1 files changed, 131 insertions, 0 deletions
diff --git a/pkg/sentry/fsimpl/kernfs/dynamic_bytes_file.go b/pkg/sentry/fsimpl/kernfs/dynamic_bytes_file.go
new file mode 100644
index 000000000..30c06baf0
--- /dev/null
+++ b/pkg/sentry/fsimpl/kernfs/dynamic_bytes_file.go
@@ -0,0 +1,131 @@
+// Copyright 2019 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 kernfs
+
+import (
+	"gvisor.dev/gvisor/pkg/abi/linux"
+	"gvisor.dev/gvisor/pkg/sentry/context"
+	"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
+	"gvisor.dev/gvisor/pkg/sentry/usermem"
+	"gvisor.dev/gvisor/pkg/sentry/vfs"
+	"gvisor.dev/gvisor/pkg/syserror"
+)
+
+// DynamicBytesFile implements kernfs.Inode and represents a read-only
+// file whose contents are backed by a vfs.DynamicBytesSource.
+//
+// Must be initialized with Init before first use.
+type DynamicBytesFile struct {
+	InodeAttrs
+	InodeNoopRefCount
+	InodeNotDirectory
+	InodeNotSymlink
+
+	data vfs.DynamicBytesSource
+}
+
+// Init intializes a dynamic bytes file.
+func (f *DynamicBytesFile) Init(creds *auth.Credentials, ino uint64, data vfs.DynamicBytesSource) {
+	f.InodeAttrs.Init(creds, ino, linux.ModeRegular|0444)
+	f.data = data
+}
+
+// Open implements Inode.Open.
+func (f *DynamicBytesFile) Open(rp *vfs.ResolvingPath, vfsd *vfs.Dentry, flags uint32) (*vfs.FileDescription, error) {
+	fd := &DynamicBytesFD{}
+	fd.Init(rp.Mount(), vfsd, f.data, flags)
+	return &fd.vfsfd, nil
+}
+
+// SetStat implements Inode.SetStat.
+func (f *DynamicBytesFile) SetStat(*vfs.Filesystem, vfs.SetStatOptions) error {
+	// DynamicBytesFiles are immutable.
+	return syserror.EPERM
+}
+
+// DynamicBytesFD implements vfs.FileDescriptionImpl for an FD backed by a
+// DynamicBytesFile.
+//
+// Must be initialized with Init before first use.
+type DynamicBytesFD struct {
+	vfs.FileDescriptionDefaultImpl
+	vfs.DynamicBytesFileDescriptionImpl
+
+	vfsfd vfs.FileDescription
+	inode Inode
+	flags uint32
+}
+
+// Init initializes a DynamicBytesFD.
+func (fd *DynamicBytesFD) Init(m *vfs.Mount, d *vfs.Dentry, data vfs.DynamicBytesSource, flags uint32) {
+	m.IncRef() // DecRef in vfs.FileDescription.vd.DecRef on final ref.
+	d.IncRef() // DecRef in vfs.FileDescription.vd.DecRef on final ref.
+	fd.flags = flags
+	fd.inode = d.Impl().(*Dentry).inode
+	fd.SetDataSource(data)
+	fd.vfsfd.Init(fd, m, d)
+}
+
+// Seek implements vfs.FileDescriptionImpl.Seek.
+func (fd *DynamicBytesFD) Seek(ctx context.Context, offset int64, whence int32) (int64, error) {
+	return fd.DynamicBytesFileDescriptionImpl.Seek(ctx, offset, whence)
+}
+
+// Read implmenets vfs.FileDescriptionImpl.Read.
+func (fd *DynamicBytesFD) Read(ctx context.Context, dst usermem.IOSequence, opts vfs.ReadOptions) (int64, error) {
+	return fd.DynamicBytesFileDescriptionImpl.Read(ctx, dst, opts)
+}
+
+// PRead implmenets vfs.FileDescriptionImpl.PRead.
+func (fd *DynamicBytesFD) PRead(ctx context.Context, dst usermem.IOSequence, offset int64, opts vfs.ReadOptions) (int64, error) {
+	return fd.DynamicBytesFileDescriptionImpl.PRead(ctx, dst, offset, opts)
+}
+
+// Write implements vfs.FileDescriptionImpl.Write.
+func (fd *DynamicBytesFD) Write(ctx context.Context, src usermem.IOSequence, opts vfs.WriteOptions) (int64, error) {
+	return fd.FileDescriptionDefaultImpl.Write(ctx, src, opts)
+}
+
+// PWrite implements vfs.FileDescriptionImpl.PWrite.
+func (fd *DynamicBytesFD) PWrite(ctx context.Context, src usermem.IOSequence, offset int64, opts vfs.WriteOptions) (int64, error) {
+	return fd.FileDescriptionDefaultImpl.PWrite(ctx, src, offset, opts)
+}
+
+// Release implements vfs.FileDescriptionImpl.Release.
+func (fd *DynamicBytesFD) Release() {}
+
+// Stat implements vfs.FileDescriptionImpl.Stat.
+func (fd *DynamicBytesFD) Stat(ctx context.Context, opts vfs.StatOptions) (linux.Statx, error) {
+	fs := fd.vfsfd.VirtualDentry().Mount().Filesystem()
+	return fd.inode.Stat(fs), nil
+}
+
+// SetStat implements vfs.FileDescriptionImpl.SetStat.
+func (fd *DynamicBytesFD) SetStat(context.Context, vfs.SetStatOptions) error {
+	// DynamicBytesFiles are immutable.
+	return syserror.EPERM
+}
+
+// StatusFlags implements vfs.FileDescriptionImpl.StatusFlags.
+func (fd *DynamicBytesFD) StatusFlags(ctx context.Context) (uint32, error) {
+	return fd.flags, nil
+}
+
+// SetStatusFlags implements vfs.FileDescriptionImpl.SetStatusFlags.
+func (fd *DynamicBytesFD) SetStatusFlags(ctx context.Context, flags uint32) error {
+	// None of the flags settable by fcntl(F_SETFL) are supported, so this is a
+	// no-op.
+	return nil
+}