fusebox/fuse_path_inodes_test.cc

// Copyright 2021 The ChromiumOS Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "fusebox/fuse_path_inodes.h"

#include <gtest/gtest.h>

namespace fusebox {

TEST(FusePathInodesTest, RootNode) {
  InodeTable inodes;

  // The root node always exists.
  Node* root = inodes.Lookup(1);
  EXPECT_TRUE(root);
  EXPECT_EQ(0, root->device);
  EXPECT_EQ(1, root->ino);

  // Root has a name and full path name.
  EXPECT_EQ("/", inodes.GetName(root->ino));
  EXPECT_EQ("/", inodes.GetPath(root));

  // Root node cannot be forgotten.
  EXPECT_FALSE(inodes.Forget(root->ino));

  // Root node parent inode is ino 0.
  EXPECT_EQ(0, root->parent);

  // Root node cannot be recreated.
  errno = 0;
  EXPECT_FALSE(inodes.Create(0, "/"));
  EXPECT_EQ(EINVAL, errno);

  // Create a child of the root node.
  Node* child = inodes.Create(root->ino, "foo");
  EXPECT_TRUE(child);

  // Root node cannot be overwritten.
  errno = 0;
  EXPECT_FALSE(inodes.Move(child, 0, "/"));
  EXPECT_EQ(EINVAL, errno);

  // Root node cannot be moved.
  EXPECT_DEATH(inodes.Move(root, 2, "bar"), "");
}

TEST(FusePathInodesTest, RootNodeParent) {
  InodeTable inodes;

  // The root node parent ino is ino 0.
  Node* root = inodes.Lookup(1);
  EXPECT_TRUE(root);
  EXPECT_EQ(0, root->parent);

  // Root node parent is not present in the node table.
  errno = 0;
  Node* root_parent = inodes.Lookup(0);
  EXPECT_EQ(errno, ENOENT);
  EXPECT_FALSE(root_parent);

  // Root node parent has no name.
  EXPECT_TRUE(inodes.GetName(0).empty());

  // Root node parent cannot be forgotten.
  EXPECT_FALSE(inodes.Forget(0));

  // It only has one child: the root node.
  errno = 0;
  EXPECT_FALSE(inodes.Create(0, "child"));
  EXPECT_EQ(EINVAL, errno);
  errno = 0;
  EXPECT_FALSE(inodes.Ensure(0, "child"));
  EXPECT_EQ(EINVAL, errno);

  // Create a child of the root node.
  Node* child = inodes.Create(1, "foo");
  EXPECT_TRUE(child);

  // Cannot move a child to the root parent.
  errno = 0;
  EXPECT_FALSE(inodes.Move(child, 0, "foo"));
  EXPECT_EQ(EINVAL, errno);
}

TEST(FusePathInodesTest, LookupNodes) {
  InodeTable inodes;

  errno = 0;
  Node* root_parent = inodes.Lookup(0);
  EXPECT_FALSE(root_parent);
  EXPECT_EQ(ENOENT, errno);

  Node* root = inodes.Lookup(1);
  EXPECT_TRUE(root);
  EXPECT_EQ(0, root->parent);

  errno = 0;
  EXPECT_FALSE(inodes.Lookup(2));
  EXPECT_EQ(ENOENT, errno);
  EXPECT_TRUE(inodes.GetName(2).empty());

  errno = 0;
  EXPECT_FALSE(inodes.Lookup(1, "/foo"));
  EXPECT_EQ(EINVAL, errno);

  errno = 0;
  EXPECT_FALSE(inodes.Lookup(1, "foo"));
  EXPECT_EQ(ENOENT, errno);
}

TEST(FusePathInodesTest, NodeNames) {
  InodeTable inodes;

  errno = 0;
  EXPECT_FALSE(inodes.Create(1, nullptr));
  EXPECT_EQ(EINVAL, errno);

  static const char* kInvalidNames[] = {
      "",    "/",    ".",    "..",   "/.",    "/..",   "./",    "../",
      "//",  "//.",  "//..", "/foo", "//bar", "foo/",  "bar//", "/ .",
      "/a/", "//b/", "c/.",  "c/..", "d/e",   "f/./g", "/../i", ". /",
  };

  for (const char* name : kInvalidNames) {
    errno = 0;
    EXPECT_FALSE(inodes.Create(1, name));
    EXPECT_EQ(EINVAL, errno);
    errno = 0;
    EXPECT_FALSE(inodes.Lookup(1, name));
    EXPECT_EQ(EINVAL, errno);
    errno = 0;
    EXPECT_FALSE(inodes.Ensure(1, name));
    EXPECT_EQ(EINVAL, errno);
  }

  for (const char* valid : {"foo", "bar", ".foo", "foo.bar"}) {
    errno = 0;
    EXPECT_TRUE(inodes.Create(1, valid));
    EXPECT_EQ(0, errno);
    EXPECT_TRUE(inodes.Ensure(1, valid));
    EXPECT_EQ(0, errno);
    Node* node = inodes.Lookup(1, valid);
    EXPECT_EQ(0, errno);

    EXPECT_TRUE(node);
    const auto name = std::string("/").append(valid);
    EXPECT_EQ(name, inodes.GetName(node->ino));
    EXPECT_EQ(name, inodes.GetPath(node));
    EXPECT_EQ(0, errno);
  }

  for (const char* device : {"mtp:usb:5,3:65537"}) {
    errno = 0;
    EXPECT_TRUE(inodes.Create(1, device));
    EXPECT_EQ(0, errno);
    EXPECT_TRUE(inodes.Ensure(1, device));
    EXPECT_EQ(0, errno);
    Node* node = inodes.Lookup(1, device);
    EXPECT_EQ(0, errno);

    EXPECT_TRUE(node);
    const auto name = std::string("/").append(device);
    EXPECT_EQ(name, inodes.GetName(node->ino));
    EXPECT_EQ(name, inodes.GetPath(node));
    EXPECT_EQ(0, errno);
  }
}

TEST(FusePathInodesTest, ChildNode) {
  InodeTable inodes;

  // Create a child of the root node.
  Node* node = inodes.Create(1, "foo");
  EXPECT_TRUE(node);
  EXPECT_EQ(FIRST_UNRESERVED_INO + 0, node->ino);
  EXPECT_EQ(1, node->parent);

  // Node can be found by ino lookup.
  EXPECT_EQ(node, inodes.Lookup(node->ino));

  // Node can be found by parent child lookup.
  EXPECT_EQ(node, inodes.Lookup(1, "foo"));

  // Node has a name and a full path name.
  EXPECT_EQ("/foo", inodes.GetName(node->ino));
  EXPECT_EQ("/foo", inodes.GetPath(node));

  // Node cannot be recreated.
  errno = 0;
  EXPECT_FALSE(inodes.Create(1, "foo"));
  EXPECT_EQ(EEXIST, errno);
}

TEST(FusePathInodesTest, ChildNodeForget) {
  InodeTable inodes;

  // Create a child of the root node.
  Node* node = inodes.Create(1, "foo");
  EXPECT_TRUE(node);
  const ino_t ino = FIRST_UNRESERVED_INO + 0;
  EXPECT_EQ(ino, node->ino);
  EXPECT_EQ(1, node->parent);

  // Forget removes the node.
  EXPECT_TRUE(inodes.Forget(ino));
  errno = 0;
  EXPECT_FALSE(inodes.Lookup(ino));
  EXPECT_EQ(ENOENT, errno);
  EXPECT_TRUE(inodes.GetName(ino).empty());

  // Forgetting a non-existent ino should fail.
  EXPECT_FALSE(inodes.Forget(FIRST_UNRESERVED_INO + 999));
}

TEST(FusePathInodesTest, ChildNodeChild) {
  InodeTable inodes;

  // Create a child of the root node.
  Node* node = inodes.Create(1, "foo");
  EXPECT_TRUE(node);
  EXPECT_EQ(FIRST_UNRESERVED_INO + 0, node->ino);
  EXPECT_EQ(1, node->parent);

  // Create a child of the "foo" node.
  Node* child = inodes.Create(FIRST_UNRESERVED_INO + 0, "bar");
  EXPECT_TRUE(child);
  EXPECT_EQ(FIRST_UNRESERVED_INO + 1, child->ino);
  EXPECT_EQ(FIRST_UNRESERVED_INO + 0, child->parent);

  // Child node has a name and a full path name.
  EXPECT_EQ("/bar", inodes.GetName(child->ino));
  EXPECT_EQ("/foo/bar", inodes.GetPath(child));

  // Child node can be found by ino lookup.
  EXPECT_EQ(child, inodes.Lookup(child->ino));

  // Child node can be found by parent child lookup.
  EXPECT_EQ(child, inodes.Lookup(FIRST_UNRESERVED_INO + 0, "bar"));

  // Child node cannot be recreated.
  errno = 0;
  EXPECT_FALSE(inodes.Create(FIRST_UNRESERVED_INO + 0, "bar"));
  EXPECT_EQ(EEXIST, errno);

  // Child node cannot be overwritten.
  errno = 0;
  EXPECT_FALSE(inodes.Move(node, FIRST_UNRESERVED_INO + 0, "bar"));
  EXPECT_EQ(EINVAL, errno);
}

TEST(FusePathInodesTest, ChildNodeMove) {
  InodeTable inodes;

  // Create a child of the root node.
  Node* node = inodes.Create(1, "foo");
  EXPECT_TRUE(node);
  EXPECT_EQ(1, node->parent);
  EXPECT_EQ(FIRST_UNRESERVED_INO + 0, node->ino);

  // Create a child of the "foo" node.
  Node* child = inodes.Create(FIRST_UNRESERVED_INO + 0, "bar");
  EXPECT_TRUE(child);
  EXPECT_EQ(FIRST_UNRESERVED_INO + 0, child->parent);
  EXPECT_EQ(FIRST_UNRESERVED_INO + 1, child->ino);

  // Create a child of the "bar" node.
  Node* child_child = inodes.Create(FIRST_UNRESERVED_INO + 1, "baz");
  EXPECT_TRUE(child_child);
  EXPECT_EQ(FIRST_UNRESERVED_INO + 1, child_child->parent);
  EXPECT_EQ(FIRST_UNRESERVED_INO + 2, child_child->ino);

  // Child node has a name and a full path name.
  EXPECT_EQ("/bar", inodes.GetName(child->ino));
  EXPECT_EQ("/foo/bar", inodes.GetPath(child));

  // Same for the child of the child node names.
  EXPECT_EQ("/baz", inodes.GetName(child_child->ino));
  EXPECT_EQ("/foo/bar/baz", inodes.GetPath(child_child));

  // Child node can be moved to a new child node.
  EXPECT_EQ(FIRST_UNRESERVED_INO + 0, child->parent);
  EXPECT_EQ(FIRST_UNRESERVED_INO + 1, child->ino);
  Node* move = inodes.Move(child, 1, "move");
  EXPECT_EQ(child, move);
  EXPECT_EQ(1, child->parent);
  EXPECT_EQ(FIRST_UNRESERVED_INO + 1, child->ino);

  // And also be renamed while being moved.
  EXPECT_EQ("/move", inodes.GetName(child->ino));
  EXPECT_EQ("/move", inodes.GetPath(child));

  // Child of the child moves with its parent.
  EXPECT_EQ("/baz", inodes.GetName(child_child->ino));
  EXPECT_EQ("/move/baz", inodes.GetPath(child_child));

  // And its parent and ino should not change.
  EXPECT_EQ(FIRST_UNRESERVED_INO + 1, child_child->parent);
  EXPECT_EQ(FIRST_UNRESERVED_INO + 2, child_child->ino);
}

TEST(FusePathInodesTest, MoveOverwrites) {
  InodeTable inodes;

  // Create this tree of nodes:
  //
  // /
  // /a
  // /a/f
  // /a/f/i
  // /a/f/j
  // /a/f/k
  // /a/g
  // /a/g/p
  // /a/g/p/x
  // /a/g/q
  // /a/h
  ino_t a = inodes.Ensure(1, "a")->ino;
  ino_t f = inodes.Ensure(a, "f")->ino;
  ino_t g = inodes.Ensure(a, "g")->ino;
  ino_t h = inodes.Ensure(a, "h")->ino;
  ino_t i = inodes.Ensure(f, "i")->ino;
  ino_t j = inodes.Ensure(f, "j")->ino;
  ino_t k = inodes.Ensure(f, "k")->ino;
  ino_t p = inodes.Ensure(g, "p")->ino;
  ino_t q = inodes.Ensure(g, "q")->ino;
  ino_t x = inodes.Ensure(p, "x")->ino;

  EXPECT_TRUE(inodes.Lookup(a));
  EXPECT_TRUE(inodes.Lookup(f));
  EXPECT_TRUE(inodes.Lookup(g));
  EXPECT_TRUE(inodes.Lookup(h));
  EXPECT_TRUE(inodes.Lookup(i));
  EXPECT_TRUE(inodes.Lookup(j));
  EXPECT_TRUE(inodes.Lookup(k));
  EXPECT_TRUE(inodes.Lookup(p));
  EXPECT_TRUE(inodes.Lookup(q));
  EXPECT_TRUE(inodes.Lookup(x));
  EXPECT_EQ("/a/f", inodes.GetPath(inodes.Lookup(f)));
  EXPECT_EQ("/a/f/i", inodes.GetPath(inodes.Lookup(i)));
  EXPECT_EQ("/a/f/j", inodes.GetPath(inodes.Lookup(j)));

  // mv /a/f /a/g
  EXPECT_TRUE(inodes.Move(inodes.Lookup(f), a, "g"));

  // The tree is now:
  //
  // /
  // /a
  // /a/g      # Basename is "g" but still uses the f inode.
  // /a/g/i
  // /a/g/j
  // /a/g/k
  // /a/h
  EXPECT_TRUE(inodes.Lookup(a));
  EXPECT_TRUE(inodes.Lookup(f));
  EXPECT_FALSE(inodes.Lookup(g));
  EXPECT_TRUE(inodes.Lookup(h));
  EXPECT_TRUE(inodes.Lookup(i));
  EXPECT_TRUE(inodes.Lookup(j));
  EXPECT_TRUE(inodes.Lookup(k));
  EXPECT_FALSE(inodes.Lookup(p));
  EXPECT_FALSE(inodes.Lookup(q));
  EXPECT_FALSE(inodes.Lookup(x));
  EXPECT_EQ("/a/g", inodes.GetPath(inodes.Lookup(f)));
  EXPECT_EQ("/a/g/i", inodes.GetPath(inodes.Lookup(i)));
  EXPECT_EQ("/a/g/j", inodes.GetPath(inodes.Lookup(j)));

  // mv /a/g/j /a/h
  EXPECT_TRUE(inodes.Move(inodes.Lookup(j), a, "h"));

  // The tree is now:
  //
  // /
  // /a
  // /a/g      # Basename is "g" but still uses the f inode.
  // /a/g/i
  // /a/g/k
  // /a/h      # Basename is "h" but still uses the j inode.
  EXPECT_TRUE(inodes.Lookup(a));
  EXPECT_TRUE(inodes.Lookup(f));
  EXPECT_FALSE(inodes.Lookup(g));
  EXPECT_FALSE(inodes.Lookup(h));
  EXPECT_TRUE(inodes.Lookup(i));
  EXPECT_TRUE(inodes.Lookup(j));
  EXPECT_TRUE(inodes.Lookup(k));
  EXPECT_FALSE(inodes.Lookup(p));
  EXPECT_FALSE(inodes.Lookup(q));
  EXPECT_FALSE(inodes.Lookup(x));
  EXPECT_EQ("/a/g", inodes.GetPath(inodes.Lookup(f)));
  EXPECT_EQ("/a/g/i", inodes.GetPath(inodes.Lookup(i)));
  EXPECT_EQ("/a/h", inodes.GetPath(inodes.Lookup(j)));
}

TEST(FusePathInodesTest, ChildNodeRename) {
  InodeTable inodes;

  // Create a child of the root node.
  Node* node = inodes.Create(1, "foo");
  EXPECT_TRUE(node);
  EXPECT_EQ("/foo", inodes.GetName(node->ino));
  EXPECT_EQ("/foo", inodes.GetPath(node));

  // Child nodes can be renamed.
  Node* move = inodes.Move(node, node->parent, "bar");
  EXPECT_EQ(node, move);
  EXPECT_EQ("/bar", inodes.GetName(node->ino));
  EXPECT_EQ("/bar", inodes.GetPath(node));

  // Nodes cannot self-parent because inodes must be unique.
  Node* parent_self = inodes.Move(node, node->ino, "baz");
  EXPECT_FALSE(parent_self);
}

TEST(FusePathInodesTest, ChildNodeEnsure) {
  InodeTable inodes;

  // Ensure can be used to create child nodes.
  Node* foo = inodes.Ensure(1, "foo");
  EXPECT_TRUE(foo);
  EXPECT_EQ(FIRST_UNRESERVED_INO + 0, foo->ino);
  EXPECT_EQ(1, foo->parent);

  // Ensure and Lookup should return that node.
  EXPECT_EQ(foo, inodes.Ensure(1, "foo"));
  EXPECT_EQ(foo, inodes.Lookup(1, "foo"));

  // Create a child of the "foo" node.
  Node* bar = inodes.Ensure(FIRST_UNRESERVED_INO + 0, "bar");
  EXPECT_TRUE(bar);
  EXPECT_EQ(FIRST_UNRESERVED_INO + 1, bar->ino);
  EXPECT_EQ(FIRST_UNRESERVED_INO + 0, bar->parent);

  // Ensure and Lookup should return that node.
  EXPECT_EQ(bar, inodes.Lookup(FIRST_UNRESERVED_INO + 0, "bar"));
  EXPECT_EQ(bar, inodes.Ensure(FIRST_UNRESERVED_INO + 0, "bar"));
}

TEST(FusePathInodesTest, NodeStatCache) {
  InodeTable inodes;

  // Nodes initially have no cached stat.
  const ino_t ino = inodes.Lookup(1)->ino;
  struct stat stat = {0};
  EXPECT_FALSE(inodes.GetStat(ino, &stat));

  // Cache a stat on the node.
  struct stat stbuf = {0};
  const mode_t mode = S_IFDIR | 0755;
  stbuf.st_mode = mode;
  stbuf.st_nlink = 2;
  inodes.SetStat(ino, stbuf);

  // Get the cached node stat.
  EXPECT_TRUE(inodes.GetStat(ino, &stat));
  EXPECT_EQ(0, stat.st_dev);
  EXPECT_EQ(1, stat.st_ino);
  EXPECT_EQ(mode, stat.st_mode);
  EXPECT_EQ(0, stat.st_size);
  EXPECT_EQ(2, stat.st_nlink);
}

TEST(FusePathInodesTest, NodeStatCacheTimeout) {
  InodeTable inodes;

  Node* node = inodes.Lookup(1);
  EXPECT_TRUE(node);

  // Cache a stat on the node.
  const mode_t mode = S_IFREG | 0755;
  struct stat stbuf = {0};
  stbuf.st_mode = mode;
  stbuf.st_uid = 2;
  stbuf.st_gid = 3;
  inodes.SetStat(node->ino, stbuf, 5.0);

  // Get the cached node stat.
  struct stat stat = {0};
  EXPECT_TRUE(inodes.GetStat(node->ino, &stat));
  EXPECT_EQ(mode, stat.st_mode);
  EXPECT_EQ(1, stat.st_ino);
  EXPECT_EQ(2, stat.st_uid);
  EXPECT_EQ(3, stat.st_gid);

  // Cache stat: use time < 0 to make time move forward.
  inodes.SetStat(node->ino, stbuf, -5.0);

  // Get the stat: should fail due to cache stat timeout.
  EXPECT_FALSE(inodes.GetStat(node->ino, &stat));
}

TEST(FusePathInodesTest, NodeStatCacheForget) {
  InodeTable inodes;

  Node* node = inodes.Lookup(1);
  EXPECT_TRUE(node);

  // Cache a stat on the node.
  const mode_t mode = S_IFREG | 0755;
  struct stat stbuf = {0};
  stbuf.st_dev = 2;
  stbuf.st_mode = mode;
  inodes.SetStat(node->ino, stbuf);

  // Get the cached node stat.
  struct stat stat = {0};
  EXPECT_TRUE(inodes.GetStat(node->ino, &stat));
  EXPECT_EQ(1, stat.st_ino);
  EXPECT_EQ(2, stat.st_dev);
  EXPECT_EQ(mode, stat.st_mode);

  // Forget the cached node stat.
  inodes.ForgetStat(node->ino);
  EXPECT_FALSE(inodes.GetStat(node->ino, &stat));
}

TEST(FusePathInodesTest, DeviceMakeFromName) {
  InodeTable inodes;

  // Make a device struct.
  Device device = inodes.MakeFromName("mtp filesystem://escaped-url");
  EXPECT_EQ("mtp", device.name);
  EXPECT_EQ("filesystem://escaped-url", device.path);
  EXPECT_EQ("rw", device.mode);
  EXPECT_EQ(0, device.device);
  EXPECT_EQ(0, device.ino);

  // Make a device struct: read-only case.
  device = inodes.MakeFromName("mtp filesystem://escaped-url ro");
  EXPECT_EQ("mtp", device.name);
  EXPECT_EQ("filesystem://escaped-url", device.path);
  EXPECT_EQ("ro", device.mode);
  EXPECT_EQ(0, device.device);
  EXPECT_EQ(0, device.ino);
}

TEST(FusePathInodesTest, DeviceRootNode) {
  InodeTable inodes;

  // Get the root node.
  Node* root = inodes.Lookup(1);
  EXPECT_TRUE(root);
  EXPECT_EQ("/", inodes.GetName(root->ino));
  EXPECT_EQ("/", inodes.GetPath(root));
  EXPECT_EQ(0, root->device);
  EXPECT_EQ(0, root->parent);

  // Root node has a device path name.
  auto device_path = inodes.GetDevicePath(root);
  EXPECT_EQ("/", device_path);

  // Create a device for the root node.
  Device device;
  device.mode = "rw";
  EXPECT_EQ(root, inodes.AttachDevice(0, device));
  EXPECT_TRUE(device.path.empty());
  EXPECT_TRUE(device.name.empty());
  EXPECT_EQ("rw", device.mode);

  // Root node and device ino numbers should match.
  EXPECT_EQ(root->device, device.device);
  EXPECT_EQ(root->ino, device.ino);

  // Root node device path name should not change.
  device_path = inodes.GetDevicePath(root);
  EXPECT_EQ("/", device_path);

  // Create a child of the root node.
  Node* node = inodes.Create(1, "foo");
  EXPECT_TRUE(node);
  EXPECT_EQ("/foo", inodes.GetName(node->ino));
  EXPECT_EQ("/foo", inodes.GetPath(node));
  EXPECT_EQ(root->device, node->device);
  EXPECT_EQ(0, node->device);
  EXPECT_EQ(1, node->parent);
  EXPECT_EQ(FIRST_UNRESERVED_INO + 0, node->ino);

  // Root child node has a device path name.
  device_path = inodes.GetDevicePath(node);
  EXPECT_EQ("/foo", device_path);

  // Root device cannot be detached (root node cannot be deleted).
  errno = 0;
  EXPECT_EQ(1, device.ino);
  EXPECT_FALSE(inodes.DetachDevice(device.ino));
  EXPECT_EQ(EINVAL, errno);

  // Root device can be re-attached though: here with a path name.
  device.path = "filesystem://escaped-url";
  EXPECT_EQ(root, inodes.AttachDevice(0, device));
  EXPECT_EQ("filesystem://escaped-url", device.path);
  EXPECT_TRUE(device.name.empty());
  EXPECT_EQ("rw", device.mode);
  EXPECT_EQ(root->device, device.device);
  EXPECT_EQ(root->ino, device.ino);

  // Device node paths should be prefixed by the path name.
  device_path = inodes.GetDevicePath(root);
  EXPECT_EQ("filesystem://escaped-url", device_path);
  device_path = inodes.GetDevicePath(node);
  EXPECT_EQ("filesystem://escaped-url/foo", device_path);

  // Create a child of the child node.
  Node* child = inodes.Create(FIRST_UNRESERVED_INO + 0, "bar");
  EXPECT_TRUE(child);
  EXPECT_EQ("/bar", inodes.GetName(child->ino));
  EXPECT_EQ("/foo/bar", inodes.GetPath(child));
  EXPECT_EQ(root->device, node->device);
  EXPECT_EQ(0, child->device);
  EXPECT_EQ(FIRST_UNRESERVED_INO + 0, child->parent);
  EXPECT_EQ(FIRST_UNRESERVED_INO + 1, child->ino);

  // Device node paths should be prefixed by the path name.
  device_path = inodes.GetDevicePath(child);
  EXPECT_EQ("filesystem://escaped-url/foo/bar", device_path);
}

TEST(FusePathInodesTest, DeviceChildNode) {
  InodeTable inodes;

  // Get the root node.
  Node* root = inodes.Lookup(1);
  EXPECT_TRUE(root);
  EXPECT_EQ(0, root->device);
  EXPECT_EQ(0, root->parent);

  // Create a device node child of the root node.
  auto device = inodes.MakeFromName("mtp filesystem://escaped-url");
  Node* node = inodes.AttachDevice(1, device);
  EXPECT_TRUE(node);

  // Attached child node should have a new device number.
  EXPECT_EQ("mtp", device.name);
  EXPECT_EQ("filesystem://escaped-url", device.path);
  EXPECT_EQ(node->device, device.device);
  EXPECT_EQ(node->ino, device.ino);
  EXPECT_EQ(1, node->device);
  EXPECT_EQ(1, node->parent);
  EXPECT_EQ(FIRST_UNRESERVED_INO + 0, node->ino);

  // Attaching the device again should error: errno EEXIST.
  errno = 0;
  EXPECT_FALSE(inodes.AttachDevice(1, device));
  EXPECT_EQ(EEXIST, errno);
  EXPECT_EQ("mtp", device.name);
  EXPECT_EQ("filesystem://escaped-url", device.path);
  EXPECT_EQ(1, device.device);
  EXPECT_EQ(FIRST_UNRESERVED_INO + 0, device.ino);

  // Device nodes can be found by node lookup.
  EXPECT_EQ(node, inodes.Lookup(1, device.name.c_str()));
  EXPECT_EQ(node, inodes.Lookup(node->ino));
  EXPECT_EQ("/mtp", inodes.GetName(node->ino));

  // Device node child path name includes the device name.
  EXPECT_EQ("/mtp", inodes.GetPath(node));

  // Device node device path names elide the device name.
  auto device_path = inodes.GetDevicePath(node);
  EXPECT_EQ("filesystem://escaped-url", device_path);

  // Device node children should have the same device number.
  Node* child = inodes.Create(FIRST_UNRESERVED_INO + 0, "foo");
  EXPECT_TRUE(child);
  EXPECT_EQ("/foo", inodes.GetName(child->ino));
  EXPECT_EQ(node->device, device.device);
  EXPECT_EQ(1, child->device);
  EXPECT_EQ(FIRST_UNRESERVED_INO + 0, child->parent);
  EXPECT_EQ(FIRST_UNRESERVED_INO + 1, child->ino);

  // Device node child path name includes the device name.
  EXPECT_EQ("/mtp/foo", inodes.GetPath(child));

  // Device node device path names elide the device name.
  device_path = inodes.GetDevicePath(child);
  EXPECT_EQ("filesystem://escaped-url/foo", device_path);

  // Device node children should have the same device number.
  Node* child_child = inodes.Create(FIRST_UNRESERVED_INO + 1, "bar");
  EXPECT_TRUE(child_child);
  EXPECT_EQ("/bar", inodes.GetName(child_child->ino));
  EXPECT_EQ(child_child->device, device.device);
  EXPECT_EQ(1, child_child->device);
  EXPECT_EQ(FIRST_UNRESERVED_INO + 1, child_child->parent);
  EXPECT_EQ(FIRST_UNRESERVED_INO + 2, child_child->ino);

  // Device node child path name includes the device name.
  EXPECT_EQ("/mtp/foo/bar", inodes.GetPath(child_child));

  // Device node device path names elide the device name.
  device_path = inodes.GetDevicePath(child_child);
  EXPECT_EQ("filesystem://escaped-url/foo/bar", device_path);

  // Device nodes must attach to the root node.
  errno = 0;
  EXPECT_FALSE(inodes.AttachDevice(3, device));
  EXPECT_EQ(EINVAL, errno);

  // Device nodes cannot be moved to a different device.
  errno = 0;
  EXPECT_FALSE(inodes.Move(child, 1, "name"));
  EXPECT_EQ(ENOTSUP, errno);
  EXPECT_FALSE(inodes.Lookup(1, "name"));
  errno = 0;
  EXPECT_FALSE(inodes.Move(node, 1, "name"));
  EXPECT_EQ(ENOTSUP, errno);
  EXPECT_FALSE(inodes.Lookup(1, "name"));

  // Create a child of the root node.
  Node* baz = inodes.Create(1, "baz");
  EXPECT_EQ(0, baz->device);
  EXPECT_EQ(1, baz->parent);
  EXPECT_EQ(FIRST_UNRESERVED_INO + 3, baz->ino);

  // Detach the device nodes from the inode table.
  EXPECT_EQ(FIRST_UNRESERVED_INO + 0, device.ino);
  EXPECT_TRUE(inodes.DetachDevice(device.ino));
  EXPECT_FALSE(inodes.Lookup(FIRST_UNRESERVED_INO + 2));
  EXPECT_FALSE(inodes.Lookup(FIRST_UNRESERVED_INO + 1));
  EXPECT_FALSE(inodes.Lookup(FIRST_UNRESERVED_INO + 0));

  // Detaching the device again should error: errno EINVAL.
  errno = 0;
  EXPECT_EQ(FIRST_UNRESERVED_INO + 0, device.ino);
  EXPECT_FALSE(inodes.DetachDevice(device.ino));
  EXPECT_EQ(EINVAL, errno);

  // Root and baz nodes should remain in the inode table.
  EXPECT_TRUE(inodes.Lookup(1));
  EXPECT_TRUE(inodes.Lookup(FIRST_UNRESERVED_INO + 3));

  // Device nodes must attach to the root node.
  errno = 0;
  EXPECT_FALSE(inodes.AttachDevice(FIRST_UNRESERVED_INO + 3, device));
  EXPECT_EQ(EINVAL, errno);
}

}  // namespace fusebox