Changing field::field_name and Item::name to LEX_CSTRING

Benefits of this patch:
- Removed a lot of calls to strlen(), especially for field_string
- Strings generated by parser are now const strings, less chance of
  accidently changing a string
- Removed a lot of calls with LEX_STRING as parameter (changed to pointer)
- More uniform code
- Item::name_length was not kept up to date. Now fixed
- Several bugs found and fixed (Access to null pointers,
  access of freed memory, wrong arguments to printf like functions)
- Removed a lot of casts from (const char*) to (char*)

Changes:
- This caused some ABI changes
  - lex_string_set now uses LEX_CSTRING
  - Some fucntions are now taking const char* instead of char*
- Create_field::change and after changed to LEX_CSTRING
- handler::connect_string, comment and engine_name() changed to LEX_CSTRING
- Checked printf() related calls to find bugs. Found and fixed several
  errors in old code.
- A lot of changes from LEX_STRING to LEX_CSTRING, especially related to
  parsing and events.
- Some changes from LEX_STRING and LEX_STRING & to LEX_CSTRING*
- Some changes for char* to const char*
- Added printf argument checking for my_snprintf()
- Introduced null_clex_str, star_clex_string, temp_lex_str to simplify
  code
- Added item_empty_name and item_used_name to be able to distingush between
  items that was given an empty name and items that was not given a name
  This is used in sql_yacc.yy to know when to give an item a name.
- select table_name."*' is not anymore same as table_name.*
- removed not used function Item::rename()
- Added comparision of item->name_length before some calls to
  my_strcasecmp() to speed up comparison
- Moved Item_sp_variable::make_field() from item.h to item.cc
- Some minimal code changes to avoid copying to const char *
- Fixed wrong error message in wsrep_mysql_parse()
- Fixed wrong code in find_field_in_natural_join() where real_item() was
  set when it shouldn't
- ER_ERROR_ON_RENAME was used with extra arguments.
- Removed some (wrong) ER_OUTOFMEMORY, as alloc_root will already
  give the error.

TODO:
- Check possible unsafe casts in plugin/auth_examples/qa_auth_interface.c
- Change code to not modify LEX_CSTRING for database name
  (as part of lower_case_table_names)

13 files changed, 111 insertions, 47 deletions

diff --git a/include/m_string.h b/include/m_string.h
index 708c2562e0f..f06acbea358 100644
--- a/include/m_string.h
+++ b/include/m_string.h
@@ -212,11 +212,6 @@ extern ulonglong strtoull(const char *str, char **ptr, int base);
 #define USTRING_WITH_LEN(X) ((uchar*) X), ((size_t) (sizeof(X) - 1))
 #define C_STRING_WITH_LEN(X) ((char *) (X)), ((size_t) (sizeof(X) - 1))
 
-struct st_mysql_const_lex_string
-{
-  const char *str;
-  size_t length;
-};
 typedef struct st_mysql_const_lex_string LEX_CSTRING;
 
 /* A variant with const and unsigned */
@@ -227,15 +222,15 @@ struct st_mysql_const_unsigned_lex_string
 };
 typedef struct st_mysql_const_unsigned_lex_string LEX_CUSTRING;
 
-static inline void lex_string_set(LEX_STRING *lex_str, const char *c_str)
+static inline void lex_string_set(LEX_CSTRING *lex_str, const char *c_str)
 {
-  lex_str->str= (char *) c_str;
+  lex_str->str= c_str;
   lex_str->length= strlen(c_str);
 }
-static inline void lex_string_set3(LEX_STRING *lex_str, const char *c_str,
+static inline void lex_string_set3(LEX_CSTRING *lex_str, const char *c_str,
                                    size_t len)
 {
-  lex_str->str= (char *) c_str;
+  lex_str->str= c_str;
   lex_str->length= len;
 }
 
diff --git a/include/my_time.h b/include/my_time.h
index 90d19c8861a..02e8f32ee23 100644
--- a/include/my_time.h
+++ b/include/my_time.h
@@ -173,8 +173,10 @@ static inline my_bool validate_timestamp_range(const MYSQL_TIME *t)
 }
 
 /* Can't include mysqld_error.h, it needs mysys to build, thus hardcode 2 error values here. */
+#ifndef ER_WARN_DATA_OUT_OF_RANGE
 #define ER_WARN_DATA_OUT_OF_RANGE 1264
 #define ER_WARN_INVALID_TIMESTAMP 1299
+#endif
 
 my_time_t 
 my_system_gmt_sec(const MYSQL_TIME *t, long *my_timezone, uint *error_code);
diff --git a/include/mysql.h.pp b/include/mysql.h.pp
index 517516aeb30..3316574a423 100644
--- a/include/mysql.h.pp
+++ b/include/mysql.h.pp
@@ -136,7 +136,7 @@ typedef struct st_udf_args
   char **args;
   unsigned long *lengths;
   char *maybe_null;
-  char **attributes;
+  const char **attributes;
   unsigned long *attribute_lengths;
   void *extension;
 } UDF_ARGS;
diff --git a/include/mysql/plugin_audit.h.pp b/include/mysql/plugin_audit.h.pp
index 2adde48dc22..1772c0f6b87 100644
--- a/include/mysql/plugin_audit.h.pp
+++ b/include/mysql/plugin_audit.h.pp
@@ -141,7 +141,8 @@ extern struct my_snprintf_service_st {
   size_t (*my_snprintf_type)(char*, size_t, const char*, ...);
   size_t (*my_vsnprintf_type)(char *, size_t, const char*, va_list);
 } *my_snprintf_service;
-size_t my_snprintf(char* to, size_t n, const char* fmt, ...);
+size_t my_snprintf(char* to, size_t n, const char* fmt, ...)
+  ;
 size_t my_vsnprintf(char *to, size_t n, const char* fmt, va_list ap);
 extern struct progress_report_service_st {
   void (*thd_progress_init_func)(void* thd, unsigned int max_stage);
@@ -233,13 +234,20 @@ struct st_mysql_lex_string
   size_t length;
 };
 typedef struct st_mysql_lex_string MYSQL_LEX_STRING;
+struct st_mysql_const_lex_string
+{
+  const char *str;
+  size_t length;
+};
+typedef struct st_mysql_const_lex_string MYSQL_CONST_LEX_STRING;
 extern struct thd_alloc_service_st {
   void *(*thd_alloc_func)(void*, unsigned int);
   void *(*thd_calloc_func)(void*, unsigned int);
   char *(*thd_strdup_func)(void*, const char *);
   char *(*thd_strmake_func)(void*, const char *, unsigned int);
   void *(*thd_memdup_func)(void*, const void*, unsigned int);
-  MYSQL_LEX_STRING *(*thd_make_lex_string_func)(void*, MYSQL_LEX_STRING *,
+  MYSQL_CONST_LEX_STRING *(*thd_make_lex_string_func)(void*,
+                                        MYSQL_CONST_LEX_STRING *,
                                         const char *, unsigned int, int);
 } *thd_alloc_service;
 void *thd_alloc(void* thd, unsigned int size);
@@ -247,9 +255,10 @@ void *thd_calloc(void* thd, unsigned int size);
 char *thd_strdup(void* thd, const char *str);
 char *thd_strmake(void* thd, const char *str, unsigned int size);
 void *thd_memdup(void* thd, const void* str, unsigned int size);
-MYSQL_LEX_STRING *thd_make_lex_string(void* thd, MYSQL_LEX_STRING *lex_str,
-                                      const char *str, unsigned int size,
-                                      int allocate_lex_string);
+MYSQL_CONST_LEX_STRING
+*thd_make_lex_string(void* thd, MYSQL_CONST_LEX_STRING *lex_str,
+                     const char *str, unsigned int size,
+                     int allocate_lex_string);
 extern struct thd_autoinc_service_st {
   void (*thd_get_autoinc_func)(const void* thd,
                                unsigned long* off, unsigned long* inc);
diff --git a/include/mysql/plugin_auth.h b/include/mysql/plugin_auth.h
index 807bfd4e652..638d9b57fd9 100644
--- a/include/mysql/plugin_auth.h
+++ b/include/mysql/plugin_auth.h
@@ -51,7 +51,7 @@ typedef struct st_mysql_server_auth_info
     User name as sent by the client and shown in USER().
     NULL if the client packet with the user name was not received yet.
   */
-  char *user_name;
+  const char *user_name;
 
   /**
     Length of user_name
diff --git a/include/mysql/plugin_auth.h.pp b/include/mysql/plugin_auth.h.pp
index a9cb8044c4f..bc873626fab 100644
--- a/include/mysql/plugin_auth.h.pp
+++ b/include/mysql/plugin_auth.h.pp
@@ -141,7 +141,8 @@ extern struct my_snprintf_service_st {
   size_t (*my_snprintf_type)(char*, size_t, const char*, ...);
   size_t (*my_vsnprintf_type)(char *, size_t, const char*, va_list);
 } *my_snprintf_service;
-size_t my_snprintf(char* to, size_t n, const char* fmt, ...);
+size_t my_snprintf(char* to, size_t n, const char* fmt, ...)
+  ;
 size_t my_vsnprintf(char *to, size_t n, const char* fmt, va_list ap);
 extern struct progress_report_service_st {
   void (*thd_progress_init_func)(void* thd, unsigned int max_stage);
@@ -233,13 +234,20 @@ struct st_mysql_lex_string
   size_t length;
 };
 typedef struct st_mysql_lex_string MYSQL_LEX_STRING;
+struct st_mysql_const_lex_string
+{
+  const char *str;
+  size_t length;
+};
+typedef struct st_mysql_const_lex_string MYSQL_CONST_LEX_STRING;
 extern struct thd_alloc_service_st {
   void *(*thd_alloc_func)(void*, unsigned int);
   void *(*thd_calloc_func)(void*, unsigned int);
   char *(*thd_strdup_func)(void*, const char *);
   char *(*thd_strmake_func)(void*, const char *, unsigned int);
   void *(*thd_memdup_func)(void*, const void*, unsigned int);
-  MYSQL_LEX_STRING *(*thd_make_lex_string_func)(void*, MYSQL_LEX_STRING *,
+  MYSQL_CONST_LEX_STRING *(*thd_make_lex_string_func)(void*,
+                                        MYSQL_CONST_LEX_STRING *,
                                         const char *, unsigned int, int);
 } *thd_alloc_service;
 void *thd_alloc(void* thd, unsigned int size);
@@ -247,9 +255,10 @@ void *thd_calloc(void* thd, unsigned int size);
 char *thd_strdup(void* thd, const char *str);
 char *thd_strmake(void* thd, const char *str, unsigned int size);
 void *thd_memdup(void* thd, const void* str, unsigned int size);
-MYSQL_LEX_STRING *thd_make_lex_string(void* thd, MYSQL_LEX_STRING *lex_str,
-                                      const char *str, unsigned int size,
-                                      int allocate_lex_string);
+MYSQL_CONST_LEX_STRING
+*thd_make_lex_string(void* thd, MYSQL_CONST_LEX_STRING *lex_str,
+                     const char *str, unsigned int size,
+                     int allocate_lex_string);
 extern struct thd_autoinc_service_st {
   void (*thd_get_autoinc_func)(const void* thd,
                                unsigned long* off, unsigned long* inc);
@@ -501,7 +510,7 @@ typedef struct st_plugin_vio
 } MYSQL_PLUGIN_VIO;
 typedef struct st_mysql_server_auth_info
 {
-  char *user_name;
+  const char *user_name;
   unsigned int user_name_length;
   const char *auth_string;
   unsigned long auth_string_length;
diff --git a/include/mysql/plugin_encryption.h.pp b/include/mysql/plugin_encryption.h.pp
index 4675f0cf6ec..4113e6d24a9 100644
--- a/include/mysql/plugin_encryption.h.pp
+++ b/include/mysql/plugin_encryption.h.pp
@@ -141,7 +141,8 @@ extern struct my_snprintf_service_st {
   size_t (*my_snprintf_type)(char*, size_t, const char*, ...);
   size_t (*my_vsnprintf_type)(char *, size_t, const char*, va_list);
 } *my_snprintf_service;
-size_t my_snprintf(char* to, size_t n, const char* fmt, ...);
+size_t my_snprintf(char* to, size_t n, const char* fmt, ...)
+  ;
 size_t my_vsnprintf(char *to, size_t n, const char* fmt, va_list ap);
 extern struct progress_report_service_st {
   void (*thd_progress_init_func)(void* thd, unsigned int max_stage);
@@ -233,13 +234,20 @@ struct st_mysql_lex_string
   size_t length;
 };
 typedef struct st_mysql_lex_string MYSQL_LEX_STRING;
+struct st_mysql_const_lex_string
+{
+  const char *str;
+  size_t length;
+};
+typedef struct st_mysql_const_lex_string MYSQL_CONST_LEX_STRING;
 extern struct thd_alloc_service_st {
   void *(*thd_alloc_func)(void*, unsigned int);
   void *(*thd_calloc_func)(void*, unsigned int);
   char *(*thd_strdup_func)(void*, const char *);
   char *(*thd_strmake_func)(void*, const char *, unsigned int);
   void *(*thd_memdup_func)(void*, const void*, unsigned int);
-  MYSQL_LEX_STRING *(*thd_make_lex_string_func)(void*, MYSQL_LEX_STRING *,
+  MYSQL_CONST_LEX_STRING *(*thd_make_lex_string_func)(void*,
+                                        MYSQL_CONST_LEX_STRING *,
                                         const char *, unsigned int, int);
 } *thd_alloc_service;
 void *thd_alloc(void* thd, unsigned int size);
@@ -247,9 +255,10 @@ void *thd_calloc(void* thd, unsigned int size);
 char *thd_strdup(void* thd, const char *str);
 char *thd_strmake(void* thd, const char *str, unsigned int size);
 void *thd_memdup(void* thd, const void* str, unsigned int size);
-MYSQL_LEX_STRING *thd_make_lex_string(void* thd, MYSQL_LEX_STRING *lex_str,
-                                      const char *str, unsigned int size,
-                                      int allocate_lex_string);
+MYSQL_CONST_LEX_STRING
+*thd_make_lex_string(void* thd, MYSQL_CONST_LEX_STRING *lex_str,
+                     const char *str, unsigned int size,
+                     int allocate_lex_string);
 extern struct thd_autoinc_service_st {
   void (*thd_get_autoinc_func)(const void* thd,
                                unsigned long* off, unsigned long* inc);
diff --git a/include/mysql/plugin_ftparser.h.pp b/include/mysql/plugin_ftparser.h.pp
index 34d968b60ab..8147d793801 100644
--- a/include/mysql/plugin_ftparser.h.pp
+++ b/include/mysql/plugin_ftparser.h.pp
@@ -141,7 +141,8 @@ extern struct my_snprintf_service_st {
   size_t (*my_snprintf_type)(char*, size_t, const char*, ...);
   size_t (*my_vsnprintf_type)(char *, size_t, const char*, va_list);
 } *my_snprintf_service;
-size_t my_snprintf(char* to, size_t n, const char* fmt, ...);
+size_t my_snprintf(char* to, size_t n, const char* fmt, ...)
+  ;
 size_t my_vsnprintf(char *to, size_t n, const char* fmt, va_list ap);
 extern struct progress_report_service_st {
   void (*thd_progress_init_func)(void* thd, unsigned int max_stage);
@@ -233,13 +234,20 @@ struct st_mysql_lex_string
   size_t length;
 };
 typedef struct st_mysql_lex_string MYSQL_LEX_STRING;
+struct st_mysql_const_lex_string
+{
+  const char *str;
+  size_t length;
+};
+typedef struct st_mysql_const_lex_string MYSQL_CONST_LEX_STRING;
 extern struct thd_alloc_service_st {
   void *(*thd_alloc_func)(void*, unsigned int);
   void *(*thd_calloc_func)(void*, unsigned int);
   char *(*thd_strdup_func)(void*, const char *);
   char *(*thd_strmake_func)(void*, const char *, unsigned int);
   void *(*thd_memdup_func)(void*, const void*, unsigned int);
-  MYSQL_LEX_STRING *(*thd_make_lex_string_func)(void*, MYSQL_LEX_STRING *,
+  MYSQL_CONST_LEX_STRING *(*thd_make_lex_string_func)(void*,
+                                        MYSQL_CONST_LEX_STRING *,
                                         const char *, unsigned int, int);
 } *thd_alloc_service;
 void *thd_alloc(void* thd, unsigned int size);
@@ -247,9 +255,10 @@ void *thd_calloc(void* thd, unsigned int size);
 char *thd_strdup(void* thd, const char *str);
 char *thd_strmake(void* thd, const char *str, unsigned int size);
 void *thd_memdup(void* thd, const void* str, unsigned int size);
-MYSQL_LEX_STRING *thd_make_lex_string(void* thd, MYSQL_LEX_STRING *lex_str,
-                                      const char *str, unsigned int size,
-                                      int allocate_lex_string);
+MYSQL_CONST_LEX_STRING
+*thd_make_lex_string(void* thd, MYSQL_CONST_LEX_STRING *lex_str,
+                     const char *str, unsigned int size,
+                     int allocate_lex_string);
 extern struct thd_autoinc_service_st {
   void (*thd_get_autoinc_func)(const void* thd,
                                unsigned long* off, unsigned long* inc);
diff --git a/include/mysql/plugin_password_validation.h b/include/mysql/plugin_password_validation.h
index 18c643e877b..e2763483db6 100644
--- a/include/mysql/plugin_password_validation.h
+++ b/include/mysql/plugin_password_validation.h
@@ -42,8 +42,8 @@ struct st_mariadb_password_validation
     Function provided by the plugin which should perform password validation
     and return 0 if the password has passed the validation.
   */
-  int (*validate_password)(MYSQL_LEX_STRING *username,
-                           MYSQL_LEX_STRING *password);
+  int (*validate_password)(MYSQL_CONST_LEX_STRING *username,
+                           MYSQL_CONST_LEX_STRING *password);
 };
 
 #ifdef __cplusplus
diff --git a/include/mysql/plugin_password_validation.h.pp b/include/mysql/plugin_password_validation.h.pp
index 5a642a55d08..929b3307f9e 100644
--- a/include/mysql/plugin_password_validation.h.pp
+++ b/include/mysql/plugin_password_validation.h.pp
@@ -141,7 +141,8 @@ extern struct my_snprintf_service_st {
   size_t (*my_snprintf_type)(char*, size_t, const char*, ...);
   size_t (*my_vsnprintf_type)(char *, size_t, const char*, va_list);
 } *my_snprintf_service;
-size_t my_snprintf(char* to, size_t n, const char* fmt, ...);
+size_t my_snprintf(char* to, size_t n, const char* fmt, ...)
+  ;
 size_t my_vsnprintf(char *to, size_t n, const char* fmt, va_list ap);
 extern struct progress_report_service_st {
   void (*thd_progress_init_func)(void* thd, unsigned int max_stage);
@@ -233,13 +234,20 @@ struct st_mysql_lex_string
   size_t length;
 };
 typedef struct st_mysql_lex_string MYSQL_LEX_STRING;
+struct st_mysql_const_lex_string
+{
+  const char *str;
+  size_t length;
+};
+typedef struct st_mysql_const_lex_string MYSQL_CONST_LEX_STRING;
 extern struct thd_alloc_service_st {
   void *(*thd_alloc_func)(void*, unsigned int);
   void *(*thd_calloc_func)(void*, unsigned int);
   char *(*thd_strdup_func)(void*, const char *);
   char *(*thd_strmake_func)(void*, const char *, unsigned int);
   void *(*thd_memdup_func)(void*, const void*, unsigned int);
-  MYSQL_LEX_STRING *(*thd_make_lex_string_func)(void*, MYSQL_LEX_STRING *,
+  MYSQL_CONST_LEX_STRING *(*thd_make_lex_string_func)(void*,
+                                        MYSQL_CONST_LEX_STRING *,
                                         const char *, unsigned int, int);
 } *thd_alloc_service;
 void *thd_alloc(void* thd, unsigned int size);
@@ -247,9 +255,10 @@ void *thd_calloc(void* thd, unsigned int size);
 char *thd_strdup(void* thd, const char *str);
 char *thd_strmake(void* thd, const char *str, unsigned int size);
 void *thd_memdup(void* thd, const void* str, unsigned int size);
-MYSQL_LEX_STRING *thd_make_lex_string(void* thd, MYSQL_LEX_STRING *lex_str,
-                                      const char *str, unsigned int size,
-                                      int allocate_lex_string);
+MYSQL_CONST_LEX_STRING
+*thd_make_lex_string(void* thd, MYSQL_CONST_LEX_STRING *lex_str,
+                     const char *str, unsigned int size,
+                     int allocate_lex_string);
 extern struct thd_autoinc_service_st {
   void (*thd_get_autoinc_func)(const void* thd,
                                unsigned long* off, unsigned long* inc);
@@ -487,6 +496,6 @@ void thd_wakeup_subsequent_commits(void* thd, int wakeup_error);
 struct st_mariadb_password_validation
 {
   int interface_version;
-  int (*validate_password)(MYSQL_LEX_STRING *username,
-                           MYSQL_LEX_STRING *password);
+  int (*validate_password)(MYSQL_CONST_LEX_STRING *username,
+                           MYSQL_CONST_LEX_STRING *password);
 };
diff --git a/include/mysql/service_my_snprintf.h b/include/mysql/service_my_snprintf.h
index 4a99561dd00..586a539d48c 100644
--- a/include/mysql/service_my_snprintf.h
+++ b/include/mysql/service_my_snprintf.h
@@ -92,9 +92,22 @@ extern struct my_snprintf_service_st {
 
 #else
 
-size_t my_snprintf(char* to, size_t n, const char* fmt, ...);
+#ifndef ATTRIBUTE_FORMAT
+#define ATTRIBUTE_FORMAT_DEFINED
+#define ATTRIBUTE_FORMAT(A,B,C)
+#endif
+#ifdef MYSQL_ABI_CHECK
+#undef ATTRIBUTE_FORMAT
+#define ATTRIBUTE_FORMAT(A,B,C)
+#endif
+size_t my_snprintf(char* to, size_t n, const char* fmt, ...)
+  ATTRIBUTE_FORMAT(printf, 3, 4);
 size_t my_vsnprintf(char *to, size_t n, const char* fmt, va_list ap);
 
+#ifdef ATTRIBUTE_FORMAT_DEFINED
+#undef ATTRIBUTE_FORMAT_DEFINED
+#undef ATTRIBUTE_FORMAT
+#endif
 #endif
 
 #ifdef __cplusplus
diff --git a/include/mysql/service_thd_alloc.h b/include/mysql/service_thd_alloc.h
index e92f81b52c3..8d6ed8e4190 100644
--- a/include/mysql/service_thd_alloc.h
+++ b/include/mysql/service_thd_alloc.h
@@ -42,13 +42,21 @@ struct st_mysql_lex_string
 };
 typedef struct st_mysql_lex_string MYSQL_LEX_STRING;
 
+struct st_mysql_const_lex_string
+{
+  const char *str;
+  size_t length;
+};
+typedef struct st_mysql_const_lex_string MYSQL_CONST_LEX_STRING;
+
 extern struct thd_alloc_service_st {
   void *(*thd_alloc_func)(MYSQL_THD, unsigned int);
   void *(*thd_calloc_func)(MYSQL_THD, unsigned int);
   char *(*thd_strdup_func)(MYSQL_THD, const char *);
   char *(*thd_strmake_func)(MYSQL_THD, const char *, unsigned int);
   void *(*thd_memdup_func)(MYSQL_THD, const void*, unsigned int);
-  MYSQL_LEX_STRING *(*thd_make_lex_string_func)(MYSQL_THD, MYSQL_LEX_STRING *,
+  MYSQL_CONST_LEX_STRING *(*thd_make_lex_string_func)(MYSQL_THD,
+                                        MYSQL_CONST_LEX_STRING *,
                                         const char *, unsigned int, int);
 } *thd_alloc_service;
 
@@ -115,9 +123,10 @@ void *thd_memdup(MYSQL_THD thd, const void* str, unsigned int size);
 
   @see thd_alloc()
 */
-MYSQL_LEX_STRING *thd_make_lex_string(MYSQL_THD thd, MYSQL_LEX_STRING *lex_str,
-                                      const char *str, unsigned int size,
-                                      int allocate_lex_string);
+MYSQL_CONST_LEX_STRING
+*thd_make_lex_string(MYSQL_THD thd, MYSQL_CONST_LEX_STRING *lex_str,
+                     const char *str, unsigned int size,
+                     int allocate_lex_string);
 
 #endif
 
diff --git a/include/mysql_com.h b/include/mysql_com.h
index ace54767b06..d24957d1990 100644
--- a/include/mysql_com.h
+++ b/include/mysql_com.h
@@ -634,7 +634,7 @@ typedef struct st_udf_args
   char **args;				/* Pointer to argument */
   unsigned long *lengths;		/* Length of string arguments */
   char *maybe_null;			/* Set to 1 for all maybe_null args */
-  char **attributes;                    /* Pointer to attribute name */
+  const char **attributes;              /* Pointer to attribute name */
   unsigned long *attribute_lengths;     /* Length of attribute arguments */
   void *extension;
 } UDF_ARGS;