#include <db.h>
int
db_env_set_func_pwrite(ssize_t (*func_pwrite)(int fd, const void *buf, 
    size_t nbytes, off_t offset));  
      Replace Berkeley DB calls to the IEEE/ANSI Std 1003.1 (POSIX) pwrite function with func_pwrite, which must conform to the standard interface specification.
         The db_env_set_func_pwrite() configures all operations performed
         by a process and all of its threads of control, not operations
         confined to a single database environment.
    
         Although the db_env_set_func_pwrite() may be called at any time
         during the life of the application, it should normally be called
         before making calls to the db_env_create or
         db_create methods.
    
         The db_env_set_func_pwrite() 
                  function returns a non-zero error value on failure and 0 on success.