Fix issue 21113: Use sysctl for thisExePath on BSD.

[euantorano]

Fixes issue 21113.

I'm quite new to D, and wasn't sure if there's a way to do a condition inside a version, like the following:

version (FreeBSD || NetBSD || DragonFlyBSD) {}

Which would make some of this code slightly cleaner in my opinion.

Sysctl numbers are taken from relevant headers:

• FreeBSD
• NetBSD
• DragonFlyBSD

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Bugzilla references

Auto-close	Bugzilla	Severity	Description
✓	21113	enhancement	std.file.thisExePath on NetBSD depends upon the /proc filesystem

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 "master + phobos#7578"

[thewilsonator]

version (FreeBSD || NetBSD || DragonFlyBSD) {}

No, the way you have done it is the intended way. Forcing giving a name to the version gives documentation and forces you to think about the versioning logic, i.e. not making arbitrary combinations.

[euantorano]

version (FreeBSD || NetBSD || DragonFlyBSD) {}

No, the way you have done it is the intended way. Forcing giving a name to the version gives documentation and forces you to think about the versioning logic, i.e. not making arbitrary combinations.

Ah, ok. That makes sense, thanks!

[thewilsonator]

The linked netBSD has #define KERN_PROC_PATHNAME 5 not 9

[euantorano]

The linked netBSD has #define KERN_PROC_PATHNAME 5 not 9

        version (NetBSD)
        {
            enum
            {
                KERN_PROC_ARGS = 48,
                KERN_PROC_PATHNAME = 5
            }

            int[4] mib = [CTL_KERN, KERN_PROC_ARGS, -1, KERN_PROC_PATHNAME];
        }

I think you might be misreading the else which applies to DragonFlyBSD. It's a little confusing because of the nesting of versions.

[thewilsonator]

Oh right, I stand corrected.