Process/FreeBSD/ProcessMonitor.h

//===-- ProcessMonitor.h -------------------------------------- -*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#ifndef liblldb_ProcessMonitor_H_
#define liblldb_ProcessMonitor_H_

// C Includes
#include <semaphore.h>
#include <signal.h>

// C++ Includes
#include <mutex>

// Other libraries and framework includes
#include "lldb/lldb-types.h"
#include "lldb/Host/FileSpec.h"
#include "lldb/Host/HostThread.h"

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

class ProcessFreeBSD;
class Operation;

/// @class ProcessMonitor
/// @brief 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[],
                   char const *envp[],
                   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::Error &error);

    ProcessMonitor(ProcessFreeBSD *process,
                   lldb::pid_t pid,
                   lldb_private::Error &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::Error &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::Error &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::Error
    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;

    lldb_private::HostThread m_operation_thread;
    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::Error m_error;    // Set if process operation failed.
    };

    /// @class LauchArgs
    ///
    /// @brief 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,
                   char const **envp,
                   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.
        char const **m_envp;                             // 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::Error &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::Error &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_