Processing usage ?

[Distant_storm]

I plan to use this in a page as an example

 

header("image/png"); < or whaterver it is

imagefrompng("image.png");

 

ok now creating an image everytime a user see's the iamge or navigates to a new iamge. and destroying it after woudl this lay heavy on the server ?

 

This is to stop image pathnames from being revealed

[corbin]

So are you trying to read the file from disk or generate an image and spit it out?

 

If you're wanting to generate it, you could always cache it, and if you already have it on disk, the most effecient thing possible short of caching it in memory is just reading it out to the client.

[Distant_storm]

can you please give an example of reading it out to the user

[corbin]

$file = (isset($_GET['file'])) ? $_GET['file'] : false;
if($file === false || str_pos($file, '/') !== false || str_pos($file, '\\') !== false) exit; //if the file isn't given or it has / or \ die
if($handle = @fopen('files/' . $file) {
      while(!feof($handle)) {
           echo fread($handle, 8192); //read 8KB at a time
      }
}
else {
     //file not found or unable to open
}

 

The reason I would do it with fopen and fread there instead of file_get_contents is because with file_get_contents you load the entire file into PHP, and larger files could become cumbersome.

[Distant_storm]

Would this be put in a file with header type as image and then called like

 

<img src=make_image.php

 

also the paths are checked and so do i just use the full path of the file ?

[corbin]

OK....  Example time.

 

Pretend the following

 

Your web root is /html/

Your images are in /images/

Your wanting the file /images/image1.jpg

You're at the page http://yoursite.com/images.php?file=image1.jpg

 

To show /images/image1.jpg, images.php would need to look like this:

 

$file = (isset($_GET['file'])) ? $_GET['file'] : false;
if($file === false || str_pos($file, '/') !== false || str_pos($file, '\\') !== false) exit; //if the file isn't given or it has / or \ die
if($handle = @fopen('/images/' . $file) {
      header("Content-type: image/jpeg");
      while(!feof($handle)) {
           echo fread($handle, 8192); //read 8KB at a time
      }
}
else {
     //file not found or unable to open
}

 

So

<img src="images.php?file=image1.jpg" />

 

Would correctly show the content from /images/image1.jpg.

 

You would most likely want to make the Content-type change depending on the file extension by the way....

[corbin]

Grrr I think I had a brain lapse earlier...

 

All of the fopen's should have 'r' as their second argument.  (With the quotes)