src: add commands to inspect the workqueue

Add two new commands: `v8 getactivehandles` and `v8 getactiverequests`. These comamnds will print all pending handles and requests. The result should be similar to running process._getActiveHandles() and process._getActiveRequests() on the living process. Fixes: #100
mmarchini · Mar 16, 2018 · Jul 1, 2018 · Jul 1, 2018 · Jul 1, 2018 · Jun 28, 2018
commit 2b695fdafb4706782922aacb6e3f9f51ef8f07de
diff --git a/README.md b/README.md
@@ -230,6 +230,12 @@ The following subcommands are supported:
                           * -n, --name  name     - all properties with the specified name
                           * -s, --string string  - all properties that refer to the specified JavaScript string value
 
+      getactivehandles  -- Print all pending handles in the queue. Equivalent to running process._getActiveHandles() on
+                           the living process.
+
+      getactiverequests -- Print all pending handles in the queue. Equivalent to running process._getActiveHandles() on
+                           the living process.
+
       inspect         -- Print detailed description and contents of the JavaScript value.
 
                          Possible flags (all optional):

diff --git a/binding.gyp b/binding.gyp
@@ -16,6 +16,7 @@
       "<(lldb_include_dir)",
     ],
 
+
     "cflags" : [ "-std=c++11" ],
 
     "conditions": [
@@ -76,6 +77,7 @@
       "src/llv8.cc",
       "src/llv8-constants.cc",
       "src/llscan.cc",
+      "src/node.cc",
       "src/node-constants.cc",
     ]
   }],

diff --git a/src/llnode.cc b/src/llnode.cc
@@ -4,13 +4,16 @@
 #include <string.h>
 
 #include <cinttypes>
+#include <sstream>
+#include <string>
 
 #include <lldb/API/SBExpressionOptions.h>
 
 #include "src/error.h"
 #include "src/llnode.h"
 #include "src/llscan.h"
 #include "src/llv8.h"
+#include "src/node-inl.h"
 
 namespace llnode {
 
@@ -20,6 +23,7 @@ using lldb::SBDebugger;
 using lldb::SBError;
 using lldb::SBExpressionOptions;
 using lldb::SBFrame;
+using lldb::SBProcess;
 using lldb::SBStream;
 using lldb::SBSymbol;
 using lldb::SBTarget;
@@ -245,6 +249,112 @@ bool ListCmd::DoExecute(SBDebugger d, char** cmd,
   return true;
 }
 
+bool WorkqueueCmd::DoExecute(SBDebugger d, char** cmd,
+                             SBCommandReturnObject& result) {
+  SBTarget>
+  SBProcess process = target.GetProcess();
+  SBThread thread = process.GetSelectedThread();
+  std::string result_message;
+  Error err;
+
+  llv8_->Load(target);
+  node_->Load(target);
+
+  if (!thread.IsValid()) {
+    result.SetError("No valid process, please start something\n");
+    return false;
+  }
+
+  node::Environment env = node::Environment::GetCurrent(node_, err);
+  if (err.Fail()) {
+    result.SetError(err.GetMessage());
+    return false;
+  }
+
+  result_message = GetResultMessage(&env, err);
+
+  if (err.Fail()) {
+    result.SetError(err.GetMessage());
+    return false;
+  }
+
+  result.Printf("%s", result_message.c_str());
+  return true;
+}
+
+std::string GetActiveHandlesCmd::GetResultMessage(node::Environment* env,
+                                                  Error& err) {
+  int active_handles = 0;
+  v8::Value::InspectOptions inspect_options;
+  inspect_options.detailed = true;
+  std::ostringstream result_message;
+
+  for (auto w : env->handle_wrap_queue()) {
+    addr_t persistent_addr = w.persistent_addr(err);
+    if (err.Fail()) {
+      break;
+    }
+    if (persistent_addr == 0) {
+      continue;
+    }
+
+    addr_t v8_object_addr = w.v8_object_addr(err);
+    if (err.Fail()) {
+      break;
+    }
+    v8::JSObject v8_object(llv8(), v8_object_addr);
+    std::string res = v8_object.Inspect(&inspect_options, err);
+    if (err.Fail()) {
+      Error::PrintInDebugMode("Failed to load object at address %" PRIx64,
+                              v8_object_addr);
+      break;
+    }
+
+    active_handles++;
+    result_message << res.c_str() << std::endl;
+  }
+
+  result_message << "Total: " << active_handles << std::endl;
+  return result_message.str();
+}
+
+
+std::string GetActiveRequestsCmd::GetResultMessage(node::Environment* env,
+                                                   Error& err) {
+  int active_handles = 0;
+  v8::Value::InspectOptions inspect_options;
+  inspect_options.detailed = true;
+  std::ostringstream result_message;
+
+  for (auto w : env->req_wrap_queue()) {
+    addr_t persistent_addr = w.persistent_addr(err);
+    if (err.Fail()) {
+      break;
+    }
+    if (persistent_addr == 0) {
+      continue;
+    }
+
+    addr_t v8_object_addr = w.v8_object_addr(err);
+    if (err.Fail()) {
+      break;
+    }
+    v8::JSObject v8_object(llv8(), v8_object_addr);
+    std::string res = v8_object.Inspect(&inspect_options, err);
+    if (err.Fail()) {
+      Error::PrintInDebugMode("Failed to load object at address %" PRIx64,
+                              v8_object_addr);
+      break;
+    }
+
+    active_handles++;
+    result_message << res.c_str() << std::endl;
+  }
+
+  result_message << "Total: " << active_handles << std::endl;
+  return result_message.str();
+}
+
 
 void InitDebugMode() {
   bool is_debug_mode = false;
@@ -264,6 +374,7 @@ bool PluginInitialize(SBDebugger d) {
   llnode::InitDebugMode();
 
   static llnode::v8::LLV8 llv8;
+  static llnode::node::Node node(&llv8);
   static llnode::LLScan llscan = llnode::LLScan(&llv8);
 
   SBCommandInterpreter interpreter = d.GetCommandInterpreter();
@@ -349,6 +460,16 @@ bool PluginInitialize(SBDebugger d) {
       "JavaScript string value\n"
       "\n");
 
+  v8.AddCommand("getactivehandles",
+                new llnode::GetActiveHandlesCmd(&llv8, &node),
+                "Print all pending handles in the queue. Equivalent to running "
+                "process._getActiveHandles() on the living process.\n");
+
+  v8.AddCommand(
+      "getactiverequests", new llnode::GetActiveRequestsCmd(&llv8, &node),
+      "Print all pending requests in the queue. Equivalent to "
+      "running process._getActiveRequests() on the living process.\n");
+
   return true;
 }
 

diff --git a/src/llnode.h b/src/llnode.h
@@ -6,6 +6,7 @@
 #include <lldb/API/LLDB.h>
 
 #include "src/llv8.h"
+#include "src/node.h"
 
 namespace llnode {
 
@@ -50,6 +51,43 @@ class ListCmd : public CommandBase {
   v8::LLV8* llv8_;
 };
 
+class WorkqueueCmd : public CommandBase {
+ public:
+  WorkqueueCmd(v8::LLV8* llv8, node::Node* node) : llv8_(llv8), node_(node) {}
+  ~WorkqueueCmd() override {}
+
+  inline v8::LLV8* llv8() { return llv8_; };
+  inline node::Node* node() { return node_; };
+
+  bool DoExecute(lldb::SBDebugger d, char** cmd,
+                 lldb::SBCommandReturnObject& result) override;
+
+  virtual std::string GetResultMessage(node::Environment* env, Error& err) {
+    return std::string();
+  };
+
+ private:
+  v8::LLV8* llv8_;
+  node::Node* node_;
+};
+
+class GetActiveHandlesCmd : public WorkqueueCmd {
+ public:
+  GetActiveHandlesCmd(v8::LLV8* llv8, node::Node* node)
+      : WorkqueueCmd(llv8, node) {}
+
+  std::string GetResultMessage(node::Environment* env, Error& err) override;
+};
+
+class GetActiveRequestsCmd : public WorkqueueCmd {
+ public:
+  GetActiveRequestsCmd(v8::LLV8* llv8, node::Node* node)
+      : WorkqueueCmd(llv8, node) {}
+
+  std::string GetResultMessage(node::Environment* env, Error& err) override;
+};
+
+
 }  // namespace llnode
 
 #endif  // SRC_LLNODE_H_
diff --git a/src/node-constants.cc b/src/node-constants.cc
@@ -19,7 +19,8 @@ void Environment::Load() {
   kHandleWrapQueueOffset = LoadConstant(
       "offset_Environment__handle_wrap_queue___Environment_HandleWrapQueue");
   kEnvContextEmbedderDataIndex =
-      LoadConstant("const_Environment__kContextEmbedderDataIndex__int");
+      LoadConstant("const_Environment__kContextEmbedderDataIndex__int",
+                   "const_ContextEmbedderIndex__kEnvironment__int");
 
   Error err;
   kCurrentEnvironment = LoadCurrentEnvironment(err);

diff --git a/src/node-inl.h b/src/node-inl.h
@@ -0,0 +1,42 @@
+#include "node.h"
+
+namespace llnode {
+namespace node {
+
+template <typename T, typename C>
+T Queue<T, C>::Iterator::operator*() const {
+  return T::FromListNode(node_, current_);
+}
+
+template <typename T, typename C>
+const typename Queue<T, C>::Iterator Queue<T, C>::Iterator::operator++() {
+  lldb::SBError sberr;
+
+  addr_t current = current_ + constants_->kNextOffset;
+  current = node_->process().ReadPointerFromMemory(current, sberr);
+  current_ = current;
+  return Iterator(node_, current, constants_);
+}
+
+template <typename T, typename C>
+bool Queue<T, C>::Iterator::operator!=(const Iterator& that) const {
+  return current_ != that.current_;
+}
+
+template <typename T, typename C>
+typename Queue<T, C>::Iterator Queue<T, C>::begin() const {
+  lldb::SBError sberr;
+  addr_t currentNode = raw_ + constants_->kHeadOffset;
+
+  currentNode = currentNode + constants_->kNextOffset;
+  currentNode = node_->process().ReadPointerFromMemory(currentNode, sberr);
+
+  return Iterator(node_, currentNode, constants_);
+}
+
+template <typename T, typename C>
+typename Queue<T, C>::Iterator Queue<T, C>::end() const {
+  return Iterator(node_, raw_ + constants_->kHeadOffset, constants_);
+}
+}  // namespace node
+}  // namespace llnode
diff --git a/src/node.cc b/src/node.cc
@@ -0,0 +1,77 @@
+#include "node.h"
+
+namespace llnode {
+namespace node {
+
+addr_t BaseObject::persistent_addr(Error& err) {
+  lldb::SBError sberr;
+
+  addr_t persistentHandlePtr =
+      raw_ + node_->base_object()->kPersistentHandleOffset;
+  addr_t persistentHandle =
+      node_->process().ReadPointerFromMemory(persistentHandlePtr, sberr);
+  if (sberr.Fail()) {
+    err = Error::Failure("Failed to load persistent handle");
+    return 0;
+  }
+  return persistentHandle;
+}
+
+addr_t BaseObject::v8_object_addr(Error& err) {
+  lldb::SBError sberr;
+
+  addr_t persistentHandle = persistent_addr(err);
+  addr_t obj = node_->process().ReadPointerFromMemory(persistentHandle, sberr);
+  if (sberr.Fail()) {
+    err = Error::Failure("Failed to load object from persistent handle");
+    return 0;
+  }
+  return obj;
+}
+
+HandleWrap HandleWrap::FromListNode(Node* node, addr_t list_node_addr) {
+  return HandleWrap(node,
+                    list_node_addr - node->handle_wrap()->kListNodeOffset);
+}
+
+ReqWrap ReqWrap::FromListNode(Node* node, addr_t list_node_addr) {
+  return ReqWrap(node, list_node_addr - node->req_wrap()->kListNodeOffset);
+}
+
+Environment Environment::GetCurrent(Node* node, Error& err) {
+  addr_t envAddr = node->env()->kCurrentEnvironment;
+  if (envAddr == 0) {
+    err = Error::Failure("Couldn't get node's Environment");
+  }
+
+  return Environment(node, envAddr);
+}
+
+HandleWrapQueue Environment::handle_wrap_queue() const {
+  return HandleWrapQueue(node_, raw_ + node_->env()->kHandleWrapQueueOffset,
+                         node_->handle_wrap_queue());
+}
+
+ReqWrapQueue Environment::req_wrap_queue() const {
+  return ReqWrapQueue(node_, raw_ + node_->env()->kReqWrapQueueOffset,
+                      node_->req_wrap_queue());
+}
+
+void Node::Load(SBTarget target) {
+  // Reload process anyway
+  process_ = target.GetProcess();
+
+  // No need to reload
+  if (target_ == target) return;
+
+  target_ = target;
+
+  env.Assign(target);
+  req_wrap_queue.Assign(target);
+  req_wrap.Assign(target);
+  handle_wrap_queue.Assign(target);
+  handle_wrap.Assign(target);
+  base_object.Assign(target);
+}
+}  // namespace node
+}  // namespace llnode