[clang] [clang][analyzer] Model more getline/getdelim pre and postconditions (PR #83027)

[Alejandro Álvarez Ayllón via cfe-commits]

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@@ -1158,6 +1173,118 @@ void StreamChecker::evalUngetc(const FnDescription *Desc, const CallEvent &Call,
   C.addTransition(StateFailed);
 }
 
+ProgramStateRef
+StreamChecker::ensurePtrNotNull(SVal PtrVal, const Expr *PtrExpr,
+                                CheckerContext &C, ProgramStateRef State,
+                                const StringRef PtrDescr) const {
+  const auto Ptr = PtrVal.getAs<DefinedSVal>();
+  if (!Ptr)
+    return nullptr;
+
+  assert(PtrExpr && "Expected an argument");
+
+  const auto [PtrNotNull, PtrNull] = State->assume(*Ptr);
+  if (!PtrNotNull && PtrNull) {
+    if (ExplodedNode *N = C.generateErrorNode(PtrNull)) {
+      auto R = std::make_unique<PathSensitiveBugReport>(
+          BT_SizeNull, (PtrDescr + " pointer might be NULL.").str(), N);
+      bugreporter::trackExpressionValue(N, PtrExpr, *R);
+      C.emitReport(std::move(R));
+    }
+    return nullptr;
+  }
+
+  return PtrNotNull;
+}
+
+ProgramStateRef StreamChecker::ensureSizeZeroIfLineNull(
+    SVal LinePtrPtrSVal, SVal SizePtrSVal, const Expr *LinePtrPtrExpr,
+    const Expr *SizePtrExpr, CheckerContext &C, ProgramStateRef State) const {
+  static constexpr char SizeNotZeroMsg[] =
+      "Line pointer might be null while n value is not zero";
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alejandro-alvarez-sonarsource wrote:

I have followed this advise after changing the function to follow POSIX 2018.

https://github.com/llvm/llvm-project/pull/83027