Add support for NetBSD

[0-wiz-0]

PureGo Version

6cd1224

Operating System

• Windows
• macOS
• Linux
• FreeBSD
• Android
• iOS

Go Version (go version)

1.21.10

What steps will reproduce the problem?

I wanted to track down a build problem in an older version, but started with building main, and it didn't build:

$ go121  build .                                                                                                                                                                                                   # github.com/ebitengine/purego
./struct_amd64.go:12:46: undefined: syscall15Args

What is the expected result?

Successful build.

What happens instead?

see above.

Anything else you feel useful to add?

That's on NetBSD/amd64.

[TotallyGamerJet]

NetBSD isn't supported so this is a feature request?

[0-wiz-0]

I have no idea if that version did anything, but since 0.5.0 built on NetBSD I thought it was a regression.
Yes, please, let's make this a feature request then :)

[0-wiz-0]

I have started adding the dlfcn_* code for NetBSD based on the FreeBSD one here, but that still fails to build with

./struct_amd64.go:12:46: undefined: syscall15Args

and I have no idea what to do about that.

[TotallyGamerJet]

and I have no idea what to do about that.

You have to add netbsd to the build tag in syscall.go

[TotallyGamerJet]

I have no idea if that version did anything, but since 0.5.0 built on NetBSD I thought it was a regression.

We probably added build tags to ensure that only the supported platforms actually build which we were missing before.

[0-wiz-0]

I've added netbsd to three files but I got a missing syscall15X and now missing runtime_cgocall and numOfIntegerRegisters. Does the current version work on FreeBSD?
I'm out of my depth hear.

[TotallyGamerJet]

You are just missing build tags. Add netbsd to the //go:build at the top of the files

[0-wiz-0]

Ok, adding lots of tags makes it build. Yay! I've pushed them to my fork.

go test reports:

# github.com/ebitengine/purego
package github.com/ebitengine/purego_test
        imports github.com/ebitengine/purego/internal/load: build constraints exclude all Go files in /archive/foreign/purego-fork/internal/load
FAIL    github.com/ebitengine/purego [setup failed]

[0-wiz-0]

I've added the netbsd tag to the libc example and tried to run it, but:

./libc
fatal error: cgocall nil

goroutine 1 [running]:
runtime.throw({0x48a7c6?, 0x1?})
        /usr/pkg/go121/src/runtime/panic.go:1077 +0x5c fp=0xc0000cd4a8 sp=0xc0000cd478 pc=0x4304dc
runtime.cgocall(0x0?, 0xc000014160?)
        /usr/pkg/go121/src/runtime/cgocall.go:130 +0xc5 fp=0xc0000cd4e0 sp=0xc0000cd4a8 pc=0x4045a5
github.com/ebitengine/purego.RegisterFunc.func4({0xc0000c4390?, 0x2?, 0x2?})
        /archive/foreign/purego-fork/func.go:319 +0xc5f fp=0xc0000cd960 sp=0xc0000cd4e0 pc=0x46eadf
reflect.callReflect(0xc0000c4180, 0xc0000cdec0, 0xc0000cdd98, 0xc0000cdda0)
        /usr/pkg/go121/src/reflect/value.go:782 +0x54b fp=0xc0000cdd48 sp=0xc0000cd960 pc=0x46764b
reflect.callReflect(0xc0000c4180, 0xc0000cdec0, 0xc0000cdd98, 0xc0000cdda0)
        <autogenerated>:1 +0x45 fp=0xc0000cdd78 sp=0xc0000cdd48 pc=0x46b625
reflect.makeFuncStub()
        /usr/pkg/go121/src/reflect/asm_amd64.s:47 +0x6e fp=0xc0000cdec0 sp=0xc0000cdd78 pc=0x46b0ae
github.com/ebitengine/purego.Dlopen({0x48a100?, 0x404585?}, 0x4010cf?)
        /archive/foreign/purego-fork/dlfcn.go:37 +0x1f fp=0xc0000cdef8 sp=0xc0000cdec0 pc=0x46d6ff
main.openLibrary(...)
        /archive/foreign/purego-fork/examples/libc/main_unix.go:11
main.main()
        /archive/foreign/purego-fork/examples/libc/main.go:33 +0x29 fp=0xc0000cdf40 sp=0xc0000cdef8 pc=0x471109
runtime.main()
        /usr/pkg/go121/src/runtime/proc.go:267 +0x2bb fp=0xc0000cdfe0 sp=0xc0000cdf40 pc=0x432ebb
runtime.goexit()
        /usr/pkg/go121/src/runtime/asm_amd64.s:1650 +0x1 fp=0xc0000cdfe8 sp=0xc0000cdfe0 pc=0x45b941

goroutine 2 [force gc (idle)]:
runtime.gopark(0x0?, 0x0?, 0x0?, 0x0?, 0x0?)
        /usr/pkg/go121/src/runtime/proc.go:398 +0xce fp=0xc000084fa8 sp=0xc000084f88 pc=0x43330e
runtime.goparkunlock(...)
        /usr/pkg/go121/src/runtime/proc.go:404
runtime.forcegchelper()
        /usr/pkg/go121/src/runtime/proc.go:322 +0xb3 fp=0xc000084fe0 sp=0xc000084fa8 pc=0x433193
runtime.goexit()
        /usr/pkg/go121/src/runtime/asm_amd64.s:1650 +0x1 fp=0xc000084fe8 sp=0xc000084fe0 pc=0x45b941
created by runtime.init.6 in goroutine 1
        /usr/pkg/go121/src/runtime/proc.go:310 +0x1a

goroutine 3 [GC sweep wait]:
runtime.gopark(0x0?, 0x0?, 0x0?, 0x0?, 0x0?)
        /usr/pkg/go121/src/runtime/proc.go:398 +0xce fp=0xc000085778 sp=0xc000085758 pc=0x43330e
runtime.goparkunlock(...)
        /usr/pkg/go121/src/runtime/proc.go:404
runtime.bgsweep(0x0?)
        /usr/pkg/go121/src/runtime/mgcsweep.go:280 +0x94 fp=0xc0000857c8 sp=0xc000085778 pc=0x420954
runtime.gcenable.func1()
        /usr/pkg/go121/src/runtime/mgc.go:200 +0x25 fp=0xc0000857e0 sp=0xc0000857c8 pc=0x415b05
runtime.goexit()
        /usr/pkg/go121/src/runtime/asm_amd64.s:1650 +0x1 fp=0xc0000857e8 sp=0xc0000857e0 pc=0x45b941
created by runtime.gcenable in goroutine 1
        /usr/pkg/go121/src/runtime/mgc.go:200 +0x66

goroutine 4 [GC scavenge wait]:
runtime.gopark(0xc0000aa000?, 0x4a71e0?, 0x1?, 0x0?, 0xc0000071e0?)
        /usr/pkg/go121/src/runtime/proc.go:398 +0xce fp=0xc000085f70 sp=0xc000085f50 pc=0x43330e
runtime.goparkunlock(...)
        /usr/pkg/go121/src/runtime/proc.go:404
runtime.(*scavengerState).park(0x50c6c0)
        /usr/pkg/go121/src/runtime/mgcscavenge.go:425 +0x49 fp=0xc000085fa0 sp=0xc000085f70 pc=0x41e229
runtime.bgscavenge(0x0?)
        /usr/pkg/go121/src/runtime/mgcscavenge.go:653 +0x3c fp=0xc000085fc8 sp=0xc000085fa0 pc=0x41e7bc
runtime.gcenable.func2()
        /usr/pkg/go121/src/runtime/mgc.go:201 +0x25 fp=0xc000085fe0 sp=0xc000085fc8 pc=0x415aa5
runtime.goexit()
        /usr/pkg/go121/src/runtime/asm_amd64.s:1650 +0x1 fp=0xc000085fe8 sp=0xc000085fe0 pc=0x45b941
created by runtime.gcenable in goroutine 1
        /usr/pkg/go121/src/runtime/mgc.go:201 +0xa5

goroutine 5 [finalizer wait]:
runtime.gopark(0x0?, 0x0?, 0x0?, 0x0?, 0x0?)
        /usr/pkg/go121/src/runtime/proc.go:398 +0xce fp=0xc000086620 sp=0xc000086600 pc=0x43330e
runtime.runfinq()
        /usr/pkg/go121/src/runtime/mfinal.go:193 +0x107 fp=0xc0000867e0 sp=0xc000086620 pc=0x414b27
runtime.goexit()
        /usr/pkg/go121/src/runtime/asm_amd64.s:1650 +0x1 fp=0xc0000867e8 sp=0xc0000867e0 pc=0x45b941
created by runtime.createfing in goroutine 1
        /usr/pkg/go121/src/runtime/mfinal.go:163 +0x3d

[TotallyGamerJet]

Ok, adding lots of tags makes it build. Yay! I've pushed them to my fork.

go test reports:

# github.com/ebitengine/purego

package github.com/ebitengine/purego_test

        imports github.com/ebitengine/purego/internal/load: build constraints exclude all Go files in /archive/foreign/purego-fork/internal/load

FAIL    github.com/ebitengine/purego [setup failed]

It's telling you that you are missing a build tag in that file.

[0-wiz-0]

I tried looking at all files with build tags. I think I found a problem for FreeBSD (because it affects NetBSD too).

purego/internal/cgo/dlfcn_cgo_unix.go

Line 9 in 6cd1224

#cgo LDFLAGS: -ldl

purego/internal/cgo/syscall_cgo_unix.go

Line 12 in 6cd1224

#cgo LDFLAGS: -ldl

both have

 #cgo LDFLAGS: -ldl

but *BSD do not provide this library, the dl*() functions are in libc.
What's the proper go way to conditionalize this without making complete copies of the files?

[TotallyGamerJet]

Well build tags in the Cgo comment can be used.

The directive can include a list of build constraints limiting its effect to systems satisfying one of the constraints

https://pkg.go.dev/cmd/cgo

I'm a little confused as FreeBSD is tested in CI and it passes with the current code

[0-wiz-0]

I have no clue why it works on FreeBSD in CI.

Thanks, that worked. I've pushed my changes to the fork.
It builds now, but segfaults when I run go test.
log.txt

[JupiterRider]

I just want to let you know, that I do not have any issues with purego and FreeBSD.