Handle symlinking edge cases

[withinboredom]

This one is interesting — though I’m not sure the best way to provide a test. I will have to look into maybe an integration test because it is a careful dance between how we resolve paths in the Caddy module vs. workers. I looked into making a proper change (literally using the same logic everywhere), but I think it is best to wait until #1646 is merged.

But anyway, this change deals with some interesting edge cases. I will use gherkin to describe them:

Feature: FrankenPHP symlinked edge cases
  Background: 
    Given a `test` folder
    And a `public` folder linked to `test`
    And a worker script located at `test/index.php`
    And a `test/nested` folder
    And a worker script located at `test/nested/index.php`
  Scenario: neighboring worker script
    Given frankenphp located in the test folder
    When I execute `frankenphp php-server --listen localhost:8080 -w index.php` from `public`
    Then I expect to see the worker script executed successfully
  Scenario: nested worker script
    Given frankenphp located in the test folder
    When I execute `frankenphp --listen localhost:8080 -w nested/index.php` from `public`
    Then I expect to see the worker script executed successfully
  Scenario: outside the symlinked folder
    Given frankenphp located in the root folder
    When I execute `frankenphp --listen localhost:8080 -w public/index.php` from the root folder
    Then I expect to see the worker script executed successfully
  Scenario: specified root directory
    Given frankenphp located in the root folder
    When I execute `frankenphp --listen localhost:8080 -w public/index.php -r public` from the root folder
    Then I expect to see the worker script executed successfully    

Trying to write that out in regular English would be more complex IMHO.

These scenarios should all pass now with this PR.

[AlliBalliBaba]

I like it 👍 explicitly checking if a worker exists is something I actually wanted to do for a long time

[AlliBalliBaba]

Or wait, evalSymlinks will just evaluate symlinks. In that case it would also be nice to error right away if there's no file there. Can also be done in another PR though

[withinboredom]

it errors if the file doesn't exist (I had to update a failing test -- haven't pushed the commit yet)

[AlliBalliBaba]

Not checking for symlinks here seems like it might break some setups. Definitely would be nice to test all the edge cases somehow (should be possible with caddy_tests?).

Tbh though, I don't know what the current edge cases with symlinks are

[withinboredom]

I’m pretty sure we don’t want to evaluate symlinks here. In the case where a document root was expressly given (such as prod setups), we will never even enter this branch. In the case where a document root isn’t given, we need to be compatible with how we resolve workers. There is an edge case here that I didn’t cover, and I’m working out how to handle it: chained symlinks.

I suspect I’ll have to go back to the drawing board.

[henderkes]

do the edge cases only affect workers, not regular php requests?

[dunglas]

Suggested change

	//If we do not have a resolved document root, then we cannot resolve the symlink of our cwd because it may
	//resolve to a different directory than the one we are currently in.
	//This is especially important if there are workers running.
	// If we do not have a resolved document root, then we cannot resolve the symlink of our cwd because it may
	// resolve to a different directory than the one we are currently in.
	// This is especially important if there are workers running.

[dunglas]

Suggested change

	//Order is important!
	//This order ensures that FrankenPHP started from inside a symlinked directory will properly resolve any paths.
	//If it is started from outside a symlinked directory, it is resolved to the same path that we use in the Caddy module.
	// Order is important!
	// This order ensures that FrankenPHP started from inside a symlinked directory will properly resolve any paths.
	// If it is started from outside a symlinked directory, it is resolved to the same path that we use in the Caddy module.

[withinboredom]

@henderkes yes, only workers. I should have a nice test suite this weekend. Manually testing this is annoying.