Fix regression bug of Auto rolling logger when handling failures (#5622)

Summary:
Auto roll logger fails to handle file creation error in the correct way, which may expose to seg fault condition to users. Fix it.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5622

Test Plan: Add a unit test on creating file under a non-existing directory. The test fails without the fix.

Differential Revision: D16460853

fbshipit-source-id: e96da4bef4f16db171ea04a11b2ec5a9448ddbde

logging/auto_roll_logger.cc

@@ -46,9 +46,8 @@ AutoRollLogger::AutoRollLogger(Env* env, const std::string& dbname,
   }
   GetExistingFiles();
   ResetLogger();
-  s = TrimOldLogFiles();
-  if (!status_.ok()) {
-    status_ = s;
+  if (status_.ok()) {
+    status_ = TrimOldLogFiles();
   }
 }
 

logging/auto_roll_logger_test.cc

@@ -635,6 +635,15 @@ TEST_F(AutoRollLoggerTest, LogFileExistence) {
   delete db;
 }
 
+TEST_F(AutoRollLoggerTest, FileCreateFailure) {
+  Options options;
+  options.max_log_file_size = 100 * 1024 * 1024;
+  options.db_log_dir = "/a/dir/does/not/exist/at/all";
+
+  std::shared_ptr<Logger> logger;
+  ASSERT_NOK(CreateLoggerFromOptions("", options, &logger));
+  ASSERT_TRUE(!logger);
+}
 }  // namespace rocksdb
 
 int main(int argc, char** argv) {