github.com/demonoid81/containerd@v1.3.4/pkg/seed/seed.go (about)

     1  /*
     2     Copyright The containerd Authors.
     3  
     4     Licensed under the Apache License, Version 2.0 (the "License");
     5     you may not use this file except in compliance with the License.
     6     You may obtain a copy of the License at
     7  
     8         http://www.apache.org/licenses/LICENSE-2.0
     9  
    10     Unless required by applicable law or agreed to in writing, software
    11     distributed under the License is distributed on an "AS IS" BASIS,
    12     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13     See the License for the specific language governing permissions and
    14     limitations under the License.
    15  */
    16  
    17  package seed
    18  
    19  import (
    20  	"math/rand"
    21  	"time"
    22  )
    23  
    24  // WithTimeAndRand seeds the global math rand generator with nanoseconds
    25  // XOR'ed with a crypto component if available for uniqueness.
    26  func WithTimeAndRand() {
    27  	var (
    28  		b [4]byte
    29  		u int64
    30  	)
    31  
    32  	tryReadRandom(b[:])
    33  
    34  	// Set higher 32 bits, bottom 32 will be set with nanos
    35  	u |= (int64(b[0]) << 56) | (int64(b[1]) << 48) | (int64(b[2]) << 40) | (int64(b[3]) << 32)
    36  
    37  	rand.Seed(u ^ time.Now().UnixNano())
    38  }