Implement pipe(2) and pipe2(2) for VFS2.

Updates #1035

PiperOrigin-RevId: 306968644

1 files changed, 63 insertions, 0 deletions

diff --git a/pkg/sentry/syscalls/linux/vfs2/pipe.go b/pkg/sentry/syscalls/linux/vfs2/pipe.go
new file mode 100644
index 000000000..4a01e4209
--- /dev/null
+++ b/pkg/sentry/syscalls/linux/vfs2/pipe.go
@@ -0,0 +1,63 @@
+// Copyright 2020 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 vfs2
+
+import (
+	"gvisor.dev/gvisor/pkg/abi/linux"
+	"gvisor.dev/gvisor/pkg/sentry/arch"
+	"gvisor.dev/gvisor/pkg/sentry/fsimpl/pipefs"
+	"gvisor.dev/gvisor/pkg/sentry/kernel"
+	"gvisor.dev/gvisor/pkg/sentry/vfs"
+	"gvisor.dev/gvisor/pkg/syserror"
+	"gvisor.dev/gvisor/pkg/usermem"
+)
+
+// Pipe implements Linux syscall pipe(2).
+func Pipe(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	addr := args[0].Pointer()
+	return 0, nil, pipe2(t, addr, 0)
+}
+
+// Pipe2 implements Linux syscall pipe2(2).
+func Pipe2(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	addr := args[0].Pointer()
+	flags := args[1].Int()
+	return 0, nil, pipe2(t, addr, flags)
+}
+
+func pipe2(t *kernel.Task, addr usermem.Addr, flags int32) error {
+	if flags&^(linux.O_NONBLOCK|linux.O_CLOEXEC) != 0 {
+		return syserror.EINVAL
+	}
+	r, w := pipefs.NewConnectedPipeFDs(t, t.Kernel().PipeMount(), uint32(flags&linux.O_NONBLOCK))
+	defer r.DecRef()
+	defer w.DecRef()
+
+	fds, err := t.NewFDsVFS2(0, []*vfs.FileDescription{r, w}, kernel.FDFlags{
+		CloseOnExec: flags&linux.O_CLOEXEC != 0,
+	})
+	if err != nil {
+		return err
+	}
+	if _, err := t.CopyOut(addr, fds); err != nil {
+		for _, fd := range fds {
+			if _, file := t.FDTable().Remove(fd); file != nil {
+				file.DecRef()
+			}
+		}
+		return err
+	}
+	return nil
+}