1 files changed, 137 insertions, 0 deletions
diff --git a/pkg/sentry/fs/host/util_unsafe.go b/pkg/sentry/fs/host/util_unsafe.go
new file mode 100644
index 000000000..c38d2392d
--- /dev/null
+++ b/pkg/sentry/fs/host/util_unsafe.go
@@ -0,0 +1,137 @@
+// Copyright 2018 Google Inc.
+//
+// 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.
+
+package host
+
+import (
+	"syscall"
+	"unsafe"
+
+	"gvisor.googlesource.com/gvisor/pkg/abi/linux"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
+	ktime "gvisor.googlesource.com/gvisor/pkg/sentry/kernel/time"
+)
+
+func createLink(fd int, name string, linkName string) error {
+	namePtr, err := syscall.BytePtrFromString(name)
+	if err != nil {
+		return err
+	}
+	linkNamePtr, err := syscall.BytePtrFromString(linkName)
+	if err != nil {
+		return err
+	}
+	_, _, errno := syscall.Syscall(
+		syscall.SYS_SYMLINKAT,
+		uintptr(unsafe.Pointer(namePtr)),
+		uintptr(fd),
+		uintptr(unsafe.Pointer(linkNamePtr)))
+	if errno != 0 {
+		return errno
+	}
+	return nil
+}
+
+func readLink(fd int) (string, error) {
+	// Buffer sizing copied from os.Readlink.
+	for l := 128; ; l *= 2 {
+		b := make([]byte, l)
+		n, _, errno := syscall.Syscall6(
+			syscall.SYS_READLINKAT,
+			uintptr(fd),
+			uintptr(unsafe.Pointer(syscall.StringBytePtr(""))),
+			uintptr(unsafe.Pointer(&b[0])),
+			uintptr(l),
+			0, 0)
+		if n < 0 {
+			n = 0
+		}
+		if errno != 0 {
+			return "", errno
+		}
+		if n < uintptr(l) {
+			return string(b[:n]), nil
+		}
+	}
+}
+
+func unlinkAt(fd int, name string, dir bool) error {
+	namePtr, err := syscall.BytePtrFromString(name)
+	if err != nil {
+		return err
+	}
+	var flags uintptr
+	if dir {
+		flags = linux.AT_REMOVEDIR
+	}
+	_, _, errno := syscall.Syscall(
+		syscall.SYS_UNLINKAT,
+		uintptr(fd),
+		uintptr(unsafe.Pointer(namePtr)),
+		flags,
+	)
+	if errno != 0 {
+		return errno
+	}
+	return nil
+}
+
+func timespecFromTimestamp(t ktime.Time, omit, setSysTime bool) syscall.Timespec {
+	if omit {
+		return syscall.Timespec{0, linux.UTIME_OMIT}
+	}
+	if setSysTime {
+		return syscall.Timespec{0, linux.UTIME_NOW}
+	}
+	return syscall.NsecToTimespec(t.Nanoseconds())
+}
+
+func setTimestamps(fd int, ts fs.TimeSpec) error {
+	if ts.ATimeOmit && ts.MTimeOmit {
+		return nil
+	}
+	var sts [2]syscall.Timespec
+	sts[0] = timespecFromTimestamp(ts.ATime, ts.ATimeOmit, ts.ATimeSetSystemTime)
+	sts[1] = timespecFromTimestamp(ts.MTime, ts.MTimeOmit, ts.MTimeSetSystemTime)
+	_, _, errno := syscall.Syscall6(
+		syscall.SYS_UTIMENSAT,
+		uintptr(fd),
+		0, /* path */
+		uintptr(unsafe.Pointer(&sts)),
+		0, /* flags */
+		0, 0)
+	if errno != 0 {
+		return errno
+	}
+	return nil
+}
+
+func fstatat(fd int, name string, flags int) (syscall.Stat_t, error) {
+	var stat syscall.Stat_t
+	namePtr, err := syscall.BytePtrFromString(name)
+	if err != nil {
+		return stat, err
+	}
+	_, _, errno := syscall.Syscall6(
+		syscall.SYS_NEWFSTATAT,
+		uintptr(fd),
+		uintptr(unsafe.Pointer(namePtr)),
+		uintptr(unsafe.Pointer(&stat)),
+		uintptr(flags),
+		0, 0)
+	if errno != 0 {
+		return stat, errno
+	}
+	return stat, nil
+}