Merge pull request #1116 from shirou/feature/port_to_v2_from_1112

[v2][process][linux] port 1112 to v2.

process/process_linux.go

@@ -82,7 +82,7 @@ func (p *Process) PpidWithContext(ctx context.Context) (int32, error) {
 
 func (p *Process) NameWithContext(ctx context.Context) (string, error) {
 	if p.name == "" {
-		if err := p.fillFromStatusWithContext(ctx); err != nil {
+		if err := p.fillNameWithContext(ctx); err != nil {
 			return "", err
 		}
 	}
@@ -517,6 +517,28 @@ func limitToInt(val string) (int32, error) {
 	}
 }
 
+// Get name from /proc/(pid)/comm or /proc/(pid)/status
+func (p *Process) fillNameWithContext(ctx context.Context) error {
+	err := p.fillFromCommWithContext(ctx)
+	if err == nil && p.name != "" && len(p.name) < 15 {
+		return nil
+	}
+	return p.fillFromStatusWithContext(ctx)
+}
+
+// Get name from /proc/(pid)/comm
+func (p *Process) fillFromCommWithContext(ctx context.Context) error {
+	pid := p.Pid
+	statPath := common.HostProc(strconv.Itoa(int(pid)), "comm")
+	contents, err := ioutil.ReadFile(statPath)
+	if err != nil {
+		return err
+	}
+
+	p.name = strings.TrimSuffix(string(contents), "\n")
+	return nil
+}
+
 // Get num_fds from /proc/(pid)/limits
 func (p *Process) fillFromLimitsWithContext(ctx context.Context) ([]RlimitStat, error) {
 	pid := p.Pid