69 lines
1.2 KiB
Go
69 lines
1.2 KiB
Go
package main
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import (
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"io"
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"os"
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"github.com/magical/keccak"
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)
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const usage = "usage: sha3sum [-h] files..."
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var (
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stdout = os.Stdout
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stderr = os.Stderr
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)
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func main() {
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// Parse flags
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if len(os.Args) <= 1 {
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stderr.WriteString(usage + "\n")
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return
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}
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args := os.Args[1:]
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for _, a := range args {
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switch a {
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case "-h", "--help":
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stdout.WriteString(usage + "\n")
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return
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case "", "-":
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default:
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if a[0] == '-' {
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stderr.WriteString("sha3sum: unrecognized flag " + a + "\n")
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os.Exit(1)
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}
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}
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}
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// compute file hashes
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var sum [keccak.Size]byte
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h := keccak.New256()
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files := args
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for _, filename := range files {
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f, err := os.Open(filename)
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if err != nil {
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stderr.WriteString("sha3sum: " + err.Error() + "\n")
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continue
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}
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h.Reset()
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_, err = io.Copy(h, f)
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f.Close()
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if err != nil {
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stderr.WriteString("sha3sum: " + err.Error() + "\n")
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continue
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}
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h.Sum(sum[:0])
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stdout.WriteString(toHex(sum[:]) + " " + filename + "\n")
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}
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}
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func toHex(data []byte) string {
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const digits = "0123456789abcdef"
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out := make([]byte, len(data)*2)
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for i, v := range data {
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out[i*2] = digits[v>>4]
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out[i*2+1] = digits[v&15]
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}
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return string(out)
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}
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