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