src/runtime/os_openbsd_libc.go

// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build (openbsd && amd64) || (openbsd && arm64)
// +build openbsd,amd64 openbsd,arm64

package runtime

import (
	"unsafe"
)

var failThreadCreate = []byte("runtime: failed to create new OS thread\n")

// mstart_stub provides glue code to call mstart from pthread_create.
func mstart_stub()

// May run with m.p==nil, so write barriers are not allowed.
//go:nowritebarrierrec
func newosproc(mp *m) {
	if false {
		print("newosproc m=", mp, " g=", mp.g0, " id=", mp.id, " ostk=", &mp, "\n")
	}

	// Initialize an attribute object.
	var attr pthreadattr
	if err := pthread_attr_init(&attr); err != 0 {
		write(2, unsafe.Pointer(&failThreadCreate[0]), int32(len(failThreadCreate)))
		exit(1)
	}

	// Find out OS stack size for our own stack guard.
	var stacksize uintptr
	if pthread_attr_getstacksize(&attr, &stacksize) != 0 {
		write(2, unsafe.Pointer(&failThreadCreate[0]), int32(len(failThreadCreate)))
		exit(1)
	}
	mp.g0.stack.hi = stacksize // for mstart

	// Tell the pthread library we won't join with this thread.
	if pthread_attr_setdetachstate(&attr, _PTHREAD_CREATE_DETACHED) != 0 {
		write(2, unsafe.Pointer(&failThreadCreate[0]), int32(len(failThreadCreate)))
		exit(1)
	}

	// Finally, create the thread. It starts at mstart_stub, which does some low-level
	// setup and then calls mstart.
	var oset sigset
	sigprocmask(_SIG_SETMASK, &sigset_all, &oset)
	err := pthread_create(&attr, funcPC(mstart_stub), unsafe.Pointer(mp))
	sigprocmask(_SIG_SETMASK, &oset, nil)
	if err != 0 {
		write(2, unsafe.Pointer(&failThreadCreate[0]), int32(len(failThreadCreate)))
		exit(1)
	}

	pthread_attr_destroy(&attr)
}