Add listing of runners file system.

pkg/nullio/ls2json.go

@@ -0,0 +1,126 @@
+package nullio
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"github.com/openHPI/poseidon/pkg/dto"
+	"github.com/openHPI/poseidon/pkg/logging"
+	"io"
+	"regexp"
+	"strconv"
+)
+
+var (
+	log             = logging.GetLogger("nullio")
+	pathLineRegex   = regexp.MustCompile(`(.*):$`)
+	headerLineRegex = regexp.MustCompile(`([dl-])[-rwxXsS]{9} \d* .*? .*? +(\d+) (\d+) (.*)$`)
+)
+
+// Ls2JsonWriter implements io.Writer.
+// It streams the passed data to the Target and transforms the data into the json format.
+type Ls2JsonWriter struct {
+	Target         io.Writer
+	jsonStartSend  bool
+	setCommaPrefix bool
+	remaining      []byte
+	latestPath     []byte
+}
+
+func (w *Ls2JsonWriter) Write(p []byte) (int, error) {
+	i, err := w.initializeJSONObject()
+	if err != nil {
+		return i, err
+	}
+
+	start := 0
+	for i, char := range p {
+		if char != '\n' {
+			continue
+		}
+
+		line := p[start:i]
+		if len(w.remaining) > 0 {
+			line = append(w.remaining, line...)
+			w.remaining = []byte("")
+		}
+
+		if len(line) != 0 {
+			count, err := w.writeLine(line)
+			if err != nil {
+				log.WithError(err).Warn("Could not write line to Target")
+				return count, err
+			}
+		}
+		start = i + 1
+	}
+
+	if start < len(p) {
+		w.remaining = p[start:]
+	}
+
+	return len(p), nil
+}
+
+func (w *Ls2JsonWriter) initializeJSONObject() (count int, err error) {
+	if !w.jsonStartSend {
+		count, err = w.Target.Write([]byte("{\"files\": ["))
+		if count == 0 || err != nil {
+			log.WithError(err).Warn("Could not write to target")
+			err = fmt.Errorf("could not write to target: %w", err)
+		} else {
+			w.jsonStartSend = true
+		}
+	}
+	return count, err
+}
+
+func (w *Ls2JsonWriter) Close() {
+	count, err := w.Target.Write([]byte("]}"))
+	if count == 0 || err != nil {
+		log.WithError(err).Warn("Could not Close ls2json writer")
+	}
+}
+
+func (w *Ls2JsonWriter) writeLine(line []byte) (count int, err error) {
+	matches := pathLineRegex.FindSubmatch(line)
+	if matches != nil {
+		w.latestPath = append(bytes.TrimSuffix(matches[1], []byte("/")), '/')
+		return 0, nil
+	}
+
+	matches = headerLineRegex.FindSubmatch(line)
+	if matches != nil {
+		size, err1 := strconv.Atoi(string(matches[2]))
+		timestamp, err2 := strconv.Atoi(string(matches[3]))
+		if err1 != nil || err2 != nil {
+			return 0, fmt.Errorf("could not parse file details: %w %+v", err1, err2)
+		}
+
+		response, err1 := json.Marshal(dto.FileHeader{
+			Name:             dto.FilePath(append(w.latestPath, matches[4]...)),
+			ObjectType:       string(matches[1][0]),
+			Size:             size,
+			ModificationTime: timestamp,
+		})
+		if err1 != nil {
+			return 0, fmt.Errorf("could not marshal file header: %w", err)
+		}
+
+		// Skip the first leading comma
+		if w.setCommaPrefix {
+			response = append([]byte{','}, response...)
+		} else {
+			w.setCommaPrefix = true
+		}
+
+		count, err1 = w.Target.Write(response)
+		if err1 != nil {
+			err = fmt.Errorf("could not write to target: %w", err)
+		} else if count == len(response) {
+			count = len(line)
+		}
+	}
+
+	return count, err
+}