libcontainer/logs: use int for Config.LogPipeFd

It does not make sense to have a string for a numeric type.

Signed-off-by: Kir Kolyshkin <[email protected]>

init.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"os"
 	"runtime"
+	"strconv"
 
 	"github.com/opencontainers/runc/libcontainer"
 	"github.com/opencontainers/runc/libcontainer/logs"
@@ -23,8 +24,13 @@ func init() {
 			panic(fmt.Sprintf("libcontainer: failed to parse log level: %q: %v", level, err))
 		}
 
+		logPipeFdStr := os.Getenv("_LIBCONTAINER_LOGPIPE")
+		logPipeFd, err := strconv.Atoi(logPipeFdStr)
+		if err != nil {
+			panic(fmt.Sprintf("libcontainer: failed to convert environment variable _LIBCONTAINER_LOGPIPE=%s to int: %s", logPipeFdStr, err))
+		}
 		err = logs.ConfigureLogging(logs.Config{
-			LogPipeFd: os.Getenv("_LIBCONTAINER_LOGPIPE"),
+			LogPipeFd: logPipeFd,
 			LogFormat: "json",
 			LogLevel:  logLevel,
 		})

libcontainer/logs/logs.go

@@ -6,7 +6,6 @@ import (
 	"fmt"
 	"io"
 	"os"
-	"strconv"
 	"sync"
 
 	"github.com/sirupsen/logrus"
@@ -23,7 +22,7 @@ type Config struct {
 	LogLevel    logrus.Level
 	LogFormat   string
 	LogFilePath string
-	LogPipeFd   string
+	LogPipeFd   int
 }
 
 func ForwardLogs(logPipe io.Reader) {
@@ -74,12 +73,10 @@ func ConfigureLogging(config Config) error {
 
 	logrus.SetLevel(config.LogLevel)
 
-	if config.LogPipeFd != "" {
-		logPipeFdInt, err := strconv.Atoi(config.LogPipeFd)
-		if err != nil {
-			return fmt.Errorf("failed to convert _LIBCONTAINER_LOGPIPE environment variable value %q to int: %v", config.LogPipeFd, err)
-		}
-		logrus.SetOutput(os.NewFile(uintptr(logPipeFdInt), "logpipe"))
+	// XXX: while 0 is a valid fd (usually stdin), here we assume
+	// that we never deliberately set LogPipeFd to 0.
+	if config.LogPipeFd > 0 {
+		logrus.SetOutput(os.NewFile(uintptr(config.LogPipeFd), "logpipe"))
 	} else if config.LogFilePath != "" {
 		f, err := os.OpenFile(config.LogFilePath, os.O_CREATE|os.O_WRONLY|os.O_APPEND|os.O_SYNC, 0644)
 		if err != nil {

main.go

@@ -176,9 +176,9 @@ func (f *FatalWriter) Write(p []byte) (n int, err error) {
 
 func createLogConfig(context *cli.Context) logs.Config {
 	logFilePath := context.GlobalString("log")
-	logPipeFd := ""
+	logPipeFd := 0
 	if logFilePath == "" {
-		logPipeFd = "2"
+		logPipeFd = 2
 	}
 	config := logs.Config{
 		LogPipeFd:   logPipeFd,