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//===-- ProcessMonitor.h -------------------------------------- -*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#ifndef liblldb_ProcessMonitor_H_
#define liblldb_ProcessMonitor_H_

#include <semaphore.h>
#include <signal.h>

#include <mutex>

#include "lldb/Host/HostThread.h"
#include "lldb/Utility/FileSpec.h"
#include "lldb/lldb-types.h"

namespace lldb_private {
class Status;
class Module;
class Scalar;
} // End lldb_private namespace.

class ProcessFreeBSD;
class Operation;

/// \class ProcessMonitor
/// Manages communication with the inferior (debugee) process.
///
/// Upon construction, this class prepares and launches an inferior process
/// for debugging.
///
/// Changes in the inferior process state are propagated to the associated
/// ProcessFreeBSD instance by calling ProcessFreeBSD::SendMessage with the
/// appropriate ProcessMessage events.
///
/// A purposely minimal set of operations are provided to interrogate and change
/// the inferior process state.
class ProcessMonitor {
public:
  /// Launches an inferior process ready for debugging.  Forms the
  /// implementation of Process::DoLaunch.
  ProcessMonitor(ProcessFreeBSD *process, lldb_private::Module *module,
                 char const *argv[], lldb_private::Environment env,
                 const lldb_private::FileSpec &stdin_file_spec,
                 const lldb_private::FileSpec &stdout_file_spec,
                 const lldb_private::FileSpec &stderr_file_spec,
                 const lldb_private::FileSpec &working_dir,
                 const lldb_private::ProcessLaunchInfo &launch_info,
                 lldb_private::Status &error);

  ProcessMonitor(ProcessFreeBSD *process, lldb::pid_t pid,
                 lldb_private::Status &error);

  ~ProcessMonitor();

  /// Provides the process number of debugee.
  lldb::pid_t GetPID() const { return m_pid; }

  /// Returns the process associated with this ProcessMonitor.
  ProcessFreeBSD &GetProcess() { return *m_process; }

  /// Returns a file descriptor to the controlling terminal of the inferior
  /// process.
  ///
  /// Reads from this file descriptor yield both the standard output and
  /// standard error of this debugee.  Even if stderr and stdout were
  /// redirected on launch it may still happen that data is available on this
  /// descriptor (if the inferior process opens /dev/tty, for example). This
  /// descriptor is closed after a call to StopMonitor().
  ///
  /// If this monitor was attached to an existing process this method returns
  /// -1.
  int GetTerminalFD() const { return m_terminal_fd; }

  /// Reads \p size bytes from address @vm_adder in the inferior process
  /// address space.
  ///
  /// This method is provided to implement Process::DoReadMemory.
  size_t ReadMemory(lldb::addr_t vm_addr, void *buf, size_t size,
                    lldb_private::Status &error);

  /// Writes \p size bytes from address \p vm_adder in the inferior process
  /// address space.
  ///
  /// This method is provided to implement Process::DoWriteMemory.
  size_t WriteMemory(lldb::addr_t vm_addr, const void *buf, size_t size,
                     lldb_private::Status &error);

  /// Reads the contents from the register identified by the given
  /// (architecture dependent) offset.
  ///
  /// This method is provided for use by RegisterContextFreeBSD derivatives.
  bool ReadRegisterValue(lldb::tid_t tid, unsigned offset, const char *reg_name,
                         unsigned size, lldb_private::RegisterValue &value);

  /// Writes the given value to the register identified by the given
  /// (architecture dependent) offset.
  ///
  /// This method is provided for use by RegisterContextFreeBSD derivatives.
  bool WriteRegisterValue(lldb::tid_t tid, unsigned offset,
                          const char *reg_name,
                          const lldb_private::RegisterValue &value);

  /// Reads the contents from the debug register identified by the given
  /// (architecture dependent) offset.
  ///
  /// This method is provided for use by RegisterContextFreeBSD derivatives.
  bool ReadDebugRegisterValue(lldb::tid_t tid, unsigned offset,
                              const char *reg_name, unsigned size,
                              lldb_private::RegisterValue &value);

  /// Writes the given value to the debug register identified by the given
  /// (architecture dependent) offset.
  ///
  /// This method is provided for use by RegisterContextFreeBSD derivatives.
  bool WriteDebugRegisterValue(lldb::tid_t tid, unsigned offset,
                               const char *reg_name,
                               const lldb_private::RegisterValue &value);
  /// Reads all general purpose registers into the specified buffer.
  bool ReadGPR(lldb::tid_t tid, void *buf, size_t buf_size);

  /// Reads all floating point registers into the specified buffer.
  bool ReadFPR(lldb::tid_t tid, void *buf, size_t buf_size);

  /// Reads the specified register set into the specified buffer.
  ///
  /// This method is provided for use by RegisterContextFreeBSD derivatives.
  bool ReadRegisterSet(lldb::tid_t tid, void *buf, size_t buf_size,
                       unsigned int regset);

  /// Writes all general purpose registers into the specified buffer.
  bool WriteGPR(lldb::tid_t tid, void *buf, size_t buf_size);

  /// Writes all floating point registers into the specified buffer.
  bool WriteFPR(lldb::tid_t tid, void *buf, size_t buf_size);

  /// Writes the specified register set into the specified buffer.
  ///
  /// This method is provided for use by RegisterContextFreeBSD derivatives.
  bool WriteRegisterSet(lldb::tid_t tid, void *buf, size_t buf_size,
                        unsigned int regset);

  /// Reads the value of the thread-specific pointer for a given thread ID.
  bool ReadThreadPointer(lldb::tid_t tid, lldb::addr_t &value);

  /// Returns current thread IDs in process
  size_t GetCurrentThreadIDs(std::vector<lldb::tid_t> &thread_ids);

  /// Writes a ptrace_lwpinfo structure corresponding to the given thread ID
  /// to the memory region pointed to by \p lwpinfo.
  bool GetLwpInfo(lldb::tid_t tid, void *lwpinfo, int &error_no);

  /// Suspends or unsuspends a thread prior to process resume or step.
  bool ThreadSuspend(lldb::tid_t tid, bool suspend);

  /// Writes the raw event message code (vis-a-vis PTRACE_GETEVENTMSG)
  /// corresponding to the given thread IDto the memory pointed to by @p
  /// message.
  bool GetEventMessage(lldb::tid_t tid, unsigned long *message);

  /// Resumes the process.  If \p signo is anything but
  /// LLDB_INVALID_SIGNAL_NUMBER, deliver that signal to the process.
  bool Resume(lldb::tid_t unused, uint32_t signo);

  /// Single steps the process.  If \p signo is anything but
  /// LLDB_INVALID_SIGNAL_NUMBER, deliver that signal to the process.
  bool SingleStep(lldb::tid_t unused, uint32_t signo);

  /// Terminate the traced process.
  bool Kill();

  lldb_private::Status Detach(lldb::tid_t tid);

  void StopMonitor();

  // Waits for the initial stop message from a new thread.
  bool WaitForInitialTIDStop(lldb::tid_t tid);

private:
  ProcessFreeBSD *m_process;

  llvm::Expected<lldb_private::HostThread> m_operation_thread;
  llvm::Expected<lldb_private::HostThread> m_monitor_thread;
  lldb::pid_t m_pid;

  int m_terminal_fd;

  // current operation which must be executed on the privileged thread
  Operation *m_operation;
  std::mutex m_operation_mutex;

  // semaphores notified when Operation is ready to be processed and when
  // the operation is complete.
  sem_t m_operation_pending;
  sem_t m_operation_done;

  struct OperationArgs {
    OperationArgs(ProcessMonitor *monitor);

    ~OperationArgs();

    ProcessMonitor *m_monitor;   // The monitor performing the attach.
    sem_t m_semaphore;           // Posted to once operation complete.
    lldb_private::Status m_error; // Set if process operation failed.
  };

  /// \class LauchArgs
  ///
  /// Simple structure to pass data to the thread responsible for launching a
  /// child process.
  struct LaunchArgs : OperationArgs {
    LaunchArgs(ProcessMonitor *monitor, lldb_private::Module *module,
               char const **argv, lldb_private::Environment env,
               const lldb_private::FileSpec &stdin_file_spec,
               const lldb_private::FileSpec &stdout_file_spec,
               const lldb_private::FileSpec &stderr_file_spec,
               const lldb_private::FileSpec &working_dir);

    ~LaunchArgs();

    lldb_private::Module *m_module; // The executable image to launch.
    char const **m_argv;            // Process arguments.
    lldb_private::Environment m_env;                // Process environment.
    const lldb_private::FileSpec m_stdin_file_spec; // Redirect stdin or empty.
    const lldb_private::FileSpec
        m_stdout_file_spec; // Redirect stdout or empty.
    const lldb_private::FileSpec
        m_stderr_file_spec;                     // Redirect stderr or empty.
    const lldb_private::FileSpec m_working_dir; // Working directory or empty.
  };

  void StartLaunchOpThread(LaunchArgs *args, lldb_private::Status &error);

  static void *LaunchOpThread(void *arg);

  static bool Launch(LaunchArgs *args);

  struct AttachArgs : OperationArgs {
    AttachArgs(ProcessMonitor *monitor, lldb::pid_t pid);

    ~AttachArgs();

    lldb::pid_t m_pid; // pid of the process to be attached.
  };

  void StartAttachOpThread(AttachArgs *args, lldb_private::Status &error);

  static void *AttachOpThread(void *args);

  static void Attach(AttachArgs *args);

  static void ServeOperation(OperationArgs *args);

  static bool DupDescriptor(const lldb_private::FileSpec &file_spec, int fd,
                            int flags);

  static bool MonitorCallback(ProcessMonitor *monitor, lldb::pid_t pid,
                              bool exited, int signal, int status);

  static ProcessMessage MonitorSIGTRAP(ProcessMonitor *monitor,
                                       const siginfo_t *info, lldb::pid_t pid);

  static ProcessMessage MonitorSignal(ProcessMonitor *monitor,
                                      const siginfo_t *info, lldb::pid_t pid);

  void DoOperation(Operation *op);

  /// Stops the child monitor thread.
  void StopMonitoringChildProcess();

  /// Stops the operation thread used to attach/launch a process.
  void StopOpThread();
};

#endif // #ifndef liblldb_ProcessMonitor_H_