all: enable c-shared/c-archive support for freebsd/amd64

Fixes #14327
Much of the code is based on the linux/amd64 code that implements these
build modes, and code is shared where possible.

Change-Id: Ia510f2023768c0edbc863aebc585929ec593b332
Reviewed-on: https://go-review.googlesource.com/93875
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

1 files changed, 24 insertions, 0 deletions

diff --git a/src/runtime/os_freebsd_amd64.go b/src/runtime/os_freebsd_amd64.go
new file mode 100644
index 0000000000..dc0bb9ff96
--- /dev/null
+++ b/src/runtime/os_freebsd_amd64.go
@@ -0,0 +1,24 @@
+// Copyright 2011 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.
+
+package runtime
+
+func cgoSigtramp()
+
+//go:nosplit
+//go:nowritebarrierrec
+func setsig(i uint32, fn uintptr) {
+	var sa sigactiont
+	sa.sa_flags = _SA_SIGINFO | _SA_ONSTACK | _SA_RESTART
+	sa.sa_mask = sigset_all
+	if fn == funcPC(sighandler) {
+		if iscgo {
+			fn = funcPC(cgoSigtramp)
+		} else {
+			fn = funcPC(sigtramp)
+		}
+	}
+	sa.sa_handler = fn
+	sigaction(i, &sa, nil)
+}