Image Upload, Rename and Apply Restrictions Using PHP

by Hiroshi on June 17, 2008

in File Upload, Scripts, Security

This script accepts just images and uploads these into ‘images’ directory.

Functionality

– Determines Max File Size (Size Restriction)
– Accepts just jpg, jpeg, png or gif image files
– Changes extension of image into lowercase
– Stores the file in predefined directory at your server
– Replaces names of files with random digits (Rename)

Form Code

<form name="newad" method="post" enctype="multipart/form-data" action="upload.php">
<table>
<tr><td><input type="file" name="image"></td></tr>
<tr><td><input name="Submit" type="submit" value="Upload image"></td></tr>
</table>
</form>

PHP Code

<?php
//define a maxim size for the uploaded images in Kb
define ("MAX_SIZE","100");
//This function reads the extension of the file. It is used to determine if the file is an image by checking the extension.
function getExtension($str) {
$i = strrpos($str,".");
if (!$i) { return ""; }
$l = strlen($str) - $i;
$ext = substr($str,$i+1,$l);
return $ext;
}
//This variable is used as a flag. The value is initialized with 0 (meaning no error found) and it will be changed to 1 if an errro occures. If the error occures the file will not be uploaded.
$errors=0;
//checks if the form has been submitted
if(isset($_POST['Submit']))
{
//reads the name of the file the user submitted for uploading
$image=$_FILES['image']['name'];
//if it is not empty
if ($image)
{
//get the original name of the file from the clients machine
$filename = stripslashes($_FILES['image']['name']);
//get the extension of the file in a lower case format
$extension = getExtension($filename);
$extension = strtolower($extension);
//if it is not a known extension, we will suppose it is an error and will not upload the file, otherwize we will do more tests
if (($extension != "jpg") && ($extension != "jpeg") && ($extension != "png") && ($extension != "gif"))
{
//print error message
echo '<h1>Unknown extension!</h1>';
$errors=1;
}
else
{
//get the size of the image in bytes
//$_FILES['image']['tmp_name'] is the temporary filename of the file in which the uploaded file was stored on the server
$size=filesize($_FILES['image']['tmp_name']);
//compare the size with the maxim size we defined and print error if bigger
if ($size > MAX_SIZE*1024)
{
echo '<h1>You have exceeded the size limit!</h1>';
$errors=1;
}
//we will give an unique name, for example the time in unix time format
$image_name=time().'.'.$extension;
//the new name will be containing the full path where will be stored (images folder)
$newname="images/".$image_name;
//we verify if the image has been uploaded, and print error instead
$copied = copy($_FILES['image']['tmp_name'], $newname);
if (!$copied)
{
echo '<h1>Copy unsuccessfull!</h1>';
$errors=1;
}}}}
//If no errors registred, print the success message
if(isset($_POST['Submit']) && !$errors)
{
echo "<h1>File Uploaded Successfully! Try again!</h1>";
}
?>

Precautions

  • CHMOD ‘images’ folder to 777 if it is at online server
  • Use enctype=”multipart/form-data” in form tag

Upload Image & Apply Restrictions & Rename Script Download

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