Work around some new clang-analyze failures (#9515)

Summary:
... seen only in internal clang-analyze runs after facebook/rocksdb#9481

* Mostly, this works around falsely reported leaks by using
std::unique_ptr in some places where clang-analyze was getting
confused. (I didn't see any changes in C++17 that could make our Status
implementation leak memory.)
* Also fixed SetBGError returning address of a stack variable.
* Also fixed another false null deref report by adding an assert.

Also, use SKIP_LINK=1 to speed up `make analyze`

Pull Request resolved: facebook/rocksdb#9515

Test Plan:
Was able to reproduce the reported errors locally and verify
they're fixed (except SetBGError). Otherwise, existing tests

Reviewed By: hx235

Differential Revision: D34054630

Pulled By: pdillinger

fbshipit-source-id: 38600ef3da75ddca307dff96b7a1a523c2885c2e

Makefile

@@ -1221,7 +1221,7 @@ analyze_incremental:
 	$(CLANG_SCAN_BUILD) --use-analyzer=$(CLANG_ANALYZER) \
 		--use-c++=$(CXX) --use-cc=$(CC) --status-bugs \
 		-o $(CURDIR)/scan_build_report \
-		$(MAKE) dbg
+		$(MAKE) SKIP_LINK=1 dbg
 
 CLEAN_FILES += unity.cc
 unity.cc: Makefile util/build_version.cc.in

db/error_handler.cc

@@ -9,6 +9,7 @@
 #include "db/event_helpers.h"
 #include "file/sst_file_manager_impl.h"
 #include "logging/logging.h"
+#include "port/lang.h"
 
 namespace ROCKSDB_NAMESPACE {
 
@@ -251,6 +252,8 @@ void ErrorHandler::CancelErrorRecovery() {
 #endif
 }
 
+STATIC_AVOID_DESTRUCTION(const Status, kOkStatus){Status::OK()};
+
 // This is the main function for looking at an error during a background
 // operation and deciding the severity, and error recovery strategy. The high
 // level algorithm is as follows -
@@ -273,7 +276,7 @@ const Status& ErrorHandler::SetBGError(const Status& bg_err,
                                        BackgroundErrorReason reason) {
   db_mutex_->AssertHeld();
   if (bg_err.ok()) {
-    return bg_err;
+    return kOkStatus;
   }
 
   if (bg_error_stats_ != nullptr) {
@@ -383,7 +386,7 @@ const Status& ErrorHandler::SetBGError(const IOStatus& bg_io_err,
                                        BackgroundErrorReason reason) {
   db_mutex_->AssertHeld();
   if (bg_io_err.ok()) {
-    return bg_io_err;
+    return kOkStatus;
   }
   ROCKS_LOG_WARN(db_options_.info_log, "Background IO error %s",
                  bg_io_err.ToString().c_str());
@@ -625,7 +628,7 @@ const Status& ErrorHandler::StartRecoverFromRetryableBGIOError(
   if (bg_error_.ok()) {
     return bg_error_;
   } else if (io_error.ok()) {
-    return io_error;
+    return kOkStatus;
   } else if (db_options_.max_bgerror_resume_count <= 0 || recovery_in_prog_) {
     // Auto resume BG error is not enabled, directly return bg_error_.
     return bg_error_;

include/rocksdb/io_status.h

@@ -171,7 +171,7 @@ inline IOStatus::IOStatus(Code _code, SubCode _subcode, const Slice& msg,
     memcpy(result + len1 + 2, msg2.data(), len2);
   }
   result[size] = '\0';  // null terminator for C style string
-  state_ = result;
+  state_.reset(result);
 }
 
 inline IOStatus::IOStatus(const IOStatus& s) : Status(s.code_, s.subcode_) {
@@ -181,7 +181,7 @@ inline IOStatus::IOStatus(const IOStatus& s) : Status(s.code_, s.subcode_) {
   retryable_ = s.retryable_;
   data_loss_ = s.data_loss_;
   scope_ = s.scope_;
-  state_ = (s.state_ == nullptr) ? nullptr : CopyState(s.state_);
+  state_ = (s.state_ == nullptr) ? nullptr : CopyState(s.state_.get());
 }
 inline IOStatus& IOStatus::operator=(const IOStatus& s) {
   // The following condition catches both aliasing (when this == &s),
@@ -196,8 +196,7 @@ inline IOStatus& IOStatus::operator=(const IOStatus& s) {
     retryable_ = s.retryable_;
     data_loss_ = s.data_loss_;
     scope_ = s.scope_;
-    delete[] state_;
-    state_ = (s.state_ == nullptr) ? nullptr : CopyState(s.state_);
+    state_ = (s.state_ == nullptr) ? nullptr : CopyState(s.state_.get());
   }
   return *this;
 }
@@ -228,9 +227,7 @@ inline IOStatus& IOStatus::operator=(IOStatus&& s)
     data_loss_ = s.data_loss_;
     scope_ = s.scope_;
     s.scope_ = kIOErrorScopeFileSystem;
-    delete[] state_;
-    state_ = nullptr;
-    std::swap(state_, s.state_);
+    state_ = std::move(s.state_);
   }
   return *this;
 }

include/rocksdb/status.h

@@ -21,6 +21,7 @@
 #include <stdlib.h>
 #endif
 
+#include <memory>
 #include <string>
 
 #ifdef ROCKSDB_ASSERT_STATUS_CHECKED
@@ -43,7 +44,6 @@ class Status {
       abort();
     }
 #endif  // ROCKSDB_ASSERT_STATUS_CHECKED
-    delete[] state_;
   }
 
   // Copy the specified status.
@@ -144,7 +144,7 @@ class Status {
   // Returns a C style string indicating the message of the Status
   const char* getState() const {
     MarkChecked();
-    return state_;
+    return state_.get();
   }
 
   // Return a success status.
@@ -456,20 +456,20 @@ class Status {
   Severity sev_;
   // A nullptr state_ (which is at least the case for OK) means the extra
   // message is empty.
-  const char* state_;
+  std::unique_ptr<const char[]> state_;
 #ifdef ROCKSDB_ASSERT_STATUS_CHECKED
   mutable bool checked_ = false;
 #endif  // ROCKSDB_ASSERT_STATUS_CHECKED
 
   explicit Status(Code _code, SubCode _subcode = kNone)
-      : code_(_code), subcode_(_subcode), sev_(kNoError), state_(nullptr) {}
+      : code_(_code), subcode_(_subcode), sev_(kNoError) {}
 
   Status(Code _code, SubCode _subcode, const Slice& msg, const Slice& msg2,
          Severity sev = kNoError);
   Status(Code _code, const Slice& msg, const Slice& msg2)
       : Status(_code, kNone, msg, msg2) {}
 
-  static const char* CopyState(const char* s);
+  static std::unique_ptr<const char[]> CopyState(const char* s);
 
   inline void MarkChecked() const {
 #ifdef ROCKSDB_ASSERT_STATUS_CHECKED
@@ -481,12 +481,12 @@ class Status {
 inline Status::Status(const Status& s)
     : code_(s.code_), subcode_(s.subcode_), sev_(s.sev_) {
   s.MarkChecked();
-  state_ = (s.state_ == nullptr) ? nullptr : CopyState(s.state_);
+  state_ = (s.state_ == nullptr) ? nullptr : CopyState(s.state_.get());
 }
 inline Status::Status(const Status& s, Severity sev)
     : code_(s.code_), subcode_(s.subcode_), sev_(sev) {
   s.MarkChecked();
-  state_ = (s.state_ == nullptr) ? nullptr : CopyState(s.state_);
+  state_ = (s.state_ == nullptr) ? nullptr : CopyState(s.state_.get());
 }
 inline Status& Status::operator=(const Status& s) {
   if (this != &s) {
@@ -495,8 +495,7 @@ inline Status& Status::operator=(const Status& s) {
     code_ = s.code_;
     subcode_ = s.subcode_;
     sev_ = s.sev_;
-    delete[] state_;
-    state_ = (s.state_ == nullptr) ? nullptr : CopyState(s.state_);
+    state_ = (s.state_ == nullptr) ? nullptr : CopyState(s.state_.get());
   }
   return *this;
 }
@@ -524,9 +523,7 @@ inline Status& Status::operator=(Status&& s)
     s.subcode_ = kNone;
     sev_ = std::move(s.sev_);
     s.sev_ = kNoError;
-    delete[] state_;
-    state_ = nullptr;
-    std::swap(state_, s.state_);
+    state_ = std::move(s.state_);
   }
   return *this;
 }

third-party/gtest-1.8.1/fused-src/gtest/gtest.h

@@ -53,6 +53,7 @@
 #define GTEST_INCLUDE_GTEST_GTEST_H_
 
 #include <limits>
+#include <memory>
 #include <ostream>
 #include <vector>
 
@@ -2442,6 +2443,10 @@ GTEST_API_ bool IsTrue(bool condition);
 
 // Defines scoped_ptr.
 
+// RocksDB: use unique_ptr to work around some clang-analyze false reports
+template <typename T>
+using scoped_ptr = std::unique_ptr<T>;
+/*
 // This implementation of scoped_ptr is PARTIAL - it only contains
 // enough stuff to satisfy Google Test's need.
 template <typename T>
@@ -2481,6 +2486,7 @@ class scoped_ptr {
 
   GTEST_DISALLOW_COPY_AND_ASSIGN_(scoped_ptr);
 };
+*/
 
 // Defines RE.
 

util/status.cc

@@ -17,24 +17,11 @@
 
 namespace ROCKSDB_NAMESPACE {
 
-const char* Status::CopyState(const char* state) {
-#ifdef OS_WIN
-  const size_t cch = std::strlen(state) + 1;  // +1 for the null terminator
-  char* result = new char[cch];
-  errno_t ret
-#if defined(_MSC_VER)
-    ;
-#else
-    __attribute__((__unused__));
-#endif
-  ret = strncpy_s(result, cch, state, cch - 1);
-  result[cch - 1] = '\0';
-  assert(ret == 0);
-  return result;
-#else
-  const size_t cch = std::strlen(state) + 1;  // +1 for the null terminator
-  return std::strncpy(new char[cch], state, cch);
-#endif
+std::unique_ptr<const char[]> Status::CopyState(const char* s) {
+  const size_t cch = std::strlen(s) + 1;  // +1 for the null terminator
+  char* rv = new char[cch];
+  std::strncpy(rv, s, cch);
+  return std::unique_ptr<const char[]>(rv);
 }
 
 static const char* msgs[static_cast<int>(Status::kMaxSubCode)] = {
@@ -72,7 +59,7 @@ Status::Status(Code _code, SubCode _subcode, const Slice& msg,
     memcpy(result + len1 + 2, msg2.data(), len2);
   }
   result[size] = '\0';  // null terminator for C style string
-  state_ = result;
+  state_.reset(result);
 }
 
 std::string Status::ToString() const {
@@ -152,7 +139,7 @@ std::string Status::ToString() const {
     if (subcode_ != kNone) {
       result.append(": ");
     }
-    result.append(state_);
+    result.append(state_.get());
   }
   return result;
 }

utilities/ttl/ttl_test.cc

@@ -185,6 +185,7 @@ class TtlTest : public testing::Test {
 
   // Runs a manual compaction
   Status ManualCompact(ColumnFamilyHandle* cf = nullptr) {
+    assert(db_ttl_);
     if (cf == nullptr) {
       return db_ttl_->CompactRange(CompactRangeOptions(), nullptr, nullptr);
     } else {