1 files changed, 136 insertions, 0 deletions
diff --git a/pkg/sentry/fsimpl/gofer/handle.go b/pkg/sentry/fsimpl/gofer/handle.go
new file mode 100644
index 000000000..724a3f1f7
--- /dev/null
+++ b/pkg/sentry/fsimpl/gofer/handle.go
@@ -0,0 +1,136 @@
+// 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 gofer
+
+import (
+	"syscall"
+
+	"gvisor.dev/gvisor/pkg/context"
+	"gvisor.dev/gvisor/pkg/p9"
+	"gvisor.dev/gvisor/pkg/safemem"
+	"gvisor.dev/gvisor/pkg/sentry/hostfd"
+)
+
+// handle represents a remote "open file descriptor", consisting of an opened
+// fid (p9.File) and optionally a host file descriptor.
+type handle struct {
+	file p9file
+	fd   int32 // -1 if unavailable
+}
+
+// Preconditions: read || write.
+func openHandle(ctx context.Context, file p9file, read, write, trunc bool) (handle, error) {
+	_, newfile, err := file.walk(ctx, nil)
+	if err != nil {
+		return handle{fd: -1}, err
+	}
+	var flags p9.OpenFlags
+	switch {
+	case read && !write:
+		flags = p9.ReadOnly
+	case !read && write:
+		flags = p9.WriteOnly
+	case read && write:
+		flags = p9.ReadWrite
+	}
+	if trunc {
+		flags |= p9.OpenTruncate
+	}
+	fdobj, _, _, err := newfile.open(ctx, flags)
+	if err != nil {
+		newfile.close(ctx)
+		return handle{fd: -1}, err
+	}
+	fd := int32(-1)
+	if fdobj != nil {
+		fd = int32(fdobj.Release())
+	}
+	return handle{
+		file: newfile,
+		fd:   fd,
+	}, nil
+}
+
+func (h *handle) close(ctx context.Context) {
+	h.file.close(ctx)
+	h.file = p9file{}
+	if h.fd >= 0 {
+		syscall.Close(int(h.fd))
+		h.fd = -1
+	}
+}
+
+func (h *handle) readToBlocksAt(ctx context.Context, dsts safemem.BlockSeq, offset uint64) (uint64, error) {
+	if dsts.IsEmpty() {
+		return 0, nil
+	}
+	if h.fd >= 0 {
+		ctx.UninterruptibleSleepStart(false)
+		n, err := hostfd.Preadv2(h.fd, dsts, int64(offset), 0 /* flags */)
+		ctx.UninterruptibleSleepFinish(false)
+		return n, err
+	}
+	if dsts.NumBlocks() == 1 && !dsts.Head().NeedSafecopy() {
+		n, err := h.file.readAt(ctx, dsts.Head().ToSlice(), offset)
+		return uint64(n), err
+	}
+	// Buffer the read since p9.File.ReadAt() takes []byte.
+	buf := make([]byte, dsts.NumBytes())
+	n, err := h.file.readAt(ctx, buf, offset)
+	if n == 0 {
+		return 0, err
+	}
+	if cp, cperr := safemem.CopySeq(dsts, safemem.BlockSeqOf(safemem.BlockFromSafeSlice(buf[:n]))); cperr != nil {
+		return cp, cperr
+	}
+	return uint64(n), err
+}
+
+func (h *handle) writeFromBlocksAt(ctx context.Context, srcs safemem.BlockSeq, offset uint64) (uint64, error) {
+	if srcs.IsEmpty() {
+		return 0, nil
+	}
+	if h.fd >= 0 {
+		ctx.UninterruptibleSleepStart(false)
+		n, err := hostfd.Pwritev2(h.fd, srcs, int64(offset), 0 /* flags */)
+		ctx.UninterruptibleSleepFinish(false)
+		return n, err
+	}
+	if srcs.NumBlocks() == 1 && !srcs.Head().NeedSafecopy() {
+		n, err := h.file.writeAt(ctx, srcs.Head().ToSlice(), offset)
+		return uint64(n), err
+	}
+	// Buffer the write since p9.File.WriteAt() takes []byte.
+	buf := make([]byte, srcs.NumBytes())
+	cp, cperr := safemem.CopySeq(safemem.BlockSeqOf(safemem.BlockFromSafeSlice(buf)), srcs)
+	if cp == 0 {
+		return 0, cperr
+	}
+	n, err := h.file.writeAt(ctx, buf[:cp], offset)
+	if err != nil {
+		return uint64(n), err
+	}
+	return cp, cperr
+}
+
+func (h *handle) sync(ctx context.Context) error {
+	if h.fd >= 0 {
+		ctx.UninterruptibleSleepStart(false)
+		err := syscall.Fsync(int(h.fd))
+		ctx.UninterruptibleSleepFinish(false)
+		return err
+	}
+	return h.file.fsync(ctx)
+}