simple php copy function always retuns an error

Question

I've been through this code several times and still can't see what's wrong. This code is the contents of [url]/sig/index.php. Every time I run it, I get "Sorry there was an error". But when I check the values of the new and old files I'm trying to copy they're fine. Am I doing something stupid? I'm using the copy function in other pages on the same server so I'm sure it must be something wrong with the code.

This is a simple page to copy a file in the same directory, overwriting the previous file. I know the source files exist because I have a "Test link to source file" that always works.

<?php

$formval = $_POST["banners"] ;
$newname = "banner-main.png" ;
$dir = "/sig/" ;

$img_to_copy = $dir . $formval . ".png" ;
$newimg =  $dir . $newname ;



if (copy($img_to_copy, $newimg)) {
        echo ($formval . " is the new email signature image.") ;
    } else {
        echo "Sorry, there was an error.";
        } ;

echo '<a href="' . $img_to_copy . '?var=' . rand(0,1000000) . '" target="_blank">Test link to source file</a>' ;

?> 



<h1>Which banner is next?</h1>

<br>

      <form action="/sig/index.php" method="post">
         <input type="radio" name="banners" value="banner-1">Banner 1
         <br>
         <input type="radio" name="banners" value="banner-2">Banner 2
         <br>
         <input type="radio" name="banners" value="banner-3">Banner 3
         <br>
         <input type="radio" name="banners" value="banner-4">Banner 4
         <br>
         <input type="submit" value="Submit">
      </form>

Answer 1

Most likely the cause of your problem is $dir = "/sig/" you have there.

When viewing the file (in HTML) this uses the folder sig/ from the web server DocumentRoot of your domain/project.

When copying this will use the folder sig/ from your filesystem root (where the file doesn't exist).

Change $dir = "/sig/" to $dir = "./sig/" or use a full filesystem path when copying the file.