libct: Use RetryOnEINTR() instead of open-coding it

Let's move the existing code to the new helper. There are two places
that are not moved, because they currently use an unbounded for loop for
other reasons and the code seems cleaner keeping it as it is.

Signed-off-by: Rodrigo Campos <rodrigoca@microsoft.com>

Author: rata

libcontainer/specconv/spec_linux.go

@@ -19,6 +19,7 @@ import (
 	"github.com/opencontainers/runc/libcontainer/configs"
 	"github.com/opencontainers/runc/libcontainer/internal/userns"
 	"github.com/opencontainers/runc/libcontainer/seccomp"
+	"github.com/opencontainers/runc/libcontainer/utils"
 	libcontainerUtils "github.com/opencontainers/runc/libcontainer/utils"
 	"github.com/opencontainers/runtime-spec/specs-go"
 	"github.com/sirupsen/logrus"
@@ -348,12 +349,9 @@ type CreateOpts struct {
 // the value from the kernel, which guarantees the returned value
 // to be absolute and clean.
 func getwd() (wd string, err error) {
-	for {
-		wd, err = unix.Getwd()
-		if err != unix.EINTR {
-			break
-		}
-	}
+	wd, err = utils.RetryOnEINTR2(func() (string, error) {
+		return unix.Getwd()
+	})
 	return wd, os.NewSyscallError("getwd", err)
 }
 

libcontainer/sync_unix.go

@@ -6,6 +6,7 @@ import (
 	"os"
 	"sync/atomic"
 
+	"github.com/opencontainers/runc/libcontainer/utils"
 	"golang.org/x/sys/unix"
 )
 
@@ -42,18 +43,10 @@ func (s *syncSocket) WritePacket(b []byte) (int, error) {
 }
 
 func (s *syncSocket) ReadPacket() ([]byte, error) {
-	var (
-		size int
-		err  error
-	)
-
-	for {
-		size, _, err = unix.Recvfrom(int(s.f.Fd()), nil, unix.MSG_TRUNC|unix.MSG_PEEK)
-		if err != unix.EINTR { //nolint:errorlint // unix errors are bare
-			break
-		}
-	}
-
+	size, err := utils.RetryOnEINTR2(func() (int, error) {
+		size, _, err := unix.Recvfrom(int(s.f.Fd()), nil, unix.MSG_TRUNC|unix.MSG_PEEK)
+		return size, err
+	})
 	if err != nil {
 		return nil, fmt.Errorf("fetch packet length from socket: %w", os.NewSyscallError("recvfrom", err))
 	}

libcontainer/system/linux.go

@@ -8,6 +8,7 @@ import (
 	"os"
 	"unsafe"
 
+	"github.com/opencontainers/runc/libcontainer/utils"
 	"github.com/sirupsen/logrus"
 	"golang.org/x/sys/unix"
 )
@@ -33,12 +34,10 @@ func (p ParentDeathSignal) Set() error {
 }
 
 func Exec(cmd string, args []string, env []string) error {
-	for {
-		err := unix.Exec(cmd, args, env)
-		if err != unix.EINTR {
-			return &os.PathError{Op: "exec", Path: cmd, Err: err}
-		}
-	}
+	err := utils.RetryOnEINTR(func() error {
+		return unix.Exec(cmd, args, env)
+	})
+	return &os.PathError{Op: "exec", Path: cmd, Err: err}
 }
 
 func SetParentDeathSignal(sig uintptr) error {

libcontainer/utils/cmsg.go

@@ -47,13 +47,10 @@ func RecvFile(socket *os.File) (_ *os.File, Err error) {
 		err     error
 	)
 
-	for {
+	err = RetryOnEINTR(func() error {
 		n, oobn, _, _, err = unix.Recvmsg(int(sockfd), name, oob, unix.MSG_CMSG_CLOEXEC)
-		if err != unix.EINTR { //nolint:errorlint // unix errors are bare
-			break
-		}
-	}
-
+		return err
+	})
 	if err != nil {
 		return nil, os.NewSyscallError("recvmsg", err)
 	}
@@ -126,10 +123,8 @@ func SendFile(socket *os.File, file *os.File) error {
 // SendRawFd sends a specific file descriptor over the given AF_UNIX socket.
 func SendRawFd(socket *os.File, msg string, fd uintptr) error {
 	oob := unix.UnixRights(int(fd))
-	for {
-		err := unix.Sendmsg(int(socket.Fd()), []byte(msg), oob, nil, 0)
-		if err != unix.EINTR { //nolint:errorlint // unix errors are bare
-			return os.NewSyscallError("sendmsg", err)
-		}
-	}
+	err := RetryOnEINTR(func() error {
+		return unix.Sendmsg(int(socket.Fd()), []byte(msg), oob, nil, 0)
+	})
+	return os.NewSyscallError("sendmsg", err)
 }