Fix issue 24549 - std.process.environment.get(null) segfaults

[schveiguy]

The true fix I think would b to make it so tempCString never returns null (it doesn't make a lot of sense). But the code was clearly intended to work this way, and was set up because of a long ago regression.

Even if that problem is eventually fixed, this fix is not invalidated.

[dlang-bot]

Thanks for your pull request, @schveiguy!

Bugzilla references

Auto-close	Bugzilla	Severity	Description
✓	24549	normal	std.process.environment.get(null) segfaults

Testing this PR locally

If you don't have a local development environment setup, you can use Digger to test this PR:

dub run digger -- build "stable + phobos#9002"

[CyberShadow]

Would it more correct to do something like if (!name) name = ""; ?

[Geod24]

Won't this lead to a different behavior between get(null) and get("") ?

[schveiguy]

Would it more correct to do something like if (!name) name = ""; ?

I think in this case, it doesn't matter -- I don't think an empty string is a valid environment variable name.

[Geod24]

I don't think an empty string is a valid environment variable name.

Yes, but the distinction between empty string and null is a common gotcha.

[schveiguy]

There are many ways to solve this. I think if we are going to do a check for null anyway, we might as well circumvent the entire process. Why call an opaque C function when we know it's going to return "variable not found"?

[schveiguy]

All green now. Would be nice to get this in the next release...