[android][host] fallback to sysinfo() syscall for uptime

with Android O, /proc/{stat,uptime} both return permission denied

internal/common/common_linux.go

@@ -6,13 +6,13 @@ package common
 import (
 	"context"
 	"fmt"
+	"golang.org/x/sys/unix"
 	"os"
 	"os/exec"
 	"path/filepath"
 	"strconv"
 	"strings"
 	"sync"
-	"time"
 )
 
 func DoSysctrl(mib string) ([]string, error) {
@@ -68,7 +68,17 @@ func BootTimeWithContext(ctx context.Context) (uint64, error) {
 
 	filename := HostProc(statFile)
 	lines, err := ReadLines(filename)
-	if err != nil {
+	if os.IsPermission(err) {
+		var info syscall.Sysinfo_t
+		err := syscall.Sysinfo(&info)
+		if err != nil {
+			return 0, err
+		}
+
+		currentTime := time.Now().UnixNano() / int64(time.Second)
+		t := currentTime - info.Uptime
+		return uint64(t), nil
+	} else if err != nil {
 		return 0, err
 	}