crypto/rand: supports for getrandom syscall in DragonFlyBSD

Since the 5.7 release, DragonFlyBSD supports as well
the getrandom function, the actual stable is 5.8.

Change-Id: I2b8fc468771b10ac12b38ea7e8e5314342de6375
GitHub-Last-Rev: c5c496f41898d58f2c6f3ccc81f754792f49edbe
GitHub-Pull-Request: golang/go#42617
Reviewed-on: https://go-review.googlesource.com/c/go/+/269999
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Trust: Ian Lance Taylor <iant@golang.org>
Trust: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>

diff --git a/src/crypto/rand/rand_batched.go b/src/crypto/rand/rand_batched.go
index 45e9351a31565fb8ad40ad6ceddef5dcea716433..538769a868706a526f7328f448f21e98cf2dbabf 100644 (file)
--- a/src/crypto/rand/rand_batched.go
+++ b/src/crypto/rand/rand_batched.go
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build linux || freebsd
-// +build linux freebsd
+//go:build linux || freebsd || dragonfly
+// +build linux freebsd dragonfly
 
 package rand
 

diff --git a/src/crypto/rand/rand_batched_test.go b/src/crypto/rand/rand_batched_test.go
index fd50735c7de4bed1a516e3a75378ed540dd6e629..814f15201aa453eec3525416fbe148e02f8d2219 100644 (file)
--- a/src/crypto/rand/rand_batched_test.go
+++ b/src/crypto/rand/rand_batched_test.go
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build linux || freebsd
-// +build linux freebsd
+//go:build linux || freebsd || dragonfly
+// +build linux freebsd dragonfly
 
 package rand
 

diff --git a/src/crypto/rand/rand_dragonfly.go b/src/crypto/rand/rand_dragonfly.go
new file mode 100644 (file)
index 0000000..8a36fea
--- /dev/null
+++ b/src/crypto/rand/rand_dragonfly.go
@@ -0,0 +1,9 @@
+// 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 rand
+
+// maxGetRandomRead is the maximum number of bytes to ask for in one call to the
+// getrandom() syscall. In DragonFlyBSD at most 256 bytes will be returned per call.
+const maxGetRandomRead = 1 << 8

diff --git a/src/internal/syscall/unix/getrandom_dragonfly.go b/src/internal/syscall/unix/getrandom_dragonfly.go
new file mode 100644 (file)
index 0000000..b345b4c
--- /dev/null
+++ b/src/internal/syscall/unix/getrandom_dragonfly.go
@@ -0,0 +1,51 @@
+// 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 (
+       "sync/atomic"
+       "syscall"
+       "unsafe"
+)
+
+var randomUnsupported int32 // atomic
+
+// DragonFlyBSD getrandom system call number.
+const randomTrap uintptr = 550
+
+// GetRandomFlag is a flag supported by the getrandom system call.
+type GetRandomFlag uintptr
+
+const (
+       // GRND_RANDOM is only set for portability purpose, no-op on DragonFlyBSD.
+       GRND_RANDOM GetRandomFlag = 0x0001
+
+       // GRND_NONBLOCK means return EAGAIN rather than blocking.
+       GRND_NONBLOCK GetRandomFlag = 0x0002
+
+       // GRND_INSECURE is an GRND_NONBLOCK alias
+       GRND_INSECURE GetRandomFlag = 0x0004
+)
+
+// GetRandom calls the DragonFlyBSD getrandom system call.
+func GetRandom(p []byte, flags GetRandomFlag) (n int, err error) {
+       if len(p) == 0 {
+               return 0, nil
+       }
+       if atomic.LoadInt32(&randomUnsupported) != 0 {
+               return 0, syscall.ENOSYS
+       }
+       r1, _, errno := syscall.Syscall(randomTrap,
+               uintptr(unsafe.Pointer(&p[0])),
+               uintptr(len(p)),
+               uintptr(flags))
+       if errno != 0 {
+               if errno == syscall.ENOSYS {
+                       atomic.StoreInt32(&randomUnsupported, 1)
+               }
+               return 0, errno
+       }
+       return int(r1), nil
+}