Calling 'c' function from PostGreSQL

Is it possible to call a language 'C' function from a PL/pgSQL function. I have the following code:

// file myfunc.c
#include "postgres.h"

text* myfunc();

text* myfunc()
{
text* ch;
*ch = '1,2';
return ch;
}

// C file ends here

create function myfunc as
'myfunc.so' langauge 'c';

create function test() returns text as '
declare
at text;
begin
at := myfunc();
return at;
end;
' language 'plpgsql';

The above when executed gives pqReadData()-- backend closed the channel unexpectedly.