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32 lines
644 B
32 lines
644 B
3 years ago
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package testutil
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import (
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"encoding/binary"
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"math/rand"
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)
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// ZeroRand is zero random source.
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type ZeroRand struct{}
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// Read implements io.Reader.
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func (ZeroRand) Read(p []byte) (n int, err error) { return len(p), nil }
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func randSeed(data []byte) int64 {
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if len(data) == 0 {
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return 0
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}
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seedBuf := make([]byte, 64/8)
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copy(seedBuf, data)
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return int64(binary.BigEndian.Uint64(seedBuf))
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}
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// Rand returns a new rand.Rand with source deterministically initialized
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// from seed byte slice.
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//
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// Zero length seed (or nil) is valid input.
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func Rand(seed []byte) *rand.Rand {
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return rand.New(rand.NewSource(randSeed(seed))) // #nosec
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}
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