From c433011e02d44ed31c20761ce897faea535bec31 Mon Sep 17 00:00:00 2001
From: George Karpenkov <ekarpenkov@apple.com>
Date: Thu, 23 Aug 2018 00:02:35 +0000
Subject: Revert "[CStringSyntaxChecker] Check strlcat sizeof check"

This reverts commit 3073790e87378fea9a68fb052185fec9596ef135.

The check is not correct, strlact(dest, "mystr", sizeof(dest)) is fine.

llvm-svn: 340501
---
 .../Checkers/CStringSyntaxChecker.cpp              | 54 ++--------------------
 1 file changed, 4 insertions(+), 50 deletions(-)

(limited to 'clang/lib/StaticAnalyzer/Checkers/CStringSyntaxChecker.cpp')

diff --git a/clang/lib/StaticAnalyzer/Checkers/CStringSyntaxChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/CStringSyntaxChecker.cpp
index 2763408face..8b4aa857e77 100644
--- a/clang/lib/StaticAnalyzer/Checkers/CStringSyntaxChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/CStringSyntaxChecker.cpp
@@ -90,16 +90,7 @@ class WalkAST: public StmtVisitor<WalkAST> {
   ///   strlcpy(dst, "abcd", 4);
   ///   strlcpy(dst + 3, "abcd", 2);
   ///   strlcpy(dst, "abcd", cpy);
-  /// Identify erroneous patterns in the last argument to strlcat - the number
-  /// of bytes to copy.
-  /// The bad pattern checked is when the last argument is basically
-  /// pointing to the destination buffer size or argument larger or
-  /// equal to.  
-  ///   char dst[2];
-  ///   strlcat(dst, src2, sizeof(dst));
-  ///   strlcat(dst, src2, 2);
-  ///   strlcat(dst, src2, 10);
-  bool containsBadStrlcpyStrlcatPattern(const CallExpr *CE);
+  bool containsBadStrlcpyPattern(const CallExpr *CE);
 
 public:
   WalkAST(const CheckerBase *Checker, BugReporter &BR, AnalysisDeclContext *AC)
@@ -151,21 +142,15 @@ bool WalkAST::containsBadStrncatPattern(const CallExpr *CE) {
   return false;
 }
 
-bool WalkAST::containsBadStrlcpyStrlcatPattern(const CallExpr *CE) {
+bool WalkAST::containsBadStrlcpyPattern(const CallExpr *CE) {
   if (CE->getNumArgs() != 3)
     return false;
-  const FunctionDecl *FD = CE->getDirectCallee();
-  bool Append = CheckerContext::isCLibraryFunction(FD, "strlcat");
   const Expr *DstArg = CE->getArg(0);
   const Expr *LenArg = CE->getArg(2);
 
   const auto *DstArgDecl = dyn_cast<DeclRefExpr>(DstArg->IgnoreParenImpCasts());
   const auto *LenArgDecl = dyn_cast<DeclRefExpr>(LenArg->IgnoreParenLValueCasts());
   uint64_t DstOff = 0;
-  // - sizeof(dst)
-  // strlcat appends at most size - strlen(dst) - 1
-  if (Append && isSizeof(LenArg, DstArg))
-    return true;
   // - size_t dstlen = sizeof(dst)
   if (LenArgDecl) {
     const auto *LenArgVal = dyn_cast<VarDecl>(LenArgDecl->getDecl());
@@ -196,10 +181,7 @@ bool WalkAST::containsBadStrlcpyStrlcatPattern(const CallExpr *CE) {
       if (const auto *Buffer = dyn_cast<ConstantArrayType>(DstArgDecl->getType())) {
         ASTContext &C = BR.getContext();
         uint64_t BufferLen = C.getTypeSize(Buffer) / 8;
-        auto RemainingBufferLen = BufferLen - DstOff;
-        if (Append)
-          RemainingBufferLen -= 1;
-        if (RemainingBufferLen < ILRawVal)
+        if ((BufferLen - DstOff) < ILRawVal)
           return true;
       }
     }
@@ -238,7 +220,7 @@ void WalkAST::VisitCallExpr(CallExpr *CE) {
                          LenArg->getSourceRange());
     }
   } else if (CheckerContext::isCLibraryFunction(FD, "strlcpy")) {
-    if (containsBadStrlcpyStrlcatPattern(CE)) {
+    if (containsBadStrlcpyPattern(CE)) {
       const Expr *DstArg = CE->getArg(0);
       const Expr *LenArg = CE->getArg(2);
       PathDiagnosticLocation Loc =
@@ -252,34 +234,6 @@ void WalkAST::VisitCallExpr(CallExpr *CE) {
       if (!DstName.empty())
         os << "Replace with the value 'sizeof(" << DstName << ")` or lower";
 
-      BR.EmitBasicReport(FD, Checker, "Anti-pattern in the argument",
-                         "C String API", os.str(), Loc,
-                         LenArg->getSourceRange());
-    }
-  } else if (CheckerContext::isCLibraryFunction(FD, "strlcat")) {
-    if (containsBadStrlcpyStrlcatPattern(CE)) {
-      const Expr *DstArg = CE->getArg(0);
-      const Expr *LenArg = CE->getArg(2);
-      PathDiagnosticLocation Loc =
-        PathDiagnosticLocation::createBegin(LenArg, BR.getSourceManager(), AC);
-
-      StringRef DstName = getPrintableName(DstArg);
-      StringRef LenName = getPrintableName(LenArg);
-
-      SmallString<256> S;
-      llvm::raw_svector_ostream os(S);
-      os << "The third argument allows to potentially copy more bytes than it should. ";
-      os << "Replace with the value ";
-      if (!LenName.empty())
-        os << "'" << LenName << "'";
-      else
-        os << " <size> ";
-      if (!DstName.empty())
-        os << " - strlen(" << DstName << ")";
-      else
-        os << " - strlen(<destination buffer>)";
-      os << " - 1 or lower";
-
       BR.EmitBasicReport(FD, Checker, "Anti-pattern in the argument",
                          "C String API", os.str(), Loc,
                          LenArg->getSourceRange());
-- 
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