MDEV-15945 --ps-protocol does not test some queries

Make mysqltest to use --ps-protocol more

use prepared statements for everything that server supports
with the exception of CALL (for now).

Fix discovered test failures and bugs.

tests:
* PROCESSLIST shows Execute state, not Query
* SHOW STATUS increments status variables more than in text protocol
* multi-statements should be avoided (see tests with a wrong delimiter)
* performance_schema events have different names in --ps-protocol
* --enable_prepare_warnings

mysqltest.cc:
* make sure run_query_stmt() doesn't crash if there's
  no active connection (in wait_until_connected_again.inc)
* prepare all statements that server supports

protocol.h
* Protocol_discard::send_result_set_metadata() should not send
  anything to the client.

sql_acl.cc:
* extract the functionality of getting the user for SHOW GRANTS
  from check_show_access(), so that mysql_test_show_grants() could
  generate the correct column names in the prepare step

sql_class.cc:
* result->prepare() can fail, don't ignore its return value
* use correct number of decimals for EXPLAIN columns

sql_parse.cc:
* discard profiling for SHOW PROFILE. In text protocol it's done in
  prepare_schema_table(), but in --ps it is called on prepare only,
  so nothing was discarding profiling during execute.
* move the permission checking code for SHOW CREATE VIEW to
  mysqld_show_create_get_fields(), so that it would be called during
  prepare step too.
* only set sel_result when it was created here and needs to be
  destroyed in the same block. Avoid destroying lex->result.
* use the correct number of tables in check_show_access(). Saying
  "as many as possible" doesn't work when first_not_own_table isn't
  set yet.

sql_prepare.cc:
* use correct user name for SHOW GRANTS columns
* don't ignore verbose flag for SHOW SLAVE STATUS
* support preparing REVOKE ALL and ROLLBACK TO SAVEPOINT
* don't ignore errors from thd->prepare_explain_fields()
* use select_send result for sending ANALYZE and EXPLAIN, but don't
  overwrite lex->result, because it might be needed to issue execute-time
  errors (select_dumpvar - too many rows)

sql_show.cc:
* check grants for SHOW CREATE VIEW here, not in mysql_execute_command

sql_view.cc:
* use the correct function to check privileges. Old code was doing
  check_access() for thd->security_ctx, which is invoker's sctx,
  not definer's sctx. Hide various view related errors from the invoker.

sql_yacc.yy:
* initialize lex->select_lex for LOAD, otherwise it'll contain garbage
  data that happen to fail tests with views in --ps (but not otherwise).

1 files changed, 50 insertions, 42 deletions

diff --git a/sql/sql_acl.cc b/sql/sql_acl.cc
index 6052284428e..9110834b449 100644
--- a/sql/sql_acl.cc
+++ b/sql/sql_acl.cc
@@ -7776,6 +7776,51 @@ void mysql_show_grants_get_fields(THD *thd, List<Item> *fields,
   fields->push_back(field, thd->mem_root);
 }
 
+bool get_show_user(THD *thd, LEX_USER *lex_user, const char **username,
+                   const char **hostname, const char **rolename)
+{
+  if (lex_user->user.str == current_user.str)
+  {
+    *username= thd->security_ctx->priv_user;
+    *hostname= thd->security_ctx->priv_host;
+    return 0;
+  }
+  if (lex_user->user.str == current_role.str)
+  {
+    *rolename= thd->security_ctx->priv_role;
+    return 0;
+  }
+  if (lex_user->user.str == current_user_and_current_role.str)
+  {
+    *username= thd->security_ctx->priv_user;
+    *hostname= thd->security_ctx->priv_host;
+    *rolename= thd->security_ctx->priv_role;
+    return 0;
+  }
+
+  Security_context *sctx= thd->security_ctx;
+  bool do_check_access;
+
+  if (!(lex_user= get_current_user(thd, lex_user)))
+    return 1;
+
+  if (lex_user->is_role())
+  {
+    *rolename= lex_user->user.str;
+    do_check_access= strcmp(*rolename, sctx->priv_role);
+  }
+  else
+  {
+    *username= lex_user->user.str;
+    *hostname= lex_user->host.str;
+    do_check_access= strcmp(*username, sctx->priv_user) ||
+                     strcmp(*hostname, sctx->priv_host);
+  }
+
+  if (do_check_access && check_access(thd, SELECT_ACL, "mysql", 0, 0, 1, 0))
+    return 1;
+  return 0;
+}
 
 /*
   SHOW GRANTS;  Send grants for a user to the client
@@ -7791,9 +7836,9 @@ bool mysql_show_grants(THD *thd, LEX_USER *lex_user)
   ACL_ROLE *acl_role= NULL;
   char buff[1024];
   Protocol *protocol= thd->protocol;
-  char *username= NULL;
-  char *hostname= NULL;
-  char *rolename= NULL;
+  const char *username= NULL;
+  const char *hostname= NULL;
+  const char *rolename= NULL;
   DBUG_ENTER("mysql_show_grants");
 
   if (!initialized)
@@ -7802,46 +7847,9 @@ bool mysql_show_grants(THD *thd, LEX_USER *lex_user)
     DBUG_RETURN(TRUE);
   }
 
-  if (lex_user->user.str == current_user.str)
-  {
-    username= thd->security_ctx->priv_user;
-    hostname= thd->security_ctx->priv_host;
-  }
-  else if (lex_user->user.str == current_role.str)
-  {
-    rolename= thd->security_ctx->priv_role;
-  }
-  else if (lex_user->user.str == current_user_and_current_role.str)
-  {
-    username= thd->security_ctx->priv_user;
-    hostname= thd->security_ctx->priv_host;
-    rolename= thd->security_ctx->priv_role;
-  }
-  else
-  {
-    Security_context *sctx= thd->security_ctx;
-    bool do_check_access;
-
-    lex_user= get_current_user(thd, lex_user);
-    if (!lex_user)
-      DBUG_RETURN(TRUE);
-
-    if (lex_user->is_role())
-    {
-      rolename= lex_user->user.str;
-      do_check_access= strcmp(rolename, sctx->priv_role);
-    }
-    else
-    {
-      username= lex_user->user.str;
-      hostname= lex_user->host.str;
-      do_check_access= strcmp(username, sctx->priv_user) ||
-                       strcmp(hostname, sctx->priv_host);
-    }
+  if (get_show_user(thd, lex_user, &username, &hostname, &rolename))
+    DBUG_RETURN(TRUE);
 
-    if (do_check_access && check_access(thd, SELECT_ACL, "mysql", 0, 0, 1, 0))
-      DBUG_RETURN(TRUE);
-  }
   DBUG_ASSERT(rolename || username);
 
   List<Item> field_list;