Bug #56767: Make sure client plugins in 1054 are compatible with

  connectors plugins
      
Implemented changes needed to keep the client plugin API compatible with 
the existing plugins :
      
1. Provided an options() client plugin API to let the application pass
options to the plugin after loading it
2. Added "License" (const char *) to specify the client plugin's license
3. Added "mysql_api" as a placeholder that the client library can use
to pass function pointers to the plugin so that the plugin can call the 
C lib back.
4. Updated the existing client plugins to comply with the API change.
5. Added more detailed error message generation for Windows.

include/mysql/client_plugin.h

@@ -50,8 +50,11 @@
   const char *author;                                   \
   const char *desc;                                     \
   unsigned int version[3];                              \
+  const char *license;                                  \
+  void *mysql_api;                                      \
   int (*init)(char *, size_t, int, va_list);            \
-  int (*deinit)();
+  int (*deinit)();                                      \
+  int (*options)(const char *option, const void *);
 
 struct st_mysql_client_plugin
 {
@@ -142,5 +145,20 @@ struct st_mysql_client_plugin *
 mysql_client_register_plugin(struct st_mysql *mysql,
                              struct st_mysql_client_plugin *plugin);
 
+/**
+  set plugin options
+
+  Can be used to set extra options and affect behavior for a plugin.
+  This function may be called multiple times to set several options
+
+  @param plugin an st_mysql_client_plugin structure
+  @param option a string which specifies the option to set
+  @param value  value for the option.
+
+  @retval 0 on success, 1 in case of failure
+**/
+int STDCALL mysql_plugin_options(struct st_mysql_client_plugin *plugin,
+                                 const char *option,
+                                 const void *value);
 #endif
 

libmysql/libmysql.def

@@ -104,3 +104,4 @@ EXPORTS
 	mysql_server_end
 	mysql_set_character_set
 	mysql_get_character_set_info
+        mysql_plugin_options

plugin/auth/dialog.c

@@ -319,8 +319,11 @@ mysql_declare_client_plugin(AUTHENTICATION)
   "Sergei Golubchik",
   "Dialog Client Authentication Plugin",
   {0,1,0},
+  "GPL",
+  NULL,
   init_dialog,
   NULL,
+  NULL,
   perform_dialog
 mysql_end_client_plugin;
 

plugin/auth/test_plugin.c

@@ -196,6 +196,9 @@ mysql_declare_client_plugin(AUTHENTICATION)
   "Georgi Kodinov",
   "Dialog Client Authentication Plugin",
   {0,1,0},
+  "GPL",
+  NULL,
+  NULL,
   NULL,
   NULL,
   test_plugin_client

sql-common/client.c

@@ -2283,6 +2283,9 @@ static auth_plugin_t native_password_client_plugin=
   "R.J.Silk, Sergei Golubchik",
   "Native MySQL authentication",
   {1, 0, 0},
+  "GPL",
+  NULL,
+  NULL,
   NULL,
   NULL,
   native_password_auth_client
@@ -2296,6 +2299,9 @@ static auth_plugin_t old_password_client_plugin=
   "R.J.Silk, Sergei Golubchik",
   "Old MySQL-3.23 authentication",
   {1, 0, 0},
+  "GPL",
+  NULL,
+  NULL,
   NULL,
   NULL,
   old_password_auth_client

sql-common/client_plugin.c

@@ -322,6 +322,9 @@ mysql_load_plugin_v(MYSQL *mysql, const char *name, int type,
   char dlpath[FN_REFLEN+1];
   void *sym, *dlhandle;
   struct st_mysql_client_plugin *plugin;
+#ifdef WIN32
+  char win_errormsg[2048];
+#endif
 
   DBUG_ENTER ("mysql_load_plugin_v");
   DBUG_PRINT ("entry", ("name=%s type=%d int argc=%d", name, type, argc));
@@ -359,8 +362,15 @@ mysql_load_plugin_v(MYSQL *mysql, const char *name, int type,
     if ((dlhandle= dlopen(dlpath, RTLD_NOW)))
       goto have_plugin;
 #endif
+
     DBUG_PRINT ("info", ("failed to dlopen"));
+#ifdef WIN32
+    FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM,
+                  0, GetLastError(), 0, win_errormsg, 2048, NULL);
+    errormsg= win_errormsg;
+#else
     errmsg= dlerror();
+#endif
     goto err;
   }
 
@@ -451,3 +461,15 @@ mysql_client_find_plugin(MYSQL *mysql, const char *name, int type)
   DBUG_RETURN (p);
 }
 
+
+/* see <mysql/client_plugin.h> for a full description */
+int STDCALL mysql_plugin_options(struct st_mysql_client_plugin *plugin,
+                                 const char *option,
+                                 const void *value)
+{
+  DBUG_ENTER("mysql_plugin_options");
+  /* does the plugin support options call? */
+  if (!plugin || !plugin->options)
+    DBUG_RETURN(1);
+  DBUG_RETURN(plugin->options(option, value));
+}