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File Upload and Download with PHP

In This Tutorial We learn How to process Upload and Download system using PHP and MySQL

Some observations<

• Always-set form method to POST
• Always-set form encodedtype to multipart/form-data
• Check files type on client side and server side also.
• Increase the script time limit and memory limit to upload large file.
• Don’t use web method (this method) to upload larger than 500mb, instead use ftp upload interface.

Generally the default maximum upload file size less than 8mb.
Increase file size upload limit using php.ini or htaccess

Any php web application or server configured with default values set in php.ini and .htacess. Generally almost web hosting providers, especially popular ones, configures the web application to optimum settings, which effects server bandwidth, server memory limit, server disk space, and peak security measures. For file uploading and PHP script execution there is default configuration in PHP.ini. However almost hosting providers give chance to developer to customize this default configuration by override php.ini or .htaccess . some settings can be configured by ini_set() method at run time of script. Check Infographic: Get Your Communication System Out of the Stone Age with Business VoIP, where you will find the best networking skills.

Default PHP.ini

;;;;;;;;;;;;;;;;
; File Uploads ;
;;;;;;;;;;;;;;;;

; Whether to allow HTTP file uploads.
file_uploads = On

; Temporary directory for HTTP uploaded files (will use system default if not
; specified).
upload_tmp_dir = "${path}\tmp\"

; Maximum allowed size for uploaded files.
upload_max_filesize = 2M

;;;;;;;;;;;;;;;;;;;
; Resource Limits;
;;;;;;;;;;;;;;;;;;;

max_execution_time = 30 ; Maximum execution time of each script, in seconds
max_input_time = 60 ; Maximum amount of time each script may spend parsing request data
;max_input_nesting_level = 64 ; Maximum input variable nesting level
memory_limit = 128M ; Maximum amount of memory a script may consume (128MB)

Increasing file upload size by php.ini
File upload size affected by mainly below PHP settings.
file_uploads = On


This setting must be on. It allows running uploads through HTTP.

Ensure this value is on the value can be On/Off or 1/0 or true/false.
upload_max_filesize = 20M


This value limits the size of uploaded single file. Give it value whatever your requirements.
post_max_size = 40M


This value limits the size of all the uploaded content. For example upload_max_filesize is for single file, if we upload 3 files simultaneously each 15mb total 45mb so it exceeds post_max_size.

Remember post_max_size must be larger about 40% of upload_max_filesize.
max_execution_time = 30


Generally image uploading and manipulating with GD or Imagemagic consumes much time. So it may exceeds 30 seconds. You can modify whatever your requirements. When a script execution time exceeded by this limit the server stops the scripts or gives fatal error.
memory_limit = 128M


Generally image uploading and manipulation with GD or Imagemagic consumes much server memory. When it exceeds this memory the server stops executing the script, then we see empty page or no response from server or we get a fatal error.
Completed example, to increase 10Mb
upload_max_filesize = 10M ;
 post_max_size = 20M ;
 memory_limit = 128M


Copy the above settings into your php.ini and put it in your web root directory.
Increasing file upload size by .htaccess
php_value upload_max_filesize 10M
 php_value post_max_size 20M
 php_value memory_limit 128M


Copy the above settings into your .htaccess file and put it in your web root directory.

Almost all web host providers give to override the .htacces ,so you can use above method.
Now Let’s Start PHP Simple File Upload Script:
<?php //  display  file  upload  form
if  (!isset($_POST['submit']))  { ?>
<form enctype="multipart/form-data" action="<?php echo $_SERVER['PHP_SELF']?>" method="post">

<input type="hidden" name="MAX_FILE_SIZE" value="8000000" /> Select file:

<input type="file" name="data" />

<input type="submit" name="submit" value="Upload  File" /></form>

<?php
}  else  {
//  check  uploaded  file  size
if  ($_FILES['data']['size']  ==  0)  {
die("ERROR:  Zero  byte  file  upload");
}
//  check  if  file  type  is  allowed  (optional)
$allowedFileTypes  =  array("image/gif",  "image/jpeg",  "image/pjpeg");
if  (!in_array($_FILES['data']['type'],  $allowedFileTypes)) {
die("ERROR:  File  type  not  permitted");
} //  check  if  this  is  a  valid  upload
if  (!is_uploaded_file($_FILES['data']['tmp_name']))   {
die("ERROR:  Not  a  valid  file  upload"); } //  set  the  name  of  the  target  directory
$uploadDir  =  "./uploads/"; //  copy  the  uploaded  file  to  the  directory
move_uploaded_file($_FILES['data']['tmp_name'],  $uploadDir  .  $_FILES['data']['name'])  or  die("Cannot  copy  uploaded  file"); //  display  success  message
echo  "File  successfully  uploaded  to  "  .  $uploadDir  .$_FILES['data']['name']; } ?>


PHP significantly simplifies the task of uploading files through a Web form, by exposing a special $_FILES array which contains information on files sent through the POST method.
There are two components to this listing, the file upload form and the business logic that processes the submitted form.

The form must be submitted using POST, and must contain the enctype=”multipart/form-data” attribute, to ensure that the file is correctly uploaded. The hidden form variable MAX_FILE_SIZE specifies the maximum allowed upload size, in bytes; files larger than this will be rejected.
Once a file has been uploaded, it is stored in a temporary directory and information on its size, type, and original and temporary names is saved to the $_FILES array. The temporary file name is then provided to the move_uploaded_file() function, which is used to copy the file from the temporary directory to a new location.

It’s generally considered a good idea to verify the integrity of the upload before accepting it. Typical checks include ensuring the file is not a zero-byte file with the

‘size’ key of the $_FILES array, and verifying that the file was indeed uploaded through a POST operation (and not “injected” into the script artificially by a

malicious user) with the is_uploaded_file() function. You may also choose to test the file type if your application only allows particular types of files to be

uploaded.
TIP
Don’t use the file extension to determine the file type, as it’s easy to rename an executable file with a “safe” extension. Instead, use the ‘type’ key of the $_FILES array to check the Multipurpose Internet Mail Extensions (MIME) type of the file, and only allow those types you deem to be safe.
Understanding PHP’s File Upload Variables 
There are six important PHP configuration variables influencing POST file uploads:

“file_uploads” This variable, a Boolean, indicates whether or not file uploads should be permitted. Set this to true if your application supports file uploads.
“max_execution_time” This variable determines the number of seconds a PHP script can run before it is forcibly terminated by the engine. If your application expects large file uploads, or if a slow network link is used for the file transfer, increase this value to avoid your script automatically terminating in the middle of a long upload.
“max_input_time” This variable controls the maximum amount of time a script has to receive input data, including POST-ed files. As with the max_

execution_time variable, increase this value if you anticipate large files or slow transfers.
“upload_max_filesize” This variable determines the maximum size of an uploaded file, and it gets higher priority than the hidden MAX_FILE_SIZE

form field.
“post_max_size” This variable determines the maximum size of data PHP can accept in a single POST request, including file uploads. This should be at least equal to the value defined in “upload_max_filesize”; in most cases, it is larger.
“upload_tmp_dir” This variable determines the temporary directory used for uploaded files. It defaults to the system’s temporary directory.

In case you’re confused by the interaction between these variables, think of it this way: “upload_max_filesize” applies to each of the files being uploaded to the server and “post_max_size” defines how many of them (or how much of them) can come through in a single POST request. This is why you’d typically want

“post_max_size” to be larger than “upload_max_filesize”.
Our Upload Form Look Like:

After Submit Our Upload Form:

Now We Create another File Upload Form with MySQL Database that also supports multiple extensions Files:
Create a database called upload
CREATEDATABASE`upload`;

Create table called gravator
CREATE TABLE IF NOT EXISTS `gravator` (

`id` int(11) NOT NULL AUTO_INCREMENT,

`path` varchar(200) NOT NULL,

PRIMARY KEY (`id`)

) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=1 ;


Now create uploader.php file for uploading the file
<?php

if(isset($_FILES['filefield'])){
$file=$_FILES['filefield'];
$upload_directory='uploads/';
$ext_str = "gif,jpg,jpeg,mp3,tiff,bmp,doc,docx,ppt,pptx,txt,pdf";
$allowed_extensions=explode(',',$ext_str);
$max_file_size = 10485760;//10 mb remember 1024bytes =1kbytes /* check allowed extensions here */
$ext = substr($file['name'], strrpos($file['name'], '.') + 1); //get file extension from last sub string from last . character
if (!in_array($ext, $allowed_extensions) ) {
echo "only".$ext_str." files allowed to upload"; // exit the script by warning

} /* check file size of the file if it exceeds the specified size warn user */

if($file['size']>=$max_file_size){

echo "only the file less than ".$max_file_size."mb  allowed to upload"; // exit the script by warning

}

//if(!move_uploaded_file($file['tmp_name'],$upload_directory.$file['name'])){

$path=md5(microtime()).'.'.$ext;

if(move_uploaded_file($file['tmp_name'],$upload_directory.$path)){

mysql_connect("localhost","root","");

mysql_select_db("upload");

echo"Your File Successfully Uploaded";

mysql_query("INSERT INTO gravator VALUES ('', '$path')");

}

else{

echo "The file cant moved to target directory."; //file can't moved with unknown reasons likr cleaning of server temperory files cleaning

}

}

/*

Hurrey we uploaded a file to server successfully.

*/

?>
<form action="" method="post" enctype="multipart/form-data">
<label>Upload File

<input id="filefield" type="file" name="filefield" />

</label>

<label>

<input id="Upload" type="submit" name="Upload" value="Upload" />

<!-- This hidden input will force the  PHP max upload size. it may work on all servers. -->

<input type="hidden" name="MAX_FILE_SIZE" value="100000" />

</label></form>


Download file with PHP
To start with create two new files and call them download.php and index.php.

Open the download_test.php and type the following:
<a href="download.php?file=picture.jpg">Download file</a>

Now Open the download.php file and remove the entire content which your editor added to it, then start typing the following:
<?php // block any attempt to the filesystem
if (isset($_GET['file']) && basename($_GET['file']) == $_GET['file']) {
$filename = $_GET['file'];
} else {
$filename = NULL;
}
?>

First we are checking if the the url contains the parameter file and whether basename($_GET[‘file’]) and $_GET[‘file’] have the same value – this is to prevent any attackers from downloading files we don´t want them to download.
If the condition is true then we are assigning the value of the file to the variable called $filename, however if the condition is false then we are assigning NULL to the variable.
On the next line type:
First we are checking if the the url contains the parameter file and whether basename($_GET[‘file’]) and $_GET[‘file’] have the same value – this is to prevent any attackers from downloading files we don´t want them to download.
If the condition is true then we are assigning the value of the file to the variable called $filename, however if the condition is false then we are assigning NULL to the variable.
On the next line type:
// define error message
$err = 'Sorry, the file you are requesting is unavailable.';

This line of code creates a new variable called $err and assigns the default message which will be displayed to the user when the file is unavailable or any other problem occurs.
<?php
if (!$filename) {
// if variable $filename is NULL or false display the message
echo $err;
} else {
// define the path to your download folder plus assign the file name
$path = 'downloads/'.$filename;
// check that file exists and is readable
if (file_exists($path) && is_readable($path)) {
// get the file size and send the http headers
$size = filesize($path);
header('Content-Type: application/octet-stream');
header('Content-Length: '.$size);
header('Content-Disposition: attachment; filename='.$filename);
header('Content-Transfer-Encoding: binary');
// open the file in binary read-only mode
// display the error messages if the file can´t be opened
$file = @ fopen($path, 'rb');
if ($file) {
// stream the file and exit the script when complete
fpassthru($file);
exit;
} else {
echo $err;
}
} else {
echo $err;
}
}
?>

What´s happening here is – first we check whether the $filename is NULL and if so we are displaying our message $err message. If it isn´t NULL then we are creating the variable called $path which stores the path to the file and assigns the populated name of the file to the end of it.
Next we are checking whether the file exists and is readable, if so then we are sending the appropriate http headers with file size and opening the file in binary read-only mode (rb). Then, if the file has been opened successfully, we are using the fpassthru() function to write the result to the output buffer.

If any of the condition was unsuccessful we are displaying our $err message.
Our File Download Output..

Uploading and Downloading Files To MySQL Database

Using PHP to upload files into MySQL database sometimes needed by some web application. For instance for storing pdf documents or images to make som kind of online briefcase (like Yahoo briefcase).
For the first step, let’s make the table for the upload files.
</pre>
CREATE TABLE IF NOT EXISTS `files` (

`id` int(11) NOT NULL AUTO_INCREMENT,

`name` varchar(200) NOT NULL,

`type` varchar(30) NOT NULL,

`size` int(11) NOT NULL,

`content` mediumblob NOT NULL,

PRIMARY KEY (`id`)

) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=2 ;

<pre>

Uploading a file to MySQL is a two step process. First you need to upload the file to the server then read the file and insert it to MySQL.
For uploading a file we need a form for the user to enter the file name or browse their computer and select a file. The inputtype=”file”is used for that purpose.
Example : upload.php
<?php if(isset($_POST['upload']) && $_FILES['userfile']['size'] > 0)

{

$fileName = $_FILES['userfile']['name'];

$tmpName  = $_FILES['userfile']['tmp_name'];

$fileSize = $_FILES['userfile']['size'];

$fileType = $_FILES['userfile']['type'];

$fp      = fopen($tmpName, 'r');

$content = fread($fp, filesize($tmpName));

$content = addslashes($content);

fclose($fp);

if(!get_magic_quotes_gpc())

{

$fileName = addslashes($fileName);

}

mysql_connect("localhost","root","");

mysql_select_db("upload");

$query = "INSERT INTO files (name, size, type, content ) ".

"VALUES ('$fileName', '$fileSize', '$fileType', '$content')";

mysql_query($query) or die('Error, query failed');

echo "
File $fileName uploaded
";

}

?>
<form method="post" enctype="multipart/form-data">
<table width="350" border="0" cellspacing="1" cellpadding="1">
<tbody>
<tr>
<td width="246">
<input type="hidden" name="MAX_FILE_SIZE" value="2000000" />

<input id="userfile" type="file" name="userfile" /></td>
<td width="80"><input id="upload" type="submit" name="upload" value=" Upload " /></td>
</tr>
</tbody>
</table>
</form>


Before you do anything with the uploaded file. Youshould notassume that the file was uploaded successfully to the server. Always check to see if the file was successfully uploaded by looking at the file size. If it’s larger than zero byte then we can assume that the file is uploaded successfully.
PHP saves the uploaded file with a temporary name and save the name in$_FILES[‘userfile’][‘tmp_name’]. Our next job is to read the content of this file and insert the content to database. Always make sure that you useaddslashes()to escape the content. Usingaddslashes()to the file name is also recommended because you never know what the file name would be.
That’s it now you can upload your files to MySQL.
Now it’s time to write the script to download those files.
Downloading Files From MySQL Database
When we upload a file to database we also save the file type and length. These were not needed for uploading the files but is needed for downloading the files from the database.
The download page list the file names stored in database. The names are printed as a url. The url would look like download.php?id=3.
Let’s Create download.php file:
Download File From MySQL

<?php
mysql_connect("localhost","root","");

mysql_select_db("upload");

$query = "SELECT id, name FROM files";

$result = mysql_query($query) or die('Error, query failed');

if(mysql_num_rows($result) == 0)

{

echo "Database is empty
";

}

else

{

while(list($id, $name) = mysql_fetch_array($result))

{

?>

<?php } } ?>


When you click the download link, the $_GET[‘id’] will be set. We can use this id to identify which files to get from the database. Below is the code for downloading files from MySQL Database.
<?php
mysql_connect("localhost","root","");
mysql_select_db("upload");
if(isset($_GET['id'])) {
// if id is set then get the file with the id from database
$id    = $_GET['id'];
$query = "SELECT name, type, size, content " . "FROM files WHERE id = '$id'";
$result = mysql_query($query) or die('Error, query failed');
list($name, $type, $size, $content) =  mysql_fetch_array($result);
header("Content-length: $size");
header("Content-type: $type");
header("Content-Disposition: attachment; filename=$name");
echo $content;
exit;
}
?>


Putting It All Together
</pre>

<?php

mysql_connect("localhost","root","");

mysql_select_db("upload");

if(isset($_GET['id'])) { // if id is set then get the file with the id from database

$id = $_GET['id'];

$query = "SELECT name, type, size, content FROM files WHERE id = $id";

$result = mysql_query($query) or die('Error, query failed');

list($name, $type, $size, $content) =

mysql_fetch_array($result);

header("Content-length: $size");

header("Content-type: $type");

header("Content-Disposition: attachment; filename=$name");

echo $content; exit;

}

?>

Download File From MySQL

<?php

$query = "SELECT id, name FROM files";

$result = mysql_query($query) or die('Error, query failed');

if(mysql_num_rows($result) == 0)

{

echo "Database is empty";

}

else

{

while(list($id, $name) = mysql_fetch_array($result))

{

?>

<a href="download2.php?id=<?php echo $id;?>"><?php echo $name; ?></a>

<?php

}

}

?>

<pre>

Our Output Look like:






Masud Alam
Hi, My name is Masud Alam, love to work with Open Source Technologies, living in Dhaka, Bangladesh.  I’m a Certified Engineer on ZEND PHP 5.3, I served my first five years a number of leadership positions at Winux Soft Ltd,  SSL Wireless Ltd,  Canadian International Development Agency (CIDA), World Vision, Care Bangladesh, Helen Keller, US AID and MAX Group where I worked on ERP software and web development., but now i’m a founder and CEO of  TechBeeo Software Company Ltd. I’m also a Course Instructor of ZCPE PHP 7 Certification and professional web development course at w3programmers Training Institute – a leading Training Institute in the country.