Bug Summary

File:build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionSourceCode.cpp
Warning:line 378, column 11
Called C++ object pointer is null

Annotated Source Code

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clang -cc1 -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name ClangExpressionSourceCode.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mframe-pointer=none -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -ffunction-sections -fdata-sections -fcoverage-compilation-dir=/build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/build-llvm/tools/clang/stage2-bins -resource-dir /usr/lib/llvm-15/lib/clang/15.0.0 -isystem /usr/include/libxml2 -D HAVE_ROUND -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I tools/lldb/source/Plugins/ExpressionParser/Clang -I /build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/lldb/source/Plugins/ExpressionParser/Clang -I /build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/lldb/include -I tools/lldb/include -I include -I /build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/llvm/include -I /usr/include/python3.9 -I /build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/clang/include -I tools/lldb/../clang/include -I /build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/lldb/source -I tools/lldb/source -D _FORTIFY_SOURCE=2 -D NDEBUG -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/x86_64-linux-gnu/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/backward -internal-isystem /usr/lib/llvm-15/lib/clang/15.0.0/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -fmacro-prefix-map=/build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/build-llvm/tools/clang/stage2-bins=build-llvm/tools/clang/stage2-bins -fmacro-prefix-map=/build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/= -fcoverage-prefix-map=/build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/build-llvm/tools/clang/stage2-bins=build-llvm/tools/clang/stage2-bins -fcoverage-prefix-map=/build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/= -O3 -Wno-unused-command-line-argument -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -Wno-noexcept-type -Wno-comment -Wno-deprecated-declarations -Wno-unknown-pragmas -Wno-strict-aliasing -Wno-stringop-truncation -std=c++14 -fdeprecated-macro -fdebug-compilation-dir=/build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/build-llvm/tools/clang/stage2-bins -fdebug-prefix-map=/build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/build-llvm/tools/clang/stage2-bins=build-llvm/tools/clang/stage2-bins -fdebug-prefix-map=/build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/= -ferror-limit 19 -fvisibility-inlines-hidden -stack-protector 2 -fgnuc-version=4.2.1 -fcolor-diagnostics -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/scan-build-2022-04-20-140412-16051-1 -x c++ /build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionSourceCode.cpp
1//===-- ClangExpressionSourceCode.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 "ClangExpressionSourceCode.h"
10
11#include "clang/Basic/CharInfo.h"
12#include "clang/Basic/FileManager.h"
13#include "clang/Basic/SourceManager.h"
14#include "clang/Lex/Lexer.h"
15#include "llvm/ADT/StringRef.h"
16
17#include "Plugins/ExpressionParser/Clang/ClangModulesDeclVendor.h"
18#include "Plugins/ExpressionParser/Clang/ClangPersistentVariables.h"
19#include "lldb/Symbol/Block.h"
20#include "lldb/Symbol/CompileUnit.h"
21#include "lldb/Symbol/DebugMacros.h"
22#include "lldb/Symbol/TypeSystem.h"
23#include "lldb/Symbol/VariableList.h"
24#include "lldb/Target/ExecutionContext.h"
25#include "lldb/Target/Language.h"
26#include "lldb/Target/Platform.h"
27#include "lldb/Target/StackFrame.h"
28#include "lldb/Target/Target.h"
29#include "lldb/Utility/StreamString.h"
30
31using namespace lldb_private;
32
33#define PREFIX_NAME"<lldb wrapper prefix>" "<lldb wrapper prefix>"
34#define SUFFIX_NAME"<lldb wrapper suffix>" "<lldb wrapper suffix>"
35
36const llvm::StringRef ClangExpressionSourceCode::g_prefix_file_name = PREFIX_NAME"<lldb wrapper prefix>";
37
38const char *ClangExpressionSourceCode::g_expression_prefix =
39"#line 1 \"" PREFIX_NAME"<lldb wrapper prefix>" R"("
40#ifndef offsetof
41#define offsetof(t, d) __builtin_offsetof(t, d)
42#endif
43#ifndef NULL
44#define NULL (__null)
45#endif
46#ifndef Nil
47#define Nil (__null)
48#endif
49#ifndef nil
50#define nil (__null)
51#endif
52#ifndef YES
53#define YES ((BOOL)1)
54#endif
55#ifndef NO
56#define NO ((BOOL)0)
57#endif
58typedef __INT8_TYPE__ int8_t;
59typedef __UINT8_TYPE__ uint8_t;
60typedef __INT16_TYPE__ int16_t;
61typedef __UINT16_TYPE__ uint16_t;
62typedef __INT32_TYPE__ int32_t;
63typedef __UINT32_TYPE__ uint32_t;
64typedef __INT64_TYPE__ int64_t;
65typedef __UINT64_TYPE__ uint64_t;
66typedef __INTPTR_TYPE__ intptr_t;
67typedef __UINTPTR_TYPE__ uintptr_t;
68typedef __SIZE_TYPE__ size_t;
69typedef __PTRDIFF_TYPE__ ptrdiff_t;
70typedef unsigned short unichar;
71extern "C"
72{
73 int printf(const char * __restrict, ...);
74}
75)";
76
77const char *ClangExpressionSourceCode::g_expression_suffix =
78 "\n;\n#line 1 \"" SUFFIX_NAME"<lldb wrapper suffix>" "\"\n";
79
80namespace {
81
82class AddMacroState {
83 enum State {
84 CURRENT_FILE_NOT_YET_PUSHED,
85 CURRENT_FILE_PUSHED,
86 CURRENT_FILE_POPPED
87 };
88
89public:
90 AddMacroState(const FileSpec &current_file, const uint32_t current_file_line)
91 : m_current_file(current_file), m_current_file_line(current_file_line) {}
92
93 void StartFile(const FileSpec &file) {
94 m_file_stack.push_back(file);
95 if (file == m_current_file)
96 m_state = CURRENT_FILE_PUSHED;
97 }
98
99 void EndFile() {
100 if (m_file_stack.size() == 0)
101 return;
102
103 FileSpec old_top = m_file_stack.back();
104 m_file_stack.pop_back();
105 if (old_top == m_current_file)
106 m_state = CURRENT_FILE_POPPED;
107 }
108
109 // An entry is valid if it occurs before the current line in the current
110 // file.
111 bool IsValidEntry(uint32_t line) {
112 switch (m_state) {
113 case CURRENT_FILE_NOT_YET_PUSHED:
114 return true;
115 case CURRENT_FILE_PUSHED:
116 // If we are in file included in the current file, the entry should be
117 // added.
118 if (m_file_stack.back() != m_current_file)
119 return true;
120
121 return line < m_current_file_line;
122 default:
123 return false;
124 }
125 }
126
127private:
128 std::vector<FileSpec> m_file_stack;
129 State m_state = CURRENT_FILE_NOT_YET_PUSHED;
130 FileSpec m_current_file;
131 uint32_t m_current_file_line;
132};
133
134} // anonymous namespace
135
136static void AddMacros(const DebugMacros *dm, CompileUnit *comp_unit,
137 AddMacroState &state, StreamString &stream) {
138 if (dm == nullptr)
139 return;
140
141 for (size_t i = 0; i < dm->GetNumMacroEntries(); i++) {
142 const DebugMacroEntry &entry = dm->GetMacroEntryAtIndex(i);
143 uint32_t line;
144
145 switch (entry.GetType()) {
146 case DebugMacroEntry::DEFINE:
147 if (state.IsValidEntry(entry.GetLineNumber()))
148 stream.Printf("#define %s\n", entry.GetMacroString().AsCString());
149 else
150 return;
151 break;
152 case DebugMacroEntry::UNDEF:
153 if (state.IsValidEntry(entry.GetLineNumber()))
154 stream.Printf("#undef %s\n", entry.GetMacroString().AsCString());
155 else
156 return;
157 break;
158 case DebugMacroEntry::START_FILE:
159 line = entry.GetLineNumber();
160 if (state.IsValidEntry(line))
161 state.StartFile(entry.GetFileSpec(comp_unit));
162 else
163 return;
164 break;
165 case DebugMacroEntry::END_FILE:
166 state.EndFile();
167 break;
168 case DebugMacroEntry::INDIRECT:
169 AddMacros(entry.GetIndirectDebugMacros(), comp_unit, state, stream);
170 break;
171 default:
172 // This is an unknown/invalid entry. Ignore.
173 break;
174 }
175 }
176}
177
178lldb_private::ClangExpressionSourceCode::ClangExpressionSourceCode(
179 llvm::StringRef filename, llvm::StringRef name, llvm::StringRef prefix,
180 llvm::StringRef body, Wrapping wrap, WrapKind wrap_kind)
181 : ExpressionSourceCode(name, prefix, body, wrap), m_wrap_kind(wrap_kind) {
182 // Use #line markers to pretend that we have a single-line source file
183 // containing only the user expression. This will hide our wrapper code
184 // from the user when we render diagnostics with Clang.
185 m_start_marker = "#line 1 \"" + filename.str() + "\"\n";
186 m_end_marker = g_expression_suffix;
187}
188
189namespace {
190/// Allows checking if a token is contained in a given expression.
191class TokenVerifier {
192 /// The tokens we found in the expression.
193 llvm::StringSet<> m_tokens;
194
195public:
196 TokenVerifier(std::string body);
197 /// Returns true iff the given expression body contained a token with the
198 /// given content.
199 bool hasToken(llvm::StringRef token) const {
200 return m_tokens.find(token) != m_tokens.end();
201 }
202};
203} // namespace
204
205TokenVerifier::TokenVerifier(std::string body) {
206 using namespace clang;
207
208 // We only care about tokens and not their original source locations. If we
209 // move the whole expression to only be in one line we can simplify the
210 // following code that extracts the token contents.
211 std::replace(body.begin(), body.end(), '\n', ' ');
212 std::replace(body.begin(), body.end(), '\r', ' ');
213
214 FileSystemOptions file_opts;
215 FileManager file_mgr(file_opts,
216 FileSystem::Instance().GetVirtualFileSystem());
217
218 // Let's build the actual source code Clang needs and setup some utility
219 // objects.
220 llvm::IntrusiveRefCntPtr<DiagnosticIDs> diag_ids(new DiagnosticIDs());
221 llvm::IntrusiveRefCntPtr<DiagnosticOptions> diags_opts(
222 new DiagnosticOptions());
223 DiagnosticsEngine diags(diag_ids, diags_opts);
224 clang::SourceManager SM(diags, file_mgr);
225 auto buf = llvm::MemoryBuffer::getMemBuffer(body);
226
227 FileID FID = SM.createFileID(buf->getMemBufferRef());
228
229 // Let's just enable the latest ObjC and C++ which should get most tokens
230 // right.
231 LangOptions Opts;
232 Opts.ObjC = true;
233 Opts.DollarIdents = true;
234 Opts.CPlusPlus17 = true;
235 Opts.LineComment = true;
236
237 Lexer lex(FID, buf->getMemBufferRef(), SM, Opts);
238
239 Token token;
240 bool exit = false;
241 while (!exit) {
242 // Returns true if this is the last token we get from the lexer.
243 exit = lex.LexFromRawLexer(token);
244
245 // Extract the column number which we need to extract the token content.
246 // Our expression is just one line, so we don't need to handle any line
247 // numbers here.
248 bool invalid = false;
249 unsigned start = SM.getSpellingColumnNumber(token.getLocation(), &invalid);
250 if (invalid)
251 continue;
252 // Column numbers start at 1, but indexes in our string start at 0.
253 --start;
254
255 // Annotations don't have a length, so let's skip them.
256 if (token.isAnnotation())
257 continue;
258
259 // Extract the token string from our source code and store it.
260 std::string token_str = body.substr(start, token.getLength());
261 if (token_str.empty())
262 continue;
263 m_tokens.insert(token_str);
264 }
265}
266
267void ClangExpressionSourceCode::AddLocalVariableDecls(
268 const lldb::VariableListSP &var_list_sp, StreamString &stream,
269 const std::string &expr) const {
270 TokenVerifier tokens(expr);
271
272 for (size_t i = 0; i < var_list_sp->GetSize(); i++) {
273 lldb::VariableSP var_sp = var_list_sp->GetVariableAtIndex(i);
274
275 ConstString var_name = var_sp->GetName();
276
277
278 // We can check for .block_descriptor w/o checking for langauge since this
279 // is not a valid identifier in either C or C++.
280 if (!var_name || var_name == ".block_descriptor")
281 continue;
282
283 if (!expr.empty() && !tokens.hasToken(var_name.GetStringRef()))
284 continue;
285
286 const bool is_objc = m_wrap_kind == WrapKind::ObjCInstanceMethod ||
287 m_wrap_kind == WrapKind::ObjCStaticMethod;
288 if ((var_name == "self" || var_name == "_cmd") && is_objc)
289 continue;
290
291 if (var_name == "this" && m_wrap_kind == WrapKind::CppMemberFunction)
292 continue;
293
294 stream.Printf("using $__lldb_local_vars::%s;\n", var_name.AsCString());
295 }
296}
297
298bool ClangExpressionSourceCode::GetText(
299 std::string &text, ExecutionContext &exe_ctx, bool add_locals,
300 bool force_add_all_locals, llvm::ArrayRef<std::string> modules) const {
301 const char *target_specific_defines = "typedef signed char BOOL;\n";
302 std::string module_macros;
303 llvm::raw_string_ostream module_macros_stream(module_macros);
304
305 Target *target = exe_ctx.GetTargetPtr();
1
'target' initialized here
306 if (target) {
2
Assuming 'target' is null
3
Taking false branch
307 if (target->GetArchitecture().GetMachine() == llvm::Triple::aarch64 ||
308 target->GetArchitecture().GetMachine() == llvm::Triple::aarch64_32) {
309 target_specific_defines = "typedef bool BOOL;\n";
310 }
311 if (target->GetArchitecture().GetMachine() == llvm::Triple::x86_64) {
312 if (lldb::PlatformSP platform_sp = target->GetPlatform()) {
313 if (platform_sp->GetPluginName() == "ios-simulator") {
314 target_specific_defines = "typedef bool BOOL;\n";
315 }
316 }
317 }
318
319 auto *persistent_vars = llvm::cast<ClangPersistentVariables>(
320 target->GetPersistentExpressionStateForLanguage(lldb::eLanguageTypeC));
321 std::shared_ptr<ClangModulesDeclVendor> decl_vendor =
322 persistent_vars->GetClangModulesDeclVendor();
323 if (decl_vendor) {
324 const ClangModulesDeclVendor::ModuleVector &hand_imported_modules =
325 persistent_vars->GetHandLoadedClangModules();
326 ClangModulesDeclVendor::ModuleVector modules_for_macros;
327
328 for (ClangModulesDeclVendor::ModuleID module : hand_imported_modules) {
329 modules_for_macros.push_back(module);
330 }
331
332 if (target->GetEnableAutoImportClangModules()) {
333 if (StackFrame *frame = exe_ctx.GetFramePtr()) {
334 if (Block *block = frame->GetFrameBlock()) {
335 SymbolContext sc;
336
337 block->CalculateSymbolContext(&sc);
338
339 if (sc.comp_unit) {
340 StreamString error_stream;
341
342 decl_vendor->AddModulesForCompileUnit(
343 *sc.comp_unit, modules_for_macros, error_stream);
344 }
345 }
346 }
347 }
348
349 decl_vendor->ForEachMacro(
350 modules_for_macros,
351 [&module_macros_stream](llvm::StringRef token,
352 llvm::StringRef expansion) -> bool {
353 // Check if the macro hasn't already been defined in the
354 // g_expression_prefix (which defines a few builtin macros).
355 module_macros_stream << "#ifndef " << token << "\n";
356 module_macros_stream << expansion << "\n";
357 module_macros_stream << "#endif\n";
358 return false;
359 });
360 }
361 }
362
363 StreamString debug_macros_stream;
364 StreamString lldb_local_var_decls;
365 if (StackFrame *frame = exe_ctx.GetFramePtr()) {
4
Assuming 'frame' is non-null
5
Taking true branch
366 const SymbolContext &sc = frame->GetSymbolContext(
367 lldb::eSymbolContextCompUnit | lldb::eSymbolContextLineEntry);
368
369 if (sc.comp_unit && sc.line_entry.IsValid()) {
6
Assuming field 'comp_unit' is null
370 DebugMacros *dm = sc.comp_unit->GetDebugMacros();
371 if (dm) {
372 AddMacroState state(sc.line_entry.file, sc.line_entry.line);
373 AddMacros(dm, sc.comp_unit, state, debug_macros_stream);
374 }
375 }
376
377 if (add_locals)
7
Assuming 'add_locals' is true
8
Taking true branch
378 if (target->GetInjectLocalVariables(&exe_ctx)) {
9
Called C++ object pointer is null
379 lldb::VariableListSP var_list_sp =
380 frame->GetInScopeVariableList(false, true);
381 AddLocalVariableDecls(var_list_sp, lldb_local_var_decls,
382 force_add_all_locals ? "" : m_body);
383 }
384 }
385
386 if (m_wrap) {
387 // Generate a list of @import statements that will import the specified
388 // module into our expression.
389 std::string module_imports;
390 for (const std::string &module : modules) {
391 module_imports.append("@import ");
392 module_imports.append(module);
393 module_imports.append(";\n");
394 }
395
396 StreamString wrap_stream;
397
398 wrap_stream.Printf("%s\n%s\n%s\n%s\n%s\n", g_expression_prefix,
399 module_macros.c_str(), debug_macros_stream.GetData(),
400 target_specific_defines, m_prefix.c_str());
401
402 // First construct a tagged form of the user expression so we can find it
403 // later:
404 std::string tagged_body;
405 tagged_body.append(m_start_marker);
406 tagged_body.append(m_body);
407 tagged_body.append(m_end_marker);
408
409 switch (m_wrap_kind) {
410 case WrapKind::Function:
411 wrap_stream.Printf("%s"
412 "void \n"
413 "%s(void *$__lldb_arg) \n"
414 "{ \n"
415 " %s; \n"
416 "%s"
417 "} \n",
418 module_imports.c_str(), m_name.c_str(),
419 lldb_local_var_decls.GetData(), tagged_body.c_str());
420 break;
421 case WrapKind::CppMemberFunction:
422 wrap_stream.Printf("%s"
423 "void \n"
424 "$__lldb_class::%s(void *$__lldb_arg) \n"
425 "{ \n"
426 " %s; \n"
427 "%s"
428 "} \n",
429 module_imports.c_str(), m_name.c_str(),
430 lldb_local_var_decls.GetData(), tagged_body.c_str());
431 break;
432 case WrapKind::ObjCInstanceMethod:
433 wrap_stream.Printf(
434 "%s"
435 "@interface $__lldb_objc_class ($__lldb_category) \n"
436 "-(void)%s:(void *)$__lldb_arg; \n"
437 "@end \n"
438 "@implementation $__lldb_objc_class ($__lldb_category) \n"
439 "-(void)%s:(void *)$__lldb_arg \n"
440 "{ \n"
441 " %s; \n"
442 "%s"
443 "} \n"
444 "@end \n",
445 module_imports.c_str(), m_name.c_str(), m_name.c_str(),
446 lldb_local_var_decls.GetData(), tagged_body.c_str());
447 break;
448
449 case WrapKind::ObjCStaticMethod:
450 wrap_stream.Printf(
451 "%s"
452 "@interface $__lldb_objc_class ($__lldb_category) \n"
453 "+(void)%s:(void *)$__lldb_arg; \n"
454 "@end \n"
455 "@implementation $__lldb_objc_class ($__lldb_category) \n"
456 "+(void)%s:(void *)$__lldb_arg \n"
457 "{ \n"
458 " %s; \n"
459 "%s"
460 "} \n"
461 "@end \n",
462 module_imports.c_str(), m_name.c_str(), m_name.c_str(),
463 lldb_local_var_decls.GetData(), tagged_body.c_str());
464 break;
465 }
466
467 text = std::string(wrap_stream.GetString());
468 } else {
469 text.append(m_body);
470 }
471
472 return true;
473}
474
475bool ClangExpressionSourceCode::GetOriginalBodyBounds(
476 std::string transformed_text, size_t &start_loc, size_t &end_loc) {
477 start_loc = transformed_text.find(m_start_marker);
478 if (start_loc == std::string::npos)
479 return false;
480 start_loc += m_start_marker.size();
481 end_loc = transformed_text.find(m_end_marker);
482 return end_loc != std::string::npos;
483}