Workaround for MDEV-35935

If the server returns an error packet without error number
(and message) we set errno=CR_ERR_MISSING_ERROR_INFO (5026)

include/errmsg.h

@@ -115,10 +115,11 @@ extern const char *mariadb_client_errors[];	/* Error messages */
 #define CR_BINLOG_INVALID_FILE 5022
 #define CR_BINLOG_SEMI_SYNC_ERROR 5023
 #define CR_INVALID_CLIENT_FLAG 5024
+#define CR_ERR_MISSING_ERROR_INFO 5026
 
 /* Always last, if you add new error codes please update the
    value for CR_MARIADB_LAST_ERROR */
-#define CR_MARIADB_LAST_ERROR CR_INVALID_CLIENT_FLAG
+#define CR_MARIADB_LAST_ERROR CR_ERR_MISSING_ERROR_INFO
 
 #endif
 

libmariadb/ma_errmsg.c

@@ -119,6 +119,8 @@ const char *mariadb_client_errors[] =
   /* 5022 */ "File '%s' is not a binary log file",
   /* 5023 */ "Semi sync request error: %s",
   /* 5024 */ "Invalid client flags (%lu) specified. Supported flags: %lu",
+  /* 5025 */ "",
+  /* 5026 */ "Server returned an error packet without further information",
   ""
 };
 

libmariadb/mariadb_lib.c

@@ -274,6 +274,11 @@ restart:
         ma_strmake(net->last_error,(char*) pos,
                 min(len,sizeof(net->last_error)-1));
       }
+      /* MDEV-35935: if server sends error packet without error, we have to
+         set error manually */
+      if (!net->last_errno) {
+        my_set_error(mysql, CR_ERR_MISSING_ERROR_INFO, SQLSTATE_UNKNOWN, 0);
+      }
     }
     else
     {

unittest/libmariadb/errors.c

@@ -272,8 +272,77 @@ static int test_parse_error_and_bad_length(MYSQL *mysql)
   return OK;
 }
 
+#define TEST_ARRAY_SIZE 1024
+
+static int test_mdev35935(MYSQL *mysql)
+{
+  MYSQL_STMT *stmt= mysql_stmt_init(mysql);
+  const char *stmt_str= "INSERT INTO bulk1 (a,b) VALUES (?,?)";
+  unsigned int array_size= TEST_ARRAY_SIZE;
+  int rc;
+  unsigned int i;
+  char **buffer;
+  unsigned long *lengths;
+  unsigned int *vals;
+  MYSQL_BIND bind[2];
+  const char *data= "test";
+
+  SKIP_MYSQL(mysql);
+
+  rc= mysql_select_db(mysql, schema);
+
+  rc= mysql_query(mysql, "DROP TABLE IF EXISTS bulk1");
+  check_mysql_rc(rc, mysql);
+
+  rc= mysql_query(mysql, "CREATE TABLE bulk1 (a int , b VARCHAR(255))");
+  check_mysql_rc(rc, mysql);
+
+  rc= mysql_stmt_prepare(stmt, SL(stmt_str));
+  check_stmt_rc(rc, stmt);
+
+  rc= mysql_query(mysql, "ALTER TABLE bulk1 ADD c int");
+  check_mysql_rc(rc, mysql);
+
+  /* allocate memory */
+  buffer= calloc(TEST_ARRAY_SIZE, sizeof(char *));
+  lengths= calloc(TEST_ARRAY_SIZE, sizeof *lengths);
+  vals= calloc(TEST_ARRAY_SIZE, sizeof *vals);
+
+  for (i=0; i < TEST_ARRAY_SIZE; i++)
+  {
+    buffer[i]= (void *)data;
+    lengths[i]= -1;
+    vals[i]= i;
+  }
+
+  memset(bind, 0, sizeof(MYSQL_BIND) * 2);
+  bind[0].buffer_type= MYSQL_TYPE_LONG;
+  bind[0].buffer= vals;
+  bind[1].buffer_type= MYSQL_TYPE_STRING;
+  bind[1].buffer= (void *)buffer;
+  bind[1].length= (unsigned long *)lengths;
+
+  rc= mysql_stmt_attr_set(stmt, STMT_ATTR_ARRAY_SIZE, &array_size);
+  check_stmt_rc(rc, stmt);
+
+  rc= mysql_stmt_bind_param(stmt, bind);
+  check_stmt_rc(rc, stmt);
+
+  if ((rc= mysql_stmt_execute(stmt)))
+  {
+    FAIL_IF((!mysql_stmt_errno(stmt) || !mysql_errno(mysql)), "Error number > 0 expected");
+  }
+
+  mysql_stmt_close(stmt);
+  rc= mysql_query(mysql, "DROP TABLE IF EXISTS bulk1");
+  check_mysql_rc(rc, mysql);
+  return OK;
+}
+
+
 
 struct my_tests_st my_tests[] = {
+  {"test_mdev35935", test_mdev35935, TEST_CONNECTION_DEFAULT, 0, NULL , NULL},
   {"test_client_warnings", test_client_warnings, TEST_CONNECTION_DEFAULT, 0, NULL , NULL},
   {"test_ps_client_warnings", test_ps_client_warnings, TEST_CONNECTION_DEFAULT, 0, NULL , NULL},
   {"test_server_warnings", test_server_warnings, TEST_CONNECTION_DEFAULT, 0, NULL , NULL},