1 //===-- UserExpression.cpp ---------------------------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include <stdio.h>
10 #if HAVE_SYS_TYPES_H
11 #include <sys/types.h>
12 #endif
13 
14 #include <cstdlib>
15 #include <map>
16 #include <string>
17 
18 #include "Plugins/ExpressionParser/Clang/ClangPersistentVariables.h"
19 #include "lldb/Core/Module.h"
20 #include "lldb/Core/StreamFile.h"
21 #include "lldb/Core/ValueObjectConstResult.h"
22 #include "lldb/Expression/DiagnosticManager.h"
23 #include "lldb/Expression/IRExecutionUnit.h"
24 #include "lldb/Expression/IRInterpreter.h"
25 #include "lldb/Expression/Materializer.h"
26 #include "lldb/Expression/UserExpression.h"
27 #include "lldb/Host/HostInfo.h"
28 #include "lldb/Symbol/Block.h"
29 #include "lldb/Symbol/Function.h"
30 #include "lldb/Symbol/ObjectFile.h"
31 #include "lldb/Symbol/SymbolVendor.h"
32 #include "lldb/Symbol/Type.h"
33 #include "lldb/Symbol/TypeSystem.h"
34 #include "lldb/Symbol/VariableList.h"
35 #include "lldb/Target/ExecutionContext.h"
36 #include "lldb/Target/Process.h"
37 #include "lldb/Target/StackFrame.h"
38 #include "lldb/Target/Target.h"
39 #include "lldb/Target/ThreadPlan.h"
40 #include "lldb/Target/ThreadPlanCallUserExpression.h"
41 #include "lldb/Utility/ConstString.h"
42 #include "lldb/Utility/Log.h"
43 #include "lldb/Utility/StreamString.h"
44 
45 using namespace lldb_private;
46 
47 UserExpression::UserExpression(ExecutionContextScope &exe_scope,
48                                llvm::StringRef expr, llvm::StringRef prefix,
49                                lldb::LanguageType language,
50                                ResultType desired_type,
51                                const EvaluateExpressionOptions &options)
52     : Expression(exe_scope), m_expr_text(expr), m_expr_prefix(prefix),
53       m_language(language), m_desired_type(desired_type), m_options(options) {}
54 
55 UserExpression::~UserExpression() {}
56 
57 void UserExpression::InstallContext(ExecutionContext &exe_ctx) {
58   m_jit_process_wp = exe_ctx.GetProcessSP();
59 
60   lldb::StackFrameSP frame_sp = exe_ctx.GetFrameSP();
61 
62   if (frame_sp)
63     m_address = frame_sp->GetFrameCodeAddress();
64 }
65 
66 bool UserExpression::LockAndCheckContext(ExecutionContext &exe_ctx,
67                                          lldb::TargetSP &target_sp,
68                                          lldb::ProcessSP &process_sp,
69                                          lldb::StackFrameSP &frame_sp) {
70   lldb::ProcessSP expected_process_sp = m_jit_process_wp.lock();
71   process_sp = exe_ctx.GetProcessSP();
72 
73   if (process_sp != expected_process_sp)
74     return false;
75 
76   process_sp = exe_ctx.GetProcessSP();
77   target_sp = exe_ctx.GetTargetSP();
78   frame_sp = exe_ctx.GetFrameSP();
79 
80   if (m_address.IsValid()) {
81     if (!frame_sp)
82       return false;
83     else
84       return (0 == Address::CompareLoadAddress(m_address,
85                                                frame_sp->GetFrameCodeAddress(),
86                                                target_sp.get()));
87   }
88 
89   return true;
90 }
91 
92 bool UserExpression::MatchesContext(ExecutionContext &exe_ctx) {
93   lldb::TargetSP target_sp;
94   lldb::ProcessSP process_sp;
95   lldb::StackFrameSP frame_sp;
96 
97   return LockAndCheckContext(exe_ctx, target_sp, process_sp, frame_sp);
98 }
99 
100 lldb::addr_t UserExpression::GetObjectPointer(lldb::StackFrameSP frame_sp,
101                                               ConstString &object_name,
102                                               Status &err) {
103   err.Clear();
104 
105   if (!frame_sp) {
106     err.SetErrorStringWithFormat(
107         "Couldn't load '%s' because the context is incomplete",
108         object_name.AsCString());
109     return LLDB_INVALID_ADDRESS;
110   }
111 
112   lldb::VariableSP var_sp;
113   lldb::ValueObjectSP valobj_sp;
114 
115   valobj_sp = frame_sp->GetValueForVariableExpressionPath(
116       object_name.AsCString(), lldb::eNoDynamicValues,
117       StackFrame::eExpressionPathOptionCheckPtrVsMember |
118           StackFrame::eExpressionPathOptionsNoFragileObjcIvar |
119           StackFrame::eExpressionPathOptionsNoSyntheticChildren |
120           StackFrame::eExpressionPathOptionsNoSyntheticArrayRange,
121       var_sp, err);
122 
123   if (!err.Success() || !valobj_sp.get())
124     return LLDB_INVALID_ADDRESS;
125 
126   lldb::addr_t ret = valobj_sp->GetValueAsUnsigned(LLDB_INVALID_ADDRESS);
127 
128   if (ret == LLDB_INVALID_ADDRESS) {
129     err.SetErrorStringWithFormat(
130         "Couldn't load '%s' because its value couldn't be evaluated",
131         object_name.AsCString());
132     return LLDB_INVALID_ADDRESS;
133   }
134 
135   return ret;
136 }
137 
138 lldb::ExpressionResults UserExpression::Evaluate(
139     ExecutionContext &exe_ctx, const EvaluateExpressionOptions &options,
140     llvm::StringRef expr, llvm::StringRef prefix,
141     lldb::ValueObjectSP &result_valobj_sp, Status &error,
142     std::string *fixed_expression, lldb::ModuleSP *jit_module_sp_ptr,
143     ValueObject *ctx_obj) {
144   Log *log(lldb_private::GetLogIfAnyCategoriesSet(LIBLLDB_LOG_EXPRESSIONS |
145                                                   LIBLLDB_LOG_STEP));
146 
147   if (ctx_obj) {
148     static unsigned const ctx_type_mask =
149         lldb::TypeFlags::eTypeIsClass | lldb::TypeFlags::eTypeIsStructUnion;
150     if (!(ctx_obj->GetTypeInfo() & ctx_type_mask)) {
151       LLDB_LOG(log, "== [UserExpression::Evaluate] Passed a context object of "
152                     "an invalid type, can't run expressions.");
153       error.SetErrorString("a context object of an invalid type passed");
154       return lldb::eExpressionSetupError;
155     }
156   }
157 
158   lldb_private::ExecutionPolicy execution_policy = options.GetExecutionPolicy();
159   lldb::LanguageType language = options.GetLanguage();
160   const ResultType desired_type = options.DoesCoerceToId()
161                                       ? UserExpression::eResultTypeId
162                                       : UserExpression::eResultTypeAny;
163   lldb::ExpressionResults execution_results = lldb::eExpressionSetupError;
164 
165   Target *target = exe_ctx.GetTargetPtr();
166   if (!target) {
167     if (log)
168       log->Printf("== [UserExpression::Evaluate] Passed a NULL target, can't "
169                   "run expressions.");
170     error.SetErrorString("expression passed a null target");
171     return lldb::eExpressionSetupError;
172   }
173 
174   Process *process = exe_ctx.GetProcessPtr();
175 
176   if (process == NULL || process->GetState() != lldb::eStateStopped) {
177     if (execution_policy == eExecutionPolicyAlways) {
178       if (log)
179         log->Printf("== [UserExpression::Evaluate] Expression may not run, but "
180                     "is not constant ==");
181 
182       error.SetErrorString("expression needed to run but couldn't");
183 
184       return execution_results;
185     }
186   }
187 
188   if (process == NULL || !process->CanJIT())
189     execution_policy = eExecutionPolicyNever;
190 
191   // We need to set the expression execution thread here, turns out parse can
192   // call functions in the process of looking up symbols, which will escape the
193   // context set by exe_ctx passed to Execute.
194   lldb::ThreadSP thread_sp = exe_ctx.GetThreadSP();
195   ThreadList::ExpressionExecutionThreadPusher execution_thread_pusher(
196       thread_sp);
197 
198   llvm::StringRef full_prefix;
199   llvm::StringRef option_prefix(options.GetPrefix());
200   std::string full_prefix_storage;
201   if (!prefix.empty() && !option_prefix.empty()) {
202     full_prefix_storage = prefix;
203     full_prefix_storage.append(option_prefix);
204     full_prefix = full_prefix_storage;
205   } else if (!prefix.empty())
206     full_prefix = prefix;
207   else
208     full_prefix = option_prefix;
209 
210   // If the language was not specified in the expression command, set it to the
211   // language in the target's properties if specified, else default to the
212   // langage for the frame.
213   if (language == lldb::eLanguageTypeUnknown) {
214     if (target->GetLanguage() != lldb::eLanguageTypeUnknown)
215       language = target->GetLanguage();
216     else if (StackFrame *frame = exe_ctx.GetFramePtr())
217       language = frame->GetLanguage();
218   }
219 
220   lldb::UserExpressionSP user_expression_sp(
221       target->GetUserExpressionForLanguage(expr, full_prefix, language,
222                                            desired_type, options, ctx_obj,
223                                            error));
224   if (error.Fail()) {
225     if (log)
226       log->Printf("== [UserExpression::Evaluate] Getting expression: %s ==",
227                   error.AsCString());
228     return lldb::eExpressionSetupError;
229   }
230 
231   if (log)
232     log->Printf("== [UserExpression::Evaluate] Parsing expression %s ==",
233                 expr.str().c_str());
234 
235   const bool keep_expression_in_memory = true;
236   const bool generate_debug_info = options.GetGenerateDebugInfo();
237 
238   if (options.InvokeCancelCallback(lldb::eExpressionEvaluationParse)) {
239     error.SetErrorString("expression interrupted by callback before parse");
240     result_valobj_sp = ValueObjectConstResult::Create(
241         exe_ctx.GetBestExecutionContextScope(), error);
242     return lldb::eExpressionInterrupted;
243   }
244 
245   DiagnosticManager diagnostic_manager;
246 
247   bool parse_success =
248       user_expression_sp->Parse(diagnostic_manager, exe_ctx, execution_policy,
249                                 keep_expression_in_memory, generate_debug_info);
250 
251   // Calculate the fixed expression always, since we need it for errors.
252   std::string tmp_fixed_expression;
253   if (fixed_expression == nullptr)
254     fixed_expression = &tmp_fixed_expression;
255 
256   const char *fixed_text = user_expression_sp->GetFixedText();
257   if (fixed_text != nullptr)
258     fixed_expression->append(fixed_text);
259 
260   // If there is a fixed expression, try to parse it:
261   if (!parse_success) {
262     execution_results = lldb::eExpressionParseError;
263     if (fixed_expression && !fixed_expression->empty() &&
264         options.GetAutoApplyFixIts()) {
265       lldb::UserExpressionSP fixed_expression_sp(
266           target->GetUserExpressionForLanguage(fixed_expression->c_str(),
267                                                full_prefix, language,
268                                                desired_type, options, ctx_obj,
269                                                error));
270       DiagnosticManager fixed_diagnostic_manager;
271       parse_success = fixed_expression_sp->Parse(
272           fixed_diagnostic_manager, exe_ctx, execution_policy,
273           keep_expression_in_memory, generate_debug_info);
274       if (parse_success) {
275         diagnostic_manager.Clear();
276         user_expression_sp = fixed_expression_sp;
277       } else {
278         // If the fixed expression failed to parse, don't tell the user about,
279         // that won't help.
280         fixed_expression->clear();
281       }
282     }
283 
284     if (!parse_success) {
285       if (!fixed_expression->empty() && target->GetEnableNotifyAboutFixIts()) {
286         error.SetExpressionErrorWithFormat(
287             execution_results,
288             "expression failed to parse, fixed expression suggested:\n  %s",
289             fixed_expression->c_str());
290       } else {
291         if (!diagnostic_manager.Diagnostics().size())
292           error.SetExpressionError(execution_results,
293                                    "expression failed to parse, unknown error");
294         else
295           error.SetExpressionError(execution_results,
296                                    diagnostic_manager.GetString().c_str());
297       }
298     }
299   }
300 
301   if (parse_success) {
302     // If a pointer to a lldb::ModuleSP was passed in, return the JIT'ed module
303     // if one was created
304     if (jit_module_sp_ptr)
305       *jit_module_sp_ptr = user_expression_sp->GetJITModule();
306 
307     lldb::ExpressionVariableSP expr_result;
308 
309     if (execution_policy == eExecutionPolicyNever &&
310         !user_expression_sp->CanInterpret()) {
311       if (log)
312         log->Printf("== [UserExpression::Evaluate] Expression may not run, but "
313                     "is not constant ==");
314 
315       if (!diagnostic_manager.Diagnostics().size())
316         error.SetExpressionError(lldb::eExpressionSetupError,
317                                  "expression needed to run but couldn't");
318     } else if (execution_policy == eExecutionPolicyTopLevel) {
319       error.SetError(UserExpression::kNoResult, lldb::eErrorTypeGeneric);
320       return lldb::eExpressionCompleted;
321     } else {
322       if (options.InvokeCancelCallback(lldb::eExpressionEvaluationExecution)) {
323         error.SetExpressionError(
324             lldb::eExpressionInterrupted,
325             "expression interrupted by callback before execution");
326         result_valobj_sp = ValueObjectConstResult::Create(
327             exe_ctx.GetBestExecutionContextScope(), error);
328         return lldb::eExpressionInterrupted;
329       }
330 
331       diagnostic_manager.Clear();
332 
333       if (log)
334         log->Printf("== [UserExpression::Evaluate] Executing expression ==");
335 
336       execution_results =
337           user_expression_sp->Execute(diagnostic_manager, exe_ctx, options,
338                                       user_expression_sp, expr_result);
339 
340       if (execution_results != lldb::eExpressionCompleted) {
341         if (log)
342           log->Printf("== [UserExpression::Evaluate] Execution completed "
343                       "abnormally ==");
344 
345         if (!diagnostic_manager.Diagnostics().size())
346           error.SetExpressionError(
347               execution_results, "expression failed to execute, unknown error");
348         else
349           error.SetExpressionError(execution_results,
350                                    diagnostic_manager.GetString().c_str());
351       } else {
352         if (expr_result) {
353           result_valobj_sp = expr_result->GetValueObject();
354 
355           if (log)
356             log->Printf("== [UserExpression::Evaluate] Execution completed "
357                         "normally with result %s ==",
358                         result_valobj_sp->GetValueAsCString());
359         } else {
360           if (log)
361             log->Printf("== [UserExpression::Evaluate] Execution completed "
362                         "normally with no result ==");
363 
364           error.SetError(UserExpression::kNoResult, lldb::eErrorTypeGeneric);
365         }
366       }
367     }
368   }
369 
370   if (options.InvokeCancelCallback(lldb::eExpressionEvaluationComplete)) {
371     error.SetExpressionError(
372         lldb::eExpressionInterrupted,
373         "expression interrupted by callback after complete");
374     return lldb::eExpressionInterrupted;
375   }
376 
377   if (result_valobj_sp.get() == NULL) {
378     result_valobj_sp = ValueObjectConstResult::Create(
379         exe_ctx.GetBestExecutionContextScope(), error);
380   }
381 
382   return execution_results;
383 }
384 
385 lldb::ExpressionResults
386 UserExpression::Execute(DiagnosticManager &diagnostic_manager,
387                         ExecutionContext &exe_ctx,
388                         const EvaluateExpressionOptions &options,
389                         lldb::UserExpressionSP &shared_ptr_to_me,
390                         lldb::ExpressionVariableSP &result_var) {
391   lldb::ExpressionResults expr_result = DoExecute(
392       diagnostic_manager, exe_ctx, options, shared_ptr_to_me, result_var);
393   Target *target = exe_ctx.GetTargetPtr();
394   if (options.GetResultIsInternal() && result_var && target) {
395     target->GetPersistentExpressionStateForLanguage(m_language)
396         ->RemovePersistentVariable(result_var);
397   }
398   return expr_result;
399 }
400