Added simplest device mount implementation (includes NullDevice and RandomDevice)

libraries/nacl-mounts/dev/DevMount.cc

+/*
+ * Copyright (c) 2012 The Native Client Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+#include "../dev/DevMount.h"
+#include "../dev/RandomDevice.h"
+#include "../dev/NullDevice.h"
+
+DevMount::DevMount() {
+    // RandomDevice* dev_random = new RandomDevice(??);
+    // Attach("/random", dev_random);
+    NullDevice* dev_null = new NullDevice();
+    Attach("/null", dev_null);
+}
+
+void DevMount::Attach(std::string path, Device* device) {
+  if (path_to_inode.find(path) == path_to_inode.end()) {
+    int inode = device->GetInode();
+    inode_to_path[inode] = path;
+    inode_to_dev[inode]  = device;
+    inode_to_ref[inode]  = 1;
+    path_to_inode[path]  = inode;
+  }
+}
+void DevMount::Ref(ino_t node) {
+  if (inode_to_path.find(slot) != inode_to_path.end()) {
+    inode_to_ref[node]++;
+  }
+}
+void DevMount::Unref(ino_t node) {
+  if (inode_to_path.find(slot) != inode_to_path.end()) {
+    inode_to_ref[node]--;
+  }
+}
+
+int DevMount::Creat(const std::string& path, mode_t mode, struct stat *buf) {
+  if (path_to_inode.find(path) != path_to_inode.end()) {
+    return Stat(path_to_inode[path], buf);
+  }
+
+int DevMount::Stat(ino_t node, struct stat *buf) {
+  if (inode_to_path.find(node) == inode_to_path.end())
+    return -1;
+  memset(buf, 0, sizeof(struct stat));
+  buf->st_ino = node;
+  buf->st_mode = S_IFREG | 0777;
+  return 0;
+}
+
+int DevMount::Getdents(ino_t slot, off_t offset,
+                       struct dirent *dir, unsigned int count) {
+  for (std::map<string, int>::const_iterator it = path_to_inode.begin();
+    it != path_to_inode.end(); ++it) {
+    memset(dir, 0, sizeof(struct dirent));
+    // We want d_ino to be non-zero because readdir()
+    // will return null if d_ino is zero.
+    dir->d_ino = 0x60061E;
+    dir->d_reclen = sizeof(struct dirent);
+    strncpy(dir->d_name, it->first().c_str(), sizeof(dir->d_name));
+  }
+  return -1;
+}
+
+ssize_t DevMount::Read(ino_t slot, off_t offset, void *buf, size_t count) {
+  if (inode_to_path.find(slot) != inode_to_path.end()) {
+    return inode_to_dev[device->GetInode()].Read(offset, buf, count);
+  } else {
+    return -1;
+  }
+}
+
+ssize_t DevMount::Write(ino_t slot, off_t offset, const void *buf,
+                        size_t count) {
+  if (inode_to_path.find(slot) != inode_to_path.end()) {
+    return inode_to_dev[device->GetInode()].Write(offset, buf, count);
+  } else {
+    return -1;
+  }
+}
+