I read about reentrant function versions and I was goint to use them (in fact I have them already converted in my code). During the debugging I entered accidently into the _read_r function and I have seen its body:
ssize_t
_DEFUN (_read_r, (ptr, fd, buf, cnt),
struct _reent *ptr _AND
int fd _AND
_PTR buf _AND
size_t cnt)
{
_ssize_t ret;
errno = 0;
if ((ret = (_ssize_t)_read (fd, buf, cnt)) == -1 && errno != 0)
ptr->_errno = errno;
return ret;
}
Looking at this source code I find this function NOT REENTRANT!
Nothing stops an interrupt to arrive between seting global errno and copying its value to a struct _reent. Such intterupt would cause reschedule in MicroC/OS and the other task can use global errno variable for its own and modify its value before the scheduler returns control to the previous task.
I see no point of using these functions - am I correct thinking they do not do any good ?
