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// Copyright 2020 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 fsbridge
import (
"io"
"strings"
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/context"
"gvisor.dev/gvisor/pkg/errors/linuxerr"
"gvisor.dev/gvisor/pkg/sentry/fs"
"gvisor.dev/gvisor/pkg/sentry/memmap"
"gvisor.dev/gvisor/pkg/sentry/vfs"
"gvisor.dev/gvisor/pkg/syserror"
"gvisor.dev/gvisor/pkg/usermem"
)
// fsFile implements File interface over fs.File.
//
// +stateify savable
type fsFile struct {
file *fs.File
}
var _ File = (*fsFile)(nil)
// NewFSFile creates a new File over fs.File.
func NewFSFile(file *fs.File) File {
return &fsFile{file: file}
}
// PathnameWithDeleted implements File.
func (f *fsFile) PathnameWithDeleted(ctx context.Context) string {
root := fs.RootFromContext(ctx)
if root == nil {
// This doesn't correspond to anything in Linux because the vfs is
// global there.
return ""
}
defer root.DecRef(ctx)
name, _ := f.file.Dirent.FullName(root)
return name
}
// ReadFull implements File.
func (f *fsFile) ReadFull(ctx context.Context, dst usermem.IOSequence, offset int64) (int64, error) {
var total int64
for dst.NumBytes() > 0 {
n, err := f.file.Preadv(ctx, dst, offset+total)
total += n
if err == io.EOF && total != 0 {
return total, io.ErrUnexpectedEOF
} else if err != nil {
return total, err
}
dst = dst.DropFirst64(n)
}
return total, nil
}
// ConfigureMMap implements File.
func (f *fsFile) ConfigureMMap(ctx context.Context, opts *memmap.MMapOpts) error {
return f.file.ConfigureMMap(ctx, opts)
}
// Type implements File.
func (f *fsFile) Type(context.Context) (linux.FileMode, error) {
return linux.FileMode(f.file.Dirent.Inode.StableAttr.Type.LinuxType()), nil
}
// IncRef implements File.
func (f *fsFile) IncRef() {
f.file.IncRef()
}
// DecRef implements File.
func (f *fsFile) DecRef(ctx context.Context) {
f.file.DecRef(ctx)
}
// fsLookup implements Lookup interface using fs.File.
//
// +stateify savable
type fsLookup struct {
mntns *fs.MountNamespace
root *fs.Dirent
workingDir *fs.Dirent
}
var _ Lookup = (*fsLookup)(nil)
// NewFSLookup creates a new Lookup using VFS1.
func NewFSLookup(mntns *fs.MountNamespace, root, workingDir *fs.Dirent) Lookup {
return &fsLookup{
mntns: mntns,
root: root,
workingDir: workingDir,
}
}
// OpenPath implements Lookup.
func (l *fsLookup) OpenPath(ctx context.Context, path string, opts vfs.OpenOptions, remainingTraversals *uint, resolveFinal bool) (File, error) {
var d *fs.Dirent
var err error
if resolveFinal {
d, err = l.mntns.FindInode(ctx, l.root, l.workingDir, path, remainingTraversals)
} else {
d, err = l.mntns.FindLink(ctx, l.root, l.workingDir, path, remainingTraversals)
}
if err != nil {
return nil, err
}
defer d.DecRef(ctx)
if !resolveFinal && fs.IsSymlink(d.Inode.StableAttr) {
return nil, linuxerr.ELOOP
}
fsPerm := openOptionsToPermMask(&opts)
if err := d.Inode.CheckPermission(ctx, fsPerm); err != nil {
return nil, err
}
// If they claim it's a directory, then make sure.
if strings.HasSuffix(path, "/") {
if d.Inode.StableAttr.Type != fs.Directory {
return nil, syserror.ENOTDIR
}
}
if opts.FileExec && d.Inode.StableAttr.Type != fs.RegularFile {
ctx.Infof("%q is not a regular file: %v", path, d.Inode.StableAttr.Type)
return nil, linuxerr.EACCES
}
f, err := d.Inode.GetFile(ctx, d, flagsToFileFlags(opts.Flags))
if err != nil {
return nil, err
}
return &fsFile{file: f}, nil
}
func openOptionsToPermMask(opts *vfs.OpenOptions) fs.PermMask {
mode := opts.Flags & linux.O_ACCMODE
return fs.PermMask{
Read: mode == linux.O_RDONLY || mode == linux.O_RDWR,
Write: mode == linux.O_WRONLY || mode == linux.O_RDWR,
Execute: opts.FileExec,
}
}
func flagsToFileFlags(flags uint32) fs.FileFlags {
return fs.FileFlags{
Direct: flags&linux.O_DIRECT != 0,
DSync: flags&(linux.O_DSYNC|linux.O_SYNC) != 0,
Sync: flags&linux.O_SYNC != 0,
NonBlocking: flags&linux.O_NONBLOCK != 0,
Read: (flags & linux.O_ACCMODE) != linux.O_WRONLY,
Write: (flags & linux.O_ACCMODE) != linux.O_RDONLY,
Append: flags&linux.O_APPEND != 0,
Directory: flags&linux.O_DIRECTORY != 0,
Async: flags&linux.O_ASYNC != 0,
LargeFile: flags&linux.O_LARGEFILE != 0,
Truncate: flags&linux.O_TRUNC != 0,
}
}
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