From: Tobias Klauser <tklauser@distanz.ch>
Date: Wed, 17 Mar 2021 10:17:02 +0000 (+0100)
Subject: crypto/rand, internal/syscall/unix: add support for getentropy syscall on darwin
X-Git-Tag: go1.17beta1~1077
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=f38b6428a2;p=gostls13.git

crypto/rand, internal/syscall/unix: add support for getentropy syscall on darwin

The getentropy syscall is available on macOS since version 10.12, which
is the minimum required version since Go 1.15.

Change-Id: I294259af0b11df9669e4dc5fa891d2f2f039d91a
Reviewed-on: https://go-review.googlesource.com/c/go/+/302489
Trust: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
---

diff --git a/src/crypto/rand/rand_openbsd.go b/src/crypto/rand/rand_getentropy.go
similarity index 79%
rename from src/crypto/rand/rand_openbsd.go
rename to src/crypto/rand/rand_getentropy.go
index 9cc39f72d1..f82018a495 100644
--- a/src/crypto/rand/rand_openbsd.go
+++ b/src/crypto/rand/rand_getentropy.go
@@ -2,6 +2,9 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build darwin || openbsd
+// +build darwin openbsd
+
 package rand
 
 import (
@@ -9,10 +12,10 @@ import (
 )
 
 func init() {
-	altGetRandom = getRandomOpenBSD
+	altGetRandom = getEntropy
 }
 
-func getRandomOpenBSD(p []byte) (ok bool) {
+func getEntropy(p []byte) (ok bool) {
 	// getentropy(2) returns a maximum of 256 bytes per call
 	for i := 0; i < len(p); i += 256 {
 		end := i + 256
diff --git a/src/internal/syscall/unix/asm_darwin.s b/src/internal/syscall/unix/asm_darwin.s
new file mode 100644
index 0000000000..8fbdc1d866
--- /dev/null
+++ b/src/internal/syscall/unix/asm_darwin.s
@@ -0,0 +1,8 @@
+// Copyright 2021 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.
+
+#include "textflag.h"
+
+TEXT ·libc_getentropy_trampoline(SB),NOSPLIT,$0-0
+	JMP	libc_getentropy(SB)
diff --git a/src/internal/syscall/unix/getentropy_darwin.go b/src/internal/syscall/unix/getentropy_darwin.go
new file mode 100644
index 0000000000..6da6f84d95
--- /dev/null
+++ b/src/internal/syscall/unix/getentropy_darwin.go
@@ -0,0 +1,32 @@
+// Copyright 2021 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 unix
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+//go:cgo_import_dynamic libc_getentropy getentropy "/usr/lib/libSystem.B.dylib"
+
+func libc_getentropy_trampoline()
+
+// GetEntropy calls the macOS getentropy system call.
+func GetEntropy(p []byte) error {
+	_, _, errno := syscall_syscall(funcPC(libc_getentropy_trampoline),
+		uintptr(unsafe.Pointer(&p[0])),
+		uintptr(len(p)),
+		0)
+	if errno != 0 {
+		return errno
+	}
+	return nil
+}
+
+//go:linkname syscall_syscall syscall.syscall
+func syscall_syscall(fn, a1, a2, a3 uintptr) (r1, r2 uintptr, err syscall.Errno)
+
+//go:linkname funcPC runtime.funcPC
+func funcPC(f interface{}) uintptr