From b3b56bb9600d5626b706cfb3d3b5cc365cafa4dd Mon Sep 17 00:00:00 2001
From: Anna Zaks <ganna@apple.com>
Date: Thu, 3 May 2012 18:21:28 +0000
Subject: [PATCH] [analyzer] CString Checker: Do not split the path unless the
 user specifically checks for equality to null.

Enforcing this general practice, which keeps the analyzer less
noisy, in the CString Checker. This change suppresses "Assigned value is
garbage or undefined" warning in the added test case.

llvm-svn: 156085
---
 clang/lib/StaticAnalyzer/Checkers/CStringChecker.cpp |  3 ++-
 clang/test/Analysis/bstring.c                        | 10 ++++++++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/clang/lib/StaticAnalyzer/Checkers/CStringChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/CStringChecker.cpp
index 9eb7edffe6df..bd1a56a1aa05 100644
--- a/clang/lib/StaticAnalyzer/Checkers/CStringChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/CStringChecker.cpp
@@ -901,9 +901,10 @@ void CStringChecker::evalCopyCommon(CheckerContext &C,
 
   // If the size is zero, there won't be any actual memory access, so
   // just bind the return value to the destination buffer and return.
-  if (stateZeroSize) {
+  if (stateZeroSize && !stateNonZeroSize) {
     stateZeroSize = stateZeroSize->BindExpr(CE, LCtx, destVal);
     C.addTransition(stateZeroSize);
+    return;
   }
 
   // If the size can be nonzero, we have to check the other arguments.
diff --git a/clang/test/Analysis/bstring.c b/clang/test/Analysis/bstring.c
index 833c917613ed..87c91613a5d5 100644
--- a/clang/test/Analysis/bstring.c
+++ b/clang/test/Analysis/bstring.c
@@ -428,3 +428,13 @@ void bcopy2 () {
 
   bcopy(src, dst, 4); // expected-warning{{overflow}}
 }
+
+void *malloc(size_t);
+void free(void *);
+char radar_11125445_memcopythenlogfirstbyte(const char *input, size_t length) {
+  char *bytes = malloc(sizeof(char) * (length + 1));
+  memcpy(bytes, input, length);
+  char x = bytes[0]; // no warning
+  free(bytes);
+  return x;
+}