MDEV-12684 Show what config file a sysvar got a value from

make load_defaults() store the file name in the generated option list
using a special marker ---file-marker--- option.

Pick up this filename in handle_options().

Remove ---args-separator---, use ---file-marker--- with an empty file
name instead - this simplifies checks on the caller, only one special
option to recognize.

include/my_default.h

@@ -23,7 +23,7 @@ C_MODE_START
 extern const char *my_defaults_extra_file;
 extern const char *my_defaults_group_suffix;
 extern const char *my_defaults_file;
-extern my_bool my_getopt_use_args_separator;
+extern my_bool my_defaults_mark_files;
 
 extern int get_defaults_options(char **argv);
 extern int my_load_defaults(const char *conf_file, const char **groups,

mysys/my_default.c

@@ -43,38 +43,16 @@
 #include <winbase.h>
 #endif
 
-/**
-   arguments separator
-
-   load_defaults() loads arguments from config file and put them
-   before the arguments from command line, this separator is used to
-   separate the arguments loaded from config file and arguments user
-   provided on command line.
-
-   Options with value loaded from config file are always in the form
-   '--option=value', while for command line options, the value can be
-   given as the next argument. Thus we used a separator so that
-   handle_options() can distinguish them.
-
-   Note: any other places that does not need to distinguish them
-   should skip the separator.
-
-   The content of arguments separator does not matter, one should only
-   check the pointer, use "----args-separator----" here to ease debug
-   if someone misused it.
-
-   The args separator will only be added when
-   my_getopt_use_args_seprator is set to TRUE before calling
-   load_defaults();
-
-   See BUG#25192
+/*
+  Mark file names in argv[]. File marker is *always* followed by a file name
+  All options after it come from that file.
+  Empty file name ("") means command line.
 */
-
-static char *args_separator= (char*)"----args-separator----";
-my_bool my_getopt_use_args_separator= FALSE;
-my_bool my_getopt_is_args_separator(const char* arg)
+static char *file_marker= (char*)"----file-marker----";
+my_bool my_defaults_mark_files= FALSE;
+my_bool is_file_marker(const char* arg)
 {
-  return (arg == args_separator);
+  return arg == file_marker;
 }
 
 my_bool my_no_defaults=FALSE, my_print_defaults= FALSE;
@@ -335,7 +313,7 @@ int get_defaults_options(char **argv)
   if (*argv && !strcmp(*argv, "--print-defaults"))
   {
     my_print_defaults= 1;
-    my_getopt_use_args_separator= FALSE;
+    my_defaults_mark_files= FALSE;
     argv++;
   }
 
@@ -483,8 +461,11 @@ int my_load_defaults(const char *conf_file, const char **groups, int *argc,
   /* found arguments + command line arguments to new array */
   memcpy(res, args.buffer, args.elements * sizeof(char*));
 
-  if (my_getopt_use_args_separator)
-    res[args.elements++]= args_separator;
+  if (my_defaults_mark_files)
+  {
+    res[args.elements++]= file_marker;
+    res[args.elements++]= (char*)"";
+  }
 
   if (*argc)
     memcpy(res + args.elements, *argv, *argc * sizeof(char*));
@@ -665,6 +646,11 @@ static int search_default_file_with_ext(struct handle_option_ctx *ctx,
   if (!(fp= mysql_file_fopen(key_file_cnf, name, O_RDONLY, MYF(0))))
     return 1;					/* Ignore wrong files */
 
+  if (my_defaults_mark_files)
+    if (insert_dynamic(ctx->args, (uchar*) &file_marker) ||
+        add_option(ctx, name))
+      goto err;
+
   while (mysql_file_fgets(buff, sizeof(buff) - 1, fp))
   {
     line++;

mysys/my_getopt.c

@@ -24,7 +24,7 @@
 #include <my_getopt.h>
 #include <errno.h>
 
-my_bool my_getopt_is_args_separator(const char* arg);
+my_bool is_file_marker(const char* arg);
 typedef void (*init_func_p)(const struct my_option *option, void *variable,
                             longlong value);
 
@@ -193,6 +193,7 @@ int handle_options(int *argc, char ***argv, const struct my_option *longopts,
   my_bool end_of_options= 0, must_be_var, set_maximum_value,
           option_is_loose, option_is_autoset;
   char **pos, **pos_end, *optend, *opt_str, key_name[FN_REFLEN];
+  char *filename= (char*)"";
   const char *UNINIT_VAR(prev_found);
   const struct my_option *optp;
   void *value;
@@ -207,34 +208,29 @@ int handle_options(int *argc, char ***argv, const struct my_option *longopts,
   (*argv)++; /*      --- || ----      */
   init_variables(longopts, init_one_value);
 
-  /*
-    Search for args_separator, if found, then the first part of the
-    arguments are loaded from configs
-  */
-  for (pos= *argv, pos_end=pos+ *argc; pos != pos_end ; pos++)
-  {
-    if (my_getopt_is_args_separator(*pos))
-    {
-      is_cmdline_arg= 0;
-      break;
-    }
-  }
+  is_cmdline_arg= !is_file_marker(**argv);
 
   for (pos= *argv, pos_end=pos+ *argc; pos != pos_end ; pos++)
   {
     char **first= pos;
     char *cur_arg= *pos;
     opt_found= 0;
-    if (!is_cmdline_arg && (my_getopt_is_args_separator(cur_arg)))
+    if (!is_cmdline_arg)
     {
-      is_cmdline_arg= 1;
-
-      /* save the separator too if skip unknown options  */
-      if (my_getopt_skip_unknown)
-        (*argv)[argvpos++]= cur_arg;
-      else
-        (*argc)--;
-      continue;
+      if (is_file_marker(cur_arg))
+      {
+        pos++;
+        filename= *pos;
+        is_cmdline_arg= *filename == 0; /* empty file name = command line */
+        if (my_getopt_skip_unknown)
+        {
+          (*argv)[argvpos++]= cur_arg;
+          (*argv)[argvpos++]= filename;
+        }
+        else
+          (*argc)-= 2;
+        continue;
+      }
     }
     if (cur_arg[0] == '-' && cur_arg[1] && !end_of_options) /* must be opt */
     {

sql/mysqld.cc

@@ -5348,7 +5348,7 @@ int mysqld_main(int argc, char **argv)
 
   orig_argc= argc;
   orig_argv= argv;
-  my_getopt_use_args_separator= TRUE;
+  my_defaults_mark_files= TRUE;
   load_defaults_or_exit(MYSQL_CONFIG_NAME, load_default_groups, &argc, &argv);
   defaults_argc= argc;
   defaults_argv= argv;