cmd/tailscale/cli: add progress to tailscale file cp

Signed-off-by: Tom DNetto <tom@tailscale.com>

cmd/tailscale/cli/file.go

@@ -19,9 +19,12 @@
 	"path"
 	"path/filepath"
 	"strings"
+	"sync"
+	"sync/atomic"
 	"time"
 	"unicode/utf8"
 
+	"github.com/mattn/go-isatty"
 	"github.com/peterbourgon/ff/v3/ffcli"
 	"golang.org/x/time/rate"
 	"tailscale.com/client/tailscale/apitype"
@@ -49,6 +52,17 @@
 	},
 }
 
+type countingReader struct {
+	io.Reader
+	n atomic.Uint64
+}
+
+func (c *countingReader) Read(buf []byte) (int, error) {
+	n, err := c.Reader.Read(buf)
+	c.n.Add(uint64(n))
+	return n, err
+}
+
 var fileCpCmd = &ffcli.Command{
 	Name:       "cp",
 	ShortUsage: "file cp <files...> <target>:",
@@ -116,11 +130,11 @@ func runCp(ctx context.Context, args []string) error {
 	}
 
 	for _, fileArg := range files {
-		var fileContents io.Reader
+		var fileContents *countingReader
 		var name = cpArgs.name
 		var contentLength int64 = -1
 		if fileArg == "-" {
-			fileContents = os.Stdin
+			fileContents = &countingReader{Reader: os.Stdin}
 			if name == "" {
 				name, fileContents, err = pickStdinFilename()
 				if err != nil {
@@ -144,19 +158,29 @@ func runCp(ctx context.Context, args []string) error {
 				return errors.New("directories not supported")
 			}
 			contentLength = fi.Size()
-			fileContents = io.LimitReader(f, contentLength)
+			fileContents = &countingReader{Reader: io.LimitReader(f, contentLength)}
 			if name == "" {
 				name = filepath.Base(fileArg)
 			}
 
 			if envknob.Bool("TS_DEBUG_SLOW_PUSH") {
-				fileContents = &slowReader{r: fileContents}
+				fileContents = &countingReader{Reader: &slowReader{r: fileContents}}
 			}
 		}
 
 		if cpArgs.verbose {
 			log.Printf("sending %q to %v/%v/%v ...", name, target, ip, stableID)
 		}
+
+		var (
+			done = make(chan struct{}, 1)
+			wg   sync.WaitGroup
+		)
+		if isatty.IsTerminal(os.Stderr.Fd()) {
+			go printProgress(&wg, done, fileContents, name, contentLength)
+			wg.Add(1)
+		}
+
 		err := localClient.PushFile(ctx, stableID, contentLength, name, fileContents)
 		if err != nil {
 			return err
@@ -164,10 +188,61 @@ func runCp(ctx context.Context, args []string) error {
 		if cpArgs.verbose {
 			log.Printf("sent %q", name)
 		}
+		done <- struct{}{}
+		wg.Wait()
 	}
 	return nil
 }
 
+const vtRestartLine = "\r\x1b[K"
+
+func printProgress(wg *sync.WaitGroup, done <-chan struct{}, r *countingReader, name string, contentLength int64) {
+	defer wg.Done()
+	var lastBytesRead uint64
+
+	for {
+		select {
+		case <-done:
+			fmt.Fprintln(os.Stderr)
+			return
+		case <-time.After(time.Second):
+			n := r.n.Load()
+			contentLengthStr := "???"
+			if contentLength > 0 {
+				contentLengthStr = fmt.Sprint(contentLength / 1024)
+			}
+
+			fmt.Fprintf(os.Stderr, "%s%s\t\t%s", vtRestartLine, padTruncateString(name, 36), padTruncateString(fmt.Sprintf("%d/%s kb", n/1024, contentLengthStr), 16))
+			if contentLength > 0 {
+				fmt.Fprintf(os.Stderr, "\t%.02f%%", float64(n)/float64(contentLength)*100)
+			} else {
+				fmt.Fprintf(os.Stderr, "\t-------%%")
+			}
+			if lastBytesRead > 0 {
+				fmt.Fprintf(os.Stderr, "\t%d kb/s", (n-lastBytesRead)/1024)
+			} else {
+				fmt.Fprintf(os.Stderr, "\t-------")
+			}
+			lastBytesRead = n
+		}
+	}
+}
+
+func padTruncateString(str string, truncateAt int) string {
+	if len(str) <= truncateAt {
+		return str + strings.Repeat(" ", truncateAt-len(str))
+	}
+
+	// Truncate the string, but respect unicode codepoint boundaries.
+	// As of RFC3629 utf-8 codepoints can be at most 4 bytes wide.
+	for i := 1; i <= 4 && i < len(str)-truncateAt; i++ {
+		if utf8.ValidString(str[:truncateAt-i]) {
+			return str[:truncateAt-i] + "…"
+		}
+	}
+	return "" // Should be unreachable
+}
+
 func getTargetStableID(ctx context.Context, ipStr string) (id tailcfg.StableNodeID, isOffline bool, err error) {
 	ip, err := netip.ParseAddr(ipStr)
 	if err != nil {
@@ -230,12 +305,12 @@ func ext(b []byte) string {
 // pickStdinFilename reads a bit of stdin to return a good filename
 // for its contents. The returned Reader is the concatenation of the
 // read and unread bits.
-func pickStdinFilename() (name string, r io.Reader, err error) {
+func pickStdinFilename() (name string, r *countingReader, err error) {
 	sniff, err := io.ReadAll(io.LimitReader(os.Stdin, maxSniff))
 	if err != nil {
 		return "", nil, err
 	}
-	return "stdin" + ext(sniff), io.MultiReader(bytes.NewReader(sniff), os.Stdin), nil
+	return "stdin" + ext(sniff), &countingReader{Reader: io.MultiReader(bytes.NewReader(sniff), os.Stdin)}, nil
 }
 
 type slowReader struct {