From 696550abd3890faa6a2695788532b76d32bfdc48 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Marjam=C3=A4ki?= <daniel@daniel-laptop.(none)>
Date: Fri, 17 Dec 2010 21:09:12 +0100
Subject: [PATCH] Fixed #2299 (false positive: possible nullpointer
 dereference)

---
 lib/checknullpointer.cpp | 21 ++++++++++++++++++++-
 test/testnullpointer.cpp |  8 ++++++++
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/lib/checknullpointer.cpp b/lib/checknullpointer.cpp
index 766c0243c..88a6d8a29 100644
--- a/lib/checknullpointer.cpp
+++ b/lib/checknullpointer.cpp
@@ -315,7 +315,21 @@ void CheckNullPointer::nullPointerStructByDeRefAndChec()
         else if (Token::Match(tok1->tokAt(-2), "%var% ( %var% . %var%") ||
                  Token::Match(tok1->previous(), ", %var% . %var%"))
         {
-
+            // Is the function return value taken by the pointer?
+            bool assignment = false;
+            const unsigned int varid1(tok1->varId());
+            const Token *tok2 = tok1->previous();
+            while (tok2 && !Token::Match(tok2, "[;{}]"))
+            {
+                if (Token::Match(tok2, "%varid% =", varid1))
+                {
+                    assignment = true;
+                    break;
+                }
+                tok2 = tok2->previous();
+            }
+            if (assignment)
+                continue;
         }
 
         // Goto next token
@@ -399,6 +413,11 @@ void CheckNullPointer::nullPointerByDeRefAndChec()
 
             for (const Token *tok1 = tok->previous(); tok1 && tok1 != decltok; tok1 = tok1->previous())
             {
+                if (tok1->str() == ")" && Token::Match(tok1->link()->tokAt(-3), "%varid% = %var%", varid))
+                {
+                    break;
+                }
+
                 if (tok1->varId() == varid)
                 {
                     bool unknown = false;
diff --git a/test/testnullpointer.cpp b/test/testnullpointer.cpp
index 1b12745ad..a355ac3c2 100644
--- a/test/testnullpointer.cpp
+++ b/test/testnullpointer.cpp
@@ -387,6 +387,14 @@ private:
               "        ;\n"
               "}\n");
         ASSERT_EQUALS("", errout.str());
+
+        check("void foo(x *p)\n"
+              "{\n"
+              "    p = bar(p->next);\n"
+              "    if (!p)\n"
+              "        ;\n"
+              "}\n");
+        ASSERT_EQUALS("", errout.str());
     }
 
     void nullpointer5()