Can not write to temp directory

[PaulusMenheere]

Whenever I try to fill in a form using fillForm I get an error message stating
Error: Failed to open form data file: \n /tmp/php_pdftk_xfdf_uL6Hf2.xfdf\n No output created.
code:
$tempPdf = new \mikehaertl\pdftk\Pdf(__DIR__ . '/Mededelingsformulier_scheiding_2019_2.pdf'); $tempPdf->fillForm($arr = [ 'test' => 'test', ]); $tempPdf->saveAs(__DIR__ . '/tempfile.pdf'); $error = $tempPdf->getError(); $this->assertEquals('', $error);
All files are accessible, other functions work perfectly (getDataFileds, GenerateFdf)
I'm working with Laravel running on an updated Homestead vagrant instance using pdftk from a snap install.

[mikehaertl]

Hmm, sounds weird. I'd still assume a permission problem with /tmp. Can you have a look at vendor/mikehaertl/php-tmpfile/src/File.php? It's a simple helper that creates temporary files and auto-deletes them when done (See here: https://github.com/mikehaertl/php-tmpfile). If you can, you could modify this file on the fly and add some debug output (e.g. if the file is really written in the constructor, etc).

[PaulusMenheere]

I saw the file allready created in the /tmp folder. However: the command failed.
If I use the CLI of pdftk using the /tmp/path it failed too. So I assumed the xfdf was wrongly generated. if I copy the generated file out of the /tmp folder it works.... on the Commandline

[mikehaertl]

Well, can you inspect the file? XFDF is an XML format, thus text based.

[PaulusMenheere]

Yup, I even copied the executed command generated on /vendor/mikehaertl/php-shellcommand/src/Command.php:321
using the xfdf in the /tmp - Error
using the xfdf outside the /tmp - works as a charm

[mikehaertl]

Sorry, misread your answer. So it seems, that when executing pdftk from PHP it has no permission to access the /tmp file. This is not the same like "PHP has no permission". It's rather "A shell process, started from PHP has no permission". I remember something like this with selinux or something.

Sorry, I can't help you much more here. You should try to find out, what permission restrictions are active on the system. Also maybe do some tests with exec() or proc_open() like ls -l /tmp/xyz.xfdf and see if that command works.

[PaulusMenheere]

Okay, I now know what the error is.
pdftk is a bit outdated. I believe a version 3.0 is in the works using the open version of Java

However to install pdftk on a recent version of ubuntu is using snap. this will install it in a secure way so that it doesn't have access to the /tmp folder. That's why it's failing out of the box

sudo add-apt-repository ppa:malteworld/ppa
sudo apt update
sudo apt-get install pdftk 

This works. Maybe to put in your readme ? to avoid using the snaps (or you should rewrite parts of your code to generate fdf files outside of the /tmp folder

[mikehaertl]

Hmm, yeah, I'm also using the version from malteworld. I've added a note to the README.

[markstos]

I'm just noting that I also ran into the problem that pdftk-from-snap-is-failing because it can't access the temp directory.

[robmpreston]

Im having this issue now on the latest Homestead. Any ideas? Totally lost, /tmp seems to be writeable so I dont get the issue.

[markstos]

@robmpreston The issue is that the snap format improves safety and security by whitelisting filesystem access to particular directories. Apparently the snap package for pdftk lacks permission to create tmp files, badly breaking it. This assumes you are using the snap for pdftk.

[mikehaertl]

Would it help to make the temp directory configurable? Without looking at the code I think this is currently not so easy. I could add a feature that you can pass options to the underlying https://github.com/mikehaertl/php-tmpfile .

[PaulusMenheere]

Im having this issue now on the latest Homestead. Any ideas? Totally lost, /tmp seems to be writeable so I dont get the issue.

I've copied a part of my after.sh script of my homestead installation. might provide you with a start to a solution...

#!/bin/sh

# If you would like to do some extra provisioning you may
# add any commands you wish to this file and they will
# be run after the Homestead machine is provisioned.

if [ ! -f /usr/local/extra_homestead_software_installed ]; then
	echo 'installing some extra software'

    sudo locale-gen nl_NL nl_NL.utf8

    sudo snap install pdftk
    sudo ln -s /snap/pdftk/current/usr/bin/pdftk /usr/bin/pdftk
    
    
    touch /usr/local/extra_homestead_software_installed
else    
    echo "extra software already installed... moving on..."
fi