int/linux: add/use Dup3, Open, Openat

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

internal/linux/linux.go

@@ -6,6 +6,14 @@ import (
 	"golang.org/x/sys/unix"
 )
 
+// Dup3 wraps [unix.Dup3].
+func Dup3(oldfd, newfd, flags int) error {
+	err := retryOnEINTR(func() error {
+		return unix.Dup3(oldfd, newfd, flags)
+	})
+	return os.NewSyscallError("dup3", err)
+}
+
 // Exec wraps [unix.Exec].
 func Exec(cmd string, args []string, env []string) error {
 	err := retryOnEINTR(func() error {
@@ -23,6 +31,28 @@ func Getwd() (wd string, err error) {
 	return wd, os.NewSyscallError("getwd", err)
 }
 
+// Open wraps [unix.Open].
+func Open(path string, mode int, perm uint32) (fd int, err error) {
+	fd, err = retryOnEINTR2(func() (int, error) {
+		return unix.Open(path, mode, perm)
+	})
+	if err != nil {
+		return -1, &os.PathError{Op: "open", Path: path, Err: err}
+	}
+	return fd, nil
+}
+
+// Openat wraps [unix.Openat].
+func Openat(dirfd int, path string, mode int, perm uint32) (fd int, err error) {
+	fd, err = retryOnEINTR2(func() (int, error) {
+		return unix.Openat(dirfd, path, mode, perm)
+	})
+	if err != nil {
+		return -1, &os.PathError{Op: "openat", Path: path, Err: err}
+	}
+	return fd, nil
+}
+
 // Sendmsg wraps [unix.Sendmsg].
 func Sendmsg(fd int, p, oob []byte, to unix.Sockaddr, flags int) error {
 	err := retryOnEINTR(func() error {