POST method uploads

This feature lets people upload both text and binary files. With PHP's authentication and file manipulation functions, you have full control over who is allowed to upload and what is to be done with the file once it has been uploaded.

PHP is capable of receiving file uploads from any RFC-1867 compliant browser.

Note: Related Configurations Note

See also the file_uploads, upload_max_filesize, upload_tmp_dir, post_max_size and max_input_time directives in php.ini

PHP also supports PUT-method file uploads as used by Netscape Composer and W3C's Amaya clients. See the PUT Method Support for more details.

Example #1 File Upload Form

A file upload screen can be built by creating a special form which looks something like this:

<!-- The data encoding type, enctype, MUST be specified as below -->
<form enctype="multipart/form-data" action="__URL__" method="POST">
    <!-- MAX_FILE_SIZE must precede the file input field -->
    <input type="hidden" name="MAX_FILE_SIZE" value="30000" />
    <!-- Name of input element determines name in $_FILES array -->
    Send this file: <input name="userfile" type="file" />
    <input type="submit" value="Send File" />
</form>

The __URL__ in the above example should be replaced, and point to a PHP file.

The MAX_FILE_SIZE hidden field (measured in bytes) must precede the file input field, and its value is the maximum filesize accepted by PHP. This form element should always be used as it saves users the trouble of waiting for a big file being transferred only to find that it was too large and the transfer failed. Keep in mind: fooling this setting on the browser side is quite easy, so never rely on files with a greater size being blocked by this feature. It is merely a convenience feature for users on the client side of the application. The PHP settings (on the server side) for maximum-size, however, cannot be fooled.

Note:

Be sure your file upload form has attribute enctype="multipart/form-data" otherwise the file upload will not work.

The global $_FILES will contain all the uploaded file information. Its contents from the example form is as follows. Note that this assumes the use of the file upload name userfile, as used in the example script above. This can be any name.

$_FILES['userfile']['name']

The original name of the file on the client machine.

$_FILES['userfile']['type']

The mime type of the file, if the browser provided this information. An example would be "image/gif". This mime type is however not checked on the PHP side and therefore don't take its value for granted.

$_FILES['userfile']['size']

The size, in bytes, of the uploaded file.

$_FILES['userfile']['tmp_name']

The temporary filename of the file in which the uploaded file was stored on the server.

$_FILES['userfile']['error']

The error code associated with this file upload.

$_FILES['userfile']['full_path']

The full path as submitted by the browser. This value does not always contain a real directory structure, and cannot be trusted. Available as of PHP 8.1.0.

Files will, by default be stored in the server's default temporary directory, unless another location has been given with the upload_tmp_dir directive in php.ini. The server's default directory can be changed by setting the environment variable TMPDIR in the environment in which PHP runs. Setting it using putenv() from within a PHP script will not work. This environment variable can also be used to make sure that other operations are working on uploaded files, as well.

Example #2 Validating file uploads

See also the function entries for is_uploaded_file() and move_uploaded_file() for further information. The following example will process the file upload that came from a form.

<?php
$uploaddir
= '/var/www/uploads/';
$uploadfile = $uploaddir . basename($_FILES['userfile']['name']);

echo
'<pre>';
if (
move_uploaded_file($_FILES['userfile']['tmp_name'], $uploadfile)) {
echo
"File is valid, and was successfully uploaded.\n";
} else {
echo
"Possible file upload attack!\n";
}

echo
'Here is some more debugging info:';
print_r($_FILES);

print
"</pre>";

?>

The PHP script which receives the uploaded file should implement whatever logic is necessary for determining what should be done with the uploaded file. You can, for example, use the $_FILES['userfile']['size'] variable to throw away any files that are either too small or too big. You could use the $_FILES['userfile']['type'] variable to throw away any files that didn't match a certain type criteria, but use this only as first of a series of checks, because this value is completely under the control of the client and not checked on the PHP side. Also, you could use $_FILES['userfile']['error'] and plan your logic according to the error codes. Whatever the logic, you should either delete the file from the temporary directory or move it elsewhere.

If no file is selected for upload in your form, PHP will return $_FILES['userfile']['size'] as 0, and $_FILES['userfile']['tmp_name'] as none.

The file will be deleted from the temporary directory at the end of the request if it has not been moved away or renamed.

Example #3 Uploading array of files

PHP supports HTML array feature even with files.

<form action="" method="post" enctype="multipart/form-data">
<p>Pictures:
<input type="file" name="pictures[]" />
<input type="file" name="pictures[]" />
<input type="file" name="pictures[]" />
<input type="submit" value="Send" />
</p>
</form>
<?php
foreach ($_FILES["pictures"]["error"] as $key => $error) {
if (
$error == UPLOAD_ERR_OK) {
$tmp_name = $_FILES["pictures"]["tmp_name"][$key];
// basename() may prevent filesystem traversal attacks;
// further validation/sanitation of the filename may be appropriate
$name = basename($_FILES["pictures"]["name"][$key]);
move_uploaded_file($tmp_name, "data/$name");
}
}
?>

File upload progress bar can be implemented using Session Upload Progress.

add a note add a note

User Contributed Notes 12 notes

up
54
daevid at daevid dot com
14 years ago
I think the way an array of attachments works is kind of cumbersome. Usually the PHP guys are right on the money, but this is just counter-intuitive. It should have been more like:

Array
(
    [0] => Array
        (
            [name] => facepalm.jpg
            [type] => image/jpeg
            [tmp_name] => /tmp/phpn3FmFr
            [error] => 0
            [size] => 15476
        )

    [1] => Array
        (
            [name] =>
            [type] =>
            [tmp_name] =>
            [error] => 4
            [size] =>
        )
)

and not this
Array
(
    [name] => Array
        (
            [0] => facepalm.jpg
            [1] =>
        )

    [type] => Array
        (
            [0] => image/jpeg
            [1] =>
        )

    [tmp_name] => Array
        (
            [0] => /tmp/phpn3FmFr
            [1] =>
        )

    [error] => Array
        (
            [0] => 0
            [1] => 4
        )

    [size] => Array
        (
            [0] => 15476
            [1] => 0
        )
)

Anyways, here is a fuller example than the sparce one in the documentation above:

<?php
foreach ($_FILES["attachment"]["error"] as $key => $error)
{
      
$tmp_name = $_FILES["attachment"]["tmp_name"][$key];
       if (!
$tmp_name) continue;

      
$name = basename($_FILES["attachment"]["name"][$key]);

    if (
$error == UPLOAD_ERR_OK)
    {
        if (
move_uploaded_file($tmp_name, "/tmp/".$name) )
           
$uploaded_array[] .= "Uploaded file '".$name."'.<br/>\n";
        else
           
$errormsg .= "Could not move uploaded file '".$tmp_name."' to '".$name."'<br/>\n";
    }
    else
$errormsg .= "Upload error. [".$error."] on file '".$name."'<br/>\n";
}
?>
up
36
mpyw
7 years ago
Do not use Coreywelch or Daevid's way, because their methods can handle only within two-dimensional structure. $_FILES can consist of any hierarchy, such as 3d or 4d structure.

The following example form breaks their codes:

<form action="" method="post" enctype="multipart/form-data">
    <input type="file" name="files[x][y][z]">
    <input type="submit">
</form>

As the solution, you should use PSR-7 based zendframework/zend-diactoros.

GitHub:

https://github.com/zendframework/zend-diactoros

Example:

<?php

use Psr\Http\Message\UploadedFileInterface;
use
Zend\Diactoros\ServerRequestFactory;

$request = ServerRequestFactory::fromGlobals();

if (
$request->getMethod() !== 'POST') {
   
http_response_code(405);
    exit(
'Use POST method.');
}

$uploaded_files = $request->getUploadedFiles();

if (
    !isset(
$uploaded_files['files']['x']['y']['z']) ||
    !
$uploaded_files['files']['x']['y']['z'] instanceof UploadedFileInterface
) {
   
http_response_code(400);
    exit(
'Invalid request body.');
}

$file = $uploaded_files['files']['x']['y']['z'];

if (
$file->getError() !== UPLOAD_ERR_OK) {
   
http_response_code(400);
    exit(
'File uploading failed.');
}

$file->moveTo('/path/to/new/file');

?>
up
12
anon
8 years ago
For clarity; the reason you would NOT want to replace the example script with
$uploaddir = './';
is because if you have no coded file constraints a nerd could upload a php script with the same name of one of your scripts in the scripts directory.

Given the right settings and permissions php-cgi is capable of replacing even php files.

Imagine if it replaced the upload post processor file itself. The next "upload" could lead to some easy exploits.

Even when replacements are not possible; uploading an .htaccess file could cause some problems, especially if it is sent after the nerd throws in a devious script to use htaccess to redirect to his upload.

There are probably more ways of exploiting it. Don't let the nerds get you.

More sensible to use a fresh directory for uploads with some form of unique naming algorithm; maybe even a cron job for sanitizing the directory so older files do not linger for too long.
up
3
fravadona at gmail dot com
3 years ago
mpyw is right, PSR-7 is awesome but a little overkill for simple projects (in my opinion).

Here's an example of function that returns the file upload metadata in a (PSR-7 *like*) normalized tree. This function deals with whatever dimension of upload metadata.

I kept the code extremely simple, it doesn't validate anything in $_FILES, etc... AND MOST IMPORTANTLY, it calls array_walk_recursive in an *undefined behaviour* way!!!

You can test it against the examples of the PSR-7 spec ( https://www.php-fig.org/psr/psr-7/#16-uploaded-files ) and try to add your own checks that will detect the error in the last example ^^

<?php
/**
*  THIS CODE IS ABSOLUTELY NOT MEANT FOR PRODUCTION !!! MAY ITS INSIGHTS HELP YOU !!!
*/
function getNormalizedFiles()
{
 
$normalized = array();

  if ( isset(
$_FILES) ) {
   
    foreach (
$_FILES as $field => $metadata ) {
     
     
$normalized[$field] = array(); // needs initialization for array_replace_recursive
     
     
foreach ( $metadata as $meta => $data ) { // $meta is 'tmp_name', 'error', etc...
       
       
if ( is_array($data) ) {
         
         
// insert the current meta just before each leaf !!! WRONG USE OF ARRAY_WALK_RECURSIVE !!!
         
array_walk_recursive($data, function (&$v,$k) use ($meta) { $v = array( $meta => $v ); });
         
         
// fuse the current metadata with the previous ones
         
$normalized[$field] = array_replace_recursive($normalized[$field], $data);
       
        } else {
         
$normalized[$field][$meta] = $data;
        }
      }
    }
  }
  return
$normalized;
}
?>
up
13
coreywelch+phpnet at gmail dot com
8 years ago
The documentation doesn't have any details about how the HTML array feature formats the $_FILES array.

Example $_FILES array:

For single file -

Array
(
    [document] => Array
        (
            [name] => sample-file.doc
            [type] => application/msword
            [tmp_name] => /tmp/path/phpVGCDAJ
            [error] => 0
            [size] => 0
        )
)

Multi-files with HTML array feature -

Array
(
    [documents] => Array
        (
            [name] => Array
                (
                    [0] => sample-file.doc
                    [1] => sample-file.doc
                )

            [type] => Array
                (
                    [0] => application/msword
                    [1] => application/msword
                )

            [tmp_name] => Array
                (
                    [0] => /tmp/path/phpVGCDAJ
                    [1] => /tmp/path/phpVGCDAJ
                )

            [error] => Array
                (
                    [0] => 0
                    [1] => 0
                )

            [size] => Array
                (
                    [0] => 0
                    [1] => 0
                )

        )

)

The problem occurs when you have a form that uses both single file and HTML array feature. The array isn't normalized and tends to make coding for it really sloppy. I have included a nice method to normalize the $_FILES array.

<?php

   
function normalize_files_array($files = []) {

       
$normalized_array = [];

        foreach(
$files as $index => $file) {

            if (!
is_array($file['name'])) {
               
$normalized_array[$index][] = $file;
                continue;
            }

            foreach(
$file['name'] as $idx => $name) {
               
$normalized_array[$index][$idx] = [
                   
'name' => $name,
                   
'type' => $file['type'][$idx],
                   
'tmp_name' => $file['tmp_name'][$idx],
                   
'error' => $file['error'][$idx],
                   
'size' => $file['size'][$idx]
                ];
            }

        }

        return
$normalized_array;

    }

?>

The following is the output from the above method.

Array
(
    [document] => Array
        (
            [0] => Array
                (
                [name] => sample-file.doc
                    [type] => application/msword
                    [tmp_name] => /tmp/path/phpVGCDAJ
                    [error] => 0
                    [size] => 0
                )

        )

    [documents] => Array
        (
            [0] => Array
                (
                    [name] => sample-file.doc
                    [type] => application/msword
                    [tmp_name] => /tmp/path/phpVGCDAJ
                    [error] => 0
                    [size] => 0
                )

            [1] => Array
                (
                    [name] => sample-file.doc
                    [type] => application/msword
                    [tmp_name] => /tmp/path/phpVGCDAJ
                    [error] => 0
                    [size] => 0
                )

        )

)
up
8
eslindsey at gmail dot com
14 years ago
Also note that since MAX_FILE_SIZE hidden field is supplied by the browser doing the submitting, it is easily overridden from the clients' side.  You should always perform your own examination and error checking of the file after it reaches you, instead of relying on information submitted by the client.  This includes checks for file size (always check the length of the actual data versus the reported file size) as well as file type (the MIME type submitted by the browser can be inaccurate at best, and intentionally set to an incorrect value at worst).
up
2
Mark
13 years ago
$_FILES will be empty if a user attempts to upload a file greater than post_max_size in your php.ini

post_max_size should be >= upload_max_filesize in your php.ini.
up
-1
Anonymous
7 years ago
I have found it useful to re-order the multidimensional $_FILES array into a more intuitive format, as proposed by many other developers already.

Unfortunately, most of the proposed functions are not able to re-order the $_FILES array when it has more than 1 additional dimension.

Therefore, I would like to contribute the function below, which is capable of meeting the aforementioned requirement:

<?php
   
function get_fixed_files() {
       
$function = function($files, $fixed_files = array(), $path = array()) use (&$function) {
            foreach (
$files as $key => $value) {
               
$temp = $path;
               
$temp[] = $key;
           
                if (
is_array($value)) {
                   
$fixed_files = $function($value, $fixed_files, $temp);
                } else {
                   
$next = array_splice($temp, 1, 1);
                   
$temp = array_merge($temp, $next);
                   
                   
$new = &$fixed_files;
                   
                    foreach (
$temp as $key) {
                       
$new = &$new[$key];
                    }
                   
                   
$new = $value;
                }
            }
           
            return
$fixed_files;
        };
       
        return
$function($_FILES);
    }
?>

Side note: the unnamed function within the function is used to avoid confusion regarding the arguments necessary for the recursion within the function, for example when viewing the function in an IDE.
up
-1
claude dot pache at gmail dot com
14 years ago
Note that the MAX_FILE_SIZE hidden field is only used by the PHP script which receives the request, as an instruction to reject files larger than the given bound. This field has no significance for the browser, it does not provide a client-side check of the file-size, and it has nothing to do with web standards or browser features.
up
-7
Age Bosma
12 years ago
"If no file is selected for upload in your form, PHP will return $_FILES['userfile']['size'] as 0, and $_FILES['userfile']['tmp_name'] as none."

Note that the situation above is the same when a file exceeding the MAX_FILE_SIZE hidden field is being uploaded. In this case $_FILES['userfile']['size'] is also set to 0, and $_FILES['userfile']['tmp_name'] is also empty. The difference would only be the error code.
Simply checking for these two conditions and assuming no file upload has been attempted is incorrect.

Instead, check if $_FILES['userfile']['name'] is set or not. If it is, a file upload has at least been attempted (a failed attempt or not). If it is not set, no attempt has been made.
up
-17
bimal at sanjaal dot com
9 years ago
Some suggestions here:

1. It is always better to check for your error status. If MAX_FILE_SIZE is active and the uploaded file crossed the limit, it will set the error. So, only when error is zero (0), move the file.

2. If possible, never allow your script to upload in the path where file can be downloaded. Point your upload path to outside of public_html area or prevent direct browsing (using .htaccess restrictions). Think, if someone uploads malicious code, specially php codes, they will be executed on the server.

3. Do not use the file name sent by the client. Regenerate a new name for newly uploaded file. This prevents overwriting your old files.

4. Regularly track the disk space consumed, if you are running out of storage.
up
-14
katrinaelaine6 at gmail dot com
6 years ago
Here's a complete example of the $_FILES array with nested and non-nested names. Let's say we have this html form:

<form action="test.php" method="post">

    <input type="file" name="single" id="single">

    <input type="file" name="nested[]"          id="nested_one">
    <input type="file" name="nested[root]"      id="nested_root">        
    <input type="file" name="nested[][]"        id="nested_two">
    <input type="file" name="nested[][parent]"  id="nested_parent">
    <input type="file" name="nested[][][]"      id="nested_three">
    <input type="file" name="nested[][][child]" id="nested_child">

    <input type="submit" value="Submit">

</form>

In the test.php file:

<?php

    print_r
($_FILES);
    exit;

?>

If we upload a text file with the same name as the input id for each input and click submit, test.php will output this:

<?php

Array
(

    [
single] => Array
        (
            [
name] => single.txt
           
[type] => text/plain
           
[tmp_name] => /tmp/phpApO28i
           
[error] => 0
           
[size] => 3441
       
)

    [
nested] => Array
        (
            [
name] => Array
                (
                    [
0] => nested_one.txt
                   
[root] => nested_root.txt
                   
[1] => Array
                        (
                            [
0] => nested_two.txt
                       
)

                    [
2] => Array
                        (
                            [
parent] => nested_parent.txt
                       
)

                    [
3] => Array
                        (
                            [
0] => Array
                                (
                                    [
0] => nested_three.txt
                               
)

                        )

                    [
4] => Array
                        (
                            [
0] => Array
                                (
                                    [
child] => nested_child.txt
                               
)

                        )

                )

           
// type, tmp_name, size, and error will have the same structure.
       
)

)

?>
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