src/hotspot/share/utilities/stringUtils.cpp

*** 21,30 ****
--- 21,31 ----
   * questions.
   *
   */
  
  #include "precompiled.hpp"
+ #include "utilities/debug.hpp"
  #include "utilities/stringUtils.hpp"
  
  int StringUtils::replace_no_expand(char* string, const char* from, const char* to) {
    int replace_count = 0;
    size_t from_len = strlen(from);
*** 41,53 ****
  
    return replace_count;
  }
  
  double StringUtils::similarity(const char* str1, size_t len1, const char* str2, size_t len2) {
!   size_t total = len1 + len2;
  
    size_t hit = 0;
    for (size_t i = 0; i < len1 - 1; i++) {
      for (size_t j = 0; j < len2 - 1; j++) {
        if ((str1[i] == str2[j]) && (str1[i+1] == str2[j+1])) {
          ++hit;
          break;
--- 42,61 ----
  
    return replace_count;
  }
  
  double StringUtils::similarity(const char* str1, size_t len1, const char* str2, size_t len2) {
!   assert(str1 != NULL && str2 != NULL, "sanity");
  
+   size_t total = len1 + len2;
    size_t hit = 0;
+ 
+   // filter out zero-length strings else we will underflow on len-1 below
+   if (len1 == 0 || len2 == 0) {
+     return 0.0;
+   }
+ 
    for (size_t i = 0; i < len1 - 1; i++) {
      for (size_t j = 0; j < len2 - 1; j++) {
        if ((str1[i] == str2[j]) && (str1[i+1] == str2[j+1])) {
          ++hit;
          break;