implements users() on linux.

common.go

@@ -10,6 +10,7 @@ import (
 	"bufio"
 	"os"
 	"strings"
+
 )
 
 // Read contents from file and split by new line.
@@ -31,3 +32,20 @@ func ReadLines(filename string) ([]string, error) {
 
 	return ret, err
 }
+
+
+func byteToString(orig []byte) string{
+	n := -1
+	for i, b := range orig {
+		if b == 0 {
+			break
+		}
+		n = i + 1
+	}
+	if n == -1{
+		return string(orig)
+	}else{
+		return string(orig[:n])
+	}
+
+}

host.go

@@ -7,3 +7,10 @@ type HostInfoStat struct {
 	Uptime   int64  `json:"uptime"`
 	Procs    uint64 `json:"procs"`
 }
+
+type UserStat struct {
+	User     string `json:"user"`
+	Terminal string `json:"terminal"`
+	Host     string `json:"host"`
+	Started  int    `json:"started"`
+}

host_linux.go

@@ -1,12 +1,39 @@
-// +build linux
+// +build linux,amd64
 
 package gopsutil
 
 import (
+	"encoding/binary"
+	"bytes"
+	"io/ioutil"
 	"os"
 	"syscall"
+	"unsafe"
 )
 
+type exit_status struct {
+	E_termination int16 // Process termination status.
+	E_exit        int16 // Process exit status.
+}
+type timeval struct {
+	Tv_sec  uint32 // Seconds.
+	Tv_usec uint32 // Microseconds.
+}
+
+type utmp struct {
+	Ut_type    int16       // Type of login.
+	Ut_pid     int32       // Process ID of login process.
+	Ut_line    [32]byte    // Devicename.
+	Ut_id      [4]byte     // Inittab ID.
+	Ut_user    [32]byte    // Username.
+	Ut_host    [256]byte   // Hostname for remote login.
+	Ut_exit    exit_status // Exit status of a process marked
+	Ut_session int32       // Session ID, used for windowing.
+	Ut_tv      timeval     // Time entry was made.
+	Ut_addr_v6 [16]byte    // Internet address of remote host.
+	Unused     [20]byte    // Reserved for future use. // original is 20
+}
+
 func HostInfo() (HostInfoStat, error) {
 	ret := HostInfoStat{}
 
@@ -19,11 +46,50 @@ func HostInfo() (HostInfoStat, error) {
 	return ret, nil
 }
 
-
-func Boot_time() (int64, error){
+func Boot_time() (int64, error) {
 	sysinfo := &syscall.Sysinfo_t{}
 	if err := syscall.Sysinfo(sysinfo); err != nil {
 		return 0, err
 	}
 	return sysinfo.Uptime, nil
 }
+
+func Users() ([]UserStat, error) {
+	utmpfile := "/var/run/utmp"
+	ret := make([]UserStat, 0)
+
+	file, err := os.Open(utmpfile)
+	if err != nil {
+		return ret, err
+	}
+
+	buf, err := ioutil.ReadAll(file)
+	if err != nil {
+		return ret, err
+	}
+
+	u := utmp{}
+	entrySize := int(unsafe.Sizeof(u))
+	count := len(buf) / entrySize
+
+	for i := 0; i < count; i++ {
+		b := buf[i*entrySize : i*entrySize+entrySize]
+
+        var u utmp
+        br := bytes.NewReader(b)
+        err := binary.Read(br, binary.LittleEndian, &u)
+		if err != nil {
+			continue
+		}
+		user := UserStat{
+			User: byteToString(u.Ut_user[:]),
+			Terminal: byteToString(u.Ut_line[:]),
+			Host: byteToString(u.Ut_host[:]),
+			Started: int(u.Ut_tv.Tv_sec),
+		}
+		ret = append(ret, user)
+	}
+
+	return ret, nil
+
+}

host_test.go

@@ -23,3 +23,16 @@ func TestBoot_time(t *testing.T) {
 		t.Errorf("Could not boot time %v", v)
 	}
 }
+
+
+func TestUsers(t *testing.T) {
+	v, err := Users()
+	if err != nil {
+		t.Errorf("error %v", err)
+	}
+	for _, u := range v  {
+		if u.User == ""{
+			t.Errorf("Could not Users %v", v)
+		}
+	}
+}