/usr/share/gocode/src/github.com/hashicorp/serf/vendor/github.com/sean-/seed/init.go is in golang-github-hashicorp-serf-dev 0.8.1+git20171021.c20a0b1~ds1-4.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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import (
crand "crypto/rand"
"fmt"
"math"
"math/big"
"math/rand"
"sync"
"time"
)
var (
once sync.Once
secure bool
seeded bool
)
// Init provides best-effort seeding (which is better than running with Go's
// default seed of 1). If `/dev/urandom` is available, Init() will seed Go's
// runtime with entropy from `/dev/urandom` and return true because the runtime
// was securely seeded. If Init() has already initialized the random number or
// it had failed to securely initialize the random number generation, Init()
// will return false. See MustInit().
func Init() (bool, error) {
var err error
once.Do(func() {
var n *big.Int
n, err = crand.Int(crand.Reader, big.NewInt(math.MaxInt64))
if err != nil {
rand.Seed(time.Now().UTC().UnixNano())
return
}
rand.Seed(n.Int64())
secure = true
seeded = true
})
return seeded && secure, err
}
// MustInit provides guaranteed seeding. If `/dev/urandom` is not available,
// MustInit will panic() with an error indicating why reading from
// `/dev/urandom` failed. See Init()
func MustInit() {
once.Do(func() {
n, err := crand.Int(crand.Reader, big.NewInt(math.MaxInt64))
if err != nil {
panic(fmt.Sprintf("Unable to seed the random number generator: %v", err))
}
rand.Seed(n.Int64())
secure = true
seeded = true
})
}
// Secure returns true if a cryptographically secure seed was used to
// initialize rand.
func Secure() bool {
return secure
}
// Seeded returns true if Init has seeded the random number generator.
func Seeded() bool {
return seeded
}
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