1 //===-- UserExpression.cpp ------------------------------------------------===//
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 <cstdio>
10 #include <sys/types.h>
11 
12 #include <cstdlib>
13 #include <map>
14 #include <string>
15 
16 #include "lldb/Core/Module.h"
17 #include "lldb/Core/StreamFile.h"
18 #include "lldb/Core/ValueObjectConstResult.h"
19 #include "lldb/Expression/DiagnosticManager.h"
20 #include "lldb/Expression/ExpressionVariable.h"
21 #include "lldb/Expression/IRExecutionUnit.h"
22 #include "lldb/Expression/IRInterpreter.h"
23 #include "lldb/Expression/Materializer.h"
24 #include "lldb/Expression/UserExpression.h"
25 #include "lldb/Host/HostInfo.h"
26 #include "lldb/Symbol/Block.h"
27 #include "lldb/Symbol/Function.h"
28 #include "lldb/Symbol/ObjectFile.h"
29 #include "lldb/Symbol/SymbolVendor.h"
30 #include "lldb/Symbol/Type.h"
31 #include "lldb/Symbol/TypeSystem.h"
32 #include "lldb/Symbol/VariableList.h"
33 #include "lldb/Target/ExecutionContext.h"
34 #include "lldb/Target/Process.h"
35 #include "lldb/Target/StackFrame.h"
36 #include "lldb/Target/Target.h"
37 #include "lldb/Target/ThreadPlan.h"
38 #include "lldb/Target/ThreadPlanCallUserExpression.h"
39 #include "lldb/Utility/ConstString.h"
40 #include "lldb/Utility/LLDBLog.h"
41 #include "lldb/Utility/Log.h"
42 #include "lldb/Utility/StreamString.h"
43 
44 using namespace lldb_private;
45 
46 char UserExpression::ID;
47 
UserExpression(ExecutionContextScope & exe_scope,llvm::StringRef expr,llvm::StringRef prefix,lldb::LanguageType language,ResultType desired_type,const EvaluateExpressionOptions & options)48 UserExpression::UserExpression(ExecutionContextScope &exe_scope,
49                                llvm::StringRef expr, llvm::StringRef prefix,
50                                lldb::LanguageType language,
51                                ResultType desired_type,
52                                const EvaluateExpressionOptions &options)
53     : Expression(exe_scope), m_expr_text(std::string(expr)),
54       m_expr_prefix(std::string(prefix)), m_language(language),
55       m_desired_type(desired_type), m_options(options) {}
56 
57 UserExpression::~UserExpression() = default;
58 
InstallContext(ExecutionContext & exe_ctx)59 void UserExpression::InstallContext(ExecutionContext &exe_ctx) {
60   m_jit_process_wp = exe_ctx.GetProcessSP();
61 
62   lldb::StackFrameSP frame_sp = exe_ctx.GetFrameSP();
63 
64   if (frame_sp)
65     m_address = frame_sp->GetFrameCodeAddress();
66 }
67 
LockAndCheckContext(ExecutionContext & exe_ctx,lldb::TargetSP & target_sp,lldb::ProcessSP & process_sp,lldb::StackFrameSP & frame_sp)68 bool UserExpression::LockAndCheckContext(ExecutionContext &exe_ctx,
69                                          lldb::TargetSP &target_sp,
70                                          lldb::ProcessSP &process_sp,
71                                          lldb::StackFrameSP &frame_sp) {
72   lldb::ProcessSP expected_process_sp = m_jit_process_wp.lock();
73   process_sp = exe_ctx.GetProcessSP();
74 
75   if (process_sp != expected_process_sp)
76     return false;
77 
78   process_sp = exe_ctx.GetProcessSP();
79   target_sp = exe_ctx.GetTargetSP();
80   frame_sp = exe_ctx.GetFrameSP();
81 
82   if (m_address.IsValid()) {
83     if (!frame_sp)
84       return false;
85     return (Address::CompareLoadAddress(m_address,
86                                         frame_sp->GetFrameCodeAddress(),
87                                         target_sp.get()) == 0);
88   }
89 
90   return true;
91 }
92 
MatchesContext(ExecutionContext & exe_ctx)93 bool UserExpression::MatchesContext(ExecutionContext &exe_ctx) {
94   lldb::TargetSP target_sp;
95   lldb::ProcessSP process_sp;
96   lldb::StackFrameSP frame_sp;
97 
98   return LockAndCheckContext(exe_ctx, target_sp, process_sp, frame_sp);
99 }
100 
GetObjectPointerValueObject(lldb::StackFrameSP frame_sp,ConstString const & object_name,Status & err)101 lldb::ValueObjectSP UserExpression::GetObjectPointerValueObject(
102     lldb::StackFrameSP frame_sp, ConstString const &object_name, 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 {};
110   }
111 
112   lldb::VariableSP var_sp;
113   lldb::ValueObjectSP valobj_sp;
114 
115   return frame_sp->GetValueForVariableExpressionPath(
116       object_name.GetStringRef(), lldb::eNoDynamicValues,
117       StackFrame::eExpressionPathOptionCheckPtrVsMember |
118           StackFrame::eExpressionPathOptionsNoFragileObjcIvar |
119           StackFrame::eExpressionPathOptionsNoSyntheticChildren |
120           StackFrame::eExpressionPathOptionsNoSyntheticArrayRange,
121       var_sp, err);
122 }
123 
GetObjectPointer(lldb::StackFrameSP frame_sp,ConstString & object_name,Status & err)124 lldb::addr_t UserExpression::GetObjectPointer(lldb::StackFrameSP frame_sp,
125                                               ConstString &object_name,
126                                               Status &err) {
127   auto valobj_sp =
128       GetObjectPointerValueObject(std::move(frame_sp), object_name, err);
129 
130   if (!err.Success() || !valobj_sp.get())
131     return LLDB_INVALID_ADDRESS;
132 
133   lldb::addr_t ret = valobj_sp->GetValueAsUnsigned(LLDB_INVALID_ADDRESS);
134 
135   if (ret == LLDB_INVALID_ADDRESS) {
136     err.SetErrorStringWithFormat(
137         "Couldn't load '%s' because its value couldn't be evaluated",
138         object_name.AsCString());
139     return LLDB_INVALID_ADDRESS;
140   }
141 
142   return ret;
143 }
144 
145 lldb::ExpressionResults
Evaluate(ExecutionContext & exe_ctx,const EvaluateExpressionOptions & options,llvm::StringRef expr,llvm::StringRef prefix,lldb::ValueObjectSP & result_valobj_sp,Status & error,std::string * fixed_expression,ValueObject * ctx_obj)146 UserExpression::Evaluate(ExecutionContext &exe_ctx,
147                          const EvaluateExpressionOptions &options,
148                          llvm::StringRef expr, llvm::StringRef prefix,
149                          lldb::ValueObjectSP &result_valobj_sp, Status &error,
150                          std::string *fixed_expression, ValueObject *ctx_obj) {
151   Log *log(GetLog(LLDBLog::Expressions | LLDBLog::Step));
152 
153   if (ctx_obj) {
154     static unsigned const ctx_type_mask = lldb::TypeFlags::eTypeIsClass |
155                                           lldb::TypeFlags::eTypeIsStructUnion |
156                                           lldb::TypeFlags::eTypeIsReference;
157     if (!(ctx_obj->GetTypeInfo() & ctx_type_mask)) {
158       LLDB_LOG(log, "== [UserExpression::Evaluate] Passed a context object of "
159                     "an invalid type, can't run expressions.");
160       error.SetErrorString("a context object of an invalid type passed");
161       return lldb::eExpressionSetupError;
162     }
163   }
164 
165   if (ctx_obj && ctx_obj->GetTypeInfo() & lldb::TypeFlags::eTypeIsReference) {
166     Status error;
167     lldb::ValueObjectSP deref_ctx_sp = ctx_obj->Dereference(error);
168     if (!error.Success()) {
169       LLDB_LOG(log, "== [UserExpression::Evaluate] Passed a context object of "
170                     "a reference type that can't be dereferenced, can't run "
171                     "expressions.");
172       error.SetErrorString(
173           "passed context object of an reference type cannot be deferenced");
174       return lldb::eExpressionSetupError;
175     }
176 
177     ctx_obj = deref_ctx_sp.get();
178   }
179 
180   lldb_private::ExecutionPolicy execution_policy = options.GetExecutionPolicy();
181   lldb::LanguageType language = options.GetLanguage();
182   const ResultType desired_type = options.DoesCoerceToId()
183                                       ? UserExpression::eResultTypeId
184                                       : UserExpression::eResultTypeAny;
185   lldb::ExpressionResults execution_results = lldb::eExpressionSetupError;
186 
187   Target *target = exe_ctx.GetTargetPtr();
188   if (!target) {
189     LLDB_LOG(log, "== [UserExpression::Evaluate] Passed a NULL target, can't "
190                   "run expressions.");
191     error.SetErrorString("expression passed a null target");
192     return lldb::eExpressionSetupError;
193   }
194 
195   Process *process = exe_ctx.GetProcessPtr();
196 
197   if (process == nullptr && execution_policy == eExecutionPolicyAlways) {
198     LLDB_LOG(log, "== [UserExpression::Evaluate] No process, but the policy is "
199                   "eExecutionPolicyAlways");
200 
201     error.SetErrorString("expression needed to run but couldn't: no process");
202 
203     return execution_results;
204   }
205   // Since we might need to call allocate memory and maybe call code to make
206   // the caller, we need to be stopped.
207   if (process != nullptr && process->GetState() != lldb::eStateStopped) {
208     error.SetErrorString("Can't make a function caller while the process is "
209                           "running");
210     return execution_results;
211   }
212 
213 
214   // Explicitly force the IR interpreter to evaluate the expression when the
215   // there is no process that supports running the expression for us. Don't
216   // change the execution policy if we have the special top-level policy that
217   // doesn't contain any expression and there is nothing to interpret.
218   if (execution_policy != eExecutionPolicyTopLevel &&
219       (process == nullptr || !process->CanJIT()))
220     execution_policy = eExecutionPolicyNever;
221 
222   // We need to set the expression execution thread here, turns out parse can
223   // call functions in the process of looking up symbols, which will escape the
224   // context set by exe_ctx passed to Execute.
225   lldb::ThreadSP thread_sp = exe_ctx.GetThreadSP();
226   ThreadList::ExpressionExecutionThreadPusher execution_thread_pusher(
227       thread_sp);
228 
229   llvm::StringRef full_prefix;
230   llvm::StringRef option_prefix(options.GetPrefix());
231   std::string full_prefix_storage;
232   if (!prefix.empty() && !option_prefix.empty()) {
233     full_prefix_storage = std::string(prefix);
234     full_prefix_storage.append(std::string(option_prefix));
235     full_prefix = full_prefix_storage;
236   } else if (!prefix.empty())
237     full_prefix = prefix;
238   else
239     full_prefix = option_prefix;
240 
241   // If the language was not specified in the expression command, set it to the
242   // language in the target's properties if specified, else default to the
243   // langage for the frame.
244   if (language == lldb::eLanguageTypeUnknown) {
245     if (target->GetLanguage() != lldb::eLanguageTypeUnknown)
246       language = target->GetLanguage();
247     else if (StackFrame *frame = exe_ctx.GetFramePtr())
248       language = frame->GetLanguage();
249   }
250 
251   lldb::UserExpressionSP user_expression_sp(
252       target->GetUserExpressionForLanguage(expr, full_prefix, language,
253                                            desired_type, options, ctx_obj,
254                                            error));
255   if (error.Fail()) {
256     LLDB_LOG(log, "== [UserExpression::Evaluate] Getting expression: {0} ==",
257              error.AsCString());
258     return lldb::eExpressionSetupError;
259   }
260 
261   LLDB_LOG(log, "== [UserExpression::Evaluate] Parsing expression {0} ==",
262            expr.str());
263 
264   const bool keep_expression_in_memory = true;
265   const bool generate_debug_info = options.GetGenerateDebugInfo();
266 
267   if (options.InvokeCancelCallback(lldb::eExpressionEvaluationParse)) {
268     error.SetErrorString("expression interrupted by callback before parse");
269     result_valobj_sp = ValueObjectConstResult::Create(
270         exe_ctx.GetBestExecutionContextScope(), error);
271     return lldb::eExpressionInterrupted;
272   }
273 
274   DiagnosticManager diagnostic_manager;
275 
276   bool parse_success =
277       user_expression_sp->Parse(diagnostic_manager, exe_ctx, execution_policy,
278                                 keep_expression_in_memory, generate_debug_info);
279 
280   // Calculate the fixed expression always, since we need it for errors.
281   std::string tmp_fixed_expression;
282   if (fixed_expression == nullptr)
283     fixed_expression = &tmp_fixed_expression;
284 
285   *fixed_expression = user_expression_sp->GetFixedText().str();
286 
287   // If there is a fixed expression, try to parse it:
288   if (!parse_success) {
289     // Delete the expression that failed to parse before attempting to parse
290     // the next expression.
291     user_expression_sp.reset();
292 
293     execution_results = lldb::eExpressionParseError;
294     if (!fixed_expression->empty() && options.GetAutoApplyFixIts()) {
295       const uint64_t max_fix_retries = options.GetRetriesWithFixIts();
296       for (uint64_t i = 0; i < max_fix_retries; ++i) {
297         // Try parsing the fixed expression.
298         lldb::UserExpressionSP fixed_expression_sp(
299             target->GetUserExpressionForLanguage(
300                 fixed_expression->c_str(), full_prefix, language, desired_type,
301                 options, ctx_obj, error));
302         DiagnosticManager fixed_diagnostic_manager;
303         parse_success = fixed_expression_sp->Parse(
304             fixed_diagnostic_manager, exe_ctx, execution_policy,
305             keep_expression_in_memory, generate_debug_info);
306         if (parse_success) {
307           diagnostic_manager.Clear();
308           user_expression_sp = fixed_expression_sp;
309           break;
310         } else {
311           // The fixed expression also didn't parse. Let's check for any new
312           // Fix-Its we could try.
313           if (!fixed_expression_sp->GetFixedText().empty()) {
314             *fixed_expression = fixed_expression_sp->GetFixedText().str();
315           } else {
316             // Fixed expression didn't compile without a fixit, don't retry and
317             // don't tell the user about it.
318             fixed_expression->clear();
319             break;
320           }
321         }
322       }
323     }
324 
325     if (!parse_success) {
326       std::string msg;
327       {
328         llvm::raw_string_ostream os(msg);
329         os << "expression failed to parse:\n";
330         if (!diagnostic_manager.Diagnostics().empty())
331           os << diagnostic_manager.GetString();
332         else
333           os << "unknown error";
334         if (target->GetEnableNotifyAboutFixIts() && fixed_expression &&
335             !fixed_expression->empty())
336           os << "\nfixed expression suggested:\n  " << *fixed_expression;
337       }
338       error.SetExpressionError(execution_results, msg.c_str());
339     }
340   }
341 
342   if (parse_success) {
343     lldb::ExpressionVariableSP expr_result;
344 
345     if (execution_policy == eExecutionPolicyNever &&
346         !user_expression_sp->CanInterpret()) {
347       LLDB_LOG(log, "== [UserExpression::Evaluate] Expression may not run, but "
348                     "is not constant ==");
349 
350       if (!diagnostic_manager.Diagnostics().size())
351         error.SetExpressionError(lldb::eExpressionSetupError,
352                                  "expression needed to run but couldn't");
353     } else if (execution_policy == eExecutionPolicyTopLevel) {
354       error.SetError(UserExpression::kNoResult, lldb::eErrorTypeGeneric);
355       return lldb::eExpressionCompleted;
356     } else {
357       if (options.InvokeCancelCallback(lldb::eExpressionEvaluationExecution)) {
358         error.SetExpressionError(
359             lldb::eExpressionInterrupted,
360             "expression interrupted by callback before execution");
361         result_valobj_sp = ValueObjectConstResult::Create(
362             exe_ctx.GetBestExecutionContextScope(), error);
363         return lldb::eExpressionInterrupted;
364       }
365 
366       diagnostic_manager.Clear();
367 
368       LLDB_LOG(log, "== [UserExpression::Evaluate] Executing expression ==");
369 
370       execution_results =
371           user_expression_sp->Execute(diagnostic_manager, exe_ctx, options,
372                                       user_expression_sp, expr_result);
373 
374       if (execution_results != lldb::eExpressionCompleted) {
375         LLDB_LOG(log, "== [UserExpression::Evaluate] Execution completed "
376                       "abnormally ==");
377 
378         if (!diagnostic_manager.Diagnostics().size())
379           error.SetExpressionError(
380               execution_results, "expression failed to execute, unknown error");
381         else
382           error.SetExpressionError(execution_results,
383                                    diagnostic_manager.GetString().c_str());
384       } else {
385         if (expr_result) {
386           result_valobj_sp = expr_result->GetValueObject();
387           result_valobj_sp->SetPreferredDisplayLanguage(language);
388 
389           LLDB_LOG(log,
390                    "== [UserExpression::Evaluate] Execution completed "
391                    "normally with result {0} ==",
392                    result_valobj_sp->GetValueAsCString());
393         } else {
394           LLDB_LOG(log, "== [UserExpression::Evaluate] Execution completed "
395                         "normally with no result ==");
396 
397           error.SetError(UserExpression::kNoResult, lldb::eErrorTypeGeneric);
398         }
399       }
400     }
401   }
402 
403   if (options.InvokeCancelCallback(lldb::eExpressionEvaluationComplete)) {
404     error.SetExpressionError(
405         lldb::eExpressionInterrupted,
406         "expression interrupted by callback after complete");
407     return lldb::eExpressionInterrupted;
408   }
409 
410   if (result_valobj_sp.get() == nullptr) {
411     result_valobj_sp = ValueObjectConstResult::Create(
412         exe_ctx.GetBestExecutionContextScope(), error);
413   }
414 
415   return execution_results;
416 }
417 
418 lldb::ExpressionResults
Execute(DiagnosticManager & diagnostic_manager,ExecutionContext & exe_ctx,const EvaluateExpressionOptions & options,lldb::UserExpressionSP & shared_ptr_to_me,lldb::ExpressionVariableSP & result_var)419 UserExpression::Execute(DiagnosticManager &diagnostic_manager,
420                         ExecutionContext &exe_ctx,
421                         const EvaluateExpressionOptions &options,
422                         lldb::UserExpressionSP &shared_ptr_to_me,
423                         lldb::ExpressionVariableSP &result_var) {
424   lldb::ExpressionResults expr_result = DoExecute(
425       diagnostic_manager, exe_ctx, options, shared_ptr_to_me, result_var);
426   Target *target = exe_ctx.GetTargetPtr();
427   if (options.GetResultIsInternal() && result_var && target) {
428     if (auto *persistent_state =
429             target->GetPersistentExpressionStateForLanguage(m_language))
430       persistent_state->RemovePersistentVariable(result_var);
431   }
432   return expr_result;
433 }
434