print crasher log for go-fuzz

Author: Yevgeny Pats

client/gofuzz.go

@@ -201,15 +201,20 @@ func (c *FuzzitClient) runGoFuzzFuzzing() error {
 				fileName := info.Name()
 				if !strings.Contains(fileName, ".") && !uniqueCrashes[fileName] && fileName != "crashers" {
 					uniqueCrashes[fileName] = true
-					err := c.uploadGoFuzzCrash("workdir/crashers/" + fileName)
+					log.Println("found new crash")
+					err := catLastBytes(fmt.Sprintf("workdir/crashers/%s.output", fileName), 1000)
+					if err != nil {
+						return err
+					}
+
+					err = c.uploadGoFuzzCrash("workdir/crashers/" + fileName)
 					if err != nil {
 						return err
 					}
 				}
 				return nil
 			})
 			if err != nil {
-				cmd.Process.Kill()
 				return err
 			}
 

client/utils.go

@@ -3,6 +3,7 @@ package client
 import (
 	"fmt"
 	"io"
+	"log"
 	"net/http"
 	"os"
 	"os/user"
@@ -25,6 +26,41 @@ func getCacheFile() (string, error) {
 	return cacheFile, nil
 }
 
+func catFile(path string) error {
+	fh, err := os.Open(path)
+	if err != nil {
+		return err
+	}
+	defer fh.Close()
+
+	_, err = io.Copy(os.Stdout, fh)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func catLastBytes(path string, lastBytes int64) error {
+	fh, err := os.Open(path)
+	if err != nil {
+		return err
+	}
+	defer fh.Close()
+
+	buf := make([]byte, lastBytes)
+	stat, err := os.Stat(path)
+	start := stat.Size() - lastBytes
+	_, err = fh.ReadAt(buf, start)
+	if err != nil {
+		return err
+	}
+
+	log.Printf("%s\n", buf)
+
+	return nil
+}
+
 func splitAndRemoveEmpty(s string, delimiter string) []string {
 	splitted := strings.Split(s, delimiter)
 	var withoutEmptyStrings []string