Merge release-20200818.0-77-g84f04909c (automated)

29 files changed, 128 insertions, 89 deletions

diff --git a/pkg/sentry/fsimpl/devpts/root_inode_refs.go b/pkg/sentry/fsimpl/devpts/root_inode_refs.go
index 051801202..b860819f0 100644
--- a/pkg/sentry/fsimpl/devpts/root_inode_refs.go
+++ b/pkg/sentry/fsimpl/devpts/root_inode_refs.go
@@ -1,12 +1,12 @@
 package devpts
 
 import (
-	"fmt"
-	"runtime"
 	"sync/atomic"
 
+	"fmt"
 	"gvisor.dev/gvisor/pkg/log"
 	refs_vfs1 "gvisor.dev/gvisor/pkg/refs"
+	"runtime"
 )
 
 // ownerType is used to customize logging. Note that we use a pointer to T so
diff --git a/pkg/sentry/fsimpl/fuse/inode_refs.go b/pkg/sentry/fsimpl/fuse/inode_refs.go
index 6b9456e1d..646042846 100644
--- a/pkg/sentry/fsimpl/fuse/inode_refs.go
+++ b/pkg/sentry/fsimpl/fuse/inode_refs.go
@@ -1,12 +1,12 @@
 package fuse
 
 import (
-	"fmt"
-	"runtime"
 	"sync/atomic"
 
+	"fmt"
 	"gvisor.dev/gvisor/pkg/log"
 	refs_vfs1 "gvisor.dev/gvisor/pkg/refs"
+	"runtime"
 )
 
 // ownerType is used to customize logging. Note that we use a pointer to T so
diff --git a/pkg/sentry/fsimpl/host/connected_endpoint_refs.go b/pkg/sentry/fsimpl/host/connected_endpoint_refs.go
index babb3f664..670166c76 100644
--- a/pkg/sentry/fsimpl/host/connected_endpoint_refs.go
+++ b/pkg/sentry/fsimpl/host/connected_endpoint_refs.go
@@ -1,12 +1,12 @@
 package host
 
 import (
-	"fmt"
-	"runtime"
 	"sync/atomic"
 
+	"fmt"
 	"gvisor.dev/gvisor/pkg/log"
 	refs_vfs1 "gvisor.dev/gvisor/pkg/refs"
+	"runtime"
 )
 
 // ownerType is used to customize logging. Note that we use a pointer to T so
diff --git a/pkg/sentry/fsimpl/host/inode_refs.go b/pkg/sentry/fsimpl/host/inode_refs.go
index 17f90ce4a..49c57c113 100644
--- a/pkg/sentry/fsimpl/host/inode_refs.go
+++ b/pkg/sentry/fsimpl/host/inode_refs.go
@@ -1,12 +1,12 @@
 package host
 
 import (
-	"fmt"
-	"runtime"
 	"sync/atomic"
 
+	"fmt"
 	"gvisor.dev/gvisor/pkg/log"
 	refs_vfs1 "gvisor.dev/gvisor/pkg/refs"
+	"runtime"
 )
 
 // ownerType is used to customize logging. Note that we use a pointer to T so
diff --git a/pkg/sentry/fsimpl/kernfs/dentry_refs.go b/pkg/sentry/fsimpl/kernfs/dentry_refs.go
index 79863b3bc..0269851c9 100644
--- a/pkg/sentry/fsimpl/kernfs/dentry_refs.go
+++ b/pkg/sentry/fsimpl/kernfs/dentry_refs.go
@@ -1,12 +1,12 @@
 package kernfs
 
 import (
-	"fmt"
-	"runtime"
 	"sync/atomic"
 
+	"fmt"
 	"gvisor.dev/gvisor/pkg/log"
 	refs_vfs1 "gvisor.dev/gvisor/pkg/refs"
+	"runtime"
 )
 
 // ownerType is used to customize logging. Note that we use a pointer to T so
diff --git a/pkg/sentry/fsimpl/kernfs/static_directory_refs.go b/pkg/sentry/fsimpl/kernfs/static_directory_refs.go
index 478b04bdd..866620ef9 100644
--- a/pkg/sentry/fsimpl/kernfs/static_directory_refs.go
+++ b/pkg/sentry/fsimpl/kernfs/static_directory_refs.go
@@ -1,12 +1,12 @@
 package kernfs
 
 import (
-	"fmt"
-	"runtime"
 	"sync/atomic"
 
+	"fmt"
 	"gvisor.dev/gvisor/pkg/log"
 	refs_vfs1 "gvisor.dev/gvisor/pkg/refs"
+	"runtime"
 )
 
 // ownerType is used to customize logging. Note that we use a pointer to T so
diff --git a/pkg/sentry/fsimpl/proc/fd_dir_inode_refs.go b/pkg/sentry/fsimpl/proc/fd_dir_inode_refs.go
index 9431c1506..84c03e6cd 100644
--- a/pkg/sentry/fsimpl/proc/fd_dir_inode_refs.go
+++ b/pkg/sentry/fsimpl/proc/fd_dir_inode_refs.go
@@ -1,12 +1,12 @@
 package proc
 
 import (
-	"fmt"
-	"runtime"
 	"sync/atomic"
 
+	"fmt"
 	"gvisor.dev/gvisor/pkg/log"
 	refs_vfs1 "gvisor.dev/gvisor/pkg/refs"
+	"runtime"
 )
 
 // ownerType is used to customize logging. Note that we use a pointer to T so
diff --git a/pkg/sentry/fsimpl/proc/fd_info_dir_inode_refs.go b/pkg/sentry/fsimpl/proc/fd_info_dir_inode_refs.go
index 872b20eb0..5b3c7cd1c 100644
--- a/pkg/sentry/fsimpl/proc/fd_info_dir_inode_refs.go
+++ b/pkg/sentry/fsimpl/proc/fd_info_dir_inode_refs.go
@@ -1,12 +1,12 @@
 package proc
 
 import (
-	"fmt"
-	"runtime"
 	"sync/atomic"
 
+	"fmt"
 	"gvisor.dev/gvisor/pkg/log"
 	refs_vfs1 "gvisor.dev/gvisor/pkg/refs"
+	"runtime"
 )
 
 // ownerType is used to customize logging. Note that we use a pointer to T so
diff --git a/pkg/sentry/fsimpl/proc/subtasks_inode_refs.go b/pkg/sentry/fsimpl/proc/subtasks_inode_refs.go
index c6d9b3522..3091deb89 100644
--- a/pkg/sentry/fsimpl/proc/subtasks_inode_refs.go
+++ b/pkg/sentry/fsimpl/proc/subtasks_inode_refs.go
@@ -1,12 +1,12 @@
 package proc
 
 import (
-	"fmt"
-	"runtime"
 	"sync/atomic"
 
+	"fmt"
 	"gvisor.dev/gvisor/pkg/log"
 	refs_vfs1 "gvisor.dev/gvisor/pkg/refs"
+	"runtime"
 )
 
 // ownerType is used to customize logging. Note that we use a pointer to T so
diff --git a/pkg/sentry/fsimpl/proc/task_inode_refs.go b/pkg/sentry/fsimpl/proc/task_inode_refs.go
index 714488450..5833527c5 100644
--- a/pkg/sentry/fsimpl/proc/task_inode_refs.go
+++ b/pkg/sentry/fsimpl/proc/task_inode_refs.go
@@ -1,12 +1,12 @@
 package proc
 
 import (
-	"fmt"
-	"runtime"
 	"sync/atomic"
 
+	"fmt"
 	"gvisor.dev/gvisor/pkg/log"
 	refs_vfs1 "gvisor.dev/gvisor/pkg/refs"
+	"runtime"
 )
 
 // ownerType is used to customize logging. Note that we use a pointer to T so
diff --git a/pkg/sentry/fsimpl/proc/tasks_inode_refs.go b/pkg/sentry/fsimpl/proc/tasks_inode_refs.go
index 22d9cc488..0961dd629 100644
--- a/pkg/sentry/fsimpl/proc/tasks_inode_refs.go
+++ b/pkg/sentry/fsimpl/proc/tasks_inode_refs.go
@@ -1,12 +1,12 @@
 package proc
 
 import (
-	"fmt"
-	"runtime"
 	"sync/atomic"
 
+	"fmt"
 	"gvisor.dev/gvisor/pkg/log"
 	refs_vfs1 "gvisor.dev/gvisor/pkg/refs"
+	"runtime"
 )
 
 // ownerType is used to customize logging. Note that we use a pointer to T so
diff --git a/pkg/sentry/fsimpl/sys/dir_refs.go b/pkg/sentry/fsimpl/sys/dir_refs.go
index 89609b198..718d542eb 100644
--- a/pkg/sentry/fsimpl/sys/dir_refs.go
+++ b/pkg/sentry/fsimpl/sys/dir_refs.go
@@ -1,12 +1,12 @@
 package sys
 
 import (
-	"fmt"
-	"runtime"
 	"sync/atomic"
 
+	"fmt"
 	"gvisor.dev/gvisor/pkg/log"
 	refs_vfs1 "gvisor.dev/gvisor/pkg/refs"
+	"runtime"
 )
 
 // ownerType is used to customize logging. Note that we use a pointer to T so
diff --git a/pkg/sentry/fsimpl/tmpfs/inode_refs.go b/pkg/sentry/fsimpl/tmpfs/inode_refs.go
index dbf0b2766..5ec208d9e 100644
--- a/pkg/sentry/fsimpl/tmpfs/inode_refs.go
+++ b/pkg/sentry/fsimpl/tmpfs/inode_refs.go
@@ -1,12 +1,12 @@
 package tmpfs
 
 import (
-	"fmt"
-	"runtime"
 	"sync/atomic"
 
+	"fmt"
 	"gvisor.dev/gvisor/pkg/log"
 	refs_vfs1 "gvisor.dev/gvisor/pkg/refs"
+	"runtime"
 )
 
 // ownerType is used to customize logging. Note that we use a pointer to T so
diff --git a/pkg/sentry/kernel/fd_table_refs.go b/pkg/sentry/kernel/fd_table_refs.go
index ecba138ac..9330e37e4 100644
--- a/pkg/sentry/kernel/fd_table_refs.go
+++ b/pkg/sentry/kernel/fd_table_refs.go
@@ -1,12 +1,12 @@
 package kernel
 
 import (
-	"fmt"
-	"runtime"
 	"sync/atomic"
 
+	"fmt"
 	"gvisor.dev/gvisor/pkg/log"
 	refs_vfs1 "gvisor.dev/gvisor/pkg/refs"
+	"runtime"
 )
 
 // ownerType is used to customize logging. Note that we use a pointer to T so
diff --git a/pkg/sentry/kernel/fs_context_refs.go b/pkg/sentry/kernel/fs_context_refs.go
index fb2fde971..e2280f400 100644
--- a/pkg/sentry/kernel/fs_context_refs.go
+++ b/pkg/sentry/kernel/fs_context_refs.go
@@ -1,12 +1,12 @@
 package kernel
 
 import (
-	"fmt"
-	"runtime"
 	"sync/atomic"
 
+	"fmt"
 	"gvisor.dev/gvisor/pkg/log"
 	refs_vfs1 "gvisor.dev/gvisor/pkg/refs"
+	"runtime"
 )
 
 // ownerType is used to customize logging. Note that we use a pointer to T so
diff --git a/pkg/sentry/kernel/pipe/pipe.go b/pkg/sentry/kernel/pipe/pipe.go
index 297e8f28f..c410c96aa 100644
--- a/pkg/sentry/kernel/pipe/pipe.go
+++ b/pkg/sentry/kernel/pipe/pipe.go
@@ -200,17 +200,17 @@ type readOps struct {
 //
 // Precondition: this pipe must have readers.
 func (p *Pipe) read(ctx context.Context, ops readOps) (int64, error) {
-	// Don't block for a zero-length read even if the pipe is empty.
-	if ops.left() == 0 {
-		return 0, nil
-	}
-
 	p.mu.Lock()
 	defer p.mu.Unlock()
 	return p.readLocked(ctx, ops)
 }
 
 func (p *Pipe) readLocked(ctx context.Context, ops readOps) (int64, error) {
+	// Don't block for a zero-length read even if the pipe is empty.
+	if ops.left() == 0 {
+		return 0, nil
+	}
+
 	// Is the pipe empty?
 	if p.view.Size() == 0 {
 		if !p.HasWriters() {
@@ -388,6 +388,10 @@ func (p *Pipe) rwReadiness() waiter.EventMask {
 func (p *Pipe) queued() int64 {
 	p.mu.Lock()
 	defer p.mu.Unlock()
+	return p.queuedLocked()
+}
+
+func (p *Pipe) queuedLocked() int64 {
 	return p.view.Size()
 }
 
diff --git a/pkg/sentry/kernel/pipe/vfs.go b/pkg/sentry/kernel/pipe/vfs.go
index 28f998e45..f223d59e1 100644
--- a/pkg/sentry/kernel/pipe/vfs.go
+++ b/pkg/sentry/kernel/pipe/vfs.go
@@ -244,19 +244,57 @@ func (fd *VFSPipeFD) SetPipeSize(size int64) (int64, error) {
 	return fd.pipe.SetFifoSize(size)
 }
 
-// IOSequence returns a useremm.IOSequence that reads up to count bytes from,
-// or writes up to count bytes to, fd.
-func (fd *VFSPipeFD) IOSequence(count int64) usermem.IOSequence {
-	return usermem.IOSequence{
+// SpliceToNonPipe performs a splice operation from fd to a non-pipe file.
+func (fd *VFSPipeFD) SpliceToNonPipe(ctx context.Context, out *vfs.FileDescription, off, count int64) (int64, error) {
+	fd.pipe.mu.Lock()
+	defer fd.pipe.mu.Unlock()
+
+	// Cap the sequence at number of bytes actually available.
+	v := fd.pipe.queuedLocked()
+	if v < count {
+		count = v
+	}
+	src := usermem.IOSequence{
 		IO:    fd,
 		Addrs: usermem.AddrRangeSeqOf(usermem.AddrRange{0, usermem.Addr(count)}),
 	}
+
+	var (
+		n   int64
+		err error
+	)
+	if off == -1 {
+		n, err = out.Write(ctx, src, vfs.WriteOptions{})
+	} else {
+		n, err = out.PWrite(ctx, src, off, vfs.WriteOptions{})
+	}
+	if n > 0 {
+		fd.pipe.view.TrimFront(n)
+	}
+	return n, err
+}
+
+// SpliceFromNonPipe performs a splice operation from a non-pipe file to fd.
+func (fd *VFSPipeFD) SpliceFromNonPipe(ctx context.Context, in *vfs.FileDescription, off, count int64) (int64, error) {
+	fd.pipe.mu.Lock()
+	defer fd.pipe.mu.Unlock()
+
+	dst := usermem.IOSequence{
+		IO:    fd,
+		Addrs: usermem.AddrRangeSeqOf(usermem.AddrRange{0, usermem.Addr(count)}),
+	}
+
+	if off == -1 {
+		return in.Read(ctx, dst, vfs.ReadOptions{})
+	}
+	return in.PRead(ctx, dst, off, vfs.ReadOptions{})
 }
 
-// CopyIn implements usermem.IO.CopyIn.
+// CopyIn implements usermem.IO.CopyIn. Note that it is the caller's
+// responsibility to trim fd.pipe.view after the read is completed.
 func (fd *VFSPipeFD) CopyIn(ctx context.Context, addr usermem.Addr, dst []byte, opts usermem.IOOpts) (int, error) {
 	origCount := int64(len(dst))
-	n, err := fd.pipe.read(ctx, readOps{
+	n, err := fd.pipe.readLocked(ctx, readOps{
 		left: func() int64 {
 			return int64(len(dst))
 		},
@@ -265,7 +303,6 @@ func (fd *VFSPipeFD) CopyIn(ctx context.Context, addr usermem.Addr, dst []byte,
 		},
 		read: func(view *buffer.View) (int64, error) {
 			n, err := view.ReadAt(dst, 0)
-			view.TrimFront(int64(n))
 			return int64(n), err
 		},
 	})
@@ -281,7 +318,7 @@ func (fd *VFSPipeFD) CopyIn(ctx context.Context, addr usermem.Addr, dst []byte,
 // CopyOut implements usermem.IO.CopyOut.
 func (fd *VFSPipeFD) CopyOut(ctx context.Context, addr usermem.Addr, src []byte, opts usermem.IOOpts) (int, error) {
 	origCount := int64(len(src))
-	n, err := fd.pipe.write(ctx, writeOps{
+	n, err := fd.pipe.writeLocked(ctx, writeOps{
 		left: func() int64 {
 			return int64(len(src))
 		},
@@ -305,7 +342,7 @@ func (fd *VFSPipeFD) CopyOut(ctx context.Context, addr usermem.Addr, src []byte,
 // ZeroOut implements usermem.IO.ZeroOut.
 func (fd *VFSPipeFD) ZeroOut(ctx context.Context, addr usermem.Addr, toZero int64, opts usermem.IOOpts) (int64, error) {
 	origCount := toZero
-	n, err := fd.pipe.write(ctx, writeOps{
+	n, err := fd.pipe.writeLocked(ctx, writeOps{
 		left: func() int64 {
 			return toZero
 		},
@@ -326,14 +363,15 @@ func (fd *VFSPipeFD) ZeroOut(ctx context.Context, addr usermem.Addr, toZero int6
 	return n, err
 }
 
-// CopyInTo implements usermem.IO.CopyInTo.
+// CopyInTo implements usermem.IO.CopyInTo. Note that it is the caller's
+// responsibility to trim fd.pipe.view after the read is completed.
 func (fd *VFSPipeFD) CopyInTo(ctx context.Context, ars usermem.AddrRangeSeq, dst safemem.Writer, opts usermem.IOOpts) (int64, error) {
 	count := ars.NumBytes()
 	if count == 0 {
 		return 0, nil
 	}
 	origCount := count
-	n, err := fd.pipe.read(ctx, readOps{
+	n, err := fd.pipe.readLocked(ctx, readOps{
 		left: func() int64 {
 			return count
 		},
@@ -342,7 +380,6 @@ func (fd *VFSPipeFD) CopyInTo(ctx context.Context, ars usermem.AddrRangeSeq, dst
 		},
 		read: func(view *buffer.View) (int64, error) {
 			n, err := view.ReadToSafememWriter(dst, uint64(count))
-			view.TrimFront(int64(n))
 			return int64(n), err
 		},
 	})
@@ -362,7 +399,7 @@ func (fd *VFSPipeFD) CopyOutFrom(ctx context.Context, ars usermem.AddrRangeSeq,
 		return 0, nil
 	}
 	origCount := count
-	n, err := fd.pipe.write(ctx, writeOps{
+	n, err := fd.pipe.writeLocked(ctx, writeOps{
 		left: func() int64 {
 			return count
 		},
diff --git a/pkg/sentry/kernel/process_group_refs.go b/pkg/sentry/kernel/process_group_refs.go
index 4ed6e6458..832a99d66 100644
--- a/pkg/sentry/kernel/process_group_refs.go
+++ b/pkg/sentry/kernel/process_group_refs.go
@@ -1,12 +1,12 @@
 package kernel
 
 import (
-	"fmt"
-	"runtime"
 	"sync/atomic"
 
+	"fmt"
 	"gvisor.dev/gvisor/pkg/log"
 	refs_vfs1 "gvisor.dev/gvisor/pkg/refs"
+	"runtime"
 )
 
 // ownerType is used to customize logging. Note that we use a pointer to T so
diff --git a/pkg/sentry/kernel/session_refs.go b/pkg/sentry/kernel/session_refs.go
index f2e1bb797..850f56d3a 100644
--- a/pkg/sentry/kernel/session_refs.go
+++ b/pkg/sentry/kernel/session_refs.go
@@ -1,12 +1,12 @@
 package kernel
 
 import (
-	"fmt"
-	"runtime"
 	"sync/atomic"
 
+	"fmt"
 	"gvisor.dev/gvisor/pkg/log"
 	refs_vfs1 "gvisor.dev/gvisor/pkg/refs"
+	"runtime"
 )
 
 // ownerType is used to customize logging. Note that we use a pointer to T so
diff --git a/pkg/sentry/kernel/shm/shm_refs.go b/pkg/sentry/kernel/shm/shm_refs.go
index 51e07d0b3..35f74eb6c 100644
--- a/pkg/sentry/kernel/shm/shm_refs.go
+++ b/pkg/sentry/kernel/shm/shm_refs.go
@@ -1,12 +1,12 @@
 package shm
 
 import (
-	"fmt"
-	"runtime"
 	"sync/atomic"
 
+	"fmt"
 	"gvisor.dev/gvisor/pkg/log"
 	refs_vfs1 "gvisor.dev/gvisor/pkg/refs"
+	"runtime"
 )
 
 // ownerType is used to customize logging. Note that we use a pointer to T so
diff --git a/pkg/sentry/mm/aio_mappable_refs.go b/pkg/sentry/mm/aio_mappable_refs.go
index b99909f07..d4f278400 100644
--- a/pkg/sentry/mm/aio_mappable_refs.go
+++ b/pkg/sentry/mm/aio_mappable_refs.go
@@ -1,12 +1,12 @@
 package mm
 
 import (
-	"fmt"
-	"runtime"
 	"sync/atomic"
 
+	"fmt"
 	"gvisor.dev/gvisor/pkg/log"
 	refs_vfs1 "gvisor.dev/gvisor/pkg/refs"
+	"runtime"
 )
 
 // ownerType is used to customize logging. Note that we use a pointer to T so
diff --git a/pkg/sentry/mm/special_mappable_refs.go b/pkg/sentry/mm/special_mappable_refs.go
index 035bbe690..2a348bacf 100644
--- a/pkg/sentry/mm/special_mappable_refs.go
+++ b/pkg/sentry/mm/special_mappable_refs.go
@@ -1,12 +1,12 @@
 package mm
 
 import (
-	"fmt"
-	"runtime"
 	"sync/atomic"
 
+	"fmt"
 	"gvisor.dev/gvisor/pkg/log"
 	refs_vfs1 "gvisor.dev/gvisor/pkg/refs"
+	"runtime"
 )
 
 // ownerType is used to customize logging. Note that we use a pointer to T so
diff --git a/pkg/sentry/platform/ring0/defs_impl_arm64.go b/pkg/sentry/platform/ring0/defs_impl_arm64.go
index 9fb351879..2dac9ad14 100644
--- a/pkg/sentry/platform/ring0/defs_impl_arm64.go
+++ b/pkg/sentry/platform/ring0/defs_impl_arm64.go
@@ -1,12 +1,13 @@
 package ring0
 
 import (
-	"fmt"
 	"gvisor.dev/gvisor/pkg/sentry/arch"
 	"gvisor.dev/gvisor/pkg/sentry/platform/ring0/pagetables"
+	"reflect"
+
+	"fmt"
 	"gvisor.dev/gvisor/pkg/usermem"
 	"io"
-	"reflect"
 )
 
 // Useful bits.
diff --git a/pkg/sentry/socket/unix/socket_refs.go b/pkg/sentry/socket/unix/socket_refs.go
index dababb85f..a0e5d1393 100644
--- a/pkg/sentry/socket/unix/socket_refs.go
+++ b/pkg/sentry/socket/unix/socket_refs.go
@@ -1,12 +1,12 @@
 package unix
 
 import (
-	"fmt"
-	"runtime"
 	"sync/atomic"
 
+	"fmt"
 	"gvisor.dev/gvisor/pkg/log"
 	refs_vfs1 "gvisor.dev/gvisor/pkg/refs"
+	"runtime"
 )
 
 // ownerType is used to customize logging. Note that we use a pointer to T so
diff --git a/pkg/sentry/socket/unix/transport/queue_refs.go b/pkg/sentry/socket/unix/transport/queue_refs.go
index 0d4e34988..21d43fc24 100644
--- a/pkg/sentry/socket/unix/transport/queue_refs.go
+++ b/pkg/sentry/socket/unix/transport/queue_refs.go
@@ -1,12 +1,12 @@
 package transport
 
 import (
-	"fmt"
-	"runtime"
 	"sync/atomic"
 
+	"fmt"
 	"gvisor.dev/gvisor/pkg/log"
 	refs_vfs1 "gvisor.dev/gvisor/pkg/refs"
+	"runtime"
 )
 
 // ownerType is used to customize logging. Note that we use a pointer to T so
diff --git a/pkg/sentry/syscalls/linux/vfs2/splice.go b/pkg/sentry/syscalls/linux/vfs2/splice.go
index 75bfa2c79..192411393 100644
--- a/pkg/sentry/syscalls/linux/vfs2/splice.go
+++ b/pkg/sentry/syscalls/linux/vfs2/splice.go
@@ -131,18 +131,14 @@ func Splice(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscal
 		case inIsPipe && outIsPipe:
 			n, err = pipe.Splice(t, outPipeFD, inPipeFD, count)
 		case inIsPipe:
+			n, err = inPipeFD.SpliceToNonPipe(t, outFile, outOffset, count)
 			if outOffset != -1 {
-				n, err = outFile.PWrite(t, inPipeFD.IOSequence(count), outOffset, vfs.WriteOptions{})
 				outOffset += n
-			} else {
-				n, err = outFile.Write(t, inPipeFD.IOSequence(count), vfs.WriteOptions{})
 			}
 		case outIsPipe:
+			n, err = outPipeFD.SpliceFromNonPipe(t, inFile, inOffset, count)
 			if inOffset != -1 {
-				n, err = inFile.PRead(t, outPipeFD.IOSequence(count), inOffset, vfs.ReadOptions{})
 				inOffset += n
-			} else {
-				n, err = inFile.Read(t, outPipeFD.IOSequence(count), vfs.ReadOptions{})
 			}
 		default:
 			panic("not possible")
@@ -341,17 +337,15 @@ func Sendfile(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Sysc
 	if outIsPipe {
 		for n < count {
 			var spliceN int64
-			if offset != -1 {
-				spliceN, err = inFile.PRead(t, outPipeFD.IOSequence(count), offset, vfs.ReadOptions{})
-				offset += spliceN
-			} else {
-				spliceN, err = inFile.Read(t, outPipeFD.IOSequence(count), vfs.ReadOptions{})
-			}
+			spliceN, err = outPipeFD.SpliceFromNonPipe(t, inFile, offset, count)
 			if spliceN == 0 && err == io.EOF {
 				// We reached the end of the file. Eat the error and exit the loop.
 				err = nil
 				break
 			}
+			if offset != -1 {
+				offset += spliceN
+			}
 			n += spliceN
 			if err == syserror.ErrWouldBlock && !nonBlock {
 				err = dw.waitForBoth(t)
@@ -371,19 +365,18 @@ func Sendfile(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Sysc
 			} else {
 				readN, err = inFile.Read(t, usermem.BytesIOSequence(buf), vfs.ReadOptions{})
 			}
-			if readN == 0 && err == io.EOF {
-				// We reached the end of the file. Eat the error and exit the loop.
-				err = nil
+			if readN == 0 && err != nil {
+				if err == io.EOF {
+					// We reached the end of the file. Eat the error before exiting the loop.
+					err = nil
+				}
 				break
 			}
 			n += readN
-			if err != nil {
-				break
-			}
 
 			// Write all of the bytes that we read. This may need
 			// multiple write calls to complete.
-			wbuf := buf[:n]
+			wbuf := buf[:readN]
 			for len(wbuf) > 0 {
 				var writeN int64
 				writeN, err = outFile.Write(t, usermem.BytesIOSequence(wbuf), vfs.WriteOptions{})
@@ -398,6 +391,10 @@ func Sendfile(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Sysc
 					notWritten := int64(len(wbuf))
 					n -= notWritten
 					if offset != -1 {
+						// TODO(gvisor.dev/issue/3779): The inFile offset will be incorrect if we
+						// roll back, because it has already been advanced by the full amount.
+						// Merely seeking on inFile does not work, because there may be concurrent
+						// file operations.
 						offset -= notWritten
 					}
 					break
diff --git a/pkg/sentry/vfs/file_description_refs.go b/pkg/sentry/vfs/file_description_refs.go
index bdd7e6554..ebc089b4c 100644
--- a/pkg/sentry/vfs/file_description_refs.go
+++ b/pkg/sentry/vfs/file_description_refs.go
@@ -1,12 +1,12 @@
 package vfs
 
 import (
-	"fmt"
-	"runtime"
 	"sync/atomic"
 
+	"fmt"
 	"gvisor.dev/gvisor/pkg/log"
 	refs_vfs1 "gvisor.dev/gvisor/pkg/refs"
+	"runtime"
 )
 
 // ownerType is used to customize logging. Note that we use a pointer to T so
diff --git a/pkg/sentry/vfs/filesystem_refs.go b/pkg/sentry/vfs/filesystem_refs.go
index 38a9a986f..32f21c044 100644
--- a/pkg/sentry/vfs/filesystem_refs.go
+++ b/pkg/sentry/vfs/filesystem_refs.go
@@ -1,12 +1,12 @@
 package vfs
 
 import (
-	"fmt"
-	"runtime"
 	"sync/atomic"
 
+	"fmt"
 	"gvisor.dev/gvisor/pkg/log"
 	refs_vfs1 "gvisor.dev/gvisor/pkg/refs"
+	"runtime"
 )
 
 // ownerType is used to customize logging. Note that we use a pointer to T so
diff --git a/pkg/sentry/vfs/mount_namespace_refs.go b/pkg/sentry/vfs/mount_namespace_refs.go
index 63285fb8e..2c920ac41 100644
--- a/pkg/sentry/vfs/mount_namespace_refs.go
+++ b/pkg/sentry/vfs/mount_namespace_refs.go
@@ -1,12 +1,12 @@
 package vfs
 
 import (
-	"fmt"
-	"runtime"
 	"sync/atomic"
 
+	"fmt"
 	"gvisor.dev/gvisor/pkg/log"
 	refs_vfs1 "gvisor.dev/gvisor/pkg/refs"
+	"runtime"
 )
 
 // ownerType is used to customize logging. Note that we use a pointer to T so