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llvm-project/lldb/source/Expression/ClangUserExpression.cpp
Sean Callanan d5cc132b98 I have modified the part of the code that finds and 
validates the "self," "this," and "_cmd" pointers
that get passed into expressions.  It used to check
them aggressively for validity before allowing the
expression to run as an object method; now, this
functionality is gated by a bool and off by default.

Now the default is that when LLDB is stopped in a
method of a class, code entered using "expr" will
always masquerade as an instance method.  If for
some reason "self," "this," or "_cmd" is unavailable
it will be reported as NULL.  This may cause the
expression to crash if it relies on those pointers,
but for example getting the addresses of ivars will
now work as the user would expect.

llvm-svn: 146465
2011-12-13 01:42:04 +00:00

770 lines
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//===-- ClangUserExpression.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
#include <stdio.h>
#if HAVE_SYS_TYPES_H
# include <sys/types.h>
#endif
// C++ Includes
#include <cstdlib>
#include <string>
#include <map>
#include "lldb/Core/ConstString.h"
#include "lldb/Core/Log.h"
#include "lldb/Core/StreamFile.h"
#include "lldb/Core/StreamString.h"
#include "lldb/Core/ValueObjectConstResult.h"
#include "lldb/Expression/ASTResultSynthesizer.h"
#include "lldb/Expression/ClangExpressionDeclMap.h"
#include "lldb/Expression/ClangExpressionParser.h"
#include "lldb/Expression/ClangFunction.h"
#include "lldb/Expression/ClangUserExpression.h"
#include "lldb/Expression/ExpressionSourceCode.h"
#include "lldb/Host/Host.h"
#include "lldb/Symbol/VariableList.h"
#include "lldb/Target/ExecutionContext.h"
#include "lldb/Target/Process.h"
#include "lldb/Target/StackFrame.h"
#include "lldb/Target/Target.h"
#include "lldb/Target/ThreadPlan.h"
#include "lldb/Target/ThreadPlanCallUserExpression.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/DeclObjC.h"
using namespace lldb_private;
ClangUserExpression::ClangUserExpression (const char *expr,
const char *expr_prefix,
lldb::LanguageType language) :
ClangExpression (),
m_expr_text (expr),
m_expr_prefix (expr_prefix ? expr_prefix : ""),
m_language (language),
m_transformed_text (),
m_desired_type (NULL, NULL),
m_cplusplus (false),
m_objectivec (false),
m_needs_object_ptr (false),
m_const_object (false),
m_static_method(false),
m_target (NULL),
m_evaluated_statically (false),
m_const_result (),
m_enforce_valid_object (false)
{
switch (m_language)
{
case lldb::eLanguageTypeC_plus_plus:
m_allow_cxx = true;
break;
case lldb::eLanguageTypeObjC:
m_allow_objc = true;
break;
case lldb::eLanguageTypeObjC_plus_plus:
default:
m_allow_cxx = true;
m_allow_objc = true;
break;
}
}
ClangUserExpression::~ClangUserExpression ()
{
}
clang::ASTConsumer *
ClangUserExpression::ASTTransformer (clang::ASTConsumer *passthrough)
{
ClangASTContext *clang_ast_context = m_target->GetScratchClangASTContext();
if (!clang_ast_context)
return NULL;
if (!m_result_synthesizer.get())
m_result_synthesizer.reset(new ASTResultSynthesizer(passthrough,
m_desired_type,
*m_target));
return m_result_synthesizer.get();
}
void
ClangUserExpression::ScanContext(ExecutionContext &exe_ctx, Error &err)
{
m_target = exe_ctx.GetTargetPtr();
if (!(m_allow_cxx || m_allow_objc))
return;
StackFrame *frame = exe_ctx.GetFramePtr();
if (frame == NULL)
return;
SymbolContext sym_ctx = frame->GetSymbolContext(lldb::eSymbolContextFunction);
if (!sym_ctx.function)
return;
clang::DeclContext *decl_context;
if (sym_ctx.block && sym_ctx.block->GetInlinedFunctionInfo())
decl_context = sym_ctx.block->GetClangDeclContextForInlinedFunction();
else
decl_context = sym_ctx.function->GetClangDeclContext();
if (!decl_context)
return;
if (clang::CXXMethodDecl *method_decl = llvm::dyn_cast<clang::CXXMethodDecl>(decl_context))
{
if (m_allow_cxx && method_decl->isInstance())
{
if (m_enforce_valid_object)
{
VariableList *vars = frame->GetVariableList(false);
const char *thisErrorString = "Stopped in a C++ method, but 'this' isn't available; pretending we are in a generic context";
if (!vars)
{
err.SetErrorToGenericError();
err.SetErrorString(thisErrorString);
return;
}
lldb::VariableSP this_var = vars->FindVariable(ConstString("this"));
if (!this_var ||
!this_var->IsInScope(frame) ||
!this_var->LocationIsValidForFrame (frame))
{
err.SetErrorToGenericError();
err.SetErrorString(thisErrorString);
return;
}
}
m_cplusplus = true;
m_needs_object_ptr = true;
do {
clang::QualType this_type = method_decl->getThisType(decl_context->getParentASTContext());
const clang::PointerType *this_pointer_type = llvm::dyn_cast<clang::PointerType>(this_type.getTypePtr());
if (!this_pointer_type)
break;
clang::QualType this_pointee_type = this_pointer_type->getPointeeType();
} while (0);
}
}
else if (clang::ObjCMethodDecl *method_decl = llvm::dyn_cast<clang::ObjCMethodDecl>(decl_context))
{
if (m_allow_objc)
{
if (m_enforce_valid_object)
{
VariableList *vars = frame->GetVariableList(false);
const char *selfErrorString = "Stopped in an Objective-C method, but 'self' isn't available; pretending we are in a generic context";
if (!vars)
{
err.SetErrorToGenericError();
err.SetErrorString(selfErrorString);
return;
}
lldb::VariableSP self_var = vars->FindVariable(ConstString("self"));
if (!self_var ||
!self_var->IsInScope(frame) ||
!self_var->LocationIsValidForFrame (frame))
{
err.SetErrorToGenericError();
err.SetErrorString(selfErrorString);
return;
}
}
m_objectivec = true;
m_needs_object_ptr = true;
if (!method_decl->isInstanceMethod())
m_static_method = true;
}
}
}
// This is a really nasty hack, meant to fix Objective-C expressions of the form
// (int)[myArray count]. Right now, because the type information for count is
// not available, [myArray count] returns id, which can't be directly cast to
// int without causing a clang error.
static void
ApplyObjcCastHack(std::string &expr)
{
#define OBJC_CAST_HACK_FROM "(int)["
#define OBJC_CAST_HACK_TO "(int)(long long)["
size_t from_offset;
while ((from_offset = expr.find(OBJC_CAST_HACK_FROM)) != expr.npos)
expr.replace(from_offset, sizeof(OBJC_CAST_HACK_FROM) - 1, OBJC_CAST_HACK_TO);
#undef OBJC_CAST_HACK_TO
#undef OBJC_CAST_HACK_FROM
}
// Another hack, meant to allow use of unichar despite it not being available in
// the type information. Although we could special-case it in type lookup,
// hopefully we'll figure out a way to #include the same environment as is
// present in the original source file rather than try to hack specific type
// definitions in as needed.
static void
ApplyUnicharHack(std::string &expr)
{
#define UNICHAR_HACK_FROM "unichar"
#define UNICHAR_HACK_TO "unsigned short"
size_t from_offset;
while ((from_offset = expr.find(UNICHAR_HACK_FROM)) != expr.npos)
expr.replace(from_offset, sizeof(UNICHAR_HACK_FROM) - 1, UNICHAR_HACK_TO);
#undef UNICHAR_HACK_TO
#undef UNICHAR_HACK_FROM
}
bool
ClangUserExpression::Parse (Stream &error_stream,
ExecutionContext &exe_ctx,
TypeFromUser desired_type,
lldb_private::ExecutionPolicy execution_policy,
bool keep_result_in_memory)
{
lldb::LogSP log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_EXPRESSIONS));
Error err;
ScanContext(exe_ctx, err);
if (!err.Success())
{
error_stream.Printf("warning: %s\n", err.AsCString());
}
StreamString m_transformed_stream;
////////////////////////////////////
// Generate the expression
//
ApplyObjcCastHack(m_expr_text);
//ApplyUnicharHack(m_expr_text);
std::auto_ptr <ExpressionSourceCode> source_code (ExpressionSourceCode::CreateWrapped(m_expr_prefix.c_str(), m_expr_text.c_str()));
lldb::LanguageType lang_type;
if (m_cplusplus)
lang_type = lldb::eLanguageTypeC_plus_plus;
else if(m_objectivec)
lang_type = lldb::eLanguageTypeObjC;
else
lang_type = lldb::eLanguageTypeC;
if (!source_code->GetText(m_transformed_text, lang_type, m_const_object, m_static_method))
{
error_stream.PutCString ("error: couldn't construct expression body");
return false;
}
if (log)
log->Printf("Parsing the following code:\n%s", m_transformed_text.c_str());
////////////////////////////////////
// Set up the target and compiler
//
Target *target = exe_ctx.GetTargetPtr();
if (!target)
{
error_stream.PutCString ("error: invalid target\n");
return false;
}
//////////////////////////
// Parse the expression
//
m_desired_type = desired_type;
m_expr_decl_map.reset(new ClangExpressionDeclMap(keep_result_in_memory, exe_ctx));
if (!m_expr_decl_map->WillParse(exe_ctx))
{
error_stream.PutCString ("error: current process state is unsuitable for expression parsing\n");
return false;
}
Process *process = exe_ctx.GetProcessPtr();
ClangExpressionParser parser(process, *this);
unsigned num_errors = parser.Parse (error_stream);
if (num_errors)
{
error_stream.Printf ("error: %d errors parsing expression\n", num_errors);
m_expr_decl_map->DidParse();
return false;
}
//////////////////////////////////////////////////////////////////////////////////////////
// Prepare the output of the parser for execution, evaluating it statically if possible
//
if (execution_policy != eExecutionPolicyNever && process)
m_data_allocator.reset(new ProcessDataAllocator(*process));
Error jit_error = parser.PrepareForExecution (m_jit_alloc,
m_jit_start_addr,
m_jit_end_addr,
exe_ctx,
m_data_allocator.get(),
m_evaluated_statically,
m_const_result,
execution_policy);
if (log && m_data_allocator.get())
{
StreamString dump_string;
m_data_allocator->Dump(dump_string);
log->Printf("Data buffer contents:\n%s", dump_string.GetString().c_str());
}
if (jit_error.Success())
{
if (process && m_jit_alloc != LLDB_INVALID_ADDRESS)
m_jit_process_sp = process->GetSP();
return true;
}
else
{
const char *error_cstr = jit_error.AsCString();
if (error_cstr && error_cstr[0])
error_stream.Printf ("error: %s\n", error_cstr);
else
error_stream.Printf ("error: expression can't be interpreted or run\n");
return false;
}
}
bool
ClangUserExpression::PrepareToExecuteJITExpression (Stream &error_stream,
ExecutionContext &exe_ctx,
lldb::addr_t &struct_address,
lldb::addr_t &object_ptr,
lldb::addr_t &cmd_ptr)
{
lldb::LogSP log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_EXPRESSIONS));
if (m_jit_start_addr != LLDB_INVALID_ADDRESS)
{
Error materialize_error;
if (m_needs_object_ptr)
{
ConstString object_name;
if (m_cplusplus)
{
object_name.SetCString("this");
}
else if (m_objectivec)
{
object_name.SetCString("self");
}
else
{
error_stream.Printf("Need object pointer but don't know the language\n");
return false;
}
if (!(m_expr_decl_map->GetObjectPointer(object_ptr, object_name, exe_ctx, materialize_error)))
{
error_stream.Printf("warning: couldn't get required object pointer (substituting NULL): %s\n", materialize_error.AsCString());
object_ptr = 0;
}
if (m_objectivec)
{
ConstString cmd_name("_cmd");
if (!(m_expr_decl_map->GetObjectPointer(cmd_ptr, cmd_name, exe_ctx, materialize_error, true)))
{
error_stream.Printf("warning: couldn't get object pointer (substituting NULL): %s\n", materialize_error.AsCString());
cmd_ptr = 0;
}
}
}
if (!m_expr_decl_map->Materialize(exe_ctx, struct_address, materialize_error))
{
error_stream.Printf("Couldn't materialize struct: %s\n", materialize_error.AsCString());
return false;
}
#if 0
// jingham: look here
StreamFile logfile ("/tmp/exprs.txt", "a");
logfile.Printf("0x%16.16llx: thread = 0x%4.4x, expr = '%s'\n", m_jit_start_addr, exe_ctx.thread ? exe_ctx.thread->GetID() : -1, m_expr_text.c_str());
#endif
if (log)
{
log->Printf("-- [ClangUserExpression::PrepareToExecuteJITExpression] Materializing for execution --");
log->Printf(" Function address : 0x%llx", (uint64_t)m_jit_start_addr);
if (m_needs_object_ptr)
log->Printf(" Object pointer : 0x%llx", (uint64_t)object_ptr);
log->Printf(" Structure address : 0x%llx", (uint64_t)struct_address);
StreamString args;
Error dump_error;
if (struct_address)
{
if (!m_expr_decl_map->DumpMaterializedStruct(exe_ctx, args, dump_error))
{
log->Printf(" Couldn't extract variable values : %s", dump_error.AsCString("unknown error"));
}
else
{
log->Printf(" Structure contents:\n%s", args.GetData());
}
}
}
}
return true;
}
ThreadPlan *
ClangUserExpression::GetThreadPlanToExecuteJITExpression (Stream &error_stream,
ExecutionContext &exe_ctx)
{
lldb::addr_t struct_address;
lldb::addr_t object_ptr = 0;
lldb::addr_t cmd_ptr = 0;
PrepareToExecuteJITExpression (error_stream, exe_ctx, struct_address, object_ptr, cmd_ptr);
// FIXME: This should really return a ThreadPlanCallUserExpression, in order to make sure that we don't release the
// ClangUserExpression resources before the thread plan finishes execution in the target. But because we are
// forcing unwind_on_error to be true here, in practical terms that can't happen.
return ClangFunction::GetThreadPlanToCallFunction (exe_ctx,
m_jit_start_addr,
struct_address,
error_stream,
true,
true,
(m_needs_object_ptr ? &object_ptr : NULL),
(m_needs_object_ptr && m_objectivec) ? &cmd_ptr : NULL);
}
bool
ClangUserExpression::FinalizeJITExecution (Stream &error_stream,
ExecutionContext &exe_ctx,
lldb::ClangExpressionVariableSP &result,
lldb::addr_t function_stack_pointer)
{
Error expr_error;
lldb::LogSP log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_EXPRESSIONS));
if (log)
{
log->Printf("-- [ClangUserExpression::FinalizeJITExecution] Dematerializing after execution --");
StreamString args;
Error dump_error;
if (!m_expr_decl_map->DumpMaterializedStruct(exe_ctx, args, dump_error))
{
log->Printf(" Couldn't extract variable values : %s", dump_error.AsCString("unknown error"));
}
else
{
log->Printf(" Structure contents:\n%s", args.GetData());
}
}
lldb::addr_t function_stack_bottom = function_stack_pointer - Host::GetPageSize();
if (!m_expr_decl_map->Dematerialize(exe_ctx, result, function_stack_pointer, function_stack_bottom, expr_error))
{
error_stream.Printf ("Couldn't dematerialize struct : %s\n", expr_error.AsCString("unknown error"));
return false;
}
return true;
}
ExecutionResults
ClangUserExpression::Execute (Stream &error_stream,
ExecutionContext &exe_ctx,
bool discard_on_error,
ClangUserExpression::ClangUserExpressionSP &shared_ptr_to_me,
lldb::ClangExpressionVariableSP &result)
{
// The expression log is quite verbose, and if you're just tracking the execution of the
// expression, it's quite convenient to have these logs come out with the STEP log as well.
lldb::LogSP log(lldb_private::GetLogIfAnyCategoriesSet (LIBLLDB_LOG_EXPRESSIONS | LIBLLDB_LOG_STEP));
if (m_jit_start_addr != LLDB_INVALID_ADDRESS)
{
lldb::addr_t struct_address;
lldb::addr_t object_ptr = 0;
lldb::addr_t cmd_ptr = 0;
if (!PrepareToExecuteJITExpression (error_stream, exe_ctx, struct_address, object_ptr, cmd_ptr))
return eExecutionSetupError;
const bool stop_others = true;
const bool try_all_threads = true;
Address wrapper_address (NULL, m_jit_start_addr);
lldb::ThreadPlanSP call_plan_sp(new ThreadPlanCallUserExpression (exe_ctx.GetThreadRef(),
wrapper_address,
struct_address,
stop_others,
discard_on_error,
(m_needs_object_ptr ? &object_ptr : NULL),
((m_needs_object_ptr && m_objectivec) ? &cmd_ptr : NULL),
shared_ptr_to_me));
if (call_plan_sp == NULL || !call_plan_sp->ValidatePlan (NULL))
return eExecutionSetupError;
lldb::addr_t function_stack_pointer = static_cast<ThreadPlanCallFunction *>(call_plan_sp.get())->GetFunctionStackPointer();
call_plan_sp->SetPrivate(true);
uint32_t single_thread_timeout_usec = 500000;
if (log)
log->Printf("-- [ClangUserExpression::Execute] Execution of expression begins --");
if (exe_ctx.GetProcessPtr())
exe_ctx.GetProcessPtr()->SetRunningUserExpression(true);
ExecutionResults execution_result = exe_ctx.GetProcessRef().RunThreadPlan (exe_ctx,
call_plan_sp,
stop_others,
try_all_threads,
discard_on_error,
single_thread_timeout_usec,
error_stream);
if (exe_ctx.GetProcessPtr())
exe_ctx.GetProcessPtr()->SetRunningUserExpression(false);
if (log)
log->Printf("-- [ClangUserExpression::Execute] Execution of expression completed --");
if (execution_result == eExecutionInterrupted)
{
const char *error_desc = NULL;
if (call_plan_sp)
{
lldb::StopInfoSP real_stop_info_sp = call_plan_sp->GetRealStopInfo();
if (real_stop_info_sp)
error_desc = real_stop_info_sp->GetDescription();
}
if (error_desc)
error_stream.Printf ("Execution was interrupted, reason: %s.", error_desc);
else
error_stream.Printf ("Execution was interrupted.");
if (discard_on_error)
error_stream.Printf ("\nThe process has been returned to the state before execution.");
else
error_stream.Printf ("\nThe process has been left at the point where it was interrupted.");
return execution_result;
}
else if (execution_result != eExecutionCompleted)
{
error_stream.Printf ("Couldn't execute function; result was %s\n", Process::ExecutionResultAsCString (execution_result));
return execution_result;
}
if (FinalizeJITExecution (error_stream, exe_ctx, result, function_stack_pointer))
return eExecutionCompleted;
else
return eExecutionSetupError;
}
else
{
error_stream.Printf("Expression can't be run, because there is no JIT compiled function");
return eExecutionSetupError;
}
}
ExecutionResults
ClangUserExpression::Evaluate (ExecutionContext &exe_ctx,
lldb_private::ExecutionPolicy execution_policy,
lldb::LanguageType language,
bool discard_on_error,
const char *expr_cstr,
const char *expr_prefix,
lldb::ValueObjectSP &result_valobj_sp)
{
Error error;
return EvaluateWithError (exe_ctx, execution_policy, language, discard_on_error, expr_cstr, expr_prefix, result_valobj_sp, error);
}
ExecutionResults
ClangUserExpression::EvaluateWithError (ExecutionContext &exe_ctx,
lldb_private::ExecutionPolicy execution_policy,
lldb::LanguageType language,
bool discard_on_error,
const char *expr_cstr,
const char *expr_prefix,
lldb::ValueObjectSP &result_valobj_sp,
Error &error)
{
lldb::LogSP log(lldb_private::GetLogIfAnyCategoriesSet (LIBLLDB_LOG_EXPRESSIONS | LIBLLDB_LOG_STEP));
ExecutionResults execution_results = eExecutionSetupError;
Process *process = exe_ctx.GetProcessPtr();
if (process == NULL || process->GetState() != lldb::eStateStopped)
{
if (execution_policy == eExecutionPolicyAlways)
{
if (log)
log->Printf("== [ClangUserExpression::Evaluate] Expression may not run, but is not constant ==");
error.SetErrorString ("expression needed to run but couldn't");
return execution_results;
}
}
if (process == NULL || !process->CanJIT())
execution_policy = eExecutionPolicyNever;
ClangUserExpressionSP user_expression_sp (new ClangUserExpression (expr_cstr, expr_prefix, language));
StreamString error_stream;
if (log)
log->Printf("== [ClangUserExpression::Evaluate] Parsing expression %s ==", expr_cstr);
const bool keep_expression_in_memory = true;
if (!user_expression_sp->Parse (error_stream, exe_ctx, TypeFromUser(NULL, NULL), execution_policy, keep_expression_in_memory))
{
if (error_stream.GetString().empty())
error.SetErrorString ("expression failed to parse, unknown error");
else
error.SetErrorString (error_stream.GetString().c_str());
}
else
{
lldb::ClangExpressionVariableSP expr_result;
if (user_expression_sp->EvaluatedStatically())
{
if (log)
log->Printf("== [ClangUserExpression::Evaluate] Expression evaluated as a constant ==");
if (user_expression_sp->m_const_result)
result_valobj_sp = user_expression_sp->m_const_result->GetValueObject();
else
error.SetError(ClangUserExpression::kNoResult, lldb::eErrorTypeGeneric);
execution_results = eExecutionCompleted;
}
else if (execution_policy == eExecutionPolicyNever)
{
if (log)
log->Printf("== [ClangUserExpression::Evaluate] Expression may not run, but is not constant ==");
if (error_stream.GetString().empty())
error.SetErrorString ("expression needed to run but couldn't");
}
else
{
error_stream.GetString().clear();
if (log)
log->Printf("== [ClangUserExpression::Evaluate] Executing expression ==");
execution_results = user_expression_sp->Execute (error_stream,
exe_ctx,
discard_on_error,
user_expression_sp,
expr_result);
if (execution_results != eExecutionCompleted)
{
if (log)
log->Printf("== [ClangUserExpression::Evaluate] Execution completed abnormally ==");
if (error_stream.GetString().empty())
error.SetErrorString ("expression failed to execute, unknown error");
else
error.SetErrorString (error_stream.GetString().c_str());
}
else
{
if (expr_result)
{
result_valobj_sp = expr_result->GetValueObject();
if (log)
log->Printf("== [ClangUserExpression::Evaluate] Execution completed normally with result %s ==", result_valobj_sp->GetValueAsCString());
}
else
{
if (log)
log->Printf("== [ClangUserExpression::Evaluate] Execution completed normally with no result ==");
error.SetError(ClangUserExpression::kNoResult, lldb::eErrorTypeGeneric);
}
}
}
}
if (result_valobj_sp.get() == NULL)
result_valobj_sp = ValueObjectConstResult::Create (NULL, error);
return execution_results;
}
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