How to require an specific OS

[macintoshplus]

The Win32Service PHP extension can be built and used only on the Microsoft Windows operating system.

How to specify this constraint on composer.json file?

[asgrim]

Not possible at the moment, but something we can look into 👍

[alexandre-daubois]

I'd be interested in having a look at this feature! What about the following syntax?

{
    "name": "myvendor/myext",
    "php-ext": {
        "extension-name": "myext",
        "configure-options": [
            // ...
        ],
        "os-families": ['Windows', 'Darwin'] // not compatible with Linux here for example
    }
}

The values contained in os-families would have to match PHP_OS_FAMILY.

Also, it would be possible to use the wildcard, like "os-families": ["*"] (or "os-families": "*"?) if one wants to be explicit on supporting all operating systems.

[Seldaek]

I think it'd be good to have a way to negate something if you want to closely match PHP_OS_FAMILY, because I suspect most things are gonna be Windows-only, Linux/BSD/Solaris/Darwin-only, or everything. I don't think there are many that support everything except Solaris or everything except BSD.

So it could be nicer with ["!Windows"] or something? I'm just thinking it would suck if people list Linux and forget to include BSD/Solaris/Darwin and then things turn out not installable for no good reason.

Another possible syntax would be "os-families-exclude": ["Windows"]

[alexandre-daubois]

I agree with you, by reading at your comment it feels more natural to me to work with a blacklist instead of a whitelist. Also it saves us from handling the wildcard. I'd rather use os-families-exclude instead of the bit-less explicit ! operator indeed.

[asgrim]

Some examples for reference:

only Win:

"os-families-exclude": ["BSD", "Darwin", "Solaris", "Linux", "Unknown"]

only non-Win:

"os-families-exclude": ["Windows"]

only OSX:

"os-families-exclude": ["Windows", "BSD", "Solaris", "Linux", "Unknown"]

[Seldaek]

So what I was suggesting is to include BOTH options sorry it was clearly not clear :D

only Win:

"os-families": ["Windows"]

only non-Win:

"os-families-exclude": ["Windows"]

only OSX:

"os-families-exclude": ["Darwin"]

That way you can target whatever you want with the least amount of listing-distros and possibly forgetting things.

Obviuosly the "Unknown" wildcard is a bit problematic here.. But I guess those fall in the category of "rather just allow it and see if it builds 🤷🏻‍♂️ "?

[alexandre-daubois]

I'm fine accepting both keys, I agree it's more flexible because I guess you'll either exclude only one OS or allow only one in most cases actually.

About the "Unknown" value, I also think we shouldn't get too worked up about it and we shouldn't do anything special for it. Let's just wait for someone to raise an issue if there's something wrong 😄

[macintoshplus]

I’m okay to use both keys. The wildcard or “Unknown” is not necessary.

If the extension maintainer wants to exclude the unknown OS, it must list all included OS.

If the extension maintainer wants to include “unknown” it uses the exclude key or nothing.

IMO it’s necessary to make an exhaustive list of OS names used in the lists.

[asgrim]

IMO it’s necessary to make an exhaustive list of OS names used in the lists.

This list is already defined: https://www.php.net/manual/en/reserved.constants.php#constant.php-os-family

That list is where Unknown comes from.

One thing that should be defined is the behaviour if both keys are used, a few examples:

{
  "php-ext": {
    "os-families": ["Windows"],
    "os-families-exclude": ["Windows"]
  }
}

{
  "php-ext": {
    "os-families": ["Windows", "Linux"],
    "os-families-exclude": ["Linux"]
  }
}

I would suggest that perhaps the most natural method for processing would be (pseudo-code):

allowedPlatforms = Windows BSD Darwin Solaris Linux Unknown

if "os-families" is specified: replace allowedPlatforms with the list

if "os-families-exclude" is specified: subtract from the allowedPlatforms

Therefore the results of my two examples:

• first one is not installable anywhere
• second one is only installable on Windows

[Seldaek]

I think I'd declare it in the json schema as being a oneOf, so that either key should be provided, but not both, and probably need to check in the loader code to throw if both are provided because this is nonsense, even if we can reconcile it per your rules, it's just clearer to disallow it IMO.

[asgrim]

That is probably safer 💯 👍

[macintoshplus]

Both keys are declared nonsense. However, the maintainer must check if the composer.json is valid before tagging the version.

A command validate must be added to help to validate the file.