is_uploaded

说明

bool is_uploaded_file ( string filename )

如果 filename 所给出的文件是通过 HTTP POST 上传的则返回 TRUE。这可以用来确保恶意的用户无法欺骗脚本去访问本不能访问的文件，例如 /etc/passwd。

这种检查显得格外重要，如果上传的文件有可能会造成对用户或本系统的其他用户显示其内容的话。

为了能使 is_uploaded_file() 函数正常工作，必段指定类似于 $_FILES['userfile']['tmp_name'] 的变量，而在从客户端上传的文件名 $_FILES['userfile']['name'] 不能正常运作。

例子 1. is_uploaded_file() 例子


<?php
 
if (is_uploaded_file($_FILES['userfile']['tmp_name'])) {
   echo "File ". $_FILES['userfile']['name'] ." uploaded successfully.\n";
   echo "Displaying contents\n";
   readfile($_FILES['userfile']['tmp_name']);
} else {
   echo "Possible file upload attack: ";
   echo "filename '". $_FILES['userfile']['tmp_name'] . "'.";
}
 
?>

is_uploaded_file() 仅可用于 PHP 3 的 3.0.16 版之后，以及 PHP 4 的 4.0.2 版之后。如果你执意要用老版本，可以用下面的函数来保护自己：

注: 以下例子不能用于 PHP 4 的 4.0.2 版之后。它依赖的 PHP 内部函数在该版本之后改变了。

例子 2. is_uploaded_file() 可运行于 PHP 4 < 4.0.3 的例子


<?php
/* Userland test for uploaded file. */
function is_uploaded_file($filename)
{
    if (!$tmp_file = get_cfg_var('upload_tmp_dir')) {
        $tmp_file = dirname(tempnam('', ''));
    }
    $tmp_file .= '/' . basename($filename);
    /* User might have trailing slash in php.ini... */
    return (ereg_replace('/+', '/', $tmp_file) == $filename);
}

/* This is how to use it, since you also don't have
 * move_uploaded_file() in these older versions: */
if (is_uploaded_file($HTTP_POST_FILES['userfile'])) {
    copy($HTTP_POST_FILES['userfile'], "/place/to/put/uploaded/file");
} else {
    echo "Possible file upload attack: filename '$HTTP_POST_FILES[userfile]'.";
}
?>

参见 move_uploaded_file()，以及文件上传处理一章中的简单使用例子。

add a note User Contributed Notes

alexandre at plennevaux dot be
04-Nov-2006 10:22


A very helpful upload class is available at verot.net



http://www.verot.net/php_class_upload.htm



Hope this helps



Alexandre Plennevaux

tejas at kaushalam dot com
29-Mar-2006 03:28


<FORM ENCTYPE="multipart/form-data" ACTION="_URL_" METHOD=POST>

Upload this file: <INPUT NAME="userfile" TYPE="file">

<INPUT TYPE="submit" VALUE="Send File"></FORM>



This html code will display a text area with file upload button. The form tag is bit different than the normal form tag used ( see the encrypte =).



Now let us go to the php part to handle the uploaded file. We have In PHP 3, the following variables will be defined within the destination script upon a successful upload, assuming that register_globals is turned on in php3.ini. If track_vars is turned on, they will also be available in PHP 3 within the global



array $HTTP_POST_VARS. Note that the following variable names assume the use of the file upload name 'userfile', as used in the example above:



    * $userfile - The temporary filename in which the uploaded file was stored on the server machine.

    * $userfile_name - The original name or path of the file on the sender's system.

    * $userfile_size - The size of the uploaded file in bytes.

    * $userfile_type - The mime type of the file if the browser provided this information. An example would be "image/gif". 



With all these info we will make our script ready to handle the files.

Let us check the file size and we will not allow file size more than 250 KB to get uploaded to our server. Here we are using a flag $file_upload to false for processing the file upload.



if ($userfile_size >250000){$msg=$msg."Your uploaded file size is more than 250KB so please reduce the file size and then upload. Visit the help page to know how to reduce the file size.<BR>";

$file_upload="false";}



Now let us check the file extension and only jpg or gif file pictures we will allow into our server. We will check this by using $userfile_type extension



if (!($userfile_type =="image/pjpeg" OR $userfile_type=="image/gif")){$msg=$msg."Your uploaded file must be of JPG or GIF. Other file types are not allowed<BR>";

$file_upload="false";}

We will limit ourselves to these two type checks and if we find our $file_upload variable is not "false" then we can upload the file. This part is very simple in PHP and can be done in one step. Before that let us decide the file directory name where we will be placing the file. $add is the path with the file name relative to the script running this code where the uploaded file will be stored.



$add="upload/$userfile_name"; // the path with the file name where the file will be stored, upload is the directory name.



Now let us copy the file to server. The command move_uploaded_file will does that job for us and if the action is successful then it will return true.



if(move_uploaded_file ($userfile, $add)){

// do your coding here to give a thanks message or any other thing.

}else{echo "Failed to upload file Contact Site admin to fix the problem";}

Thats all... the file is placed in our directory (name: upload)

YLearn
11-Oct-2005 01:42


Just looked at what I posted again and found several mistakes of the major and minor sort.  That's what I get for posting before I finish my coffee.  This should work better (i.e. should work in the first place):



<?php

   default: //a default error, just in case!  :)

       echo "There was a problem with your upload.";

       $err_msg = "Unrecognized file POST error: ".$HTTP_POST_FILES['userfile']['error'];

       if (!(strpos($err_msg, "\n") === false)) {

           $err_lines = explode("\n", $err_msg);

           foreach ($err_lines as $msg) {

               error_log($msg, 0);

           }

       } else {

           error_log($err_msg, 0);

       }

       break;

?>

YLearn
11-Oct-2005 12:41


Regarding topcat's suggested change, I am split on doing that.  I don't like showing users errors that may give them more information than they should have (or show that I haven't provided for that particular error).  But I want to know when there are errors that fall to the default case so I can fix my code.  What I will typically do is write them to the error log something like this modification to metaltoad's post (takes into account the possibility of multi-line errors which error_log doesn't handle well):



<?php

    default: //a default error, just in case!  :)

        echo "There was a problem with your upload.";

        $err_msg = "Unrecognized file POST error: ".$HTTP_POST_FILES['userfile']['error'];

        if ((strpos($err_msg, "\n") === 0) {

            $err_lines = explode("\n", $err_msg);

            foreach ($err_lines as $msg) {

                error_log($msg, 0);

            }

        } else {

            error_log($err_msg, 0)

        }

        break;

?>

juk
19-Sep-2005 06:26


If your $_FILES and $_POST are empty, this can be due to

- the limit set by post_max_size in php.ini

- the limit set by upload_max_filesize in php.ini



Unfortunately the first limit is not reported back as an error code in $_FILES['error'].

topcat
14-Jul-2005 07:56


Just a little tip to info at metaltoad's comment:

It's good practice to print error code when it can't be recognized:



   default: //print the error code

     echo "Unrecognized error code: ".$HTTP_POST_FILES['userfile']['error'];

     break;

24-Apr-2005 03:29


make use u got the enctype="multipart/form-data" in ur form tag otrherwise nothing works... took me two hours to find that out.......

beer UNDRSCR nomaed AT hotmail DOT com
15-Apr-2005 07:21


Regarding the comment of info at metaltoad dot net

@ 19-Feb-2003 04:03



<?php

// ... yada yada yada...

preg_match("/.exe$|.com$|.bat$|.zip$|.doc$|.txt$/i", $HTTP_POST_FILES['userfile']['name']))

// ... yada yada yada...

?>



This will not work. It will, but not correctly.

You shuld escape the . (dot) for the preg function,

and escape the $ (dollar) sign for PHP, or use

single-quoted string...



The syntax should be (much shorter and neater):



<?php

// ... yada yada yada...

preg_match('/\\.(exe|com|bat|zip|doc|txt)$/i', $_FILES['userfile']['name']))

// ... yada yada yada...

?>

lots2learn at gmail dot com
07-Feb-2005 01:13


if files are not getting uploaded and $_FILE array is empty ..and your code looks fine..then check php.ini file..the file_uploads option should be turned 'On' to allow file uploads. Turn it on and restart apache to have effect .

Gordon Luk
05-Oct-2004 06:55


If the $_FILES array suddenly goes mysteriously empty, even though your form seems correct, you should check the disk space available for your temporary folder partition. In my installation, all file uploads failed without warning. After much gnashing of teeth, I tried freeing up additional space, after which file uploads suddenly worked again.

vbudov_yahoo.com
22-May-2004 07:58


Before moving the file in to place it's also a good idea to check if file with the same name already exists on the server.

If file exists then create unique name for the new file.



$num=1;

while (file_exists($destination)){     

    $num++; // if previous file name existed then thy another number+_+filename                                                                                                       

    $file_name = $num."_".$_FILES['userfile']['name'];

    $destination = $uploadpath.$file_name;

}                                                                                                                                   

move_uploaded_file( $source, $destination );

phpnetmark at nunswithguns dot co dot uk
17-Apr-2003 01:53


If you are importing the uploaded file into a BLOB field in a mysql database and you are using LOAD_FILE() sql statement then be aware that  mysql checks max-allowed-packet mysql variable. 



- if the size of the binary file LOAD_FILE is importing is bigger than

max-allowed-packet size then it LOAD_FILE will return null. 



You can specify max-allowed-packet size in the call to mysqld eg: 



./bin/safe_mysqld --user=mysql --max-allowed-packet=16M &



Full info on this variable is available here: 

http://www.mysql.com/doc/en/Packet_too_large.html

info at metaltoad dot net
20-Feb-2003 05:03


As of PHP 4.2.0, rather than automatically assuming a failed file uploaded is a file attack, you can use the error code associated with the file upload to check and see why the upload failed.  This error code is stored in the userfile array (ex: $HTTP_POST_FILES['userfile']['error']). 



Here's an example of a switch:



if (is_uploaded_file($userfile)) {

  

  //include code to copy tmp file to final location here...

  

}else{

  switch($HTTP_POST_FILES['userfile']['error']){

    case 0: //no error; possible file attack!

      echo "There was a problem with your upload.";

      break;

    case 1: //uploaded file exceeds the upload_max_filesize directive in php.ini

      echo "The file you are trying to upload is too big.";

      break;

    case 2: //uploaded file exceeds the MAX_FILE_SIZE directive that was specified in the html form

      echo "The file you are trying to upload is too big.";

      break;

    case 3: //uploaded file was only partially uploaded

      echo "The file you are trying upload was only partially uploaded.";

      break;

    case 4: //no file was uploaded

      echo "You must select an image for upload.";

      break;

    default: //a default error, just in case!  :)

      echo "There was a problem with your upload.";

      break;

}



Additionally, by testing the 'name' element of the file upload array, you can filter out unwanted file types (.exe, .zip, .bat, etc).  Here's an example of a filter that can be added before testing to see if the file was uploaded:



//rejects all .exe, .com, .bat, .zip, .doc and .txt files

if(preg_match("/.exe$|.com$|.bat$|.zip$|.doc$|.txt$/i", $HTTP_POST_FILES['userfile']['name'])){

  exit("You cannot upload this type of file.");

}



//if file is not rejected by the filter, continue normally

if (is_uploaded_file($userfile)) {



/*rest of code*/

itadmin at itmusicweb dot co dot uk
28-Nov-2002 10:11


The example brought out does not work as supposed to:



function is_uploaded_file($filename) {

    if (!$tmp_file = get_cfg_var('upload_tmp_dir')) {

        $tmp_file = dirname(tempnam('', ''));

    }

    $tmp_file .= '/' . basename($filename);

    /* User might have trailing slash in php.ini... */

    return (ereg_replace('/+', '/', $tmp_file) == $filename);

}



It works only with files under ....4 or 5 kb, other files automatically get the size of 0 bytes. So something must be wrong here. Built-in is_uploaded_file() works good.

troels at NO dot SPAM dot webcode dot dk
15-Oct-2002 03:44


to get the example to work on windows, youll have to add a line, that replaces backslashes with slashes. eg.: $filename = str_replace ("\\", "/", $filename);



also, as someone mentioned, globalizing $HTTP_POST_FILES is a good idea ...



<pre>

/* Userland test for uploaded file. */

function is_uploaded_file($filename)

{

    global $HTTP_POST_FILES;

    if (!$tmp_file = get_cfg_var("upload_tmp_dir")) {

        $tmp_file = dirname(tempnam("", ""));

    }

    $tmp_file .= "/" . basename($filename);

    /* User might have trailing slash in php.ini... */

    // fix for win platform

    $filename = str_replace ("\\", "/", $filename);

    return (ereg_replace("/+", "/", $tmp_file) == $filename);

}

</pre>

r3gan at hotmail dot com
18-Jun-2002 03:24


Remeber, if using $HTTP_POST_FILES inside a function and it doesn't seem to work, try globalizing the array:



function UploadFile() {



    global $HTTP_POST_FILES;



    // rest of your code here



}  // end UploadFile

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