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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 pipe
import (
"io"
"math"
"syscall"
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/sentry/arch"
"gvisor.dev/gvisor/pkg/sentry/context"
"gvisor.dev/gvisor/pkg/sentry/fs"
"gvisor.dev/gvisor/pkg/sentry/fs/fsutil"
"gvisor.dev/gvisor/pkg/sentry/usermem"
"gvisor.dev/gvisor/pkg/waiter"
)
// ReaderWriter satisfies the FileOperations interface and services both
// read and write requests. This should only be used directly for named pipes.
// pipe(2) and pipe2(2) only support unidirectional pipes and should use
// either pipe.Reader or pipe.Writer.
//
// +stateify savable
type ReaderWriter struct {
fsutil.FilePipeSeek `state:"nosave"`
fsutil.FileNotDirReaddir `state:"nosave"`
fsutil.FileNoFsync `state:"nosave"`
fsutil.FileNoMMap `state:"nosave"`
fsutil.FileNoSplice `state:"nosave"`
fsutil.FileNoopFlush `state:"nosave"`
fsutil.FileUseInodeUnstableAttr `state:"nosave"`
*Pipe
}
// Release implements fs.FileOperations.Release.
func (rw *ReaderWriter) Release() {
rw.Pipe.rClose()
rw.Pipe.wClose()
// Wake up readers and writers.
rw.Pipe.Notify(waiter.EventIn | waiter.EventOut)
}
// Read implements fs.FileOperations.Read.
func (rw *ReaderWriter) Read(ctx context.Context, _ *fs.File, dst usermem.IOSequence, _ int64) (int64, error) {
n, err := rw.Pipe.read(ctx, readOps{
left: func() int64 {
return dst.NumBytes()
},
limit: func(l int64) {
dst = dst.TakeFirst64(l)
},
read: func(buf *buffer) (int64, error) {
n, err := dst.CopyOutFrom(ctx, buf)
dst = dst.DropFirst64(n)
return n, err
},
})
if n > 0 {
rw.Pipe.Notify(waiter.EventOut)
}
return n, err
}
// WriteTo implements fs.FileOperations.WriteTo.
func (rw *ReaderWriter) WriteTo(ctx context.Context, _ *fs.File, w io.Writer, count int64, dup bool) (int64, error) {
ops := readOps{
left: func() int64 {
return count
},
limit: func(l int64) {
count = l
},
read: func(buf *buffer) (int64, error) {
n, err := buf.ReadToWriter(w, count, dup)
count -= n
return n, err
},
}
if dup {
// There is no notification for dup operations.
return rw.Pipe.dup(ctx, ops)
}
n, err := rw.Pipe.read(ctx, ops)
if n > 0 {
rw.Pipe.Notify(waiter.EventOut)
}
return n, err
}
// Write implements fs.FileOperations.Write.
func (rw *ReaderWriter) Write(ctx context.Context, _ *fs.File, src usermem.IOSequence, _ int64) (int64, error) {
n, err := rw.Pipe.write(ctx, writeOps{
left: func() int64 {
return src.NumBytes()
},
limit: func(l int64) {
src = src.TakeFirst64(l)
},
write: func(buf *buffer) (int64, error) {
n, err := src.CopyInTo(ctx, buf)
src = src.DropFirst64(n)
return n, err
},
})
if n > 0 {
rw.Pipe.Notify(waiter.EventIn)
}
return n, err
}
// ReadFrom implements fs.FileOperations.WriteTo.
func (rw *ReaderWriter) ReadFrom(ctx context.Context, _ *fs.File, r io.Reader, count int64) (int64, error) {
n, err := rw.Pipe.write(ctx, writeOps{
left: func() int64 {
return count
},
limit: func(l int64) {
count = l
},
write: func(buf *buffer) (int64, error) {
n, err := buf.WriteFromReader(r, count)
count -= n
return n, err
},
})
if n > 0 {
rw.Pipe.Notify(waiter.EventIn)
}
return n, err
}
// Readiness returns the ready events in the underlying pipe.
func (rw *ReaderWriter) Readiness(mask waiter.EventMask) waiter.EventMask {
return rw.Pipe.rwReadiness() & mask
}
// Ioctl implements fs.FileOperations.Ioctl.
func (rw *ReaderWriter) Ioctl(ctx context.Context, _ *fs.File, io usermem.IO, args arch.SyscallArguments) (uintptr, error) {
// Switch on ioctl request.
switch int(args[1].Int()) {
case linux.FIONREAD:
v := rw.queued()
if v > math.MaxInt32 {
v = math.MaxInt32 // Silently truncate.
}
// Copy result to user-space.
_, err := usermem.CopyObjectOut(ctx, io, args[2].Pointer(), int32(v), usermem.IOOpts{
AddressSpaceActive: true,
})
return 0, err
default:
return 0, syscall.ENOTTY
}
}
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