WIP: DevFS initial implementation

runtime/vm/dev_fs.cc

Index: runtime/vm/dev_fs.cc
diff --git a/runtime/vm/dev_fs.cc b/runtime/vm/dev_fs.cc
new file mode 100644
index 0000000000000000000000000000000000000000..bde13c3d20f0e09ffe499cc97228ebc0c40121e9
--- /dev/null
+++ b/runtime/vm/dev_fs.cc
@@ -0,0 +1,187 @@
+// Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+#include "vm/dev_fs.h"
+
+#include "vm/hash_table.h"
+#include "vm/json_stream.h"
+#include "vm/object.h"
+
+namespace dart {
+
+class StringMapTraits {
+ public:
+  static bool ReportStats() { return false; }
+  static const char* Name() { return "StringMapTraits"; }
+
+  static bool IsMatch(const Object& a, const Object& b) {
+    return String::Cast(a).Equals(String::Cast(b));
+  }
+
+  static uword Hash(const Object& obj) {
+    return String::Cast(obj).Hash();
+  }
+};
+
+
+Mutex* DevFS::mutex_ = NULL;
+RawArray* DevFS::fs_map_storage_ = NULL;
+
+
+void DevFS::VisitObjectPointers(ObjectPointerVisitor* visitor) {
+  visitor->VisitPointers(from(), to());
+}
+
+
+void DevFS::Init() {
+  mutex_ = new Mutex();
+}
+
+
+void DevFS::EnsureStorage() {
+  if (fs_map_storage_ == NULL) {
+    fs_map_storage_ = HashTables::New<UnorderedHashMap<StringMapTraits> >(4);
+  }
+}
+
+
+void DevFS::ListFileSystems(JSONStream* js) {
+  EnsureStorage();
+
+  JSONObject jsobj(js);
+  jsobj.AddProperty("type", "FSList");
+  JSONArray jsarr(&jsobj, "ids");
+
+  String& fs_name = String::Handle();
+  UnorderedHashMap<StringMapTraits> fs_map(fs_map_storage_);
+  {
+    UnorderedHashMap<StringMapTraits>::Iterator it(&fs_map);
+    while (it.MoveNext()) {
+      const intptr_t entry = it.Current();
+      fs_name = String::RawCast(fs_map.GetKey(entry));
+      jsarr.AddValue(fs_name.ToCString());
+    }
+  }
+  fs_map.Release();
+  return;
+}
+
+
+RawArray* DevFS::LookupFileSystem(const String& fs_name) {
+  EnsureStorage();
+  UnorderedHashMap<StringMapTraits> map(fs_map_storage_);
+  Array& fs = Array::Handle();
+  fs ^= map.GetOrNull(fs_name);
+  // No need to update storage address because no mutation occurred.
+  map.Release();
+  return fs.raw();
+}
+
+
+bool DevFS::UpdateFileSystem(const String& fs_name,
+                             const Array& fs_contents) {
+  UnorderedHashMap<StringMapTraits> map(fs_map_storage_);
+  bool updated = map.UpdateOrInsert(fs_name, fs_contents);
+  fs_map_storage_ = map.Release().raw();
+  return updated;
+}
+
+
+void DevFS::CreateFileSystem(JSONStream* js, const char* fs_name) {
+  EnsureStorage();
+  // TODO(turnidge): Ensure that fs_name is a legal URI host value, i.e. ascii.
+  const String& fs = String::Handle(String::New(fs_name));
+  if (LookupFileSystem(fs) != Array::null()) {
+    js->PrintError(kFileSystemAlreadyExists,
+                   "%s: file system '%s' already exists",
+                   js->method(), fs_name);
+    return;
+  }
+
+  bool update = UpdateFileSystem(
+      fs,
+      Array::Handle(HashTables::New<UnorderedHashMap<StringMapTraits> >(4)));
+  ASSERT(!update);
+
+  JSONObject jsobj(js);
+  jsobj.AddProperty("type", "Success");
+}
+
+
+void DevFS::DeleteFileSystem(JSONStream* js, const char* fs_name) {
+  EnsureStorage();
+  const String& fs = String::Handle(String::New(fs_name));
+  if (LookupFileSystem(fs) == Array::null()) {
+    js->PrintError(kFileSystemDoesNotExist,
+                   "%s: file system '%s' does not exist",
+                   js->method(), fs_name);
+    return;
+  }
+
+  UnorderedHashMap<StringMapTraits> map(fs_map_storage_);
+  map.Remove(fs);
+  fs_map_storage_ = map.Release().raw();
+
+  JSONObject jsobj(js);
+  jsobj.AddProperty("type", "Success");
+}
+
+
+void DevFS::WriteFile(JSONStream* js,
+                      const char* fs_name,
+                      const char* path_param,
+                      const char* file_contents) {
+  EnsureStorage();
+  const String& fs = String::Handle(String::New(fs_name));
+  const Array& fs_contents = Array::Handle(LookupFileSystem(fs));
+  if (fs_contents.IsNull()) {
+    js->PrintError(kFileSystemDoesNotExist,
+                   "%s: file system '%s' does not exist",
+                   js->method(), fs_name);
+    return;
+  }
+
+  const String& path = String::Handle(String::New(path_param));
+  UnorderedHashMap<StringMapTraits> map(fs_contents.raw());
+  map.UpdateOrInsert(path, String::Handle(String::New(file_contents)));
+  UpdateFileSystem(fs, map.Release());
+
+  JSONObject jsobj(js);
+  jsobj.AddProperty("type", "Success");
+}
+
+
+void DevFS::ReadFile(JSONStream* js,
+                     const char* fs_name,
+                     const char* path_param) {
+  EnsureStorage();
+  const String& fs = String::Handle(String::New(fs_name));
+  const Array& fs_contents = Array::Handle(LookupFileSystem(fs));
+  if (fs_contents.IsNull()) {
+    js->PrintError(kFileSystemDoesNotExist,
+                   "%s: file system '%s' does not exist",
+                   js->method(), fs_name);
+    return;
+  }
+
+  const String& path = String::Handle(String::New(path_param));
+  UnorderedHashMap<StringMapTraits> map(fs_contents.raw());
+  String& file_contents = String::Handle();
+  file_contents ^= map.GetOrNull(path);
+  // No need to update storage address because no mutation occurred.
+  map.Release();
+
+  if (file_contents.IsNull()) {
+    js->PrintError(kFileDoesNotExist,
+                   "%s: file 'dart-devfs://%s/%s' does not exist",
+                   js->method(), fs_name, path_param);
+    return;
+  }
+
+  JSONObject jsobj(js);
+  jsobj.AddProperty("type", "FSFile");
+  jsobj.AddProperty("fileContents", file_contents.ToCString());
+}
+
+}  // namespace dart