Check in gVisor.

PiperOrigin-RevId: 194583126
Change-Id: Ica1d8821a90f74e7e745962d71801c598c652463

1 files changed, 95 insertions, 0 deletions

diff --git a/pkg/sentry/syscalls/linux/flags.go b/pkg/sentry/syscalls/linux/flags.go
new file mode 100644
index 000000000..82bfd7c2a
--- /dev/null
+++ b/pkg/sentry/syscalls/linux/flags.go
@@ -0,0 +1,95 @@
+// 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 linux
+
+import (
+	"syscall"
+
+	"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/kernel"
+)
+
+// flagsToPermissions returns a Permissions object from Linux flags.
+// This includes truncate permission if O_TRUNC is set in the mask.
+func flagsToPermissions(mask uint) (p fs.PermMask) {
+	switch mask & syscall.O_ACCMODE {
+	case syscall.O_WRONLY:
+		p.Write = true
+	case syscall.O_RDWR:
+		p.Write = true
+		p.Read = true
+	case syscall.O_RDONLY:
+		p.Read = true
+	}
+	return
+}
+
+// fdFlagsToLinux converts a kernel.FDFlags object to a Linux representation.
+func fdFlagsToLinux(flags kernel.FDFlags) (mask uint) {
+	if flags.CloseOnExec {
+		mask |= syscall.FD_CLOEXEC
+	}
+	return
+}
+
+// flagsToLinux converts a FileFlags object to a Linux representation.
+func flagsToLinux(flags fs.FileFlags) (mask uint) {
+	if flags.Direct {
+		mask |= syscall.O_DIRECT
+	}
+	if flags.NonBlocking {
+		mask |= syscall.O_NONBLOCK
+	}
+	if flags.Sync {
+		mask |= syscall.O_SYNC
+	}
+	if flags.Append {
+		mask |= syscall.O_APPEND
+	}
+	if flags.Directory {
+		mask |= syscall.O_DIRECTORY
+	}
+	switch {
+	case flags.Read && flags.Write:
+		mask |= syscall.O_RDWR
+	case flags.Write:
+		mask |= syscall.O_WRONLY
+	case flags.Read:
+		mask |= syscall.O_RDONLY
+	}
+	return
+}
+
+// linuxToFlags converts linux file flags to a FileFlags object.
+func linuxToFlags(mask uint) (flags fs.FileFlags) {
+	return fs.FileFlags{
+		Direct:      mask&syscall.O_DIRECT != 0,
+		Sync:        mask&syscall.O_SYNC != 0,
+		NonBlocking: mask&syscall.O_NONBLOCK != 0,
+		Read:        (mask & syscall.O_ACCMODE) != syscall.O_WRONLY,
+		Write:       (mask & syscall.O_ACCMODE) != syscall.O_RDONLY,
+		Append:      mask&syscall.O_APPEND != 0,
+		Directory:   mask&syscall.O_DIRECTORY != 0,
+	}
+}
+
+// linuxToSettableFlags converts linux file flags to a SettableFileFlags object.
+func linuxToSettableFlags(mask uint) fs.SettableFileFlags {
+	return fs.SettableFileFlags{
+		Direct:      mask&syscall.O_DIRECT != 0,
+		NonBlocking: mask&syscall.O_NONBLOCK != 0,
+		Append:      mask&syscall.O_APPEND != 0,
+	}
+}