Any way to generate random file name when uploading? - php

Question

I have created a website that uploads anything. The problem I have is that I'm new to all this. I have tried every code that generates random strings but I have nothing. Here is the code anyway:
<?php
$fileName = $_FILES["file1"]["name"]; // The file name
$fileTmpLoc = $_FILES["file1"]["tmp_name"]; // File in the PHP tmp folder
$fileType = $_FILES["file1"]["type"]; // The type of file it is
$fileSize = $_FILES["file1"]["size"]; // File size in bytes
$fileErrorMsg = $_FILES["file1"]["error"]; // 0 for false... and 1 for true
if (!$fileTmpLoc) { // if file not chosen
echo "ERROR: Please browse for a file before clicking the upload button.";
exit();
}
if(move_uploaded_file($fileTmpLoc, "uploads/$fileName")) {
echo '<a href="uploads/'.$fileName.'"><input type="button" class="button"
value="Download" /></a>';
} else {
echo "move_uploaded_file function failed";
}
?>
Could there be a way to generate random file names so that when someone uploads the same name as a file already on the server, it does not overwrite the existing file?

Answer 1

$fileName = "image_".uniqid();
The uniqid() function generates a unique ID based on the microtime
(current time in microseconds).
About uniqid function: http://www.php.net/manual/en/function.uniqid.php

Answer 2

You can use md5(microtime()) to get unique file name even you uploading more than one file at a time

Answer 3

you can use microtime time to make sure file name is unique.
$file_name = "custom_name_" . microtime();

Answer 4

Because a folder is limited to 65535 files, you need to create subfolders. This technique creates 3 subfolders (with 3 characters each) depending on the timestamp then creates a random filename.
For more randomness and future-proofness (because using time() and microtime() is weak if you have multiple users uploading at the same time) :
//Get the extension of the file
$fileExtension = end(explode(".", $_FILES['item']['name']));
$randOctalName = openssl_random_pseudo_bytes(5);
$randName = bin2hex($randOctalName).".".$fileExtension;
//Save it into uploads/123/456/789/
$path = "";
$timestamp = time();
$path = substr($timestamp,0,3)."/".substr($timestamp,3,3)."/".substr($timestamp,6,3)."/";
$relativePath = './uploads/'.$path;$timestamp = time();
$path = substr($timestamp,0,3)."/".ubstr($timestamp,3,3)."/".substr($timestamp,6,3)."/";
$relativePath = './uploads/'.$path;
_r_mkdir($relativePath);
And the mkdir recursive function :
private function _r_mkdir($path, $mode = 0755, $recursive = true)
{
if(empty($path)){
return false;
}
if($recursive) {
$toDo = substr($path, 0, strrpos($path, '/'));
if($toDo !== '.' && $toDo !== '..'){
_r_mkdir($toDo, $mode);
}
}
if(!is_dir($path)){
mkdir($path, $mode);
}
return true;
}

Answer 5

use the timestamp (or microtime), so you know it is necessarily different every time
$fileName = "image_".time();
TimeStamp
Returns the current time measured in the number of seconds since the Unix Epoch (January 1 1970 00:00:00 GMT).
Microtime
microtime() returns the current Unix timestamp with microseconds. This function is only available on operating systems that support the gettimeofday() system call.

Answer 6

//you can use both random and time function to get more unique no count:
$fileName = 'mypic'.mt_rand(100000, 999999).'_'.time(). $_FILES["file1"]["name"];
use are:-
mt_rand(100000, 999999)// for randm no.
time()// for timestring
$_FILES["file1"]["name"]//also you can give your file name

Answer 7

Study this code thoroughly. This is all you need.
<?php
if (isset($_FILES["avatar"]["name"]) && $_FILES["avatar"]["tmp_name"] != "")
{
$fileName = $_FILES["avatar"]["name"];
$fileTmpLoc = $_FILES["avatar"]["tmp_name"];
$fileType = $_FILES["avatar"]["type"];
$fileSize = $_FILES["avatar"]["size"];
$fileError = $_FILES["avatar"]["error"];
$kaboom = explode(".",$fileName);
$fileExt = end($kaboom);
list($width,$height) = getimagesize($fileTmpLoc);
if($width < 10 || $height < 10)
{
header("location: ../message.php?msg=ERROR: That image has no dimensions");
exit();
}
$db_file_name = rand(100000000000,999999999999).".".$fileExt;
if($fileSize > 5048576)
{
header("location: ../message.php?msg=ERROR: Your image file was larger than 1mb");
exit();
}
else if (!preg_match("/\.(gif|jpg|png)$/i", $fileName) )
{
header("location: ../message.php?msg=ERROR: Your image file was not jpg, gif or png type");
exit();
}
else if ($fileErrorMsg == 1)
{
header("location: ../message.php?msg=ERROR: An unknown error occurred");
exit();
}
$sql = "SELECT avatar FROM users WHERE username='$log_username' LIMIT 1";
$query = mysqli_query($db_conx,$sql);
$row = mysqli_fetch_row($query);
$avatar = $row[0];
if($avatar != "")
{
$picurl = "../user/$log_username/$avatar";
if (file_exists($picurl))
unlink($picurl);
}
$moveResult = move_uploaded_file($fileTmpLoc,"../user/$log_username/$db_file_name");
if ($moveResult != true)
{
header("location: ../message.php?msg=ERROR: File upload failed");
exit();
}
include_once("../php_includes/image_resize.php");
$target_file = "../user/$log_username/$db_file_name";
$resized_file = "../user/$log_username/$db_file_name";
$wmax = 200;
$hmax = 300;
img_resize($target_file, $resized_file, $wmax, $hmax, $fileExt);
$sql = "UPDATE users SET avatar='$db_file_name' WHERE username='$log_username' LIMIT 1";
$query = mysqli_query($db_conx, $sql);
mysqli_close($db_conx);
header("location: ../user.php?u=$log_username");
exit();
}
?>

Answer 8

try this
$now=date('d/m/y');
if(move_uploaded_file($fileTmpLoc, "uploads/$now.$fileName"))
it will add date infront of the filename