[clang] [clang][Analyzer][NFC] Simplify preDefault/preFseek/preFreadFwrite of StreamChecker (PR #71394)

[Ben Shi via cfe-commits]

https://github.com/benshi001 updated https://github.com/llvm/llvm-project/pull/71394

>From 56d5604cf0442919d62def08c233e8d48b654885 Mon Sep 17 00:00:00 2001
From: Ben Shi <bennshi at tencent.com>
Date: Mon, 6 Nov 2023 21:49:36 +0800
Subject: [PATCH] [clang][Analyzer][NFC] Simplify
 preDefault/preFseek/preFreadFwrite of StreamChecker

---
 .../StaticAnalyzer/Checkers/StreamChecker.cpp | 33 +++++++++----------
 1 file changed, 16 insertions(+), 17 deletions(-)

diff --git a/clang/lib/StaticAnalyzer/Checkers/StreamChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/StreamChecker.cpp
index 898906977ba9bb6..877e5d2a09f398c 100644
--- a/clang/lib/StaticAnalyzer/Checkers/StreamChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/StreamChecker.cpp
@@ -342,6 +342,11 @@ class StreamChecker : public Checker<check::PreCall, eval::Call,
                          CheckerContext &C,
                          const StreamErrorState &ErrorKind) const;
 
+  /// Perform some common checks for all preXXX functions.
+  bool basicCheck(const FnDescription *Desc, const CallEvent &Call,
+                  CheckerContext &C, ProgramStateRef &State,
+                  SVal &StreamVal) const;
+
   /// Check that the stream (in StreamVal) is not NULL.
   /// If it can only be NULL a fatal error is emitted and nullptr returned.
   /// Otherwise the return value is a new state where the stream is constrained
@@ -639,12 +644,7 @@ void StreamChecker::preFreadFwrite(const FnDescription *Desc,
                                    bool IsFread) const {
   ProgramStateRef State = C.getState();
   SVal StreamVal = getStreamArg(Desc, Call);
-  State = ensureStreamNonNull(StreamVal, Call.getArgExpr(Desc->StreamArgNo), C,
-                              State);
-  if (!State)
-    return;
-  State = ensureStreamOpened(StreamVal, C, State);
-  if (!State)
+  if (!basicCheck(Desc, Call, C, State, StreamVal))
     return;
   State = ensureNoFilePositionIndeterminate(StreamVal, C, State);
   if (!State)
@@ -749,12 +749,7 @@ void StreamChecker::preFseek(const FnDescription *Desc, const CallEvent &Call,
                              CheckerContext &C) const {
   ProgramStateRef State = C.getState();
   SVal StreamVal = getStreamArg(Desc, Call);
-  State = ensureStreamNonNull(StreamVal, Call.getArgExpr(Desc->StreamArgNo), C,
-                              State);
-  if (!State)
-    return;
-  State = ensureStreamOpened(StreamVal, C, State);
-  if (!State)
+  if (!basicCheck(Desc, Call, C, State, StreamVal))
     return;
   State = ensureFseekWhenceCorrect(Call.getArgSVal(2), C, State);
   if (!State)
@@ -1002,15 +997,19 @@ void StreamChecker::preDefault(const FnDescription *Desc, const CallEvent &Call,
                                CheckerContext &C) const {
   ProgramStateRef State = C.getState();
   SVal StreamVal = getStreamArg(Desc, Call);
+  if (basicCheck(Desc, Call, C, State, StreamVal))
+    C.addTransition(State);
+}
+
+bool StreamChecker::basicCheck(const FnDescription *Desc, const CallEvent &Call,
+                               CheckerContext &C, ProgramStateRef &State,
+                               SVal &StreamVal) const {
   State = ensureStreamNonNull(StreamVal, Call.getArgExpr(Desc->StreamArgNo), C,
                               State);
   if (!State)
-    return;
+    return false;
   State = ensureStreamOpened(StreamVal, C, State);
-  if (!State)
-    return;
-
-  C.addTransition(State);
+  return State != nullptr;
 }
 
 void StreamChecker::evalSetFeofFerror(const FnDescription *Desc,