make append_query_string() more usable:

simplify the prototype and move it to sql_string.h

sql/item.cc

@@ -41,7 +41,6 @@
                                        // REPORT_EXCEPT_NOT_FOUND,
                                        // find_item_in_list,
                                        // RESOLVED_AGAINST_ALIAS, ...
-#include "log_event.h"                 // append_query_string
 #include "sql_expression_cache.h"
 
 const String my_null_string("NULL", 4, default_charset_info);
@@ -3749,8 +3748,9 @@ const String *Item_param::query_val_str(THD *thd, String* str) const
   case LONG_DATA_VALUE:
     {
       str->length(0);
-      append_query_string(thd, value.cs_info.character_set_client, &str_value,
-                          str);
+      append_query_string(value.cs_info.character_set_client, str,
+                          str_value.ptr(), str_value.length(),
+                          thd->variables.sql_mode & MODE_NO_BACKSLASH_ESCAPES);
       break;
     }
   case NULL_VALUE:

sql/log_event.cc

@@ -687,37 +687,35 @@ char *str_to_hex(char *to, const char *from, uint len)
 #ifndef MYSQL_CLIENT
 
 /**
-  Append a version of the 'from' string suitable for use in a query to
+  Append a version of the 'str' string suitable for use in a query to
   the 'to' string.  To generate a correct escaping, the character set
   information in 'csinfo' is used.
 */
 
-int
-append_query_string(THD *thd, CHARSET_INFO *csinfo,
-                    String const *from, String *to)
+int append_query_string(CHARSET_INFO *csinfo, String *to,
+                        const char *str, size_t len, bool no_backslash)
 {
   char *beg, *ptr;
   uint32 const orig_len= to->length();
-  if (to->reserve(orig_len + from->length() * 2 + 4))
+  if (to->reserve(orig_len + len * 2 + 4))
     return 1;
 
   beg= (char*) to->ptr() + to->length();
   ptr= beg;
   if (csinfo->escape_with_backslash_is_dangerous)
-    ptr= str_to_hex(ptr, from->ptr(), from->length());
+    ptr= str_to_hex(ptr, str, len);
   else
   {
     *ptr++= '\'';
-    if (!(thd->variables.sql_mode & MODE_NO_BACKSLASH_ESCAPES))
+    if (!no_backslash)
     {
-      ptr+= escape_string_for_mysql(csinfo, ptr, 0,
-                                    from->ptr(), from->length());
+      ptr+= escape_string_for_mysql(csinfo, ptr, 0, str, len);
     }
     else
     {
-      const char *frm_str= from->ptr();
+      const char *frm_str= str;
 
-      for (; frm_str < (from->ptr() + from->length()); frm_str++)
+      for (; frm_str < (str + len); frm_str++)
       {
         /* Using '' way to represent "'" */
         if (*frm_str == '\'')

sql/log_event.h

@@ -4766,9 +4766,6 @@ class Heartbeat_log_event: public Log_event
 bool slave_execute_deferred_events(THD *thd);
 #endif
 
-int append_query_string(THD *thd, CHARSET_INFO *csinfo,
-                        String const *from, String *to);
-
 bool rpl_get_position_info(const char **log_file_name, ulonglong *log_pos,
                            const char **group_relay_log_name,
                            ulonglong *relay_log_pos);

sql/sp_head.cc

@@ -27,7 +27,7 @@
                                // prepare_create_field
 #include "sql_acl.h"           // *_ACL
 #include "sql_array.h"         // Dynamic_array
-#include "log_event.h"         // append_query_string, Query_log_event
+#include "log_event.h"         // Query_log_event
 #include "sql_derived.h"       // mysql_handle_derived
 
 #ifdef USE_PRAGMA_IMPLEMENTATION
@@ -160,7 +160,8 @@ sp_get_item_value(THD *thd, Item *item, String *str)
         buf.append(result->charset()->csname);
         if (cs->escape_with_backslash_is_dangerous)
           buf.append(' ');
-        append_query_string(thd, cs, result, &buf);
+        append_query_string(cs, &buf, result->ptr(), result->length(),
+                           thd->variables.sql_mode & MODE_NO_BACKSLASH_ESCAPES);
         buf.append(" COLLATE '");
         buf.append(item->collation.collation->name);
         buf.append('\'');

sql/sql_string.cc

@@ -1014,7 +1014,7 @@ well_formed_copy_nchars(CHARSET_INFO *to_cs,
 
 /*
   Append characters to a single-quoted string '...', escaping special
-  characters as necessary.
+  characters with backslashes as necessary.
   Does not add the enclosing quotes, this is left up to caller.
 */
 #define APPEND(X)   if (append(X)) return 1; else break

sql/sql_string.h

@@ -568,4 +568,7 @@ static inline bool check_if_only_end_space(CHARSET_INFO *cs,
   return str+ cs->cset->scan(cs, str, end, MY_SEQ_SPACES) == end;
 }
 
+int append_query_string(CHARSET_INFO *csinfo, String *to,
+                        const char *str, size_t len, bool no_backslash);
+
 #endif /* SQL_STRING_INCLUDED */