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authorRuss Cox <rsc@golang.org>2014-09-08 00:08:51 -0400
committerRuss Cox <rsc@golang.org>2014-09-08 00:08:51 -0400
commitc007ce824d9a4fccb148f9204e04c23ed2984b71 (patch)
tree7dcac257114ef5c446be5b7b68c27dea230b7c09 /src/internal/syscall/getrandom_linux.go
parent220a6de47eced55956eb8af8d643d4f5b67fd634 (diff)
downloadgo-c007ce824d9a4fccb148f9204e04c23ed2984b71.tar.xz
build: move package sources from src/pkg to src
Preparation was in CL 134570043. This CL contains only the effect of 'hg mv src/pkg/* src'. For more about the move, see golang.org/s/go14nopkg.
Diffstat (limited to 'src/internal/syscall/getrandom_linux.go')
-rw-r--r--src/internal/syscall/getrandom_linux.go56
1 files changed, 56 insertions, 0 deletions
diff --git a/src/internal/syscall/getrandom_linux.go b/src/internal/syscall/getrandom_linux.go
new file mode 100644
index 0000000000..944bab3f5d
--- /dev/null
+++ b/src/internal/syscall/getrandom_linux.go
@@ -0,0 +1,56 @@
+// Copyright 2014 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 syscall
+
+import (
+ "runtime"
+ "sync/atomic"
+ stdsyscall "syscall"
+ "unsafe"
+)
+
+var randomTrap = map[string]uintptr{
+ "386": 355,
+ "amd64": 318,
+ "arm": 384,
+}[runtime.GOARCH]
+
+var randomUnsupported 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 Linux getrandom system call.
+// See https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=c6e9d6f38894798696f23c8084ca7edbf16ee895
+func GetRandom(p []byte, flags GetRandomFlag) (n int, err error) {
+ if randomTrap == 0 {
+ return 0, stdsyscall.ENOSYS
+ }
+ if len(p) == 0 {
+ return 0, nil
+ }
+ if atomic.LoadInt32(&randomUnsupported) != 0 {
+ return 0, stdsyscall.ENOSYS
+ }
+ r1, _, errno := stdsyscall.Syscall(randomTrap,
+ uintptr(unsafe.Pointer(&p[0])),
+ uintptr(len(p)),
+ uintptr(flags))
+ if errno != 0 {
+ if errno == stdsyscall.ENOSYS {
+ atomic.StoreInt32(&randomUnsupported, 1)
+ }
+ return 0, errno
+ }
+ return int(r1), nil
+}