Add GIDs to ProcStatus struct

Signed-off-by: Andrei Volnin <wolandr@gmail.com>

fixtures.ttar

@@ -467,7 +467,7 @@ Pid:	26231
 PPid:	1
 TracerPid:	0
 Uid:	1000	1000	1000	0
-Gid:	0	0	0	0
+Gid:	1001	1001	1001	0
 FDSize:	128
 Groups:
 NStgid:	1

proc_status.go

@@ -72,8 +72,10 @@ type ProcStatus struct {
 	// Number of involuntary context switches.
 	NonVoluntaryCtxtSwitches uint64
 
-	// UIDs of the process (Real, effective, saved set, and filesystem UIDs (GIDs))
+	// UIDs of the process (Real, effective, saved set, and filesystem UIDs)
 	UIDs [4]string
+	// GIDs of the process (Real, effective, saved set, and filesystem GIDs)
+	GIDs [4]string
 }
 
 // NewStatus returns the current status information of the process.
@@ -119,6 +121,8 @@ func (s *ProcStatus) fillStatus(k string, vString string, vUint uint64, vUintByt
 		s.Name = vString
 	case "Uid":
 		copy(s.UIDs[:], strings.Split(vString, "\t"))
+	case "Gid":
+		copy(s.GIDs[:], strings.Split(vString, "\t"))
 	case "VmPeak":
 		s.VmPeak = vUintBytes
 	case "VmSize":

proc_status_test.go

@@ -91,3 +91,19 @@ func TestProcStatusUIDs(t *testing.T) {
 		t.Errorf("want uids %s, have %s", want, have)
 	}
 }
+
+func TestProcStatusGIDs(t *testing.T) {
+	p, err := getProcFixtures(t).Proc(26231)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	s, err := p.NewStatus()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if want, have := [4]string{"1001", "1001", "1001", "0"}, s.GIDs; want != have {
+		t.Errorf("want uids %s, have %s", want, have)
+	}
+}