Loading assets by path is not working

[koertho]

Hi. First of all, thanks for this library. It worked for me wonderfull with images and external css files when using remote_enabled.

But here comes my problem: in our company we have a development setup, where we couldn't load the resources like this, so I hoped to reference the images and css files by path from the local file system. But I always get Image not found or type unknown (for images). The same images works if remote is enabled, so there seems to be a path problem.

Here is a testing code, none of the images is working:

$options = new Options();
$options->setChroot('/home/dev/Kunden/.../produkte/contao');
$dompdf = new Dompdf();
$dompdf->loadHtml('<p>hello world</p>
<img src="files/media/news/partner-logos/image.png">
<img src="file://files/media/news/partner-logos/image.png">
<img src="/home/dev/Kunden/.../produkte/contao/files/media/news/partner-logos/image.png">
<img src="/home/dev/Kunden/.../produkte/contao/web/files/media/news/partner-logos/image.png">
<img src="file:///home/dev/Kunden/.../produkte/contao/files/media/news/partner-logos/image.png">
<img src="file:///home/dev/Kunden/.../produkte/contao/web/files/media/news/partner-logos/image.png">
');
 
$dompdf->setPaper('A4');
$dompdf->render();
$dompdf->stream('file', ['Attachment' => 0]);

Explanation: I tested relative and absolute path. The files within the web folder are symlinked.
I also tried the setProtocol and setBasePath options, but they are not working (they are reseted within the code before the image processing starts).

Options (before calling the stream method):

rootDir = "/home/dev/Kunden/.../produkte/contao/vendor/dompdf/dompdf"
tempDir = "/tmp"
fontDir = "/home/dev/Kunden/.../produkte/contao/vendor/dompdf/dompdf/lib/fonts"
fontCache = "/home/dev/Kunden/.../produkte/contao/vendor/dompdf/dompdf/lib/fonts"
chroot = {array} [1]
    0 = "/home/dev/Kunden/.../produkte/contao"
logOutputFile = "/tmp/log.htm"
defaultMediaType = "screen"
defaultPaperSize = "letter"
defaultPaperOrientation = "portrait"
defaultFont = "serif"
dpi = {int} 96
fontHeightRatio = {float} 1.1
isPhpEnabled = false
isRemoteEnabled = false
isJavascriptEnabled = true
isHtml5ParserEnabled = false
isFontSubsettingEnabled = true
debugPng = false
debugKeepTemp = false
debugCss = false
debugLayout = false
debugLayoutLines = true
debugLayoutBlocks = true
debugLayoutInline = true
debugLayoutPaddingBox = true
pdfBackend = "CPDF"
pdflibLicense = ""

I also don't want to base64 encode the images, as also css files not working, I hope for a better solution. Do you have an idea where I go wrong?

Dompdf 1.0.2
PHP 7.4.16

[bsweeney]

At a high level this looks OK. Just to confirm the basic requirements: do you have the GD extension enabled and does the running script has read/write access to the tmp directory?

Have you tried a JPG image? Those can be inserted into the PDF without any extra processing.

[koertho]

I will look into your questions in the next days, but I can confirm the same images have worked when I used the remote option, so Gd and tmp should work.
When I used phpunit to debug, I stumbled over this line, where the protocol is always http, even if remote is disabled and there is no http in the file path (as shown above):

dompdf/src/Image/Cache.php

Line 68 in 0ccafeb

$remote = ($protocol && $protocol !== "file://") || ($parsed_url['protocol'] != "");

[fd6130]

I think it is better to have a dev server so you could load your assets from there instead, as a workaround.

[koertho]

Hi, now I'm able to answer your questions:
GD library is installed in version 2.3.0.
Script has read/write access to tmp folder
I also tried with jpg image, same result.

I think it is better to have a dev server so you could load your assets from there instead, as a workaround.

Sure, load the images from another server would be possible. But that would not solve the problem that loading images from paths not work (which is IMHO a bug of this library) and would lead to the point that dompdf is hard to use in a reusable way for multi project extensions.

[koertho]

Hi, I've digged a little deeper on this topic.
My problem described above was due symlinks resolved by the library and the real paths weren't in the chroot. Is realpath real needed here?

dompdf/src/Image/Cache.php

Line 126 in 0ccafeb

$realfile = realpath($resolved_url);

If I add the symlinked path, it works with image also with remote set to false. But then I have problems with the base tag and external css files. If I set a base tag, images won't work again, but css files work. Without a base tag images work, but css files won't.
Image won't work with a base tag cause the protocol is set here, if a base tag is defined:

dompdf/src/Dompdf.php

Line 607 in 0ccafeb

[$this->protocol, $this->baseHost, $this->basePath] = Helpers::explode_url($href);

This lead to an error in combination with remote disabled here:

dompdf/src/Image/Cache.php

Line 68 in 0ccafeb

$remote = ($protocol && $protocol !== "file://") || ($parsed_url['protocol'] != "");

dompdf/src/Image/Cache.php

Line 77 in 0ccafeb

if (!$enable_remote && $remote && !$data_uri) {

But without a base tag, css files are not loaded correctly from filesystem cause the library tries to get the real path from the relative path of the filesystem here:

dompdf/src/Css/Stylesheet.php

Line 372 in 0ccafeb

$realfile = realpath($file);

[sandreas]

I have the exact same issue. In my opinion this is a bug in the Cache::resolve_url method.

This check:

dompdf/src/Image/Cache.php

Line 129 in 0ccafeb

if (strpos($realfile, $rootDir) !== 0) {

leads to an exception showing the "image not found" error in PDF files, if the file is locally referenced, because it is pretty likely not in the root path if the library installation.

If I just skip this check, everything seems to work fine. I don't understand what it's all about with chroot and in which case the check should make sense, but it does prevent rendering images referenced locally.

Even worse, since this is a static call, I did not find a way to overcome this issue by adding some options, extending classes or even override autoloading to use my own class instead of \Dompdf\Image\Cache...

[rezaf-dev]

I have the same problem. If I add the image path to chroot option, it works.

$options = new Options();
$options->setChroot(['/user/home/public/img/']);
$dompdf->setOptions($options);

[drelich]

@rezaf-dev You, sir, are my hero! I was having a problem with my PHP app, it wouldn't load a logo no matter what path I used. Setting the root to / has solved my issue. Thanks so much!

[roberthenniger]

@bsweeney I am dealing with the same issue. We are using always fully qualified realpaths for our assets and they do not get loaded. I was now setting the root to "/" which solved my issue but should the fully qualified path not override the root setting? Is this a security concern or why is it handled like this?

[bsweeney]

@roberthenniger I don't quite follow? Are you saying you set the chroot option to "/"? The paths you specify for your assets, fully qualified or not, once the path is normalized should fall under the paths specified for the chroot option. So if your path is something like "/path/to/assets/image.png" then you could set you your chroot option to "/path/to/assets".

[bsweeney]

Closing this issue since the problem resolution is to set the chroot option with all the potential local paths for asset references.