HDFS-15977. Call explicit_bzero only if it is available. (#2914)

Reviewed-by: Masatake Iwasaki <iwasakims@apache.org>
Reviewed-by: Inigo Goiri <inigoiri@apache.org>
(cherry picked from commit f0241ec2161f6eccdb9bdaf1cbcbee55be379217)

 Conflicts:
	hadoop-hdfs-project/hadoop-hdfs-native-client/src/main/native/libhdfspp/lib/x-platform/syscall_linux.cc

hadoop-hdfs-project/hadoop-hdfs-native-client/src/main/native/libhdfspp/CMakeLists.txt

@@ -48,6 +48,7 @@ find_package(GSasl)
 find_package(Threads)
 
 include(CheckCXXSourceCompiles)
+include(CheckSymbolExists)
 
 # Check if thread_local is supported
 unset (THREAD_LOCAL_SUPPORTED CACHE)
@@ -141,6 +142,11 @@ else (NOT NO_SASL)
     message(STATUS "Compiling with NO SASL SUPPORT")
 endif (NOT NO_SASL)
 
+check_symbol_exists(explicit_bzero "string.h" HAVE_EXPLICIT_BZERO)
+if(HAVE_EXPLICIT_BZERO)
+    add_definitions(-DHAVE_EXPLICIT_BZERO)
+endif()
+
 add_definitions(-DASIO_STANDALONE -DASIO_CPP11_DATE_TIME)
 
 # Disable optimizations if compiling debug

hadoop-hdfs-project/hadoop-hdfs-native-client/src/main/native/libhdfspp/lib/bindings/c/hdfs.cc

@@ -1402,7 +1402,11 @@ int hdfsGetBlockLocations(hdfsFS fs, const char *path, struct hdfsBlockLocations
     hdfsBlockLocations *locations = new struct hdfsBlockLocations();
     (*locations_out) = locations;
 
+#ifdef HAVE_EXPLICIT_BZERO
     explicit_bzero(locations, sizeof(*locations));
+#else
+    bzero(locations, sizeof(*locations));
+#endif
     locations->fileLength = ppLocations->getFileLength();
     locations->isLastBlockComplete = ppLocations->isLastBlockComplete();
     locations->isUnderConstruction = ppLocations->isUnderConstruction();

hadoop-hdfs-project/hadoop-hdfs-native-client/src/main/native/libhdfspp/tests/hdfs_ext_test.cc

@@ -475,7 +475,11 @@ TEST_F(HdfsExtTest, TestReadStats) {
   hdfsFile file = hdfsOpenFile(fs, path.c_str(), O_WRONLY, 0, 0, 0);
   EXPECT_NE(nullptr, file);
   void * buf = malloc(size);
+#ifdef HAVE_EXPLICIT_BZERO
   explicit_bzero(buf, size);
+#else
+  bzero(buf, size);
+#endif
   EXPECT_EQ(size, hdfsWrite(fs, file, buf, size));
   free(buf);
   EXPECT_EQ(0, hdfsCloseFile(fs, file));

hadoop-hdfs-project/hadoop-hdfs-native-client/src/main/native/libhdfspp/tests/hdfspp_mini_dfs.h

@@ -92,7 +92,11 @@ public:
     hdfsFile file = hdfsOpenFile(*this, path.c_str(), O_WRONLY, 0, 0, 0);
     EXPECT_NE(nullptr, file);
     void * buf = malloc(size);
+#ifdef HAVE_EXPLICIT_BZERO
     explicit_bzero(buf, size);
+#else
+    bzero(buf, size);
+#endif
     EXPECT_EQ(1024, hdfsWrite(*this, file, buf, size));
     EXPECT_EQ(0, hdfsCloseFile(*this, file));
     free(buf);