diff options
Diffstat (limited to 'src/pkg/crypto/rand/rand_linux.go')
-rw-r--r-- | src/pkg/crypto/rand/rand_linux.go | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/src/pkg/crypto/rand/rand_linux.go b/src/pkg/crypto/rand/rand_linux.go new file mode 100644 index 000000000..8cb59c75d --- /dev/null +++ b/src/pkg/crypto/rand/rand_linux.go @@ -0,0 +1,39 @@ +// 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 rand + +import ( + "internal/syscall" + "sync" +) + +func init() { + altGetRandom = getRandomLinux +} + +var ( + once sync.Once + useSyscall bool +) + +func pickStrategy() { + // Test whether we should use the system call or /dev/urandom. + // We'll fall back to urandom if: + // - the kernel is too old (before 3.17) + // - the machine has no entropy available (early boot + no hardware + // entropy source?) and we want to avoid blocking later. + var buf [1]byte + n, err := syscall.GetRandom(buf[:], syscall.GRND_NONBLOCK) + useSyscall = n == 1 && err == nil +} + +func getRandomLinux(p []byte) (ok bool) { + once.Do(pickStrategy) + if !useSyscall { + return false + } + n, err := syscall.GetRandom(p, 0) + return n == len(p) && err == nil +} |