130 lines
4.4 KiB
Go
130 lines
4.4 KiB
Go
// Copyright 2019 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package kernfs
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import (
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"fmt"
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"gvisor.dev/gvisor/pkg/abi/linux"
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"gvisor.dev/gvisor/pkg/sentry/context"
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"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
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"gvisor.dev/gvisor/pkg/sentry/usermem"
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"gvisor.dev/gvisor/pkg/sentry/vfs"
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"gvisor.dev/gvisor/pkg/syserror"
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)
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// DynamicBytesFile implements kernfs.Inode and represents a read-only
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// file whose contents are backed by a vfs.DynamicBytesSource.
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//
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// Must be instantiated with NewDynamicBytesFile or initialized with Init
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// before first use.
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//
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// +stateify savable
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type DynamicBytesFile struct {
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InodeAttrs
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InodeNoopRefCount
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InodeNotDirectory
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InodeNotSymlink
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data vfs.DynamicBytesSource
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}
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var _ Inode = (*DynamicBytesFile)(nil)
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// Init initializes a dynamic bytes file.
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func (f *DynamicBytesFile) Init(creds *auth.Credentials, ino uint64, data vfs.DynamicBytesSource, perm linux.FileMode) {
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if perm&^linux.PermissionsMask != 0 {
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panic(fmt.Sprintf("Only permission mask must be set: %x", perm&linux.PermissionsMask))
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}
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f.InodeAttrs.Init(creds, ino, linux.ModeRegular|perm)
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f.data = data
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}
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// Open implements Inode.Open.
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func (f *DynamicBytesFile) Open(rp *vfs.ResolvingPath, vfsd *vfs.Dentry, flags uint32) (*vfs.FileDescription, error) {
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fd := &DynamicBytesFD{}
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fd.Init(rp.Mount(), vfsd, f.data, flags)
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return &fd.vfsfd, nil
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}
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// SetStat implements Inode.SetStat.
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func (f *DynamicBytesFile) SetStat(*vfs.Filesystem, vfs.SetStatOptions) error {
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// DynamicBytesFiles are immutable.
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return syserror.EPERM
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}
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// DynamicBytesFD implements vfs.FileDescriptionImpl for an FD backed by a
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// DynamicBytesFile.
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//
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// Must be initialized with Init before first use.
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//
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// +stateify savable
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type DynamicBytesFD struct {
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vfs.FileDescriptionDefaultImpl
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vfs.DynamicBytesFileDescriptionImpl
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vfsfd vfs.FileDescription
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inode Inode
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}
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// Init initializes a DynamicBytesFD.
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func (fd *DynamicBytesFD) Init(m *vfs.Mount, d *vfs.Dentry, data vfs.DynamicBytesSource, flags uint32) {
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m.IncRef() // DecRef in vfs.FileDescription.vd.DecRef on final ref.
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d.IncRef() // DecRef in vfs.FileDescription.vd.DecRef on final ref.
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fd.inode = d.Impl().(*Dentry).inode
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fd.SetDataSource(data)
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fd.vfsfd.Init(fd, flags, m, d, &vfs.FileDescriptionOptions{})
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}
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// Seek implements vfs.FileDescriptionImpl.Seek.
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func (fd *DynamicBytesFD) Seek(ctx context.Context, offset int64, whence int32) (int64, error) {
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return fd.DynamicBytesFileDescriptionImpl.Seek(ctx, offset, whence)
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}
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// Read implmenets vfs.FileDescriptionImpl.Read.
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func (fd *DynamicBytesFD) Read(ctx context.Context, dst usermem.IOSequence, opts vfs.ReadOptions) (int64, error) {
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return fd.DynamicBytesFileDescriptionImpl.Read(ctx, dst, opts)
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}
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// PRead implmenets vfs.FileDescriptionImpl.PRead.
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func (fd *DynamicBytesFD) PRead(ctx context.Context, dst usermem.IOSequence, offset int64, opts vfs.ReadOptions) (int64, error) {
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return fd.DynamicBytesFileDescriptionImpl.PRead(ctx, dst, offset, opts)
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}
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// Write implements vfs.FileDescriptionImpl.Write.
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func (fd *DynamicBytesFD) Write(ctx context.Context, src usermem.IOSequence, opts vfs.WriteOptions) (int64, error) {
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return fd.FileDescriptionDefaultImpl.Write(ctx, src, opts)
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}
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// PWrite implements vfs.FileDescriptionImpl.PWrite.
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func (fd *DynamicBytesFD) PWrite(ctx context.Context, src usermem.IOSequence, offset int64, opts vfs.WriteOptions) (int64, error) {
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return fd.FileDescriptionDefaultImpl.PWrite(ctx, src, offset, opts)
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}
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// Release implements vfs.FileDescriptionImpl.Release.
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func (fd *DynamicBytesFD) Release() {}
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// Stat implements vfs.FileDescriptionImpl.Stat.
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func (fd *DynamicBytesFD) Stat(ctx context.Context, opts vfs.StatOptions) (linux.Statx, error) {
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fs := fd.vfsfd.VirtualDentry().Mount().Filesystem()
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return fd.inode.Stat(fs), nil
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}
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// SetStat implements vfs.FileDescriptionImpl.SetStat.
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func (fd *DynamicBytesFD) SetStat(context.Context, vfs.SetStatOptions) error {
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// DynamicBytesFiles are immutable.
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return syserror.EPERM
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}
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