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// 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.
package fs
import (
"gvisor.dev/gvisor/pkg/abi/linux"
)
// FileFlags encodes file flags.
//
// +stateify savable
type FileFlags struct {
// Direct indicates that I/O should be done directly.
Direct bool
// NonBlocking indicates that I/O should not block.
NonBlocking bool
// DSync indicates that each write will flush data and metadata required to
// read the file's contents.
DSync bool
// Sync indicates that each write will flush data and all file metadata.
Sync bool
// Append indicates this file is append only.
Append bool
// Read indicates this file is readable.
Read bool
// Write indicates this file is writeable.
Write bool
// Pread indicates this file is readable at an arbitrary offset.
Pread bool
// Pwrite indicates this file is writable at an arbitrary offset.
Pwrite bool
// Directory indicates that this file must be a directory.
Directory bool
// Async indicates that this file sends signals on IO events.
Async bool
// LargeFile indicates that this file should be opened even if it has
// size greater than linux's off_t. When running in 64-bit mode,
// Linux sets this flag for all files. Since gVisor is only compatible
// with 64-bit Linux, it also sets this flag for all files.
LargeFile bool
// NonSeekable indicates that file.offset isn't used.
NonSeekable bool
// Truncate indicates that the file should be truncated before opened.
// This is only applicable if the file is regular.
Truncate bool
}
// SettableFileFlags is a subset of FileFlags above that can be changed
// via fcntl(2) using the F_SETFL command.
type SettableFileFlags struct {
// Direct indicates that I/O should be done directly.
Direct bool
// NonBlocking indicates that I/O should not block.
NonBlocking bool
// Append indicates this file is append only.
Append bool
// Async indicates that this file sends signals on IO events.
Async bool
}
// Settable returns the subset of f that are settable.
func (f FileFlags) Settable() SettableFileFlags {
return SettableFileFlags{
Direct: f.Direct,
NonBlocking: f.NonBlocking,
Append: f.Append,
Async: f.Async,
}
}
// ToLinux converts a FileFlags object to a Linux representation.
func (f FileFlags) ToLinux() (mask uint) {
if f.Direct {
mask |= linux.O_DIRECT
}
if f.NonBlocking {
mask |= linux.O_NONBLOCK
}
if f.DSync {
mask |= linux.O_DSYNC
}
if f.Sync {
mask |= linux.O_SYNC
}
if f.Append {
mask |= linux.O_APPEND
}
if f.Directory {
mask |= linux.O_DIRECTORY
}
if f.Async {
mask |= linux.O_ASYNC
}
if f.LargeFile {
mask |= linux.O_LARGEFILE
}
if f.Truncate {
mask |= linux.O_TRUNC
}
switch {
case f.Read && f.Write:
mask |= linux.O_RDWR
case f.Write:
mask |= linux.O_WRONLY
case f.Read:
mask |= linux.O_RDONLY
}
return
}
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