| // Copyright 2018 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 detrand provides deterministically random functionality. |
| // The pseudo-randomness of these functions is seeded by the program binary |
| // itself and guarantees that the output does not change within a program, |
| // while ensuring that the output is unstable across different builds. |
| // Disable disables detrand such that all functions returns the zero value. |
| // This function is not concurrent-safe and must be called during program init. |
| // Bool returns a deterministically random boolean. |
| // randSeed is a best-effort at an approximate hash of the Go binary. |
| var randSeed = binaryHash() |
| func binaryHash() uint64 { |
| s, err := os.Executable() |
| // Hash the size and several samples of the Go binary. |
| binary.LittleEndian.PutUint64(buf[:8], uint64(fi.Size())) |
| for i := int64(0); i < numSamples; i++ { |
| if _, err := f.ReadAt(buf[:], i*fi.Size()/numSamples); err != nil { |