// Copyright (c) 2012, 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 <process.h>

#include "bin/builtin.h"
#include "bin/process.h"
#include "bin/eventhandler.h"
#include "bin/thread.h"
#include "bin/utils.h"
#include "platform/globals.h"

static const int kReadHandle = 0;
static const int kWriteHandle = 1;


// ProcessInfo is used to map a process id to the process handle,
// wait handle for registered exit code event and the pipe used to
// communicate the exit code of the process to Dart.
// ProcessInfo objects are kept in the static singly-linked
// ProcessInfoList.
class ProcessInfo {
 public:
  ProcessInfo(DWORD process_id,
              HANDLE process_handle,
              HANDLE wait_handle,
              HANDLE exit_pipe)
      : process_id_(process_id),
        process_handle_(process_handle),
        wait_handle_(wait_handle),
        exit_pipe_(exit_pipe) { }

  ~ProcessInfo() {
    BOOL success = CloseHandle(process_handle_);
    if (!success) {
      FATAL("Failed to close process handle");
    }
    success = CloseHandle(exit_pipe_);
    if (!success) {
      FATAL("Failed to close process exit code pipe");
    }
  }

  DWORD pid() { return process_id_; }
  HANDLE process_handle() { return process_handle_; }
  HANDLE wait_handle() { return wait_handle_; }
  HANDLE exit_pipe() { return exit_pipe_; }
  ProcessInfo* next() { return next_; }
  void set_next(ProcessInfo* next) { next_ = next; }

 private:
  // Process id.
  DWORD process_id_;
  // Process handle.
  HANDLE process_handle_;
  // Wait handle identifying the exit-code wait operation registered
  // with RegisterWaitForSingleObject.
  HANDLE wait_handle_;
  // File descriptor for pipe to report exit code.
  HANDLE exit_pipe_;
  // Link to next ProcessInfo object in the singly-linked list.
  ProcessInfo* next_;
};


// Singly-linked list of ProcessInfo objects for all active processes
// started from Dart.
class ProcessInfoList {
 public:
  static void AddProcess(DWORD pid, HANDLE handle, HANDLE pipe) {
    // Register a callback to extract the exit code, when the process
    // is signaled.  The callback runs in a independent thread from the OS pool.
    // Because the callback depends on the process list containing
    // the process, lock the mutex until the process is added to the list.
    MutexLocker locker(&mutex_);
    HANDLE wait_handle = INVALID_HANDLE_VALUE;
    BOOL success = RegisterWaitForSingleObject(
        &wait_handle,
        handle,
        &ExitCodeCallback,
        reinterpret_cast<void*>(pid),
        INFINITE,
        WT_EXECUTEONLYONCE);
    if (!success) {
      FATAL("Failed to register exit code wait operation.");
    }
    ProcessInfo* info = new ProcessInfo(pid, handle, wait_handle, pipe);
    // Mutate the process list under the mutex.
    info->set_next(active_processes_);
    active_processes_ = info;
  }

  static bool LookupProcess(DWORD pid,
                            HANDLE* handle,
                            HANDLE* wait_handle,
                            HANDLE* pipe) {
    MutexLocker locker(&mutex_);
    ProcessInfo* current = active_processes_;
    while (current != NULL) {
      if (current->pid() == pid) {
        *handle = current->process_handle();
        *wait_handle = current->wait_handle();
        *pipe = current->exit_pipe();
        return true;
      }
      current = current->next();
    }
    return false;
  }

  static void RemoveProcess(DWORD pid) {
    MutexLocker locker(&mutex_);
    ProcessInfo* prev = NULL;
    ProcessInfo* current = active_processes_;
    while (current != NULL) {
      if (current->pid() == pid) {
        if (prev == NULL) {
          active_processes_ = current->next();
        } else {
          prev->set_next(current->next());
        }
        delete current;
        return;
      }
      prev = current;
      current = current->next();
    }
  }

 private:
  // Callback called when an exit code is available from one of the
  // processes in the list.
  static void CALLBACK ExitCodeCallback(PVOID data, BOOLEAN timed_out) {
    if (timed_out) return;
    DWORD pid = reinterpret_cast<DWORD>(data);
    HANDLE handle;
    HANDLE wait_handle;
    HANDLE exit_pipe;
    bool success = LookupProcess(pid, &handle, &wait_handle, &exit_pipe);
    if (!success) {
      FATAL("Failed to lookup process in list of active processes");
    }
    // Unregister the event in a non-blocking way.
    BOOL ok = UnregisterWait(wait_handle);
    if (!ok && GetLastError() != ERROR_IO_PENDING) {
      FATAL("Failed unregistering wait operation");
    }
    // Get and report the exit code to Dart.
    int exit_code;
    ok = GetExitCodeProcess(handle,
                            reinterpret_cast<DWORD*>(&exit_code));
    if (!ok) {
      FATAL1("GetExitCodeProcess failed %d\n", GetLastError());
    }
    int negative = 0;
    if (exit_code < 0) {
      exit_code = abs(exit_code);
      negative = 1;
    }
    int message[2] = { exit_code, negative };
    DWORD written;
    ok = WriteFile(exit_pipe, message, sizeof(message), &written, NULL);
    // If the process has been closed, the read end of the exit
    // pipe has been closed. It is therefore not a problem that
    // WriteFile fails with a closed pipe error
    // (ERROR_NO_DATA). Other errors should not happen.
    if (ok && written != sizeof(message)) {
      FATAL("Failed to write entire process exit message");
    } else if (!ok && GetLastError() != ERROR_NO_DATA) {
      FATAL1("Failed to write exit code: %d", GetLastError());
    }
    // Remove the process from the list of active processes.
    RemoveProcess(pid);
  }

  // Linked list of ProcessInfo objects for all active processes
  // started from Dart code.
  static ProcessInfo* active_processes_;
  // Mutex protecting all accesses to the linked list of active
  // processes.
  static dart::Mutex mutex_;
};


ProcessInfo* ProcessInfoList::active_processes_ = NULL;
dart::Mutex ProcessInfoList::mutex_;


// Types of pipes to create.
enum NamedPipeType {
  kInheritRead,
  kInheritWrite,
  kInheritNone
};


// Create a pipe for communicating with a new process. The handles array
// will contain the read and write ends of the pipe. Based on the type
// one of the handles will be inheritable.
// NOTE: If this function returns false the handles might have been allocated
// and the caller should make sure to close them in case of an error.
static bool CreateProcessPipe(HANDLE handles[2],
                              char* pipe_name,
                              NamedPipeType type) {
  // Security attributes describing an inheritable handle.
  SECURITY_ATTRIBUTES inherit_handle;
  inherit_handle.nLength = sizeof(SECURITY_ATTRIBUTES);
  inherit_handle.bInheritHandle = TRUE;
  inherit_handle.lpSecurityDescriptor = NULL;

  if (type == kInheritRead) {
    handles[kWriteHandle] =
        CreateNamedPipe(pipe_name,
                        PIPE_ACCESS_OUTBOUND | FILE_FLAG_OVERLAPPED,
                        PIPE_TYPE_BYTE | PIPE_WAIT,
                        1,             // Number of pipes
                        1024,          // Out buffer size
                        1024,          // In buffer size
                        0,             // Timeout in ms
                        NULL);

    if (handles[kWriteHandle] == INVALID_HANDLE_VALUE) {
      fprintf(stderr, "CreateNamedPipe failed %d\n", GetLastError());
      return false;
    }

    handles[kReadHandle] =
        CreateFile(pipe_name,
                   GENERIC_READ,
                   0,
                   &inherit_handle,
                   OPEN_EXISTING,
                   FILE_READ_ATTRIBUTES | FILE_FLAG_OVERLAPPED,
                   NULL);
    if (handles[kReadHandle] == INVALID_HANDLE_VALUE) {
      fprintf(stderr, "CreateFile failed %d\n", GetLastError());
      return false;
    }
  } else {
    ASSERT(type == kInheritWrite || type == kInheritNone);
    handles[kReadHandle] =
        CreateNamedPipe(pipe_name,
                        PIPE_ACCESS_INBOUND | FILE_FLAG_OVERLAPPED,
                        PIPE_TYPE_BYTE | PIPE_WAIT,
                        1,             // Number of pipes
                        1024,          // Out buffer size
                        1024,          // In buffer size
                        0,             // Timeout in ms
                        NULL);

    if (handles[kReadHandle] == INVALID_HANDLE_VALUE) {
      fprintf(stderr, "CreateNamedPipe failed %d\n", GetLastError());
      return false;
    }

    handles[kWriteHandle] =
        CreateFile(pipe_name,
                   GENERIC_WRITE,
                   0,
                   (type == kInheritWrite) ? &inherit_handle : NULL,
                   OPEN_EXISTING,
                   FILE_WRITE_ATTRIBUTES | FILE_FLAG_OVERLAPPED,
                   NULL);
    if (handles[kWriteHandle] == INVALID_HANDLE_VALUE) {
      fprintf(stderr, "CreateFile failed %d\n", GetLastError());
      return false;
    }
  }
  return true;
}


static void CloseProcessPipe(HANDLE handles[2]) {
  for (int i = kReadHandle; i < kWriteHandle; i++) {
    if (handles[i] != INVALID_HANDLE_VALUE) {
      if (!CloseHandle(handles[i])) {
        fprintf(stderr, "CloseHandle failed %d\n", GetLastError());
      }
      handles[i] = INVALID_HANDLE_VALUE;
    }
  }
}


static void CloseProcessPipes(HANDLE handles1[2],
                              HANDLE handles2[2],
                              HANDLE handles3[2],
                              HANDLE handles4[2]) {
  CloseProcessPipe(handles1);
  CloseProcessPipe(handles2);
  CloseProcessPipe(handles3);
  CloseProcessPipe(handles4);
}

static int SetOsErrorMessage(char* os_error_message,
                             int os_error_message_len) {
  int error_code = GetLastError();
  DWORD message_size =
      FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
                    NULL,
                    error_code,
                    MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
                    os_error_message,
                    os_error_message_len,
                    NULL);
  if (message_size == 0) {
    if (GetLastError() != ERROR_INSUFFICIENT_BUFFER) {
      fprintf(stderr, "FormatMessage failed %d\n", GetLastError());
    }
    snprintf(os_error_message, os_error_message_len, "OS Error %d", error_code);
  }
  os_error_message[os_error_message_len - 1] = '\0';
  return error_code;
}


int Process::Start(const char* path,
                   char* arguments[],
                   intptr_t arguments_length,
                   const char* working_directory,
                   char* environment[],
                   intptr_t environment_length,
                   intptr_t* in,
                   intptr_t* out,
                   intptr_t* err,
                   intptr_t* id,
                   intptr_t* exit_handler,
                   char* os_error_message,
                   int os_error_message_len) {
  HANDLE stdin_handles[2] = { INVALID_HANDLE_VALUE, INVALID_HANDLE_VALUE };
  HANDLE stdout_handles[2] = { INVALID_HANDLE_VALUE, INVALID_HANDLE_VALUE };
  HANDLE stderr_handles[2] = { INVALID_HANDLE_VALUE, INVALID_HANDLE_VALUE };
  HANDLE exit_handles[2] = { INVALID_HANDLE_VALUE, INVALID_HANDLE_VALUE };

  // Generate unique pipe names for the four named pipes needed.
  char pipe_names[4][80];
  UUID uuid;
  RPC_STATUS status = UuidCreateSequential(&uuid);
  if (status != RPC_S_OK && status != RPC_S_UUID_LOCAL_ONLY) {
    fprintf(stderr, "UuidCreateSequential failed %d\n", status);
    SetOsErrorMessage(os_error_message, os_error_message_len);
    return status;
  }
  RPC_CSTR uuid_string;
  status = UuidToString(&uuid, &uuid_string);
  if (status != RPC_S_OK) {
    fprintf(stderr, "UuidToString failed %d\n", status);
    SetOsErrorMessage(os_error_message, os_error_message_len);
    return status;
  }
  for (int i = 0; i < 4; i++) {
    static const char* prefix = "\\\\.\\Pipe\\dart";
    snprintf(pipe_names[i],
             sizeof(pipe_names[i]),
             "%s_%s_%d", prefix, uuid_string, i + 1);
  }
  status = RpcStringFree(&uuid_string);
  if (status != RPC_S_OK) {
    fprintf(stderr, "RpcStringFree failed %d\n", status);
    SetOsErrorMessage(os_error_message, os_error_message_len);
    return status;
  }

  if (!CreateProcessPipe(stdin_handles, pipe_names[0], kInheritRead)) {
    int error_code = SetOsErrorMessage(os_error_message, os_error_message_len);
    CloseProcessPipes(
        stdin_handles, stdout_handles, stderr_handles, exit_handles);
    return error_code;
  }
  if (!CreateProcessPipe(stdout_handles, pipe_names[1], kInheritWrite)) {
    int error_code = SetOsErrorMessage(os_error_message, os_error_message_len);
    CloseProcessPipes(
        stdin_handles, stdout_handles, stderr_handles, exit_handles);
    return error_code;
  }
  if (!CreateProcessPipe(stderr_handles, pipe_names[2], kInheritWrite)) {
    int error_code = SetOsErrorMessage(os_error_message, os_error_message_len);
    CloseProcessPipes(
        stdin_handles, stdout_handles, stderr_handles, exit_handles);
    return error_code;
  }
  if (!CreateProcessPipe(exit_handles, pipe_names[3], kInheritNone)) {
    int error_code = SetOsErrorMessage(os_error_message, os_error_message_len);
    CloseProcessPipes(
        stdin_handles, stdout_handles, stderr_handles, exit_handles);
    return error_code;
  }

  // Setup info structures.
  STARTUPINFO startup_info;
  ZeroMemory(&startup_info, sizeof(startup_info));
  startup_info.cb = sizeof(startup_info);
  startup_info.hStdInput = stdin_handles[kReadHandle];
  startup_info.hStdOutput = stdout_handles[kWriteHandle];
  startup_info.hStdError = stderr_handles[kWriteHandle];
  startup_info.dwFlags = STARTF_USESTDHANDLES;

  PROCESS_INFORMATION process_info;
  ZeroMemory(&process_info, sizeof(process_info));

  // Transform input strings to system format.
  path = StringUtils::Utf8ToSystemString(path);
  for (int i = 0; i < arguments_length; i++) {
     arguments[i] = StringUtils::Utf8ToSystemString(arguments[i]);
  }

  // Compute command-line length.
  int command_line_length = strlen(path);
  for (int i = 0; i < arguments_length; i++) {
    command_line_length += strlen(arguments[i]);
  }
  // Account for null termination and one space per argument.
  command_line_length += arguments_length + 1;
  static const int kMaxCommandLineLength = 32768;
  if (command_line_length > kMaxCommandLineLength) {
    int error_code = SetOsErrorMessage(os_error_message, os_error_message_len);
    CloseProcessPipes(
        stdin_handles, stdout_handles, stderr_handles, exit_handles);
    free(const_cast<char*>(path));
    for (int i = 0; i < arguments_length; i++) free(arguments[i]);
    return error_code;
  }

  // Put together command-line string.
  char* command_line = new char[command_line_length];
  int len = 0;
  int remaining = command_line_length;
  int written = snprintf(command_line + len, remaining, "%s", path);
  len += written;
  remaining -= written;
  ASSERT(remaining >= 0);
  for (int i = 0; i < arguments_length; i++) {
    written = snprintf(command_line + len, remaining, " %s", arguments[i]);
    len += written;
    remaining -= written;
    ASSERT(remaining >= 0);
  }
  free(const_cast<char*>(path));
  for (int i = 0; i < arguments_length; i++) free(arguments[i]);

  // Create environment block if an environment is supplied.
  char* environment_block = NULL;
  if (environment != NULL) {
    // Convert environment strings to system strings.
    for (intptr_t i = 0; i < environment_length; i++) {
      environment[i] = StringUtils::Utf8ToSystemString(environment[i]);
    }

    // An environment block is a sequence of zero-terminated strings
    // followed by a block-terminating zero char.
    intptr_t block_size = 1;
    for (intptr_t i = 0; i < environment_length; i++) {
      block_size += strlen(environment[i]) + 1;
    }
    environment_block = new char[block_size];
    intptr_t block_index = 0;
    for (intptr_t i = 0; i < environment_length; i++) {
      intptr_t len = strlen(environment[i]);
      intptr_t result = snprintf(environment_block + block_index,
                                 len,
                                 "%s",
                                 environment[i]);
      ASSERT(result == len);
      block_index += len;
      environment_block[block_index++] = '\0';
    }
    // Block-terminating zero char.
    environment_block[block_index++] = '\0';
    ASSERT(block_index == block_size);
    for (intptr_t i = 0; i < environment_length; i++) free(environment[i]);
  }

  if (working_directory != NULL) {
    working_directory = StringUtils::Utf8ToSystemString(working_directory);
  }

  // Create process.
  BOOL result = CreateProcess(NULL,   // ApplicationName
                              command_line,
                              NULL,   // ProcessAttributes
                              NULL,   // ThreadAttributes
                              TRUE,   // InheritHandles
                              0,      // CreationFlags
                              environment_block,
                              working_directory,
                              &startup_info,
                              &process_info);

  // Deallocate command-line and environment block strings.
  delete[] command_line;
  delete[] environment_block;
  if (working_directory != NULL) {
    free(const_cast<char*>(working_directory));
  }

  if (result == 0) {
    int error_code = SetOsErrorMessage(os_error_message, os_error_message_len);
    CloseProcessPipes(
        stdin_handles, stdout_handles, stderr_handles, exit_handles);
    return error_code;
  }

  ProcessInfoList::AddProcess(process_info.dwProcessId,
                              process_info.hProcess,
                              exit_handles[kWriteHandle]);

  // Connect the three std streams.
  FileHandle* stdin_handle = new FileHandle(stdin_handles[kWriteHandle]);
  CloseHandle(stdin_handles[kReadHandle]);
  FileHandle* stdout_handle = new FileHandle(stdout_handles[kReadHandle]);
  CloseHandle(stdout_handles[kWriteHandle]);
  FileHandle* stderr_handle = new FileHandle(stderr_handles[kReadHandle]);
  CloseHandle(stderr_handles[kWriteHandle]);
  FileHandle* exit_handle = new FileHandle(exit_handles[kReadHandle]);
  *in = reinterpret_cast<intptr_t>(stdout_handle);
  *out = reinterpret_cast<intptr_t>(stdin_handle);
  *err = reinterpret_cast<intptr_t>(stderr_handle);
  *exit_handler = reinterpret_cast<intptr_t>(exit_handle);

  CloseHandle(process_info.hThread);

  // Return process id.
  *id = process_info.dwProcessId;
  return 0;
}


bool Process::Kill(intptr_t id, int signal) {
  USE(signal);  // signal is not used on windows.
  HANDLE process_handle;
  HANDLE wait_handle;
  HANDLE exit_pipe;
  bool success = ProcessInfoList::LookupProcess(id,
                                                &process_handle,
                                                &wait_handle,
                                                &exit_pipe);
  // The process is already dead.
  if (!success) return false;
  BOOL result = TerminateProcess(process_handle, -1);
  return result ? true : false;
}


void Process::TerminateExitCodeHandler() {
  // Nothing needs to be done on Windows.
}


intptr_t Process::CurrentProcessId() {
  return static_cast<intptr_t>(GetCurrentProcessId());
}