From d6b8708643219776b1f0f41df32c5eccf065ed5b Mon Sep 17 00:00:00 2001
From: Ted Kremenek <kremenek@apple.com>
Date: Mon, 25 Jan 2010 04:41:41 +0000
Subject: Split libAnalysis into two libraries: libAnalysis and libChecker.

(1) libAnalysis is a generic analysis library that can be used by
    Sema.  It defines the CFG, basic dataflow analysis primitives, and
    inexpensive flow-sensitive analyses (e.g. LiveVariables).

(2) libChecker contains the guts of the static analyzer, incuding the
    path-sensitive analysis engine and domain-specific checks.

Now any clients that want to use the frontend to build their own tools
don't need to link in the entire static analyzer.

This change exposes various obvious cleanups that can be made to the
layout of files and headers in libChecker.  More changes pending.  :)

This change also exposed a layering violation between AnalysisContext
and MemRegion.  BlockInvocationContext shouldn't explicitly know about
BlockDataRegions.  For now I've removed the BlockDataRegion* from
BlockInvocationContext (removing context-sensitivity; although this
wasn't used yet).  We need to have a better way to extend
BlockInvocationContext (and any LocationContext) to add
context-sensitivty.

llvm-svn: 94406
---
 clang/lib/Checker/CheckSizeofPointer.cpp | 71 ++++++++++++++++++++++++++++++++
 1 file changed, 71 insertions(+)
 create mode 100644 clang/lib/Checker/CheckSizeofPointer.cpp

(limited to 'clang/lib/Checker/CheckSizeofPointer.cpp')

diff --git a/clang/lib/Checker/CheckSizeofPointer.cpp b/clang/lib/Checker/CheckSizeofPointer.cpp
new file mode 100644
index 00000000000..3f40235e0b3
--- /dev/null
+++ b/clang/lib/Checker/CheckSizeofPointer.cpp
@@ -0,0 +1,71 @@
+//==- CheckSizeofPointer.cpp - Check for sizeof on pointers ------*- C++ -*-==//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file defines a check for unintended use of sizeof() on pointer
+//  expressions.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Checker/PathSensitive/BugReporter.h"
+#include "clang/AST/StmtVisitor.h"
+#include "clang/Checker/LocalCheckers.h"
+
+using namespace clang;
+
+namespace {
+class WalkAST : public StmtVisitor<WalkAST> {
+  BugReporter &BR;
+
+public:
+  WalkAST(BugReporter &br) : BR(br) {}
+  void VisitSizeOfAlignOfExpr(SizeOfAlignOfExpr *E);
+  void VisitStmt(Stmt *S) { VisitChildren(S); }
+  void VisitChildren(Stmt *S);
+};
+}
+
+void WalkAST::VisitChildren(Stmt *S) {
+  for (Stmt::child_iterator I = S->child_begin(), E = S->child_end(); I!=E; ++I)
+    if (Stmt *child = *I)
+      Visit(child);
+}
+
+// CWE-467: Use of sizeof() on a Pointer Type
+void WalkAST::VisitSizeOfAlignOfExpr(SizeOfAlignOfExpr *E) {
+  if (!E->isSizeOf())
+    return;
+
+  // If an explicit type is used in the code, usually the coder knows what he is
+  // doing.
+  if (E->isArgumentType())
+    return;
+
+  QualType T = E->getTypeOfArgument();
+  if (T->isPointerType()) {
+
+    // Many false positives have the form 'sizeof *p'. This is reasonable 
+    // because people know what they are doing when they intentionally 
+    // dereference the pointer.
+    Expr *ArgEx = E->getArgumentExpr();
+    if (!isa<DeclRefExpr>(ArgEx->IgnoreParens()))
+      return;
+
+    SourceRange R = ArgEx->getSourceRange();
+    BR.EmitBasicReport("Potential unintended use of sizeof() on pointer type",
+                       "Logic",
+                       "The code calls sizeof() on a pointer type. "
+                       "This can produce an unexpected result.",
+                       E->getLocStart(), &R, 1);
+  }
+}
+
+void clang::CheckSizeofPointer(const Decl *D, BugReporter &BR) {
+  WalkAST walker(BR);
+  walker.Visit(D->getBody());
+}
-- 
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