Windows: Factor out CloseExecFrom

Signed-off-by: John Howard <jhoward@microsoft.com>

libcontainer/utils/utils.go

@@ -4,9 +4,7 @@ import (
 	"crypto/rand"
 	"encoding/hex"
 	"io"
-	"io/ioutil"
 	"path/filepath"
-	"strconv"
 	"syscall"
 )
 
@@ -37,30 +35,6 @@ func ResolveRootfs(uncleanRootfs string) (string, error) {
 	return filepath.EvalSymlinks(rootfs)
 }
 
-func CloseExecFrom(minFd int) error {
-	fdList, err := ioutil.ReadDir("/proc/self/fd")
-	if err != nil {
-		return err
-	}
-	for _, fi := range fdList {
-		fd, err := strconv.Atoi(fi.Name())
-		if err != nil {
-			// ignore non-numeric file names
-			continue
-		}
-
-		if fd < minFd {
-			// ignore descriptors lower than our specified minimum
-			continue
-		}
-
-		// intentionally ignore errors from syscall.CloseOnExec
-		syscall.CloseOnExec(fd)
-		// the cases where this might fail are basically file descriptors that have already been closed (including and especially the one that was created when ioutil.ReadDir did the "opendir" syscall)
-	}
-	return nil
-}
-
 // ExitStatus returns the correct exit status for a process based on if it
 // was signaled or existed cleanly.
 func ExitStatus(status syscall.WaitStatus) int {

libcontainer/utils/utils_unix.go

@@ -0,0 +1,33 @@
+// +build !windows
+
+package utils
+
+import (
+	"io/ioutil"
+	"strconv"
+	"syscall"
+)
+
+func CloseExecFrom(minFd int) error {
+	fdList, err := ioutil.ReadDir("/proc/self/fd")
+	if err != nil {
+		return err
+	}
+	for _, fi := range fdList {
+		fd, err := strconv.Atoi(fi.Name())
+		if err != nil {
+			// ignore non-numeric file names
+			continue
+		}
+
+		if fd < minFd {
+			// ignore descriptors lower than our specified minimum
+			continue
+		}
+
+		// intentionally ignore errors from syscall.CloseOnExec
+		syscall.CloseOnExec(fd)
+		// the cases where this might fail are basically file descriptors that have already been closed (including and especially the one that was created when ioutil.ReadDir did the "opendir" syscall)
+	}
+	return nil
+}