Move //pkg/sentry/memutil to //pkg/memutil.

PiperOrigin-RevId: 252124156

2 files changed, 53 insertions, 0 deletions

diff --git a/pkg/memutil/BUILD b/pkg/memutil/BUILD
new file mode 100644
index 000000000..71b48a972
--- /dev/null
+++ b/pkg/memutil/BUILD
@@ -0,0 +1,11 @@
+load("//tools/go_stateify:defs.bzl", "go_library")
+
+package(licenses = ["notice"])
+
+go_library(
+    name = "memutil",
+    srcs = ["memutil_unsafe.go"],
+    importpath = "gvisor.googlesource.com/gvisor/pkg/memutil",
+    visibility = ["//visibility:public"],
+    deps = ["@org_golang_x_sys//unix:go_default_library"],
+)
diff --git a/pkg/memutil/memutil_unsafe.go b/pkg/memutil/memutil_unsafe.go
new file mode 100644
index 000000000..979d942a9
--- /dev/null
+++ b/pkg/memutil/memutil_unsafe.go
@@ -0,0 +1,42 @@
+// Copyright 2018 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build linux
+
+// Package memutil provides a wrapper for the memfd_create() system call.
+package memutil
+
+import (
+	"fmt"
+	"syscall"
+	"unsafe"
+
+	"golang.org/x/sys/unix"
+)
+
+// CreateMemFD creates a memfd file and returns the fd.
+func CreateMemFD(name string, flags int) (int, error) {
+	p, err := syscall.BytePtrFromString(name)
+	if err != nil {
+		return -1, err
+	}
+	fd, _, e := syscall.Syscall(unix.SYS_MEMFD_CREATE, uintptr(unsafe.Pointer(p)), uintptr(flags), 0)
+	if e != 0 {
+		if e == syscall.ENOSYS {
+			return -1, fmt.Errorf("memfd_create(2) is not implemented. Check that you have Linux 3.17 or higher")
+		}
+		return -1, e
+	}
+	return int(fd), nil
+}