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160 lines
2.8 KiB
160 lines
2.8 KiB
package main
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import (
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"bufio"
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"crypto/md5"
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"crypto/sha1"
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"crypto/sha256"
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"crypto/sha512"
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"fmt"
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"hash"
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"io"
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"log"
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"os"
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"strings"
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"sync"
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)
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// input contains a file-ish piece of work to perform
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type input struct {
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f io.ReadCloser
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err error
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}
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// checksum contains the path to a file, a way to hash it, and the results of
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// the hash
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type checksum struct {
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filename string
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hash hash.Hash
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checksum string
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err error
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}
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// check is the entry point for -c operation.
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func check(args []string, verbose bool) chan error {
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jobs := make(chan checksum)
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go func() {
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for i := range toInput(args) {
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if i.err != nil {
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jobs <- checksum{err: i.err}
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break
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}
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s := bufio.NewScanner(i.f)
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for s.Scan() {
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jobs <- parseCS(s.Text())
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}
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i.f.Close()
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if s.Err() != nil {
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jobs <- checksum{err: s.Err()}
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}
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}
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close(jobs)
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}()
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results := []<-chan error{}
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for w := 0; w < *ngo; w++ {
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results = append(results, verify(jobs, verbose))
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}
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return merge(results)
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}
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// toInput converts args to a stream of input
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func toInput(args []string) chan input {
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r := make(chan input)
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go func() {
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for _, name := range args {
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f, err := os.Open(name)
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r <- input{f, err}
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}
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if len(args) == 0 {
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r <- input{f: os.Stdin}
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}
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close(r)
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}()
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return r
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}
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// parseCS picks apart a line from a checksum file and returns everything
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// needed to perform a checksum.
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func parseCS(line string) checksum {
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elems := strings.Fields(line)
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if len(elems) < 1 {
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return checksum{err: fmt.Errorf("couldn't find checksum in %q", line)}
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}
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cs := elems[0]
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var hsh hash.Hash
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switch len(cs) {
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case 32:
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hsh = md5.New()
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case 40:
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hsh = sha1.New()
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case 64:
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hsh = sha256.New()
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case 128:
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hsh = sha512.New()
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default:
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return checksum{err: fmt.Errorf("unknown format: %q", line)}
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}
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return checksum{filename: strings.TrimSpace(line[len(cs):]), hash: hsh, checksum: cs}
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}
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// verify does grunt work of verifying a stream of jobs (filenames).
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func verify(jobs chan checksum, verbose bool) chan error {
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r := make(chan error)
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go func() {
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for job := range jobs {
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if job.err != nil {
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log.Printf("%+v", job.err)
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continue
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}
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f, err := os.Open(job.filename)
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if err != nil {
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r <- err
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continue
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}
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if _, err := io.Copy(job.hash, f); err != nil {
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r <- err
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continue
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}
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f.Close()
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if fmt.Sprintf("%x", job.hash.Sum(nil)) != job.checksum {
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r <- fmt.Errorf("%s: bad", job.filename)
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} else if verbose {
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fmt.Fprintf(os.Stderr, "ok: %v\n", job.filename)
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}
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}
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close(r)
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}()
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return r
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}
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// merge is simple error fan-in
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func merge(cs []<-chan error) chan error {
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out := make(chan error)
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var wg sync.WaitGroup
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output := func(c <-chan error) {
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for n := range c {
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out <- n
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}
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wg.Done()
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}
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wg.Add(len(cs))
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for _, c := range cs {
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go output(c)
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}
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go func() {
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wg.Wait()
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close(out)
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}()
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return out
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}
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