Move progress into pkg

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

pkg/progress/writer.go

@@ -0,0 +1,115 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package progress
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"os"
+	"regexp"
+	"strings"
+
+	"github.com/containerd/console"
+)
+
+var (
+	regexCleanLine = regexp.MustCompile("\x1b\\[[0-9]+m[\x1b]?")
+)
+
+// Writer buffers writes until flush, at which time the last screen is cleared
+// and the current buffer contents are written. This is useful for
+// implementing progress displays, such as those implemented in docker and
+// git.
+type Writer struct {
+	buf   bytes.Buffer
+	w     io.Writer
+	lines int
+}
+
+// NewWriter returns a writer
+func NewWriter(w io.Writer) *Writer {
+	return &Writer{
+		w: w,
+	}
+}
+
+// Write the provided bytes
+func (w *Writer) Write(p []byte) (n int, err error) {
+	return w.buf.Write(p)
+}
+
+// Flush should be called when refreshing the current display.
+func (w *Writer) Flush() error {
+	if w.buf.Len() == 0 {
+		return nil
+	}
+
+	if err := w.clearLines(); err != nil {
+		return err
+	}
+	w.lines = countLines(w.buf.String())
+
+	if _, err := w.w.Write(w.buf.Bytes()); err != nil {
+		return err
+	}
+
+	w.buf.Reset()
+	return nil
+}
+
+// TODO(stevvooe): The following are system specific. Break these out if we
+// decide to build this package further.
+
+func (w *Writer) clearLines() error {
+	for i := 0; i < w.lines; i++ {
+		if _, err := fmt.Fprintf(w.w, "\x1b[1A\x1b[2K\r"); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// countLines in the output. If a line is longer than the console width then
+// an extra line is added to the count for each wrapped line. If the console
+// width is undefined then 0 is returned so that no lines are cleared on the next
+// flush.
+func countLines(output string) int {
+	con, err := console.ConsoleFromFile(os.Stdin)
+	if err != nil {
+		return 0
+	}
+	ws, err := con.Size()
+	if err != nil {
+		return 0
+	}
+	width := int(ws.Width)
+	if width <= 0 {
+		return 0
+	}
+	strlines := strings.Split(output, "\n")
+	lines := -1
+	for _, line := range strlines {
+		lines += (len(stripLine(line))-1)/width + 1
+	}
+	return lines
+}
+
+func stripLine(line string) string {
+	return string(regexCleanLine.ReplaceAll([]byte(line), []byte{}))
+}