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 "lldb/Core/Module.h"
19 #include "lldb/Core/StreamFile.h"
20 #include "lldb/Core/ValueObjectConstResult.h"
21 #include "lldb/Expression/DiagnosticManager.h"
22 #include "lldb/Expression/ExpressionVariable.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                                ExpressionKind kind)
53     : Expression(exe_scope, kind), m_expr_text(expr), m_expr_prefix(prefix),
54       m_language(language), m_desired_type(desired_type), m_options(options) {}
55 
56 UserExpression::~UserExpression() {}
57 
58 void UserExpression::InstallContext(ExecutionContext &exe_ctx) {
59   m_jit_process_wp = exe_ctx.GetProcessSP();
60 
61   lldb::StackFrameSP frame_sp = exe_ctx.GetFrameSP();
62 
63   if (frame_sp)
64     m_address = frame_sp->GetFrameCodeAddress();
65 }
66 
67 bool UserExpression::LockAndCheckContext(ExecutionContext &exe_ctx,
68                                          lldb::TargetSP &target_sp,
69                                          lldb::ProcessSP &process_sp,
70                                          lldb::StackFrameSP &frame_sp) {
71   lldb::ProcessSP expected_process_sp = m_jit_process_wp.lock();
72   process_sp = exe_ctx.GetProcessSP();
73 
74   if (process_sp != expected_process_sp)
75     return false;
76 
77   process_sp = exe_ctx.GetProcessSP();
78   target_sp = exe_ctx.GetTargetSP();
79   frame_sp = exe_ctx.GetFrameSP();
80 
81   if (m_address.IsValid()) {
82     if (!frame_sp)
83       return false;
84     else
85       return (0 == Address::CompareLoadAddress(m_address,
86                                                frame_sp->GetFrameCodeAddress(),
87                                                target_sp.get()));
88   }
89 
90   return true;
91 }
92 
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 
101 lldb::addr_t UserExpression::GetObjectPointer(lldb::StackFrameSP frame_sp,
102                                               ConstString &object_name,
103                                               Status &err) {
104   err.Clear();
105 
106   if (!frame_sp) {
107     err.SetErrorStringWithFormat(
108         "Couldn't load '%s' because the context is incomplete",
109         object_name.AsCString());
110     return LLDB_INVALID_ADDRESS;
111   }
112 
113   lldb::VariableSP var_sp;
114   lldb::ValueObjectSP valobj_sp;
115 
116   valobj_sp = frame_sp->GetValueForVariableExpressionPath(
117       object_name.AsCString(), lldb::eNoDynamicValues,
118       StackFrame::eExpressionPathOptionCheckPtrVsMember |
119           StackFrame::eExpressionPathOptionsNoFragileObjcIvar |
120           StackFrame::eExpressionPathOptionsNoSyntheticChildren |
121           StackFrame::eExpressionPathOptionsNoSyntheticArrayRange,
122       var_sp, err);
123 
124   if (!err.Success() || !valobj_sp.get())
125     return LLDB_INVALID_ADDRESS;
126 
127   lldb::addr_t ret = valobj_sp->GetValueAsUnsigned(LLDB_INVALID_ADDRESS);
128 
129   if (ret == LLDB_INVALID_ADDRESS) {
130     err.SetErrorStringWithFormat(
131         "Couldn't load '%s' because its value couldn't be evaluated",
132         object_name.AsCString());
133     return LLDB_INVALID_ADDRESS;
134   }
135 
136   return ret;
137 }
138 
139 lldb::ExpressionResults UserExpression::Evaluate(
140     ExecutionContext &exe_ctx, const EvaluateExpressionOptions &options,
141     llvm::StringRef expr, llvm::StringRef prefix,
142     lldb::ValueObjectSP &result_valobj_sp, Status &error,
143     std::string *fixed_expression, lldb::ModuleSP *jit_module_sp_ptr,
144     ValueObject *ctx_obj) {
145   Log *log(lldb_private::GetLogIfAnyCategoriesSet(LIBLLDB_LOG_EXPRESSIONS |
146                                                   LIBLLDB_LOG_STEP));
147 
148   if (ctx_obj) {
149     static unsigned const ctx_type_mask =
150         lldb::TypeFlags::eTypeIsClass | lldb::TypeFlags::eTypeIsStructUnion;
151     if (!(ctx_obj->GetTypeInfo() & ctx_type_mask)) {
152       LLDB_LOG(log, "== [UserExpression::Evaluate] Passed a context object of "
153                     "an invalid type, can't run expressions.");
154       error.SetErrorString("a context object of an invalid type passed");
155       return lldb::eExpressionSetupError;
156     }
157   }
158 
159   lldb_private::ExecutionPolicy execution_policy = options.GetExecutionPolicy();
160   lldb::LanguageType language = options.GetLanguage();
161   const ResultType desired_type = options.DoesCoerceToId()
162                                       ? UserExpression::eResultTypeId
163                                       : UserExpression::eResultTypeAny;
164   lldb::ExpressionResults execution_results = lldb::eExpressionSetupError;
165 
166   Target *target = exe_ctx.GetTargetPtr();
167   if (!target) {
168     LLDB_LOGF(log, "== [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 == nullptr || process->GetState() != lldb::eStateStopped) {
177     if (execution_policy == eExecutionPolicyAlways) {
178       LLDB_LOGF(log,
179                 "== [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 == nullptr || !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       LLDB_LOGF(log, "== [UserExpression::Evaluate] Getting expression: %s ==",
227                 error.AsCString());
228     return lldb::eExpressionSetupError;
229   }
230 
231   if (log)
232     LLDB_LOGF(log, "== [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         LLDB_LOGF(log,
313                   "== [UserExpression::Evaluate] Expression may not run, but "
314                   "is not constant ==");
315 
316       if (!diagnostic_manager.Diagnostics().size())
317         error.SetExpressionError(lldb::eExpressionSetupError,
318                                  "expression needed to run but couldn't");
319     } else if (execution_policy == eExecutionPolicyTopLevel) {
320       error.SetError(UserExpression::kNoResult, lldb::eErrorTypeGeneric);
321       return lldb::eExpressionCompleted;
322     } else {
323       if (options.InvokeCancelCallback(lldb::eExpressionEvaluationExecution)) {
324         error.SetExpressionError(
325             lldb::eExpressionInterrupted,
326             "expression interrupted by callback before execution");
327         result_valobj_sp = ValueObjectConstResult::Create(
328             exe_ctx.GetBestExecutionContextScope(), error);
329         return lldb::eExpressionInterrupted;
330       }
331 
332       diagnostic_manager.Clear();
333 
334       if (log)
335         LLDB_LOGF(log, "== [UserExpression::Evaluate] Executing expression ==");
336 
337       execution_results =
338           user_expression_sp->Execute(diagnostic_manager, exe_ctx, options,
339                                       user_expression_sp, expr_result);
340 
341       if (execution_results != lldb::eExpressionCompleted) {
342         if (log)
343           LLDB_LOGF(log, "== [UserExpression::Evaluate] Execution completed "
344                          "abnormally ==");
345 
346         if (!diagnostic_manager.Diagnostics().size())
347           error.SetExpressionError(
348               execution_results, "expression failed to execute, unknown error");
349         else
350           error.SetExpressionError(execution_results,
351                                    diagnostic_manager.GetString().c_str());
352       } else {
353         if (expr_result) {
354           result_valobj_sp = expr_result->GetValueObject();
355 
356           if (log)
357             LLDB_LOGF(log,
358                       "== [UserExpression::Evaluate] Execution completed "
359                       "normally with result %s ==",
360                       result_valobj_sp->GetValueAsCString());
361         } else {
362           if (log)
363             LLDB_LOGF(log, "== [UserExpression::Evaluate] Execution completed "
364                            "normally with no result ==");
365 
366           error.SetError(UserExpression::kNoResult, lldb::eErrorTypeGeneric);
367         }
368       }
369     }
370   }
371 
372   if (options.InvokeCancelCallback(lldb::eExpressionEvaluationComplete)) {
373     error.SetExpressionError(
374         lldb::eExpressionInterrupted,
375         "expression interrupted by callback after complete");
376     return lldb::eExpressionInterrupted;
377   }
378 
379   if (result_valobj_sp.get() == nullptr) {
380     result_valobj_sp = ValueObjectConstResult::Create(
381         exe_ctx.GetBestExecutionContextScope(), error);
382   }
383 
384   return execution_results;
385 }
386 
387 lldb::ExpressionResults
388 UserExpression::Execute(DiagnosticManager &diagnostic_manager,
389                         ExecutionContext &exe_ctx,
390                         const EvaluateExpressionOptions &options,
391                         lldb::UserExpressionSP &shared_ptr_to_me,
392                         lldb::ExpressionVariableSP &result_var) {
393   lldb::ExpressionResults expr_result = DoExecute(
394       diagnostic_manager, exe_ctx, options, shared_ptr_to_me, result_var);
395   Target *target = exe_ctx.GetTargetPtr();
396   if (options.GetResultIsInternal() && result_var && target) {
397     target->GetPersistentExpressionStateForLanguage(m_language)
398         ->RemovePersistentVariable(result_var);
399   }
400   return expr_result;
401 }
402