--- old/test/hotspot/jtreg/vmTestbase/nsk/share/jni/ExceptionCheckingJniEnv.cpp	2018-12-05 11:22:32.720541037 -0800
+++ new/test/hotspot/jtreg/vmTestbase/nsk/share/jni/ExceptionCheckingJniEnv.cpp	2018-12-05 11:22:32.456541843 -0800
@@ -141,18 +141,30 @@
     //              _file, _line);
     //   but will use strlen + memcpy instead.
     const char* pre_message = "JNI method ";
-    size_t pre_len = strlen(pre_message);
-    size_t base_len = strlen(_base_message);
-    const char* between_message = " : ";
-    size_t between_len = strlen(between_message);
-    const char* from_message = " from ";
-    size_t from_len = strlen(from_message);
-    size_t error_len = strlen(_error_message);
-    const char* file_name = _file ? _file : "Unknown file";
-    size_t file_len = strlen(file_name);
+    const char* between_msg = " : ";
+    const char* from_msg = " from ";
 
-    // +10 for the integer and +1 for the '\0'
-    size_t len = pre_len + base_len + between_len + error_len + from_len + file_len + between_len + 10 + 1;
+    const char* file_name = _file ? _file : "Unknown File";
+    const char* strs[] = {
+      pre_message,
+      _base_message,
+      between_msg,
+      _error_message,
+      from_msg,
+      file_name,
+      between_msg,
+    };
+
+    size_t msg_number = sizeof(strs) / sizeof(strs[0]);
+    size_t len = 0;
+    for (size_t i = 0; i < msg_number; i++) {
+      len += strlen(strs[i]);
+    }
+
+    // 32-bit signed means 11 characters due to the '-'.
+    const int MAX_INTEGER_DIGITS = 11;
+    // Add for the line number and 1 for the '\0'.
+    len += MAX_INTEGER_DIGITS + 1;
 
     char* full_message = (char*) malloc(len);
     if (full_message == NULL) {
@@ -160,25 +172,31 @@
       return;
     }
 
-    // Now we construct the string using memcpy to not use sprintf/std::string
+    // Now we construct the string using strncat to not use sprintf/std::string
     // instead of:
-    //     snprintf(full_message, len, "%s : %s", _base_message, _error_message);
-    memcpy(full_message, pre_message, pre_len);
-    memcpy(full_message + pre_len, _base_message, base_len);
-    memcpy(full_message + pre_len + base_len, between_message, between_len);
-    memcpy(full_message + pre_len + base_len + between_len, _error_message, error_len);
-    memcpy(full_message + pre_len + base_len + between_len + error_len, from_message, from_len);
-    memcpy(full_message + pre_len + base_len + between_len + error_len + from_len, file_name, file_len);
-    memcpy(full_message + pre_len + base_len + between_len + error_len + from_len + file_len,
-           between_message, between_len);
-
-    DecimalToAscii(
-        full_message + pre_len + base_len + between_len + error_len + from_len + file_len + between_len,
-        _line);
-
-    // -1 due to the '\0' not counted by strlen but is counted for the allocation.
-    if (strlen(full_message) >= len - 1) {
-      _env->GetJNIEnv()->FatalError("Length of message is greater than expected");
+    //     snprintf(full_message, len, "JNI method %s : %s from %s:%d", _base_message,
+    //         _error_message, _file, _line);
+    full_message[0] = '\0';
+    size_t current_len = 0;
+    for (size_t i = 0; i < msg_number; i++) {
+      size_t current_src_len = strlen(strs[i]);
+      current_len += current_src_len;
+      if (current_len >= len) {
+        _env->GetJNIEnv()->FatalError("Length of message is not what was expected");
+      }
+
+      strncat(full_message, strs[i], current_src_len);
+    }
+
+    // 10 is the max for an integer transformation.
+    if (current_len + MAX_INTEGER_DIGITS >= len) {
+      _env->GetJNIEnv()->FatalError("Length of message is not what was expected with line");
+    }
+
+    DecimalToAscii(full_message + current_len, _line);
+
+    if (strlen(full_message) >= len) {
+      _env->GetJNIEnv()->FatalError("Final length of message is not what was expected");
     }
 
     _env->HandleError(full_message);