lldb/source/Commands/CommandObjectWatchpointCommand.cpp

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

// C Includes
// C++ Includes
#include <vector>

// Other libraries and framework includes
// Project includes
#include "CommandObjectWatchpointCommand.h"
#include "CommandObjectWatchpoint.h"
#include "lldb/Core/IOHandler.h"
#include "lldb/Interpreter/CommandInterpreter.h"
#include "lldb/Interpreter/CommandReturnObject.h"
#include "lldb/Target/Target.h"
#include "lldb/Target/Thread.h"
#include "lldb/Breakpoint/Watchpoint.h"
#include "lldb/Breakpoint/StoppointCallbackContext.h"
#include "lldb/Core/State.h"

using namespace lldb;
using namespace lldb_private;

//-------------------------------------------------------------------------
// CommandObjectWatchpointCommandAdd
//-------------------------------------------------------------------------

class CommandObjectWatchpointCommandAdd :
    public CommandObjectParsed,
    public IOHandlerDelegateMultiline
{
public:
    CommandObjectWatchpointCommandAdd(CommandInterpreter &interpreter)
        : CommandObjectParsed(
              interpreter, "add",
              "Add a set of LLDB commands to a watchpoint, to be executed whenever the watchpoint is hit.", nullptr),
          IOHandlerDelegateMultiline("DONE", IOHandlerDelegate::Completion::LLDBCommand),
          m_options()
    {
        SetHelpLong (
R"(
General information about entering watchpoint commands
------------------------------------------------------

)" "This command will prompt for commands to be executed when the specified \
watchpoint is hit.  Each command is typed on its own line following the '> ' \
prompt until 'DONE' is entered." R"(

)" "Syntactic errors may not be detected when initially entered, and many \
malformed commands can silently fail when executed.  If your watchpoint commands \
do not appear to be executing, double-check the command syntax." R"(

)" "Note: You may enter any debugger command exactly as you would at the debugger \
prompt.  There is no limit to the number of commands supplied, but do NOT enter \
more than one command per line." R"(

Special information about PYTHON watchpoint commands
----------------------------------------------------

)" "You may enter either one or more lines of Python, including function \
definitions or calls to functions that will have been imported by the time \
the code executes.  Single line watchpoint commands will be interpreted 'as is' \
when the watchpoint is hit.  Multiple lines of Python will be wrapped in a \
generated function, and a call to the function will be attached to the watchpoint." R"(

This auto-generated function is passed in three arguments:

    frame:  an lldb.SBFrame object for the frame which hit the watchpoint.

    wp:     the watchpoint that was hit.

)" "When specifying a python function with the --python-function option, you need \
to supply the function name prepended by the module name:" R"(

    --python-function myutils.watchpoint_callback

The function itself must have the following prototype:

def watchpoint_callback(frame, wp):
  # Your code goes here

)" "The arguments are the same as the arguments passed to generated functions as \
described above.  Note that the global variable 'lldb.frame' will NOT be updated when \
this function is called, so be sure to use the 'frame' argument. The 'frame' argument \
can get you to the thread via frame.GetThread(), the thread can get you to the \
process via thread.GetProcess(), and the process can get you back to the target \
via process.GetTarget()." R"(

)" "Important Note: As Python code gets collected into functions, access to global \
variables requires explicit scoping using the 'global' keyword.  Be sure to use correct \
Python syntax, including indentation, when entering Python watchpoint commands." R"(

Example Python one-line watchpoint command:

(lldb) watchpoint command add -s python 1
Enter your Python command(s). Type 'DONE' to end.
> print "Hit this watchpoint!"
> DONE

As a convenience, this also works for a short Python one-liner:

(lldb) watchpoint command add -s python 1 -o 'import time; print time.asctime()'
(lldb) run
Launching '.../a.out'  (x86_64)
(lldb) Fri Sep 10 12:17:45 2010
Process 21778 Stopped
* thread #1: tid = 0x2e03, 0x0000000100000de8 a.out`c + 7 at main.c:39, stop reason = watchpoint 1.1, queue = com.apple.main-thread
  36
  37   	int c(int val)
  38   	{
  39 ->	    return val + 3;
  40   	}
  41
  42   	int main (int argc, char const *argv[])

Example multiple line Python watchpoint command, using function definition:

(lldb) watchpoint command add -s python 1
Enter your Python command(s). Type 'DONE' to end.
> def watchpoint_output (wp_no):
>     out_string = "Hit watchpoint number " + repr (wp_no)
>     print out_string
>     return True
> watchpoint_output (1)
> DONE

Example multiple line Python watchpoint command, using 'loose' Python:

(lldb) watchpoint command add -s p 1
Enter your Python command(s). Type 'DONE' to end.
> global wp_count
> wp_count = wp_count + 1
> print "Hit this watchpoint " + repr(wp_count) + " times!"
> DONE

)" "In this case, since there is a reference to a global variable, \
'wp_count', you will also need to make sure 'wp_count' exists and is \
initialized:" R"(

(lldb) script
>>> wp_count = 0
>>> quit()

)" "Final Note: A warning that no watchpoint command was generated when there \
are no syntax errors may indicate that a function was declared but never called."
        );

        CommandArgumentEntry arg;
        CommandArgumentData wp_id_arg;

        // Define the first (and only) variant of this arg.
        wp_id_arg.arg_type = eArgTypeWatchpointID;
        wp_id_arg.arg_repetition = eArgRepeatPlain;

        // There is only one variant this argument could be; put it into the argument entry.
        arg.push_back (wp_id_arg);

        // Push the data for the first argument into the m_arguments vector.
        m_arguments.push_back (arg);
    }

    ~CommandObjectWatchpointCommandAdd() override = default;

    Options *
    GetOptions () override
    {
        return &m_options;
    }

    void
    IOHandlerActivated (IOHandler &io_handler) override
    {
        StreamFileSP output_sp(io_handler.GetOutputStreamFile());
        if (output_sp)
        {
            output_sp->PutCString("Enter your debugger command(s).  Type 'DONE' to end.\n");
            output_sp->Flush();
        }
    }

    void
    IOHandlerInputComplete (IOHandler &io_handler, std::string &line) override
    {
        io_handler.SetIsDone(true);
        
        // The WatchpointOptions object is owned by the watchpoint or watchpoint location
        WatchpointOptions *wp_options = (WatchpointOptions *) io_handler.GetUserData();
        if (wp_options)
        {
            std::unique_ptr<WatchpointOptions::CommandData> data_ap(new WatchpointOptions::CommandData());
            if (data_ap)
            {
                data_ap->user_source.SplitIntoLines(line);
                BatonSP baton_sp (new WatchpointOptions::CommandBaton (data_ap.release()));
                wp_options->SetCallback (WatchpointOptionsCallbackFunction, baton_sp);
            }
        }
    }

    void
    CollectDataForWatchpointCommandCallback (WatchpointOptions *wp_options, 
                                             CommandReturnObject &result)
    {
        m_interpreter.GetLLDBCommandsFromIOHandler ("> ",           // Prompt
                                                    *this,          // IOHandlerDelegate
                                                    true,           // Run IOHandler in async mode
                                                    wp_options);    // Baton for the "io_handler" that will be passed back into our IOHandlerDelegate functions
    }
    
    /// Set a one-liner as the callback for the watchpoint.
    void 
    SetWatchpointCommandCallback (WatchpointOptions *wp_options,
                                  const char *oneliner)
    {
        std::unique_ptr<WatchpointOptions::CommandData> data_ap(new WatchpointOptions::CommandData());

        // It's necessary to set both user_source and script_source to the oneliner.
        // The former is used to generate callback description (as in watchpoint command list)
        // while the latter is used for Python to interpret during the actual callback.
        data_ap->user_source.AppendString (oneliner);
        data_ap->script_source.assign (oneliner);
        data_ap->stop_on_error = m_options.m_stop_on_error;

        BatonSP baton_sp (new WatchpointOptions::CommandBaton (data_ap.release()));
        wp_options->SetCallback (WatchpointOptionsCallbackFunction, baton_sp);
    }
    
    static bool
    WatchpointOptionsCallbackFunction (void *baton,
                                       StoppointCallbackContext *context, 
                                       lldb::user_id_t watch_id)
    {
        bool ret_value = true;
        if (baton == nullptr)
            return true;

        WatchpointOptions::CommandData *data = (WatchpointOptions::CommandData *) baton;
        StringList &commands = data->user_source;
        
        if (commands.GetSize() > 0)
        {
            ExecutionContext exe_ctx (context->exe_ctx_ref);
            Target *target = exe_ctx.GetTargetPtr();
            if (target)
            {
                CommandReturnObject result;
                Debugger &debugger = target->GetDebugger();
                // Rig up the results secondary output stream to the debugger's, so the output will come out synchronously
                // if the debugger is set up that way.
                    
                StreamSP output_stream (debugger.GetAsyncOutputStream());
                StreamSP error_stream (debugger.GetAsyncErrorStream());
                result.SetImmediateOutputStream (output_stream);
                result.SetImmediateErrorStream (error_stream);
        
                CommandInterpreterRunOptions options;
                options.SetStopOnContinue (true);
                options.SetStopOnError (data->stop_on_error);
                options.SetEchoCommands (false);
                options.SetPrintResults (true);
                options.SetAddToHistory (false);

                debugger.GetCommandInterpreter().HandleCommands (commands, 
                                                                 &exe_ctx,
                                                                 options,
                                                                 result);
                result.GetImmediateOutputStream()->Flush();
                result.GetImmediateErrorStream()->Flush();
           }
        }
        return ret_value;
    }    

    class CommandOptions : public Options
    {
    public:
        CommandOptions() :
            Options(),
            m_use_commands (false),
            m_use_script_language (false),
            m_script_language (eScriptLanguageNone),
            m_use_one_liner (false),
            m_one_liner(),
            m_function_name()
        {
        }

        ~CommandOptions() override = default;

        Error
        SetOptionValue(uint32_t option_idx, const char *option_arg,
                       ExecutionContext *execution_context) override
        {
            Error error;
            const int short_option = m_getopt_table[option_idx].val;

            switch (short_option)
            {
            case 'o':
                m_use_one_liner = true;
                m_one_liner = option_arg;
                break;

            case 's':
                m_script_language = (lldb::ScriptLanguage) Args::StringToOptionEnum (option_arg, 
                                                                                     g_option_table[option_idx].enum_values, 
                                                                                     eScriptLanguageNone,
                                                                                     error);

                m_use_script_language =
                    (m_script_language == eScriptLanguagePython || m_script_language == eScriptLanguageDefault);
                break;

            case 'e':
                {
                    bool success = false;
                    m_stop_on_error = Args::StringToBoolean(option_arg, false, &success);
                    if (!success)
                        error.SetErrorStringWithFormat("invalid value for stop-on-error: \"%s\"", option_arg);
                }
                break;
                    
            case 'F':
                m_use_one_liner = false;
                m_use_script_language = true;
                m_function_name.assign(option_arg);
                break;

            default:
                break;
            }
            return error;
        }

        void
        OptionParsingStarting(ExecutionContext *execution_context) override
        {
            m_use_commands = true;
            m_use_script_language = false;
            m_script_language = eScriptLanguageNone;

            m_use_one_liner = false;
            m_stop_on_error = true;
            m_one_liner.clear();
            m_function_name.clear();
        }

        const OptionDefinition*
        GetDefinitions () override
        {
            return g_option_table;
        }

        // Options table: Required for subclasses of Options.

        static OptionDefinition g_option_table[];

        // Instance variables to hold the values for command options.

        bool m_use_commands;
        bool m_use_script_language;
        lldb::ScriptLanguage m_script_language;

        // Instance variables to hold the values for one_liner options.
        bool m_use_one_liner;
        std::string m_one_liner;
        bool m_stop_on_error;
        std::string m_function_name;
    };

protected:
    bool
    DoExecute (Args& command, CommandReturnObject &result) override
    {
        Target *target = m_interpreter.GetDebugger().GetSelectedTarget().get();

        if (target == nullptr)
        {
            result.AppendError ("There is not a current executable; there are no watchpoints to which to add commands");
            result.SetStatus (eReturnStatusFailed);
            return false;
        }

        const WatchpointList &watchpoints = target->GetWatchpointList();
        size_t num_watchpoints = watchpoints.GetSize();

        if (num_watchpoints == 0)
        {
            result.AppendError ("No watchpoints exist to have commands added");
            result.SetStatus (eReturnStatusFailed);
            return false;
        }

        if (!m_options.m_use_script_language && !m_options.m_function_name.empty())
        {
            result.AppendError ("need to enable scripting to have a function run as a watchpoint command");
            result.SetStatus (eReturnStatusFailed);
            return false;
        }
        
        std::vector<uint32_t> valid_wp_ids;
        if (!CommandObjectMultiwordWatchpoint::VerifyWatchpointIDs(target, command, valid_wp_ids))
        {
            result.AppendError("Invalid watchpoints specification.");
            result.SetStatus(eReturnStatusFailed);
            return false;
        }

        result.SetStatus(eReturnStatusSuccessFinishNoResult);
        const size_t count = valid_wp_ids.size();
        for (size_t i = 0; i < count; ++i)
        {
            uint32_t cur_wp_id = valid_wp_ids.at (i);
            if (cur_wp_id != LLDB_INVALID_WATCH_ID)
            {
                Watchpoint *wp = target->GetWatchpointList().FindByID (cur_wp_id).get();
                // Sanity check wp first.
                if (wp == nullptr) continue;

                WatchpointOptions *wp_options = wp->GetOptions();
                // Skip this watchpoint if wp_options is not good.
                if (wp_options == nullptr) continue;

                // If we are using script language, get the script interpreter
                // in order to set or collect command callback.  Otherwise, call
                // the methods associated with this object.
                if (m_options.m_use_script_language)
                {
                    // Special handling for one-liner specified inline.
                    if (m_options.m_use_one_liner)
                    {
                        m_interpreter.GetScriptInterpreter()->SetWatchpointCommandCallback (wp_options,
                                                                                            m_options.m_one_liner.c_str());
                    }
                    // Special handling for using a Python function by name
                    // instead of extending the watchpoint callback data structures, we just automatize
                    // what the user would do manually: make their watchpoint command be a function call
                    else if (!m_options.m_function_name.empty())
                    {
                        std::string oneliner(m_options.m_function_name);
                        oneliner += "(frame, wp, internal_dict)";
                        m_interpreter.GetScriptInterpreter()->SetWatchpointCommandCallback (wp_options,
                                                                                            oneliner.c_str());
                    }
                    else
                    {
                        m_interpreter.GetScriptInterpreter()->CollectDataForWatchpointCommandCallback (wp_options,
                                                                                                       result);
                    }
                }
                else
                {
                    // Special handling for one-liner specified inline.
                    if (m_options.m_use_one_liner)
                        SetWatchpointCommandCallback (wp_options,
                                                      m_options.m_one_liner.c_str());
                    else
                        CollectDataForWatchpointCommandCallback (wp_options, 
                                                                 result);
                }
            }
        }

        return result.Succeeded();
    }

private:
    CommandOptions m_options;
};

// FIXME: "script-type" needs to have its contents determined dynamically, so somebody can add a new scripting
// language to lldb and have it pickable here without having to change this enumeration by hand and rebuild lldb proper.

static OptionEnumValueElement
g_script_option_enumeration[4] =
{
    { eScriptLanguageNone,    "command",         "Commands are in the lldb command interpreter language"},
    { eScriptLanguagePython,  "python",          "Commands are in the Python language."},
    { eSortOrderByName,       "default-script",  "Commands are in the default scripting language."},
    { 0,                      nullptr,           nullptr }
};

OptionDefinition
CommandObjectWatchpointCommandAdd::CommandOptions::g_option_table[] =
{
  // clang-format off
  {LLDB_OPT_SET_1,   false, "one-liner",       'o', OptionParser::eRequiredArgument, nullptr, nullptr,                     0, eArgTypeOneLiner,       "Specify a one-line watchpoint command inline. Be sure to surround it with quotes."},
  {LLDB_OPT_SET_ALL, false, "stop-on-error",   'e', OptionParser::eRequiredArgument, nullptr, nullptr,                     0, eArgTypeBoolean,        "Specify whether watchpoint command execution should terminate on error."},
  {LLDB_OPT_SET_ALL, false, "script-type",     's', OptionParser::eRequiredArgument, nullptr, g_script_option_enumeration, 0, eArgTypeNone,           "Specify the language for the commands - if none is specified, the lldb command interpreter will be used."},
  {LLDB_OPT_SET_2,   false, "python-function", 'F', OptionParser::eRequiredArgument, nullptr, nullptr,                     0, eArgTypePythonFunction, "Give the name of a Python function to run as command for this watchpoint. Be sure to give a module name if appropriate."},
  {0, false, nullptr, 0, 0, nullptr, nullptr, 0, eArgTypeNone, nullptr }
  // clang-format on
};

//-------------------------------------------------------------------------
// CommandObjectWatchpointCommandDelete
//-------------------------------------------------------------------------

class CommandObjectWatchpointCommandDelete : public CommandObjectParsed
{
public:
    CommandObjectWatchpointCommandDelete (CommandInterpreter &interpreter) :
        CommandObjectParsed(interpreter,
                            "delete",
                            "Delete the set of commands from a watchpoint.",
                            nullptr)
    {
        CommandArgumentEntry arg;
        CommandArgumentData wp_id_arg;

        // Define the first (and only) variant of this arg.
        wp_id_arg.arg_type = eArgTypeWatchpointID;
        wp_id_arg.arg_repetition = eArgRepeatPlain;

        // There is only one variant this argument could be; put it into the argument entry.
        arg.push_back (wp_id_arg);

        // Push the data for the first argument into the m_arguments vector.
        m_arguments.push_back (arg);
    }

    ~CommandObjectWatchpointCommandDelete() override = default;

protected:
    bool
    DoExecute (Args& command, CommandReturnObject &result) override
    {
        Target *target = m_interpreter.GetDebugger().GetSelectedTarget().get();

        if (target == nullptr)
        {
            result.AppendError ("There is not a current executable; there are no watchpoints from which to delete commands");
            result.SetStatus (eReturnStatusFailed);
            return false;
        }

        const WatchpointList &watchpoints = target->GetWatchpointList();
        size_t num_watchpoints = watchpoints.GetSize();

        if (num_watchpoints == 0)
        {
            result.AppendError ("No watchpoints exist to have commands deleted");
            result.SetStatus (eReturnStatusFailed);
            return false;
        }

        if (command.GetArgumentCount() == 0)
        {
            result.AppendError ("No watchpoint specified from which to delete the commands");
            result.SetStatus (eReturnStatusFailed);
            return false;
        }

        std::vector<uint32_t> valid_wp_ids;
        if (!CommandObjectMultiwordWatchpoint::VerifyWatchpointIDs(target, command, valid_wp_ids))
        {
            result.AppendError("Invalid watchpoints specification.");
            result.SetStatus(eReturnStatusFailed);
            return false;
        }

        result.SetStatus(eReturnStatusSuccessFinishNoResult);
        const size_t count = valid_wp_ids.size();
        for (size_t i = 0; i < count; ++i)
        {
            uint32_t cur_wp_id = valid_wp_ids.at (i);
            if (cur_wp_id != LLDB_INVALID_WATCH_ID)
            {
                Watchpoint *wp = target->GetWatchpointList().FindByID (cur_wp_id).get();
                if (wp)
                    wp->ClearCallback();
            }
            else
            {
                result.AppendErrorWithFormat("Invalid watchpoint ID: %u.\n", 
                                             cur_wp_id);
                result.SetStatus (eReturnStatusFailed);
                return false;
            }
        }
        return result.Succeeded();
    }
};

//-------------------------------------------------------------------------
// CommandObjectWatchpointCommandList
//-------------------------------------------------------------------------

class CommandObjectWatchpointCommandList : public CommandObjectParsed
{
public:
    CommandObjectWatchpointCommandList (CommandInterpreter &interpreter) :
        CommandObjectParsed(interpreter,
                            "list",
                            "List the script or set of commands to be executed when the watchpoint is hit.",
                            nullptr)
    {
        CommandArgumentEntry arg;
        CommandArgumentData wp_id_arg;

        // Define the first (and only) variant of this arg.
        wp_id_arg.arg_type = eArgTypeWatchpointID;
        wp_id_arg.arg_repetition = eArgRepeatPlain;

        // There is only one variant this argument could be; put it into the argument entry.
        arg.push_back (wp_id_arg);

        // Push the data for the first argument into the m_arguments vector.
        m_arguments.push_back (arg);
    }

    ~CommandObjectWatchpointCommandList() override = default;

protected:
    bool
    DoExecute (Args& command, CommandReturnObject &result) override
    {
        Target *target = m_interpreter.GetDebugger().GetSelectedTarget().get();

        if (target == nullptr)
        {
            result.AppendError ("There is not a current executable; there are no watchpoints for which to list commands");
            result.SetStatus (eReturnStatusFailed);
            return false;
        }

        const WatchpointList &watchpoints = target->GetWatchpointList();
        size_t num_watchpoints = watchpoints.GetSize();

        if (num_watchpoints == 0)
        {
            result.AppendError ("No watchpoints exist for which to list commands");
            result.SetStatus (eReturnStatusFailed);
            return false;
        }

        if (command.GetArgumentCount() == 0)
        {
            result.AppendError ("No watchpoint specified for which to list the commands");
            result.SetStatus (eReturnStatusFailed);
            return false;
        }

        std::vector<uint32_t> valid_wp_ids;
        if (!CommandObjectMultiwordWatchpoint::VerifyWatchpointIDs(target, command, valid_wp_ids))
        {
            result.AppendError("Invalid watchpoints specification.");
            result.SetStatus(eReturnStatusFailed);
            return false;
        }

        result.SetStatus(eReturnStatusSuccessFinishNoResult);
        const size_t count = valid_wp_ids.size();
        for (size_t i = 0; i < count; ++i)
        {
            uint32_t cur_wp_id = valid_wp_ids.at (i);
            if (cur_wp_id != LLDB_INVALID_WATCH_ID)
            {
                Watchpoint *wp = target->GetWatchpointList().FindByID (cur_wp_id).get();
                
                if (wp)
                {
                    const WatchpointOptions *wp_options = wp->GetOptions();
                    if (wp_options)
                    {
                        // Get the callback baton associated with the current watchpoint.
                        const Baton *baton = wp_options->GetBaton();
                        if (baton)
                        {
                            result.GetOutputStream().Printf ("Watchpoint %u:\n", cur_wp_id);
                            result.GetOutputStream().IndentMore ();
                            baton->GetDescription(&result.GetOutputStream(), eDescriptionLevelFull);
                            result.GetOutputStream().IndentLess ();
                        }
                        else
                        {
                            result.AppendMessageWithFormat ("Watchpoint %u does not have an associated command.\n", 
                                                            cur_wp_id);
                        }
                    }
                    result.SetStatus (eReturnStatusSuccessFinishResult);
                }
                else
                {
                    result.AppendErrorWithFormat("Invalid watchpoint ID: %u.\n", cur_wp_id);
                    result.SetStatus (eReturnStatusFailed);
                }
            }
        }

        return result.Succeeded();
    }
};

//-------------------------------------------------------------------------
// CommandObjectWatchpointCommand
//-------------------------------------------------------------------------

CommandObjectWatchpointCommand::CommandObjectWatchpointCommand(CommandInterpreter &interpreter)
    : CommandObjectMultiword(interpreter, "command", "Commands for adding, removing and examining LLDB commands "
                                                     "executed when the watchpoint is hit (watchpoint 'commmands').",
                             "command <sub-command> [<sub-command-options>] <watchpoint-id>")
{
    CommandObjectSP add_command_object (new CommandObjectWatchpointCommandAdd (interpreter));
    CommandObjectSP delete_command_object (new CommandObjectWatchpointCommandDelete (interpreter));
    CommandObjectSP list_command_object (new CommandObjectWatchpointCommandList (interpreter));

    add_command_object->SetCommandName ("watchpoint command add");
    delete_command_object->SetCommandName ("watchpoint command delete");
    list_command_object->SetCommandName ("watchpoint command list");

    LoadSubCommand ("add",    add_command_object);
    LoadSubCommand ("delete", delete_command_object);
    LoadSubCommand ("list",   list_command_object);
}

CommandObjectWatchpointCommand::~CommandObjectWatchpointCommand() = default;