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/Log.h"
41 #include "lldb/Utility/StreamString.h"
42 
43 using namespace lldb_private;
44 
45 char UserExpression::ID;
46 
UserExpression(ExecutionContextScope & exe_scope,llvm::StringRef expr,llvm::StringRef prefix,lldb::LanguageType language,ResultType desired_type,const EvaluateExpressionOptions & options)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(std::string(expr)),
53       m_expr_prefix(std::string(prefix)), m_language(language),
54       m_desired_type(desired_type), m_options(options) {}
55 
56 UserExpression::~UserExpression() = default;
57 
InstallContext(ExecutionContext & exe_ctx)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 
LockAndCheckContext(ExecutionContext & exe_ctx,lldb::TargetSP & target_sp,lldb::ProcessSP & process_sp,lldb::StackFrameSP & frame_sp)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     return (Address::CompareLoadAddress(m_address,
85                                         frame_sp->GetFrameCodeAddress(),
86                                         target_sp.get()) == 0);
87   }
88 
89   return true;
90 }
91 
MatchesContext(ExecutionContext & exe_ctx)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 
GetObjectPointer(lldb::StackFrameSP frame_sp,ConstString & object_name,Status & err)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.GetStringRef(), 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
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)139 UserExpression::Evaluate(ExecutionContext &exe_ctx,
140                          const EvaluateExpressionOptions &options,
141                          llvm::StringRef expr, llvm::StringRef prefix,
142                          lldb::ValueObjectSP &result_valobj_sp, Status &error,
143                          std::string *fixed_expression, 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     LLDB_LOG(log, "== [UserExpression::Evaluate] Passed a NULL target, can't "
168                   "run expressions.");
169     error.SetErrorString("expression passed a null target");
170     return lldb::eExpressionSetupError;
171   }
172 
173   Process *process = exe_ctx.GetProcessPtr();
174 
175   if (process == nullptr || process->GetState() != lldb::eStateStopped) {
176     if (execution_policy == eExecutionPolicyAlways) {
177       LLDB_LOG(log, "== [UserExpression::Evaluate] Expression may not run, but "
178                     "is not constant ==");
179 
180       error.SetErrorString("expression needed to run but couldn't");
181 
182       return execution_results;
183     }
184   }
185 
186   // Explicitly force the IR interpreter to evaluate the expression when the
187   // there is no process that supports running the expression for us. Don't
188   // change the execution policy if we have the special top-level policy that
189   // doesn't contain any expression and there is nothing to interpret.
190   if (execution_policy != eExecutionPolicyTopLevel &&
191       (process == nullptr || !process->CanJIT()))
192     execution_policy = eExecutionPolicyNever;
193 
194   // We need to set the expression execution thread here, turns out parse can
195   // call functions in the process of looking up symbols, which will escape the
196   // context set by exe_ctx passed to Execute.
197   lldb::ThreadSP thread_sp = exe_ctx.GetThreadSP();
198   ThreadList::ExpressionExecutionThreadPusher execution_thread_pusher(
199       thread_sp);
200 
201   llvm::StringRef full_prefix;
202   llvm::StringRef option_prefix(options.GetPrefix());
203   std::string full_prefix_storage;
204   if (!prefix.empty() && !option_prefix.empty()) {
205     full_prefix_storage = std::string(prefix);
206     full_prefix_storage.append(std::string(option_prefix));
207     full_prefix = full_prefix_storage;
208   } else if (!prefix.empty())
209     full_prefix = prefix;
210   else
211     full_prefix = option_prefix;
212 
213   // If the language was not specified in the expression command, set it to the
214   // language in the target's properties if specified, else default to the
215   // langage for the frame.
216   if (language == lldb::eLanguageTypeUnknown) {
217     if (target->GetLanguage() != lldb::eLanguageTypeUnknown)
218       language = target->GetLanguage();
219     else if (StackFrame *frame = exe_ctx.GetFramePtr())
220       language = frame->GetLanguage();
221   }
222 
223   lldb::UserExpressionSP user_expression_sp(
224       target->GetUserExpressionForLanguage(expr, full_prefix, language,
225                                            desired_type, options, ctx_obj,
226                                            error));
227   if (error.Fail()) {
228     LLDB_LOG(log, "== [UserExpression::Evaluate] Getting expression: {0} ==",
229              error.AsCString());
230     return lldb::eExpressionSetupError;
231   }
232 
233   LLDB_LOG(log, "== [UserExpression::Evaluate] Parsing expression {0} ==",
234            expr.str());
235 
236   const bool keep_expression_in_memory = true;
237   const bool generate_debug_info = options.GetGenerateDebugInfo();
238 
239   if (options.InvokeCancelCallback(lldb::eExpressionEvaluationParse)) {
240     error.SetErrorString("expression interrupted by callback before parse");
241     result_valobj_sp = ValueObjectConstResult::Create(
242         exe_ctx.GetBestExecutionContextScope(), error);
243     return lldb::eExpressionInterrupted;
244   }
245 
246   DiagnosticManager diagnostic_manager;
247 
248   bool parse_success =
249       user_expression_sp->Parse(diagnostic_manager, exe_ctx, execution_policy,
250                                 keep_expression_in_memory, generate_debug_info);
251 
252   // Calculate the fixed expression always, since we need it for errors.
253   std::string tmp_fixed_expression;
254   if (fixed_expression == nullptr)
255     fixed_expression = &tmp_fixed_expression;
256 
257   const char *fixed_text = user_expression_sp->GetFixedText();
258   if (fixed_text != nullptr)
259     fixed_expression->append(fixed_text);
260 
261   // If there is a fixed expression, try to parse it:
262   if (!parse_success) {
263     // Delete the expression that failed to parse before attempting to parse
264     // the next expression.
265     user_expression_sp.reset();
266 
267     execution_results = lldb::eExpressionParseError;
268     if (fixed_expression && !fixed_expression->empty() &&
269         options.GetAutoApplyFixIts()) {
270       const uint64_t max_fix_retries = options.GetRetriesWithFixIts();
271       for (uint64_t i = 0; i < max_fix_retries; ++i) {
272         // Try parsing the fixed expression.
273         lldb::UserExpressionSP fixed_expression_sp(
274             target->GetUserExpressionForLanguage(
275                 fixed_expression->c_str(), full_prefix, language, desired_type,
276                 options, ctx_obj, error));
277         DiagnosticManager fixed_diagnostic_manager;
278         parse_success = fixed_expression_sp->Parse(
279             fixed_diagnostic_manager, exe_ctx, execution_policy,
280             keep_expression_in_memory, generate_debug_info);
281         if (parse_success) {
282           diagnostic_manager.Clear();
283           user_expression_sp = fixed_expression_sp;
284           break;
285         } else {
286           // The fixed expression also didn't parse. Let's check for any new
287           // Fix-Its we could try.
288           if (fixed_expression_sp->GetFixedText()) {
289             *fixed_expression = fixed_expression_sp->GetFixedText();
290           } else {
291             // Fixed expression didn't compile without a fixit, don't retry and
292             // don't tell the user about it.
293             fixed_expression->clear();
294             break;
295           }
296         }
297       }
298     }
299 
300     if (!parse_success) {
301       std::string msg;
302       {
303         llvm::raw_string_ostream os(msg);
304         os << "expression failed to parse:\n";
305         if (!diagnostic_manager.Diagnostics().empty())
306           os << diagnostic_manager.GetString();
307         else
308           os << "unknown error";
309         if (target->GetEnableNotifyAboutFixIts() && fixed_expression &&
310             !fixed_expression->empty())
311           os << "\nfixed expression suggested:\n  " << *fixed_expression;
312       }
313       error.SetExpressionError(execution_results, msg.c_str());
314     }
315   }
316 
317   if (parse_success) {
318     lldb::ExpressionVariableSP expr_result;
319 
320     if (execution_policy == eExecutionPolicyNever &&
321         !user_expression_sp->CanInterpret()) {
322       LLDB_LOG(log, "== [UserExpression::Evaluate] Expression may not run, but "
323                     "is not constant ==");
324 
325       if (!diagnostic_manager.Diagnostics().size())
326         error.SetExpressionError(lldb::eExpressionSetupError,
327                                  "expression needed to run but couldn't");
328     } else if (execution_policy == eExecutionPolicyTopLevel) {
329       error.SetError(UserExpression::kNoResult, lldb::eErrorTypeGeneric);
330       return lldb::eExpressionCompleted;
331     } else {
332       if (options.InvokeCancelCallback(lldb::eExpressionEvaluationExecution)) {
333         error.SetExpressionError(
334             lldb::eExpressionInterrupted,
335             "expression interrupted by callback before execution");
336         result_valobj_sp = ValueObjectConstResult::Create(
337             exe_ctx.GetBestExecutionContextScope(), error);
338         return lldb::eExpressionInterrupted;
339       }
340 
341       diagnostic_manager.Clear();
342 
343       LLDB_LOG(log, "== [UserExpression::Evaluate] Executing expression ==");
344 
345       execution_results =
346           user_expression_sp->Execute(diagnostic_manager, exe_ctx, options,
347                                       user_expression_sp, expr_result);
348 
349       if (execution_results != lldb::eExpressionCompleted) {
350         LLDB_LOG(log, "== [UserExpression::Evaluate] Execution completed "
351                       "abnormally ==");
352 
353         if (!diagnostic_manager.Diagnostics().size())
354           error.SetExpressionError(
355               execution_results, "expression failed to execute, unknown error");
356         else
357           error.SetExpressionError(execution_results,
358                                    diagnostic_manager.GetString().c_str());
359       } else {
360         if (expr_result) {
361           result_valobj_sp = expr_result->GetValueObject();
362           result_valobj_sp->SetPreferredDisplayLanguage(language);
363 
364           LLDB_LOG(log,
365                    "== [UserExpression::Evaluate] Execution completed "
366                    "normally with result {0} ==",
367                    result_valobj_sp->GetValueAsCString());
368         } else {
369           LLDB_LOG(log, "== [UserExpression::Evaluate] Execution completed "
370                         "normally with no result ==");
371 
372           error.SetError(UserExpression::kNoResult, lldb::eErrorTypeGeneric);
373         }
374       }
375     }
376   }
377 
378   if (options.InvokeCancelCallback(lldb::eExpressionEvaluationComplete)) {
379     error.SetExpressionError(
380         lldb::eExpressionInterrupted,
381         "expression interrupted by callback after complete");
382     return lldb::eExpressionInterrupted;
383   }
384 
385   if (result_valobj_sp.get() == nullptr) {
386     result_valobj_sp = ValueObjectConstResult::Create(
387         exe_ctx.GetBestExecutionContextScope(), error);
388   }
389 
390   return execution_results;
391 }
392 
393 lldb::ExpressionResults
Execute(DiagnosticManager & diagnostic_manager,ExecutionContext & exe_ctx,const EvaluateExpressionOptions & options,lldb::UserExpressionSP & shared_ptr_to_me,lldb::ExpressionVariableSP & result_var)394 UserExpression::Execute(DiagnosticManager &diagnostic_manager,
395                         ExecutionContext &exe_ctx,
396                         const EvaluateExpressionOptions &options,
397                         lldb::UserExpressionSP &shared_ptr_to_me,
398                         lldb::ExpressionVariableSP &result_var) {
399   lldb::ExpressionResults expr_result = DoExecute(
400       diagnostic_manager, exe_ctx, options, shared_ptr_to_me, result_var);
401   Target *target = exe_ctx.GetTargetPtr();
402   if (options.GetResultIsInternal() && result_var && target) {
403     if (auto *persistent_state =
404             target->GetPersistentExpressionStateForLanguage(m_language))
405       persistent_state->RemovePersistentVariable(result_var);
406   }
407   return expr_result;
408 }
409