73 lines
1.6 KiB
Go
73 lines
1.6 KiB
Go
// CRC is a simple command-line utility to compute CRC values for one or more files.
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package main
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import (
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"flag"
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"fmt"
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"hash"
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"hash/crc32"
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"hash/crc64"
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"encoding/binary"
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"io"
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"os"
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)
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func main() {
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mode := flag.String("mode", "crc32",
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"CRC method to use. Valid values are 'crc32' (IEEE), 'crc64-iso', and 'crc64-ecma'")
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flag.Usage = func() {
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fmt.Fprintf(os.Stderr, "Usage: %s [-mode=<MODE>] file [file ...]\n", os.Args[0])
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flag.PrintDefaults()
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}
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flag.Parse()
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hasher, err := NewHasher(*mode)
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if err != nil {
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fmt.Fprintln(os.Stderr, err)
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os.Exit(1)
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}
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if flag.NArg() == 0 {
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fmt.Fprintf(os.Stderr, "Specify one or more filenames to checksum.\n")
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os.Exit(2)
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}
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exitCode := 0
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for _, filename := range flag.Args() {
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hasher, _ = NewHasher(*mode)
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f, err := os.Open(filename)
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if err != nil {
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exitCode = 3
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fmt.Fprintf(os.Stderr, "Cannot open %q: %v\n", filename, err)
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continue
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}
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_, err = io.Copy(hasher, f)
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f.Close()
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if err != nil {
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exitCode = 3
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fmt.Fprintf(os.Stderr, "Error reading %q: %v\n", filename, err)
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continue
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}
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if flag.NArg() == 1 {
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fmt.Printf("%0*d\n", hasher.Size(), binary.BigEndian.Uint32(hasher.Sum(nil)))
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} else {
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fmt.Printf("%0*d\t%s\n", hasher.Size(), binary.BigEndian.Uint32(hasher.Sum(nil)), filename)
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}
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}
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os.Exit(exitCode)
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}
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func NewHasher(mode string) (hash.Hash, error) {
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switch mode {
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case "crc32", "crc32-ieee":
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return crc32.NewIEEE(), nil
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case "crc64-iso":
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return crc64.New(crc64.MakeTable(crc64.ISO)), nil
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case "crc64-ecma":
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return crc64.New(crc64.MakeTable(crc64.ECMA)), nil
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default:
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return nil, fmt.Errorf("ERROR: Invalid mode %q", mode)
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}
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}
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