[analyzer] Fix analyzer warnings on analyzer.

Write tests for the actual crash that was found. Write comments and refactor
code around 17 style bugs and suppress 3 false positives.

Differential Revision: https://reviews.llvm.org/D66847

llvm-svn: 370246

1 files changed, 18 insertions, 9 deletions

diff --git a/clang/lib/StaticAnalyzer/Checkers/CStringSyntaxChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/CStringSyntaxChecker.cpp
index b828ac05923..d84fcc69a49 100644
--- a/clang/lib/StaticAnalyzer/Checkers/CStringSyntaxChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/CStringSyntaxChecker.cpp
@@ -156,14 +156,21 @@ bool WalkAST::containsBadStrlcpyStrlcatPattern(const CallExpr *CE) {
   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());
+  const auto *DstArgDRE = dyn_cast<DeclRefExpr>(DstArg->IgnoreParenImpCasts());
+  const auto *LenArgDRE =
+      dyn_cast<DeclRefExpr>(LenArg->IgnoreParenLValueCasts());
   uint64_t DstOff = 0;
   if (isSizeof(LenArg, DstArg))
     return false;
+
   // - size_t dstlen = sizeof(dst)
-  if (LenArgDecl) {
-    const auto *LenArgVal = dyn_cast<VarDecl>(LenArgDecl->getDecl());
+  if (LenArgDRE) {
+    const auto *LenArgVal = dyn_cast<VarDecl>(LenArgDRE->getDecl());
+    // If it's an EnumConstantDecl instead, then we're missing out on something.
+    if (!LenArgVal) {
+      assert(isa<EnumConstantDecl>(LenArgDRE->getDecl()));
+      return false;
+    }
     if (LenArgVal->getInit())
       LenArg = LenArgVal->getInit();
   }
@@ -177,9 +184,10 @@ bool WalkAST::containsBadStrlcpyStrlcatPattern(const CallExpr *CE) {
     // Case when there is pointer arithmetic on the destination buffer
     // especially when we offset from the base decreasing the
     // buffer length accordingly.
-    if (!DstArgDecl) {
-      if (const auto *BE = dyn_cast<BinaryOperator>(DstArg->IgnoreParenImpCasts())) {
-        DstArgDecl = dyn_cast<DeclRefExpr>(BE->getLHS()->IgnoreParenImpCasts());
+    if (!DstArgDRE) {
+      if (const auto *BE =
+              dyn_cast<BinaryOperator>(DstArg->IgnoreParenImpCasts())) {
+        DstArgDRE = dyn_cast<DeclRefExpr>(BE->getLHS()->IgnoreParenImpCasts());
         if (BE->getOpcode() == BO_Add) {
           if ((IL = dyn_cast<IntegerLiteral>(BE->getRHS()->IgnoreParenImpCasts()))) {
             DstOff = IL->getValue().getZExtValue();
@@ -187,8 +195,9 @@ bool WalkAST::containsBadStrlcpyStrlcatPattern(const CallExpr *CE) {
         }
       }
     }
-    if (DstArgDecl) {
-      if (const auto *Buffer = dyn_cast<ConstantArrayType>(DstArgDecl->getType())) {
+    if (DstArgDRE) {
+      if (const auto *Buffer =
+              dyn_cast<ConstantArrayType>(DstArgDRE->getType())) {
         ASTContext &C = BR.getContext();
         uint64_t BufferLen = C.getTypeSize(Buffer) / 8;
         auto RemainingBufferLen = BufferLen - DstOff;