[clang-tidy] Add a close-on-exec check on epoll_create() in Android module.

[yawanng]

Summary

epoll_create() is better to be replaced by epoll_create1() with EPOLL_CLOEXEC flag to avoid file descriptor leakage.

[Eugene.Zelenko]

docs/ReleaseNotes.rst

60

Please sort checks in alphabetical order.

[alexfh]

See the comment on D35372.

[alexfh]

LG with a nit.

clang-tidy/android/CloexecEpollCreateCheck.cpp

28–32

nit: Please remove argument comments, they don't add any useful information.

[chh]

clang-tidy/android/CloexecEpollCreateCheck.cpp

28–32

Done.

clang-tidy/android/AndroidTidyModule.cpp

 #include "../ClangTidyModule.h"
 #include "../ClangTidyModuleRegistry.h"
 #include "CloexecCreatCheck.h"
+#include "CloexecEpollCreateCheck.h"
 #include "CloexecFopenCheck.h"
 #include "CloexecOpenCheck.h"
 #include "CloexecSocketCheck.h"

 public:
   void addCheckFactories(ClangTidyCheckFactories &CheckFactories) override {
     CheckFactories.registerCheck<CloexecCreatCheck>("android-cloexec-creat");
+    CheckFactories.registerCheck<CloexecEpollCreateCheck>(
+        "android-cloexec-epoll-create");
     CheckFactories.registerCheck<CloexecFopenCheck>("android-cloexec-fopen");
     CheckFactories.registerCheck<CloexecOpenCheck>("android-cloexec-open");
     CheckFactories.registerCheck<CloexecSocketCheck>("android-cloexec-socket");

clang-tidy/android/CMakeLists.txt

 add_clang_library(clangTidyAndroidModule
   AndroidTidyModule.cpp
   CloexecCreatCheck.cpp
+  CloexecEpollCreateCheck.cpp
   CloexecFopenCheck.cpp
   CloexecOpenCheck.cpp
   CloexecSocketCheck.cpp

clang-tidy/android/CloexecEpollCreateCheck.h

+//===--- CloexecEpollCreateCheck.h - clang-tidy------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_ANDROID_CLOEXEC_EPOLL_CREATE_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_ANDROID_CLOEXEC_EPOLL_CREATE_H
+
+#include "../ClangTidy.h"
+
+namespace clang {
+namespace tidy {
+namespace android {
+
+/// epoll_create() is better to be replaced by epoll_create1().
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/android-cloexec-epoll-create.html
+class CloexecEpollCreateCheck : public ClangTidyCheck {
+public:
+  CloexecEpollCreateCheck(StringRef Name, ClangTidyContext *Context)
+      : ClangTidyCheck(Name, Context) {}
+  void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+  void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+};
+
+} // namespace android
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_ANDROID_CLOEXEC_EPOLL_CREATE_H

clang-tidy/android/CloexecEpollCreateCheck.cpp

+//===--- CloexecEpollCreateCheck.cpp - clang-tidy--------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "CloexecEpollCreateCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+namespace android {
+
+void CloexecEpollCreateCheck::registerMatchers(MatchFinder *Finder) {
+  Finder->addMatcher(
+      callExpr(callee(functionDecl(isExternC(), returns(isInteger()),
+                                   hasName("epoll_create"),
+                                   hasParameter(0, hasType(isInteger())))
+                          .bind("funcDecl")))
+          .bind("epollCreateFn"),
+      this);
+}
+
+void CloexecEpollCreateCheck::check(const MatchFinder::MatchResult &Result) {
+  const auto *MatchedCall = Result.Nodes.getNodeAs<CallExpr>("epollCreateFn");
+
+  diag(MatchedCall->getLocStart(), "prefer epoll_create() to epoll_create1() "
+                                   "because epoll_create1() allows "
+                                   "EPOLL_CLOEXEC")
+      << FixItHint::CreateReplacement(MatchedCall->getSourceRange(),
+                                      "epoll_create1(EPOLL_CLOEXEC)");
+}
+
+} // namespace android
+} // namespace tidy
+} // namespace clang

docs/ReleaseNotes.rst

 Improvements to clang-tidy
 --------------------------
 
+- New `android-cloexec-epoll-create
+  <http://clang.llvm.org/extra/clang-tidy/checks/android-cloexec-epoll-create.html>`_ check
+
+  Detects usage of ``epoll_create()``.
+
 - New `android-cloexec-creat
   <http://clang.llvm.org/extra/clang-tidy/checks/android-cloexec-creat.html>`_ check
 

docs/clang-tidy/checks/android-cloexec-epoll-create.rst

+.. title:: clang-tidy - android-cloexec-epoll-create
+
+android-cloexec-epoll-create
+============================
+
+The usage of ``epoll_create()`` is not recommended, it's better to use
+``epoll_create1()``, which allows close-on-exec.
+
+Examples:
+
+.. code-block:: c++
+
+  epoll_create(size);
+
+  // becomes
+
+  epoll_create1(EPOLL_CLOEXEC);

docs/clang-tidy/checks/list.rst

 
 .. toctree::
    android-cloexec-creat
+   android-cloexec-epoll-create
    android-cloexec-fopen
    android-cloexec-open
    android-cloexec-socket

test/clang-tidy/android-cloexec-epoll-create.cpp

+// RUN: %check_clang_tidy %s android-cloexec-epoll-create %t
+
+extern "C" int epoll_create(int size);
+
+void f() {
+  epoll_create(0);
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: prefer epoll_create() to epoll_create1() because epoll_create1() allows EPOLL_CLOEXEC [android-cloexec-epoll-create]
+  // CHECK-FIXES: epoll_create1(EPOLL_CLOEXEC)
+}
+
+namespace i {
+int epoll_create(int size);
+void g() {
+  epoll_create(0);
+}
+} // namespace i
+
+class C {
+public:
+  int epoll_create(int size);
+  void h() {
+    epoll_create(0);
+  }
+};