bin/debug_agent/debugged_process.cc

// Copyright 2018 The Fuchsia 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 "garnet/bin/debug_agent/debugged_process.h"

#include <inttypes.h>
#include <zircon/syscalls/exception.h>
#include <utility>

#include "garnet/bin/debug_agent/debug_agent.h"
#include "garnet/bin/debug_agent/debugged_thread.h"
#include "garnet/bin/debug_agent/debugged_thread.h"
#include "garnet/bin/debug_agent/object_util.h"
#include "garnet/bin/debug_agent/process_breakpoint.h"
#include "garnet/bin/debug_agent/process_info.h"
#include "garnet/bin/debug_agent/process_memory_accessor.h"
#include "garnet/lib/debug_ipc/agent_protocol.h"
#include "garnet/lib/debug_ipc/helper/message_loop_zircon.h"
#include "garnet/lib/debug_ipc/message_reader.h"
#include "garnet/lib/debug_ipc/message_writer.h"
#include "garnet/public/lib/fxl/logging.h"

namespace debug_agent {

DebuggedProcess::DebuggedProcess(DebugAgent* debug_agent, zx_koid_t koid,
                                 zx::process proc)
    : debug_agent_(debug_agent), koid_(koid), process_(std::move(proc)) {}
DebuggedProcess::~DebuggedProcess() = default;

bool DebuggedProcess::Init() {
  debug_ipc::MessageLoopZircon* loop = debug_ipc::MessageLoopZircon::Current();
  FXL_DCHECK(loop);  // Loop must be created on this thread first.

  // Register for debug exceptions.
  process_watch_handle_ =
      loop->WatchProcessExceptions(process_.get(), koid_, this);
  return process_watch_handle_.watching();
}

void DebuggedProcess::OnPause(const debug_ipc::PauseRequest& request) {
  if (request.thread_koid) {
    DebuggedThread* thread = GetThread(request.thread_koid);
    if (thread) thread->Pause();
    // Could be not found if there is a race between the thread exiting and
    // the client sending the request.
  } else {
    // 0 thread ID means resume all in process.
    for (const auto& pair : threads_) pair.second->Pause();
  }
}

void DebuggedProcess::OnResume(const debug_ipc::ResumeRequest& request) {
  if (request.thread_koid) {
    DebuggedThread* thread = GetThread(request.thread_koid);
    if (thread) thread->Resume(request.how);
    // Could be not found if there is a race between the thread exiting and
    // the client sending the request.
  } else {
    // 0 thread ID means resume all in process.
    for (const auto& pair : threads_) pair.second->Resume(request.how);
  }
}

void DebuggedProcess::OnReadMemory(const debug_ipc::ReadMemoryRequest& request,
                                   debug_ipc::ReadMemoryReply* reply) {
  // TODO(brettw) break into blocks if a portion of the memory range is mapped
  // but a portion isn't. Currently this assumes the entire range is in one
  // block.
  debug_ipc::MemoryBlock block;
  block.address = request.address;
  block.size = request.size;
  block.data.resize(request.size);

  size_t bytes_read = 0;
  if (process_.read_memory(request.address, &block.data[0], block.size,
                           &bytes_read) == ZX_OK &&
      bytes_read == block.size) {
    block.valid = true;
  } else {
    block.valid = false;
    block.data.resize(0);
  }

  reply->blocks.emplace_back(std::move(block));
}

void DebuggedProcess::OnKill(const debug_ipc::KillRequest& request,
                             debug_ipc::KillReply* reply) {
  reply->status = process_.kill();
}

DebuggedThread* DebuggedProcess::GetThread(zx_koid_t thread_koid) {
  auto found_thread = threads_.find(thread_koid);
  if (found_thread == threads_.end()) return nullptr;
  return found_thread->second.get();
}

void DebuggedProcess::PopulateCurrentThreads() {
  for (zx_koid_t koid :
       GetChildKoids(process_.get(), ZX_INFO_PROCESS_THREADS)) {
    FXL_DCHECK(threads_.find(koid) == threads_.end());

    zx_handle_t handle;
    if (zx_object_get_child(process_.get(), koid, ZX_RIGHT_SAME_RIGHTS,
                            &handle) == ZX_OK) {
      auto added =
          threads_.emplace(koid, std::make_unique<DebuggedThread>(
                                     this, zx::thread(handle), koid, true));
      added.first->second->SendThreadNotification();
    }
  }
}

ProcessBreakpoint* DebuggedProcess::FindProcessBreakpointForAddr(
    uint64_t address) {
  auto found = breakpoints_.find(address);
  if (found == breakpoints_.end()) return nullptr;
  return found->second.get();
}

zx_status_t DebuggedProcess::RegisterBreakpoint(Breakpoint* bp,
                                                uint64_t address) {
  auto found = breakpoints_.find(address);
  if (found == breakpoints_.end()) {
    auto process_breakpoint =
        std::make_unique<ProcessBreakpoint>(bp, this, koid_, address);
    zx_status_t status = process_breakpoint->Init();
    if (status != ZX_OK) return status;

    breakpoints_[address] = std::move(process_breakpoint);
  } else {
    found->second->RegisterBreakpoint(bp);
  }
  return ZX_OK;
}

void DebuggedProcess::UnregisterBreakpoint(Breakpoint* bp, uint64_t address) {
  auto found = breakpoints_.find(address);
  if (found == breakpoints_.end()) {
    FXL_NOTREACHED();  // Should always be found.
    return;
  }

  bool still_used = found->second->UnregisterBreakpoint(bp);
  if (!still_used) breakpoints_.erase(found);
}

void DebuggedProcess::OnProcessTerminated(zx_koid_t process_koid) {
  debug_ipc::NotifyProcess notify;
  notify.process_koid = process_koid;

  zx_info_process info;
  GetProcessInfo(process_.get(), &info);
  notify.return_code = info.return_code;

  debug_ipc::MessageWriter writer;
  debug_ipc::WriteNotifyProcess(notify, &writer);
  debug_agent_->stream()->Write(writer.MessageComplete());

  debug_agent_->RemoveDebuggedProcess(process_koid);
  // "THIS" IS NOW DELETED.
}

void DebuggedProcess::OnThreadStarting(zx_koid_t process_koid,
                                       zx_koid_t thread_koid) {
  zx::thread thread = ThreadForKoid(process_.get(), thread_koid);

  // The thread will currently be in a suspended state, resume it.
  thread.resume(ZX_RESUME_EXCEPTION);

  FXL_DCHECK(threads_.find(thread_koid) == threads_.end());
  auto added = threads_.emplace(
      thread_koid, std::make_unique<DebuggedThread>(this, std::move(thread),
                                                    thread_koid, true));

  // Notify the client.
  added.first->second->SendThreadNotification();
}

void DebuggedProcess::OnThreadExiting(zx_koid_t process_koid,
                                      zx_koid_t thread_koid) {
  // Clean up our DebuggedThread object.
  FXL_DCHECK(threads_.find(thread_koid) != threads_.end());
  threads_.erase(thread_koid);

  // Notify the client. Can't call FillThreadRecord since the thread doesn't
  // exist any more.
  debug_ipc::NotifyThread notify;
  notify.process_koid = process_koid;
  notify.record.koid = thread_koid;
  notify.record.state = debug_ipc::ThreadRecord::State::kDead;

  debug_ipc::MessageWriter writer;
  debug_ipc::WriteNotifyThread(debug_ipc::MsgHeader::Type::kNotifyThreadExiting,
                               notify, &writer);
  debug_agent_->stream()->Write(writer.MessageComplete());
}

void DebuggedProcess::OnException(zx_koid_t process_koid, zx_koid_t thread_koid,
                                  uint32_t type) {
  DebuggedThread* thread = GetThread(thread_koid);
  if (thread) {
    thread->OnException(type);
  } else {
    fprintf(stderr,
            "Exception for thread %" PRIu64 " which we don't know about.\n",
            thread_koid);
  }
}

void DebuggedProcess::OnAddressSpace(
    const debug_ipc::AddressSpaceRequest& request,
    debug_ipc::AddressSpaceReply* reply) {
  const size_t kRegionsCountGuess = 64u;
  const size_t kNewRegionsCountGuess = 4u;

  size_t count_guess = kRegionsCountGuess;

  std::vector<zx_info_maps_t> map;
  size_t actual;
  size_t avail;

  while (true) {
    map.resize(count_guess);

    zx_status_t status =
        zx_object_get_info(process_.get(), ZX_INFO_PROCESS_MAPS, &map[0],
                           sizeof(zx_info_maps) * map.size(), &actual, &avail);

    if (status != ZX_OK) {
      fprintf(stderr, "error %d for zx_object_get_info\n", status);
      return;
    } else if (actual == avail) {
      break;
    }

    count_guess = avail + kNewRegionsCountGuess;
  }

  map.resize(actual);

  if (request.address != 0u) {
    for (const auto& entry : map) {
      if (request.address < entry.base)
        continue;
      if (request.address <= (entry.base + entry.size)) {
        reply->map.push_back({entry.name, entry.base, entry.size, entry.depth});
      }
    }
    return;
  }

  reply->map.resize(actual);

  size_t ix = 0;
  for (const auto& entry : map) {
    reply->map[ix].name = entry.name;
    reply->map[ix].base = entry.base;
    reply->map[ix].size = entry.size;
    reply->map[ix].depth = entry.depth;
    ++ix;
  }
}

zx_status_t DebuggedProcess::ReadProcessMemory(uintptr_t address, void* buffer,
                                               size_t len, size_t* actual) {
  return process_.read_memory(address, buffer, len, actual);
}

zx_status_t DebuggedProcess::WriteProcessMemory(uintptr_t address,
                                                const void* buffer, size_t len,
                                                size_t* actual) {
  return process_.write_memory(address, buffer, len, actual);
}

}  // namespace debug_agent