Optimized version of safe_strcpy()

Note: We should replace most case of safe_strcpy() with strmake() to avoid the not needed zerofill.

Author: montywi

include/m_string.h

@@ -249,14 +249,15 @@ static inline void lex_string_set3(LEX_CSTRING *lex_str, const char *c_str,
 */
 static inline int safe_strcpy(char *dst, size_t dst_size, const char *src)
 {
- memset(dst, '\0', dst_size);
- strncpy(dst, src, dst_size - 1);
- /*
- If the first condition is true, we are guaranteed to have src length
- >= (dst_size - 1), hence safe to access src[dst_size - 1].
- */
- if (dst[dst_size - 2] != '\0' && src[dst_size - 1] != '\0')
- return 1; /* Truncation of src. */
+ DBUG_ASSERT(dst_size > 0);
+ /* Note, strncpy will zerofill end of dst if src shorter than dst_size */
+ strncpy(dst, src, dst_size);
+ if (dst[dst_size-1])
+ {
+ /* Ensure string is zero terminated */
+ dst[dst_size-1]= 0;
+ return 1;
+ }
  return 0;
 }