crypto/rand, internal/syscall/unix: add support for getrandom syscall on solaris

The getrandom syscall is available on Solaris and Illumos, see
https://docs.oracle.com/cd/E88353_01/html/E37841/getrandom-2.html and
https://illumos.org/man/2/getrandom

Change-Id: Id1c65d6a5b2fbc80d20b43d8b32dab137ca950ca
Reviewed-on: https://go-review.googlesource.com/c/go/+/299134
Trust: Tobias Klauser <tobias.klauser@gmail.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

diff --git a/src/crypto/rand/rand_batched.go b/src/crypto/rand/rand_batched.go
index 538769a868706a526f7328f448f21e98cf2dbabf..d7c5bf3562d54747f0ab5db368f90a219dae964c 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 || dragonfly
-// +build linux freebsd dragonfly
+//go:build linux || freebsd || dragonfly || solaris
+// +build linux freebsd dragonfly solaris
 
 package rand
 

diff --git a/src/crypto/rand/rand_batched_test.go b/src/crypto/rand/rand_batched_test.go
index 814f15201aa453eec3525416fbe148e02f8d2219..2d20922c8253098f59eac79fe913c28ff9631cf1 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 || dragonfly
-// +build linux freebsd dragonfly
+//go:build linux || freebsd || dragonfly || solaris
+// +build linux freebsd dragonfly solaris
 
 package rand
 

diff --git a/src/crypto/rand/rand_solaris.go b/src/crypto/rand/rand_solaris.go
new file mode 100644 (file)
index 0000000..bbad0fe
--- /dev/null
+++ b/src/crypto/rand/rand_solaris.go
@@ -0,0 +1,10 @@
+// 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. Across all the Solaris platforms, 256 bytes is the
+// lowest number of bytes returned atomically per call.
+const maxGetRandomRead = 1 << 8

diff --git a/src/internal/syscall/unix/getrandom_solaris.go b/src/internal/syscall/unix/getrandom_solaris.go
new file mode 100644 (file)
index 0000000..d86775c
--- /dev/null
+++ b/src/internal/syscall/unix/getrandom_solaris.go
@@ -0,0 +1,53 @@
+// 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"
+)
+
+//go:cgo_import_dynamic libc_getrandom getrandom "libc.so"
+
+//go:linkname procGetrandom libc_getrandom
+
+var procGetrandom uintptr
+
+var getrandomUnsupported int32 // atomic
+
+// GetRandomFlag is a flag supported by the getrandom system call.
+type GetRandomFlag uintptr
+
+const (
+       // GRND_NONBLOCK means return EAGAIN rather than blocking.
+       GRND_NONBLOCK GetRandomFlag = 0x0001
+
+       // GRND_RANDOM means use the /dev/random pool instead of /dev/urandom.
+       GRND_RANDOM GetRandomFlag = 0x0002
+)
+
+// GetRandom calls the getrandom system call.
+func GetRandom(p []byte, flags GetRandomFlag) (n int, err error) {
+       if len(p) == 0 {
+               return 0, nil
+       }
+       if atomic.LoadInt32(&getrandomUnsupported) != 0 {
+               return 0, syscall.ENOSYS
+       }
+       r1, _, errno := syscall6(uintptr(unsafe.Pointer(&procGetrandom)),
+               3,
+               uintptr(unsafe.Pointer(&p[0])),
+               uintptr(len(p)),
+               uintptr(flags),
+               0, 0, 0)
+       if errno != 0 {
+               if errno == syscall.ENOSYS {
+                       atomic.StoreInt32(&getrandomUnsupported, 1)
+               }
+               return 0, errno
+       }
+       return int(r1), nil
+}