can't initialize MySQL library - c++

Question

when i try to run a simple program like this:
int main(void) {
mysql_library_init(0, NULL, NULL);
mysql_library_end();
return 0;}
i get the following output errors:
mysql_embedded: Can't find file: '/var/lib/mysql/mysql/plugin.frm' (errno: 13 - Permission denied)
2015-12-30 00:23:04 7fd31a6be740 InnoDB: Operating system error number 13 in a file operation.
InnoDB: The error means mysqld does not have the access rights to
InnoDB: the directory.
mysql_embedded: File '/var/lib/mysql/auto.cnf' not found (Errcode: 13 - Permission denied)
here is some info about the directory and files:
$ ls -l --time-style=long-iso /var/lib/
...
drwx------ 4 mysql mysql 4096 2015-12-26 12:58 mysql
...
$ sudo ls -l --time-style=long-iso /var/lib/mysql/mysql/plugin.frm
-rw-rw---- 1 mysql mysql 8586 2015-12-25 21:49 /var/lib/mysql/mysql/plugin.frm
$ sudo ls -l --time-style=long-iso /var/lib/mysql/auto.cnf
-rw-rw---- 1 mysql mysql 56 2015-12-25 21:49 /var/lib/mysql/auto.cnf
what's the problem?
$ dpkg -s libmysqld-dev | grep 'Version'
Version: 5.6.27-0ubuntu1