[clang] [clang][analyzer] Change modeling of 'fileno' in checkers. (PR #81842)

[Ben Shi via cfe-commits]

=?utf-8?q?Balázs_Kéri?= <balazs.keri at ericsson.com>
Message-ID:
In-Reply-To: <llvm.org/llvm/llvm-project/pull/81842 at github.com>


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@@ -1404,6 +1486,47 @@ void StreamChecker::evalFeofFerror(const FnDescription *Desc,
   }
 }
 
+void StreamChecker::evalFileno(const FnDescription *Desc, const CallEvent &Call,
+                               CheckerContext &C) const {
+  // Fileno should fail only if the passed pointer is invalid.
+  // Some of the preconditions are checked already in preDefault.
+  // Here we can assume that the operation does not fail.
+  // An added failure case causes many unexpected warnings because a file number
+  // becomes -1 that is not expected by the program.
+  // The stream error states are not modified by 'fileno', and not the 'errno'.
+  // (To ensure that errno is not changed, this evalCall is needed to not
+  // invalidate 'errno' like in a default case.)
+  ProgramStateRef State = C.getState();
+  SymbolRef StreamSym = getStreamArg(Desc, Call).getAsSymbol();
+  if (!StreamSym)
+    return;
+
+  const CallExpr *CE = dyn_cast_or_null<CallExpr>(Call.getOriginExpr());
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benshi001 wrote:

Shall we change to `StreamOperationEvaluator` which is introduced by your previous simplification patch ?

https://github.com/llvm/llvm-project/pull/81842