List RX ports on Linux. (issue #36)

list_linux.go

@@ -0,0 +1,43 @@
+package serial
+
+import (
+	"bytes"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"sort"
+)
+
+// ListRX returns the detected serial ports sorted.
+func ListRX() (names []string, err error) {
+	matches, err := filepath.Glob("/sys/class/tty/*/rx_trig_bytes")
+	if err != nil {
+		return nil, err
+	}
+
+	names = make([]string, 0, len(matches))
+	for _, m := range matches {
+		uevent, err := ioutil.ReadFile(filepath.Clean(m + "/../uevent"))
+		if err != nil && !os.IsNotExist(err) {
+			return nil, err
+		}
+
+		var name string
+		for _, line := range bytes.Split(uevent, []byte{'\n'}) {
+			if bytes.HasPrefix(line, []byte("DEVNAME=")) {
+				name = "/dev/" + string(line[8:])
+				break
+			}
+		}
+
+		if _, err := os.Lstat(name); err == nil {
+			names = append(names, name)
+		} else if !os.IsNotExist(err) {
+			return nil, err
+		}
+	}
+
+	sort.Strings(names)
+
+	return
+}

list_linux_test.go

@@ -0,0 +1,34 @@
+package serial
+
+import (
+	"os"
+	"testing"
+)
+
+func TestListRX(t *testing.T) {
+	port0 := os.Getenv("PORT0")
+	port1 := os.Getenv("PORT1")
+
+	names, err := ListRX()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	for _, name := range names {
+		t.Log("got", name)
+
+		switch {
+		case name == port0:
+			port0 = ""
+		case name == port1:
+			port1 = ""
+		}
+	}
+
+	if port0 != "" {
+		t.Errorf("PORT0=%q not found", port0)
+	}
+	if port1 != "" {
+		t.Errorf("PORT1=%q not found", port1)
+	}
+}