From ac7583ae2b142a8e95a2150ef5f702eea6fee827 Mon Sep 17 00:00:00 2001
From: Devin Coughlin <dcoughlin@apple.com>
Date: Sat, 17 Dec 2016 01:08:17 +0000
Subject: [PATCH] [analyzer] UnixAPIChecker: Don't diagnose for functions in
 C++ namespaces

Update the UnixAPIChecker to not diagnose for calls to functions that
are declared in C++ namespaces. This avoids false positives when a
namespaced function has the same name as a Unix API.

This address PR28331.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@290023 91177308-0d34-0410-b5e6-96231b3b80d8
---
 .../Checkers/UnixAPIChecker.cpp               |  6 ++
 test/Analysis/unix-api.cpp                    | 62 +++++++++++++++++++
 2 files changed, 68 insertions(+)
 create mode 100644 test/Analysis/unix-api.cpp

diff --git a/lib/StaticAnalyzer/Checkers/UnixAPIChecker.cpp b/lib/StaticAnalyzer/Checkers/UnixAPIChecker.cpp
index 0945bbf09f..26bf597bd9 100644
--- a/lib/StaticAnalyzer/Checkers/UnixAPIChecker.cpp
+++ b/lib/StaticAnalyzer/Checkers/UnixAPIChecker.cpp
@@ -427,6 +427,12 @@ void UnixAPIChecker::checkPreStmt(const CallExpr *CE,
   if (!FD || FD->getKind() != Decl::Function)
     return;
 
+  // Don't treat functions in namespaces with the same name a Unix function
+  // as a call to the Unix function.
+  const DeclContext *NamespaceCtx = FD->getEnclosingNamespaceContext();
+  if (NamespaceCtx && isa<NamespaceDecl>(NamespaceCtx))
+    return;
+
   StringRef FName = C.getCalleeName(FD);
   if (FName.empty())
     return;
diff --git a/test/Analysis/unix-api.cpp b/test/Analysis/unix-api.cpp
new file mode 100644
index 0000000000..1c8f99632c
--- /dev/null
+++ b/test/Analysis/unix-api.cpp
@@ -0,0 +1,62 @@
+// RUN: %clang_cc1 -analyze -analyzer-checker=core,unix.API -verify %s
+extern "C" {
+#ifndef O_RDONLY
+#define O_RDONLY 0
+#endif
+
+#ifndef NULL
+#define NULL ((void*) 0)
+#endif
+
+int open(const char *, int, ...);
+int close(int fildes);
+
+} // extern "C"
+
+namespace MyNameSpace {
+int open(const char *a, int b, int c, int d);
+}
+
+void unix_open(const char *path) {
+  int fd;
+  fd = open(path, O_RDONLY); // no-warning
+  if (fd > -1)
+    close(fd);
+}
+
+void unix_open_misuse(const char *path) {
+  int fd;
+  int mode = 0x0;
+  fd = open(path, O_RDONLY, mode, NULL); // expected-warning{{Call to 'open' with more than 3 arguments}}
+  if (fd > -1)
+    close(fd);
+}
+
+// Don't treat open() in namespaces as the POSIX open()
+void namespaced_open(const char *path) {
+  MyNameSpace::open("Hi", 2, 3, 4); // no-warning
+
+  using namespace MyNameSpace;
+
+  open("Hi", 2, 3, 4); // no-warning
+
+  int fd;
+  int mode = 0x0;
+  fd = ::open(path, O_RDONLY, mode, NULL); // expected-warning{{Call to 'open' with more than 3 arguments}}
+  if (fd > -1)
+    close(fd);
+}
+
+class MyClass {
+public:
+  static int open(const char *a, int b, int c, int d);
+
+  int open(int a, int, int c, int d);
+};
+
+void class_qualified_open() {
+  MyClass::open("Hi", 2, 3, 4); // no-warning
+
+  MyClass mc;
+  mc.open(1, 2, 3, 4); // no-warning
+}
-- 
2.40.0