Add new bugreport command to lldb

[tberghammer]

Summary

Add new bugreport command to lldb

The new command add functionality to print out domain specific
information for reporting a bug. Currently the only supported
domain is stack unwinding (with "bugreport unwind") but adding
new domains is fairly easy.

[labath]

source/Commands/CommandObjectBugreport.cpp

89

In no-append mode, you will start overwriting the file without first erasing it's contents. This leads to funny-looking files and is a pretty useless mode. I recommend setting eOpenOptionAppend unconditionally and adding eOpenOptionTruncate if --append is *not* specified.

[tberghammer]

Address review comment about append and truncate

[jingham]

So much of the useful bug reporting information in lldb is gathered by turning on logs BEFORE the bad thing occurs, then making it happen, then gathering the logs that were produced as a part of that process. For instance, once a bad unwind has occurred that info is cached, and you can't watch lldb figure that out any more. And for expressions or stepping, you really can't do much after the fact.

So maybe a transactional design might be better, where you say

(lldb) bugreport begin <AREA>
...
(lldb) do stuff

(lldb) bugreport end <AREA>

or if you want them to nest you might hand back a token, but that seems over-designing.

[tberghammer]

I agree that we can collect only a very limited information with a single command after the problem already occurred but my intuition is that if we want the user to reproduce the issue then there is much lower chance that they will submit a bug report even for people working on LLDB.

For stack unwinding in special it is significantly easier to find out what was the issue if we have logs but in most of the case the information I display also sufficient (usually the CFI is the part what is incorrect). I think the same is true for expression evaluation with the only different that we should ask the user to specify the expression for the bugreport command (or we can try to find it on the command history).

[ovyalov]

source/Commands/CommandObjectBugreport.cpp

72

I'd defined this buffer before the loop to avoid memory allocation per each frame.

88

File::eOpenOptionCloseOnExec ?

94

Could you add a returned error to result.AppendErrorWithFormat ?

106

This block might be generic for all multiword commands and you may put it into CommandObjectMultiwordBugreport

[clayborg]

Good start. We can iterate on it to improve it. Sounds like for unwinding we can get away with a single command that gets run afterward. For more complex things, we can implement things like Jim was requesting, but they should probably be more domain specific:

(lldb) bug report step start
// Now make problem happen...
(lldb) s
(lldb) bug report step stop

[tberghammer]

source/Commands/CommandObjectBugreport.cpp

72

Done

88

Done (I don't think it matters here but definitely won't harm)

94

Done

106

In command objects "multiword" refers to the multiple word in the command itself, not to the fact it uses several other commands in the background (see CommandObjectMultiwordTarget). At the moment I am not sure how the other bugreporting commands will look like so don't want to over-engineer it with an additional base class. If we need it anywhere else we can do it when adding the next command using the same pattern.

lldb.xcodeproj/project.pbxproj

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26BC7D0D10F1B71D00F91463 /* Commands */ = {
         4CA9637A11B6E99A00780E28 /* CommandObjectApropos.h */,
         4CA9637911B6E99A00780E28 /* CommandObjectApropos.cpp */,
         499F381E11A5B3F300F5CE02 /* CommandObjectArgs.h */,
         499F381F11A5B3F300F5CE02 /* CommandObjectArgs.cpp */,
         26BC7D1410F1B76300F91463 /* CommandObjectBreakpoint.h */,
         26BC7E2D10F1B84700F91463 /* CommandObjectBreakpoint.cpp */,
         9A42976111861A9F00FE05CD /* CommandObjectBreakpointCommand.h */,
         9A42976211861AA600FE05CD /* CommandObjectBreakpointCommand.cpp */,
+        6D86CE9F1B440F6B00A7FBFA /* CommandObjectBugreport.h */,
+        6D86CE9E1B440F6B00A7FBFA /* CommandObjectBugreport.cpp */,
         4C5DBBC711E3FEC60035160F /* CommandObjectCommands.h */,
         4C5DBBC611E3FEC60035160F /* CommandObjectCommands.cpp */,
         26BC7D1710F1B76300F91463 /* CommandObjectDisassemble.h */,
         26BC7E3010F1B84700F91463 /* CommandObjectDisassemble.cpp */,
         26BC7D1810F1B76300F91463 /* CommandObjectExpression.h */,
         26BC7E3110F1B84700F91463 /* CommandObjectExpression.cpp */,
         2672D8471189055500FF4019 /* CommandObjectFrame.h */,
         2672D8461189055500FF4019 /* CommandObjectFrame.cpp */,
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         260CC64915D0440D002BF2E0 /* OptionValueArray.cpp in Sources */,
         260CC64A15D0440D002BF2E0 /* OptionValueBoolean.cpp in Sources */,
         260CC64B15D0440D002BF2E0 /* OptionValueProperties.cpp in Sources */,
         3FDFED0C19B7C8E7009756A7 /* ThisThread.cpp in Sources */,
+        6D86CEA01B440F8500A7FBFA /* CommandObjectBugreport.cpp in Sources */,
         260CC64C15D0440D002BF2E0 /* OptionValueDictionary.cpp in Sources */,
         49DCF6FE170E6B4A0092F75E /* IRMemoryMap.cpp in Sources */,
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         260CC64E15D0440D002BF2E0 /* OptionValueFileSpec.cpp in Sources */,
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         260CC64F15D0440D002BF2E0 /* OptionValueFileSpecLIst.cpp in Sources */,
         490A36C0180F0E6F00BA31F8 /* PlatformWindows.cpp in Sources */,
         260CC65015D0440D002BF2E0 /* OptionValueFormat.cpp in Sources */,

source/Commands/CMakeLists.txt

 set(LLVM_NO_RTTI 1)
 
 add_lldb_library(lldbCommands
   CommandCompletions.cpp
   CommandObjectApropos.cpp
   CommandObjectArgs.cpp
   CommandObjectBreakpoint.cpp
   CommandObjectBreakpointCommand.cpp
+  CommandObjectBugreport.cpp
   CommandObjectCommands.cpp
   CommandObjectDisassemble.cpp
   CommandObjectExpression.cpp
   CommandObjectFrame.cpp
   CommandObjectGUI.cpp
   CommandObjectHelp.cpp
   CommandObjectLog.cpp
   CommandObjectMemory.cpp

source/Commands/CommandObjectBugreport.h

+//===-- CommandObjectBugreport.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_CommandObjectBugreport_h_
+#define liblldb_CommandObjectBugreport_h_
+
+// C Includes
+// C++ Includes
+// Other libraries and framework includes
+// Project includes
+#include "lldb/Interpreter/CommandObjectMultiword.h"
+
+namespace lldb_private {
+
+//-------------------------------------------------------------------------
+// CommandObjectMultiwordBugreport
+//-------------------------------------------------------------------------
+
+class CommandObjectMultiwordBugreport : public CommandObjectMultiword
+{
+public:
+    CommandObjectMultiwordBugreport(CommandInterpreter &interpreter);
+
+    virtual
+    ~CommandObjectMultiwordBugreport();
+};
+
+} // namespace lldb_private
+
+#endif  // liblldb_CommandObjectBugreport_h_

source/Commands/CommandObjectBugreport.cpp

+//===-- CommandObjectBugreport.cpp ------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "CommandObjectBugreport.h"
+
+// C Includes
+#include <cstdio>
+
+// C++ Includes
+// Other libraries and framework includes
+
+// Project includes
+#include "lldb/Interpreter/CommandInterpreter.h"
+#include "lldb/Interpreter/CommandReturnObject.h"
+#include "lldb/Interpreter/OptionGroupOutputFile.h"
+#include "lldb/Target/Thread.h"
+
+using namespace lldb;
+using namespace lldb_private;
+
+//-------------------------------------------------------------------------
+// "bugreport unwind"
+//-------------------------------------------------------------------------
+
+class CommandObjectBugreportUnwind : public CommandObjectParsed
+{
+public:
+    CommandObjectBugreportUnwind(CommandInterpreter &interpreter) :
+        CommandObjectParsed(interpreter,
+                            "bugreport unwind",
+                            "Create a bugreport for a bug in the stack unwinding code.",
+                            nullptr),
+        m_option_group(interpreter),
+        m_outfile_options()
+    {
+        m_option_group.Append (&m_outfile_options, LLDB_OPT_SET_ALL, LLDB_OPT_SET_1 | LLDB_OPT_SET_2 | LLDB_OPT_SET_3);
+        m_option_group.Finalize();
+    }
+
+    ~CommandObjectBugreportUnwind()
+    {
+    }
+
+    Options *
+    GetOptions() override
+    {
+        return &m_option_group;
+    }
+
+protected:
+    bool
+    DoExecute(Args& command, CommandReturnObject &result) override
+    {
+        StringList commands;
+        commands.AppendString("thread backtrace");
+
+        Thread *thread = m_exe_ctx.GetThreadPtr();
+        if (thread)
+        {
+            uint32_t frame_count = thread->GetStackFrameCount();
+            for (uint32_t i = 0; i < frame_count; ++i)
+            {
+                StackFrameSP frame = thread->GetStackFrameAtIndex(i);
+                lldb::addr_t pc = frame->GetStackID().GetPC();
+
+                char command_buffer[256];
+
+                snprintf(command_buffer, sizeof(command_buffer), "disassemble --bytes --address 0x%" PRIx64, pc);
+                commands.AppendString(command_buffer);
+
+                snprintf(command_buffer, sizeof(command_buffer), "image show-unwind --address 0x%" PRIx64, pc);
+                commands.AppendString(command_buffer);
+            }
+        }
+
+        const FileSpec &outfile_spec = m_outfile_options.GetFile().GetCurrentValue();
+        if (outfile_spec)
+        {
+            char path[PATH_MAX];
+            outfile_spec.GetPath (path, sizeof(path));
+            
+            uint32_t open_options = File::eOpenOptionWrite | File::eOpenOptionCanCreate | File::eOpenOptionAppend;
+            const bool append = m_outfile_options.GetAppend().GetCurrentValue();
+            if (!append)
+                open_options |= File::eOpenOptionTruncate;
+            
+            StreamFileSP outfile_stream = std::make_shared<StreamFile>();
+            if (outfile_stream->GetFile().Open(path, open_options).Success())
+            {
+                result.SetImmediateOutputStream(outfile_stream);
+            }
+            else 
+            {
+                result.AppendErrorWithFormat("Failed to open file '%s' for %s.\n", path, append ? "append" : "write");
+                result.SetStatus(eReturnStatusFailed);
+                return false;
+            }
+        }
+
+        CommandInterpreterRunOptions options;
+        options.SetStopOnError(false);
+        options.SetEchoCommands(true);
+        options.SetPrintResults(true);
+        options.SetAddToHistory(false);
+        m_interpreter.HandleCommands(commands, &m_exe_ctx, options, result);
+
+        return result.Succeeded();
+    }
+
+private:
+    OptionGroupOptions m_option_group;
+    OptionGroupOutputFile m_outfile_options;
+};
+
+#pragma mark CommandObjectMultiwordBugreport
+
+//-------------------------------------------------------------------------
+// CommandObjectMultiwordBugreport
+//-------------------------------------------------------------------------
+
+CommandObjectMultiwordBugreport::CommandObjectMultiwordBugreport(CommandInterpreter &interpreter) :
+    CommandObjectMultiword(interpreter,
+                           "bugreport",
+                           "Set of commands for creating domain specific bugreports.",
+                           "bugreport <subcommand> [<subcommand-options>]")
+{
+
+    LoadSubCommand("unwind", CommandObjectSP(new CommandObjectBugreportUnwind(interpreter)));
+}
+
+CommandObjectMultiwordBugreport::~CommandObjectMultiwordBugreport ()
+{
+}

source/Interpreter/CommandInterpreter.cpp

 #include <stdlib.h>
 
 #include "CommandObjectScript.h"
 #include "lldb/Interpreter/CommandObjectRegexCommand.h"
 
 #include "../Commands/CommandObjectApropos.h"
 #include "../Commands/CommandObjectArgs.h"
 #include "../Commands/CommandObjectBreakpoint.h"
+#include "../Commands/CommandObjectBugreport.h"
 #include "../Commands/CommandObjectDisassemble.h"
 #include "../Commands/CommandObjectExpression.h"
 #include "../Commands/CommandObjectFrame.h"
 #include "../Commands/CommandObjectGUI.h"
 #include "../Commands/CommandObjectHelp.h"
 #include "../Commands/CommandObjectLog.h"
 #include "../Commands/CommandObjectMemory.h"
 #include "../Commands/CommandObjectPlatform.h"

 CommandInterpreter::LoadCommandDictionary ()
 {
     Timer scoped_timer (__PRETTY_FUNCTION__, __PRETTY_FUNCTION__);
 
     lldb::ScriptLanguage script_language = m_debugger.GetScriptLanguage();
     
     m_command_dict["apropos"]   = CommandObjectSP (new CommandObjectApropos (*this));
     m_command_dict["breakpoint"]= CommandObjectSP (new CommandObjectMultiwordBreakpoint (*this));
+    m_command_dict["bugreport"] = CommandObjectSP (new CommandObjectMultiwordBugreport (*this));
     m_command_dict["command"]   = CommandObjectSP (new CommandObjectMultiwordCommands (*this));
     m_command_dict["disassemble"] = CommandObjectSP (new CommandObjectDisassemble (*this));
     m_command_dict["expression"]= CommandObjectSP (new CommandObjectExpression (*this));
     m_command_dict["frame"]     = CommandObjectSP (new CommandObjectMultiwordFrame (*this));
     m_command_dict["gui"]       = CommandObjectSP (new CommandObjectGUI (*this));
     m_command_dict["help"]      = CommandObjectSP (new CommandObjectHelp (*this));
     m_command_dict["log"]       = CommandObjectSP (new CommandObjectLog (*this));
     m_command_dict["memory"]    = CommandObjectSP (new CommandObjectMemory (*this));