Tag my_vsnprintf.c with ATTRIBUTE_FORMAT

[Breaking]
Good news:
GCC now checks your `my_snprintf` (direct) calls (`-Wformat` was on);
Bad news:
The build process no longer lets your incorrect
formats/arguments sneak past (`-Werror` was also on).

As such, this commit also migrates all direct `my_snprintf` calls from
the old specifiers to MDEV-21978’s new `-Wformat`-compatible suffixes.
The next commits will cover non-direct calls to `my_snprintf`.
(I call them “`my_snprintf` descendants”.)

This commit does not update the ABI records because
there’re more ABI “changes” to come – half a dozen
`include/mysql/plugin_*.h.pp`s are now missing the new `__attribute__`s.

client/mysql_upgrade.c

@@ -556,7 +556,7 @@ static void find_tool(char *tool_executable_name, const char *tool_name,
 
     len= (int)(last_fn_libchar - self_name);
 
-    my_snprintf(tool_executable_name, FN_REFLEN, "%.*b%c%s",
+    my_snprintf(tool_executable_name, FN_REFLEN, "%.*sB%c%s",
                 len, self_name, FN_LIBCHAR, tool_name);
   }
 

client/mysqlbinlog.cc

@@ -631,7 +631,7 @@ print_use_stmt(PRINT_EVENT_INFO* pinfo, const Query_log_event *ev)
     return;
 
   // In case of rewrite rule print USE statement for db_to
-  my_fprintf(result_file, "use %`s%s\n", db_to, pinfo->delimiter);
+  my_fprintf(result_file, "use %sQ%s\n", db_to, pinfo->delimiter);
 
   // Copy the *original* db to pinfo to suppress emitting
   // of USE stmts by log_event print-functions.

client/mysqlcheck.c

@@ -551,7 +551,7 @@ static int is_view(const char *table)
   int view;
   DBUG_ENTER("is_view");
 
-  my_snprintf(query, sizeof(query), "SHOW CREATE TABLE %`s", table);
+  my_snprintf(query, sizeof(query), "SHOW CREATE TABLE %sQ", table);
   if (mysql_query(sock, query))
   {
     fprintf(stderr, "Failed to %s\n", query);
@@ -800,7 +800,7 @@ static int fix_table_storage_name(const char *name)
 
   if (strncmp(name, "#mysql50#", 9))
     DBUG_RETURN(1);
-  my_snprintf(qbuf, sizeof(qbuf), "RENAME TABLE %`s TO %`s",
+  my_snprintf(qbuf, sizeof(qbuf), "RENAME TABLE %sQ TO %sQ",
               name, name + 9);
 
   rc= run_query(qbuf, 1);
@@ -817,7 +817,7 @@ static int fix_database_storage_name(const char *name)
 
   if (strncmp(name, "#mysql50#", 9))
     DBUG_RETURN(1);
-  my_snprintf(qbuf, sizeof(qbuf), "ALTER DATABASE %`s UPGRADE DATA DIRECTORY "
+  my_snprintf(qbuf, sizeof(qbuf), "ALTER DATABASE %sQ UPGRADE DATA DIRECTORY "
               "NAME", name);
   rc= run_query(qbuf, 1);
   if (!opt_silent)
@@ -1026,7 +1026,7 @@ static void insert_table_name(DYNAMIC_ARRAY *arr, char *in, size_t dblen)
 {
   char buf[NAME_LEN*2+2];
   in[dblen]= 0;
-  my_snprintf(buf, sizeof(buf), "%`s.%`s", in, in + dblen + 1);
+  my_snprintf(buf, sizeof(buf), "%sQ.%sQ", in, in + dblen + 1);
   insert_dynamic(arr, (uchar*) buf);
 }
 

include/m_ctype.h

@@ -1776,7 +1776,8 @@ const MY_CONTRACTIONS *my_charset_get_contractions(CHARSET_INFO *cs,
                                                    int level);
 
 extern size_t my_vsnprintf_ex(CHARSET_INFO *cs, char *to, size_t n,
-                              const char* fmt, va_list ap);
+                              const char* fmt, va_list ap)
+                              ATTRIBUTE_FORMAT(printf, 4, 0);
 
 /*
   Convert a string between two character sets.

include/my_sys.h

@@ -723,9 +723,11 @@ extern FILE *my_fopen(const char *FileName,int Flags,myf MyFlags);
 extern FILE *my_fdopen(File Filedes,const char *name, int Flags,myf MyFlags);
 extern FILE *my_freopen(const char *path, const char *mode, FILE *stream);
 extern int my_fclose(FILE *fd,myf MyFlags);
-extern int my_vfprintf(FILE *stream, const char* format, va_list args);
+extern int my_vfprintf(FILE *stream, const char* format, va_list args)
+  ATTRIBUTE_FORMAT(printf, 2, 0);
 extern const char* my_strerror(char *buf, size_t len, int nr);
-extern int my_fprintf(FILE *stream, const char* format, ...);
+extern int my_fprintf(FILE *stream, const char* format, ...)
+  ATTRIBUTE_FORMAT(printf, 2, 3);
 extern File my_fileno(FILE *fd);
 extern int my_chsize(File fd,my_off_t newlength, int filler, myf MyFlags);
 extern int my_chmod(const char *name, mode_t mode, myf my_flags);

include/mysql/service_my_snprintf.h

@@ -93,10 +93,13 @@ extern "C" {
 #include <stdarg.h>
 #include <stdlib.h>
 #endif
+#include <my_attribute.h>
 
 extern struct my_snprintf_service_st {
-  size_t (*my_snprintf_type)(char*, size_t, const char*, ...);
+  size_t (*my_snprintf_type)(char*, size_t, const char*, ...)
-  size_t (*my_vsnprintf_type)(char *, size_t, const char*, va_list);
+    ATTRIBUTE_FORMAT_FPTR(printf, 3, 4);
+  size_t (*my_vsnprintf_type)(char *, size_t, const char*, va_list)
+    ATTRIBUTE_FORMAT_FPTR(printf, 3, 0);
 } *my_snprintf_service;
 
 #ifdef MYSQL_DYNAMIC_PLUGIN
@@ -106,8 +109,10 @@ extern struct my_snprintf_service_st {
 
 #else
 
-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);
+  ATTRIBUTE_FORMAT(printf, 3, 4);
+size_t my_vsnprintf(char *to, size_t n, const char* fmt, va_list ap)
+  ATTRIBUTE_FORMAT(printf, 3, 0);
 
 #endif
 

sql/log_event_client.cc

@@ -3303,7 +3303,7 @@ static void get_type_name(uint type, unsigned char** meta_ptr,
 {
   switch (type) {
   case MYSQL_TYPE_LONG:
-    my_snprintf(typestr, typestr_length, "%s", "INT");
+    my_snprintf(typestr, typestr_length, "INT");
     break;
   case MYSQL_TYPE_TINY:
     my_snprintf(typestr, typestr_length, "TINYINT");
@@ -3373,20 +3373,21 @@ static void get_type_name(uint type, unsigned char** meta_ptr,
     break;
   case MYSQL_TYPE_BLOB:
     {
-      bool is_text= (cs && cs->number != my_charset_bin.number);
+      const char *type_name=
-      const char *names[5][2] = {
+        (cs && cs->number != my_charset_bin.number) ? "TEXT" : "BLOB";
-        {"INVALID_BLOB(%d)", "INVALID_TEXT(%d)"},
+      const char *names[5]= {
-        {"TINYBLOB", "TINYTEXT"},
+        NullS,
-        {"BLOB", "TEXT"},
+        "TINY",
-        {"MEDIUMBLOB", "MEDIUMTEXT"},
+        "",
-        {"LONGBLOB", "LONGTEXT"}
+        "MEDIUM",
+        "LONG"
       };
       unsigned char size= **meta_ptr;
 
       if (size == 0 || size > 4)
-        my_snprintf(typestr, typestr_length, names[0][is_text], size);
+        my_snprintf(typestr, typestr_length, "INVALID_%s(%d)", type_name, size);
       else
-        my_snprintf(typestr, typestr_length, names[**meta_ptr][is_text]);
+        my_snprintf(typestr, typestr_length, "%s%s", names[size], type_name);
 
       (*meta_ptr)++;
     }
@@ -3423,7 +3424,7 @@ static void get_type_name(uint type, unsigned char** meta_ptr,
         "MULTILINESTRING", "MULTIPOLYGON", "GEOMETRYCOLLECTION"
       };
       if (geometry_type < 8)
-        my_snprintf(typestr, typestr_length, names[geometry_type]);
+        my_snprintf(typestr, typestr_length, "%s", names[geometry_type]);
       else
         my_snprintf(typestr, typestr_length, "INVALID_GEOMETRY_TYPE(%u)",
                     geometry_type);

sql/sql_admin.cc

@@ -711,7 +711,7 @@ static bool mysql_admin_table(THD* thd, TABLE_LIST* tables,
             protocol->store(&table_name, system_charset_info);
             protocol->store(operator_name, system_charset_info);
             protocol->store(&error_clex_str, system_charset_info);
-            length= my_snprintf(buff, sizeof(buff),
+            length= my_snprintf(buff, sizeof(buff), "%s",
                                 ER_THD(thd, ER_PARTITION_DOES_NOT_EXIST));
             protocol->store(buff, length, system_charset_info);
             if(protocol->write())

sql/sql_db.cc

@@ -1237,7 +1237,7 @@ update_binlog:
       if (ha_table_exists(thd, &tbl->db, &tbl->table_name))
         continue;
 
-      tbl_name_len= my_snprintf(quoted_name, sizeof(quoted_name), "%`s",
+      tbl_name_len= my_snprintf(quoted_name, sizeof(quoted_name), "%sQ",
                                 tbl->table_name.str);
       tbl_name_len++;                           /* +1 for the comma */
       if (query_pos + tbl_name_len + 1 >= query_end)

storage/example/ha_example.cc

@@ -1070,7 +1070,7 @@ static int show_func_example(MYSQL_THD thd, struct st_mysql_show_var *var,
   var->value= buf; // it's of SHOW_VAR_FUNC_BUFF_SIZE bytes
   my_snprintf(buf, SHOW_VAR_FUNC_BUFF_SIZE,
               "enum_var is %lu, ulong_var is %lu, int_var is %d, "
-              "double_var is %f, %.6b", // %b is a MariaDB/MySQL extension
+              "double_var is %f, %.6sB", // %sB is a MariaDB extension
               srv_enum_var, srv_ulong_var, THDVAR(thd, int_var),
               srv_double_var, "really");
   return 0;