From 10d551cbba521857f3967968348fd107f32651df Mon Sep 17 00:00:00 2001
From: Tom Clegg <tclegg@veritasgenetics.com>
Date: Mon, 18 Dec 2017 00:49:36 -0500
Subject: [PATCH] 13111: .arvados#collection special file.

Arvados-DCO-1.1-Signed-off-by: Tom Clegg <tclegg@veritasgenetics.com>
---
 sdk/go/arvados/collection_fs.go | 20 ++++++++++
 sdk/go/arvados/fs_getternode.go | 66 +++++++++++++++++++++++++++++++++
 2 files changed, 86 insertions(+)
 create mode 100644 sdk/go/arvados/fs_getternode.go

diff --git a/sdk/go/arvados/collection_fs.go b/sdk/go/arvados/collection_fs.go
index 46470557a4..72ef49feec 100644
--- a/sdk/go/arvados/collection_fs.go
+++ b/sdk/go/arvados/collection_fs.go
@@ -5,6 +5,7 @@
 package arvados
 
 import (
+	"encoding/json"
 	"errors"
 	"fmt"
 	"io"
@@ -144,6 +145,25 @@ type collectionFileSystem struct {
 	fileSystem
 }
 
+func (fs collectionFileSystem) Child(name string, replace func(inode) inode) inode {
+	if name == ".arvados#collection" {
+		return &getternode{Getter: func() ([]byte, error) {
+			var coll Collection
+			var err error
+			coll.ManifestText, err = fs.MarshalManifest(".")
+			if err != nil {
+				return nil, err
+			}
+			data, err := json.Marshal(&coll)
+			if err == nil {
+				data = append(data, 10)
+			}
+			return data, err
+		}}
+	}
+	return fs.fileSystem.Child(name, replace)
+}
+
 func (fs collectionFileSystem) MarshalManifest(prefix string) (string, error) {
 	fs.fileSystem.inode.Lock()
 	defer fs.fileSystem.inode.Unlock()
diff --git a/sdk/go/arvados/fs_getternode.go b/sdk/go/arvados/fs_getternode.go
new file mode 100644
index 0000000000..c9ffb387d3
--- /dev/null
+++ b/sdk/go/arvados/fs_getternode.go
@@ -0,0 +1,66 @@
+// Copyright (C) The Arvados Authors. All rights reserved.
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package arvados
+
+import (
+	"bytes"
+	"os"
+	"time"
+)
+
+// A getternode is a read-only character device that returns whatever
+// data is returned by the supplied function.
+type getternode struct {
+	Getter func() ([]byte, error)
+
+	treenode
+	data *bytes.Reader
+}
+
+func (*getternode) IsDir() bool {
+	return false
+}
+
+func (*getternode) Child(string, func(inode) inode) inode {
+	return nil
+}
+
+func (gn *getternode) get() error {
+	if gn.data != nil {
+		return nil
+	}
+	data, err := gn.Getter()
+	if err != nil {
+		return err
+	}
+	gn.data = bytes.NewReader(data)
+	return nil
+}
+
+func (gn *getternode) Size() int64 {
+	return gn.FileInfo().Size()
+}
+
+func (gn *getternode) FileInfo() os.FileInfo {
+	gn.Lock()
+	defer gn.Unlock()
+	var size int64
+	if gn.get() == nil {
+		size = gn.data.Size()
+	}
+	return fileinfo{
+		modTime: time.Now(),
+		mode:    0444,
+		size:    size,
+	}
+}
+
+func (gn *getternode) Read(p []byte, ptr filenodePtr) (int, filenodePtr, error) {
+	if err := gn.get(); err != nil {
+		return 0, ptr, err
+	}
+	n, err := gn.data.ReadAt(p, ptr.off)
+	return n, filenodePtr{off: ptr.off + int64(n)}, err
+}
-- 
2.30.2