1//=== LLVMConventionsChecker.cpp - Check LLVM codebase conventions ---*- C++ -*-
2//
3// The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This defines LLVMConventionsChecker, a bunch of small little checks
11// for checking specific coding conventions in the LLVM/Clang codebase.
12//
13//===----------------------------------------------------------------------===//
14
15#include "ClangSACheckers.h"
16#include "clang/StaticAnalyzer/Core/Checker.h"
17#include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
18#include "clang/AST/DeclTemplate.h"
19#include "clang/AST/StmtVisitor.h"
|
20#include <string>
21#include "llvm/ADT/StringRef.h"
|
| 20#include "llvm/ADT/SmallString.h" |
21
22using namespace clang;
23using namespace ento;
24
25//===----------------------------------------------------------------------===//
26// Generic type checking routines.
27//===----------------------------------------------------------------------===//
28
29static bool IsLLVMStringRef(QualType T) {
30 const RecordType *RT = T->getAs<RecordType>();
31 if (!RT)
32 return false;
33
34 return StringRef(QualType(RT, 0).getAsString()) ==
35 "class StringRef";
36}
37
38/// Check whether the declaration is semantically inside the top-level
39/// namespace named by ns.
40static bool InNamespace(const Decl *D, StringRef NS) {
41 const NamespaceDecl *ND = dyn_cast<NamespaceDecl>(D->getDeclContext());
42 if (!ND)
43 return false;
44 const IdentifierInfo *II = ND->getIdentifier();
45 if (!II || !II->getName().equals(NS))
46 return false;
47 return isa<TranslationUnitDecl>(ND->getDeclContext());
48}
49
50static bool IsStdString(QualType T) {
51 if (const ElaboratedType *QT = T->getAs<ElaboratedType>())
52 T = QT->getNamedType();
53
54 const TypedefType *TT = T->getAs<TypedefType>();
55 if (!TT)
56 return false;
57
58 const TypedefNameDecl *TD = TT->getDecl();
59
60 if (!InNamespace(TD, "std"))
61 return false;
62
63 return TD->getName() == "string";
64}
65
66static bool IsClangType(const RecordDecl *RD) {
67 return RD->getName() == "Type" && InNamespace(RD, "clang");
68}
69
70static bool IsClangDecl(const RecordDecl *RD) {
71 return RD->getName() == "Decl" && InNamespace(RD, "clang");
72}
73
74static bool IsClangStmt(const RecordDecl *RD) {
75 return RD->getName() == "Stmt" && InNamespace(RD, "clang");
76}
77
78static bool IsClangAttr(const RecordDecl *RD) {
79 return RD->getName() == "Attr" && InNamespace(RD, "clang");
80}
81
82static bool IsStdVector(QualType T) {
83 const TemplateSpecializationType *TS = T->getAs<TemplateSpecializationType>();
84 if (!TS)
85 return false;
86
87 TemplateName TM = TS->getTemplateName();
88 TemplateDecl *TD = TM.getAsTemplateDecl();
89
90 if (!TD || !InNamespace(TD, "std"))
91 return false;
92
93 return TD->getName() == "vector";
94}
95
96static bool IsSmallVector(QualType T) {
97 const TemplateSpecializationType *TS = T->getAs<TemplateSpecializationType>();
98 if (!TS)
99 return false;
100
101 TemplateName TM = TS->getTemplateName();
102 TemplateDecl *TD = TM.getAsTemplateDecl();
103
104 if (!TD || !InNamespace(TD, "llvm"))
105 return false;
106
107 return TD->getName() == "SmallVector";
108}
109
110//===----------------------------------------------------------------------===//
111// CHECK: a StringRef should not be bound to a temporary std::string whose
112// lifetime is shorter than the StringRef's.
113//===----------------------------------------------------------------------===//
114
115namespace {
116class StringRefCheckerVisitor : public StmtVisitor<StringRefCheckerVisitor> {
117 BugReporter &BR;
|
| 118 const Decl *DeclWithIssue; |
119public:
|
120 StringRefCheckerVisitor(BugReporter &br) : BR(br) {}
|
120 StringRefCheckerVisitor(const Decl *declWithIssue, BugReporter &br)
121 : BR(br), DeclWithIssue(declWithIssue) {} |
122 void VisitChildren(Stmt *S) {
123 for (Stmt::child_iterator I = S->child_begin(), E = S->child_end() ;
124 I != E; ++I)
125 if (Stmt *child = *I)
126 Visit(child);
127 }
128 void VisitStmt(Stmt *S) { VisitChildren(S); }
129 void VisitDeclStmt(DeclStmt *DS);
130private:
131 void VisitVarDecl(VarDecl *VD);
132};
133} // end anonymous namespace
134
135static void CheckStringRefAssignedTemporary(const Decl *D, BugReporter &BR) {
|
135 StringRefCheckerVisitor walker(BR);
|
| 136 StringRefCheckerVisitor walker(D, BR); |
137 walker.Visit(D->getBody());
138}
139
140void StringRefCheckerVisitor::VisitDeclStmt(DeclStmt *S) {
141 VisitChildren(S);
142
143 for (DeclStmt::decl_iterator I = S->decl_begin(), E = S->decl_end();I!=E; ++I)
144 if (VarDecl *VD = dyn_cast<VarDecl>(*I))
145 VisitVarDecl(VD);
146}
147
148void StringRefCheckerVisitor::VisitVarDecl(VarDecl *VD) {
149 Expr *Init = VD->getInit();
150 if (!Init)
151 return;
152
153 // Pattern match for:
154 // StringRef x = call() (where call returns std::string)
155 if (!IsLLVMStringRef(VD->getType()))
156 return;
157 ExprWithCleanups *Ex1 = dyn_cast<ExprWithCleanups>(Init);
158 if (!Ex1)
159 return;
160 CXXConstructExpr *Ex2 = dyn_cast<CXXConstructExpr>(Ex1->getSubExpr());
161 if (!Ex2 || Ex2->getNumArgs() != 1)
162 return;
163 ImplicitCastExpr *Ex3 = dyn_cast<ImplicitCastExpr>(Ex2->getArg(0));
164 if (!Ex3)
165 return;
166 CXXConstructExpr *Ex4 = dyn_cast<CXXConstructExpr>(Ex3->getSubExpr());
167 if (!Ex4 || Ex4->getNumArgs() != 1)
168 return;
169 ImplicitCastExpr *Ex5 = dyn_cast<ImplicitCastExpr>(Ex4->getArg(0));
170 if (!Ex5)
171 return;
172 CXXBindTemporaryExpr *Ex6 = dyn_cast<CXXBindTemporaryExpr>(Ex5->getSubExpr());
173 if (!Ex6 || !IsStdString(Ex6->getType()))
174 return;
175
176 // Okay, badness! Report an error.
177 const char *desc = "StringRef should not be bound to temporary "
178 "std::string that it outlives";
179 PathDiagnosticLocation VDLoc =
180 PathDiagnosticLocation::createBegin(VD, BR.getSourceManager());
|
180 BR.EmitBasicReport(desc, "LLVM Conventions", desc,
|
| 181 BR.EmitBasicReport(DeclWithIssue, desc, "LLVM Conventions", desc, |
182 VDLoc, Init->getSourceRange());
183}
184
185//===----------------------------------------------------------------------===//
186// CHECK: Clang AST nodes should not have fields that can allocate
187// memory.
188//===----------------------------------------------------------------------===//
189
190static bool AllocatesMemory(QualType T) {
191 return IsStdVector(T) || IsStdString(T) || IsSmallVector(T);
192}
193
194// This type checking could be sped up via dynamic programming.
195static bool IsPartOfAST(const CXXRecordDecl *R) {
196 if (IsClangStmt(R) || IsClangType(R) || IsClangDecl(R) || IsClangAttr(R))
197 return true;
198
199 for (CXXRecordDecl::base_class_const_iterator I = R->bases_begin(),
200 E = R->bases_end(); I!=E; ++I) {
201 CXXBaseSpecifier BS = *I;
202 QualType T = BS.getType();
203 if (const RecordType *baseT = T->getAs<RecordType>()) {
204 CXXRecordDecl *baseD = cast<CXXRecordDecl>(baseT->getDecl());
205 if (IsPartOfAST(baseD))
206 return true;
207 }
208 }
209
210 return false;
211}
212
213namespace {
214class ASTFieldVisitor {
215 SmallVector<FieldDecl*, 10> FieldChain;
216 const CXXRecordDecl *Root;
217 BugReporter &BR;
218public:
219 ASTFieldVisitor(const CXXRecordDecl *root, BugReporter &br)
220 : Root(root), BR(br) {}
221
222 void Visit(FieldDecl *D);
223 void ReportError(QualType T);
224};
225} // end anonymous namespace
226
227static void CheckASTMemory(const CXXRecordDecl *R, BugReporter &BR) {
228 if (!IsPartOfAST(R))
229 return;
230
231 for (RecordDecl::field_iterator I = R->field_begin(), E = R->field_end();
232 I != E; ++I) {
233 ASTFieldVisitor walker(R, BR);
234 walker.Visit(*I);
235 }
236}
237
238void ASTFieldVisitor::Visit(FieldDecl *D) {
239 FieldChain.push_back(D);
240
241 QualType T = D->getType();
242
243 if (AllocatesMemory(T))
244 ReportError(T);
245
246 if (const RecordType *RT = T->getAs<RecordType>()) {
247 const RecordDecl *RD = RT->getDecl()->getDefinition();
248 for (RecordDecl::field_iterator I = RD->field_begin(), E = RD->field_end();
249 I != E; ++I)
250 Visit(*I);
251 }
252
253 FieldChain.pop_back();
254}
255
256void ASTFieldVisitor::ReportError(QualType T) {
|
256 llvm::SmallString<1024> buf;
|
| 257 SmallString<1024> buf; |
258 llvm::raw_svector_ostream os(buf);
259
260 os << "AST class '" << Root->getName() << "' has a field '"
261 << FieldChain.front()->getName() << "' that allocates heap memory";
262 if (FieldChain.size() > 1) {
263 os << " via the following chain: ";
264 bool isFirst = true;
265 for (SmallVectorImpl<FieldDecl*>::iterator I=FieldChain.begin(),
266 E=FieldChain.end(); I!=E; ++I) {
267 if (!isFirst)
268 os << '.';
269 else
270 isFirst = false;
271 os << (*I)->getName();
272 }
273 }
274 os << " (type " << FieldChain.back()->getType().getAsString() << ")";
275 os.flush();
276
277 // Note that this will fire for every translation unit that uses this
278 // class. This is suboptimal, but at least scan-build will merge
279 // duplicate HTML reports. In the future we need a unified way of merging
280 // duplicate reports across translation units. For C++ classes we cannot
281 // just report warnings when we see an out-of-line method definition for a
282 // class, as that heuristic doesn't always work (the complete definition of
283 // the class may be in the header file, for example).
284 PathDiagnosticLocation L = PathDiagnosticLocation::createBegin(
285 FieldChain.front(), BR.getSourceManager());
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285 BR.EmitBasicReport("AST node allocates heap memory", "LLVM Conventions",
|
| 286 BR.EmitBasicReport(Root, "AST node allocates heap memory", "LLVM Conventions", |
287 os.str(), L);
288}
289
290//===----------------------------------------------------------------------===//
291// LLVMConventionsChecker
292//===----------------------------------------------------------------------===//
293
294namespace {
295class LLVMConventionsChecker : public Checker<
296 check::ASTDecl<CXXRecordDecl>,
297 check::ASTCodeBody > {
298public:
299 void checkASTDecl(const CXXRecordDecl *R, AnalysisManager& mgr,
300 BugReporter &BR) const {
301 if (R->isCompleteDefinition())
302 CheckASTMemory(R, BR);
303 }
304
305 void checkASTCodeBody(const Decl *D, AnalysisManager& mgr,
306 BugReporter &BR) const {
307 CheckStringRefAssignedTemporary(D, BR);
308 }
309};
310}
311
312void ento::registerLLVMConventionsChecker(CheckerManager &mgr) {
313 mgr.registerChecker<LLVMConventionsChecker>();
314}
|