) < 1)
{ echo "<table border='"0'" cellspacing='"4'" cellpadding='"4'"  style='"border: 1px solid black; text-align: center; font-family: arial; font-size: 14px;'" width='"600px'" align='"center'">
<tr>
<td>
<font size='"3'" color='"red'"><strong><u>Upload Error</u></strong></font>
<br>
<br>
<b>You must upload one file.</b>
<br><br>
<a href='"javascript: history.go(-1)'">Back to upload form</a>
<br>
</td>
</tr>
</table> <div style='"display: none;'"> ";  }
//count($active_keys)
//or error('No files were uploaded', $uploadForm);
// check for standard uploading errors
foreach($active_keys as $key)
{
($_FILES[$fieldname]['error'][$key] == 0)
or error($_FILES[$fieldname]['tmp_name'][$key].': '.$errors[$_FILES[$fieldname]['error'][$key]], $uploadForm);
}
// check that the file we are working on really was an HTTP upload
foreach($active_keys as $key)
{
@is_uploaded_file($_FILES[$fieldname]['tmp_name'][$key])
or error($_FILES[$fieldname]['tmp_name'][$key].' not an HTTP upload', $uploadForm);
}
// make a unique filename for the uploaded file and check it is 
// not taken... if it is keep trying until we find a vacant one
foreach($active_keys as $key)
{
$now = time();
while(file_exists($uploadFilename[$key] = $uploadsDirectory.$now.'-'.$_FILES[$fieldname]['name'][$key]))
{
$now++;
}
}
// now let's move the file to its final and allocate it with the new filename
foreach($active_keys as $key)
{
@move_uploaded_file($_FILES[$fieldname]['tmp_name'][$key], $uploadFilename[$key])
or error('receiving directory insuffiecient permission', $uploadForm);
}
// If you got this far, everything has worked and the file has been successfully saved.
// We are now going to redirect the client to the success page.

if($_FILES['file']['error'] === UPLOAD_ERR_INI_SIZE) {
    // Handle the error
    echo 'Your file is too large.';
    die();
}
// make an error handler which will be used if the upload fails
function error($error, $location, $seconds = 5)
{
echo "<table border='"0'" cellspacing='"4'" cellpadding='"4'"  style='"border: 1px solid black; text-align: center; font-family: arial; font-size: 14px;'" width='"600px'" align='"center'">
<tr>
<td>
<font size='"3'" color='"red'"><strong><u>Upload Error</u></strong></font>
<br>
<br>
<!--<b>Your proof is not a supported filetype.<br>
Please upload an image (jpg, gif, png, bmp file) or PDF file.
<br>
<br>
or</b>
<br>
<br>-->
<b>Your File Size is bigger then the maximum allowed - 2 MB.<br>
Please upload a smaller file.</b>
<br><br>
<a href='"javascript: history.go(-1)'">Back to upload form</a>
<br>
</td>
</tr>
</table> <div style='"display: none;'">";
}
/*
{
header("Refresh: $seconds; URL='"$location'"");
echo '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"'."'n".
'"http://www.w3.org/TR/html4/strict.dtd">'."'n'n".
'<html lang="en">'."'n".
'<head>'."'n".
'<meta http-equiv="content-type" content="text/html; charset=iso-8859-1">'."'n'n".
'<link rel="stylesheet" type="text/css" href="stylesheet.css">'."'n'n".
'<title>Upload error</title>'."'n'n".
'</head>'."'n'n".
'<body>'."'n'n".
'<div id="Upload">'."'n'n".
'<h1>Upload failure</h1>'."'n'n".
'<p>An error has occured: '."'n'n".
'<span class="red">' . $error . '...</span>'."'n'n".
' The upload form is reloading</p>'."'n'n".
' </div>'."'n'n".
'</html>';
exit;
} // end error handler
*/
// < input id="file1" name="file[]" type="file" style="border: 1px solid white;">
//$fi= $_POST['file[]'];
//$fi = "(0)";
$fi = array($_FILES['file']['name']['0'],$_FILES['file']['name']['1'],$_FILES['file']['name']['2']);

= = = = = = = =

我能够让它只允许图像，但现在我如何允许PDF也上传?

我将这段代码添加到脚本中。

foreach($active_keys as $key)
{
@getimagesize($_FILES[$fieldname]['tmp_name'][$key])
or error($_FILES[$fieldname]['tmp_name'][$key].' not an image', $uploadForm);
}