Select() with callbacks per event

select.c

#include <sys/select.h>

#include <stdio.h>
#include <stdlib.h>

void fd_set_v2(unsigned int fd,
			         fd_set       *fds,
			         unsigned int *max_fd)
{
	if(!(fds && max_fd)) return;
	
	FD_SET(fd, fds);
	if(fd > *max_fd)
		*max_fd = fd;
}

void fd_clr_v2(unsigned int fd,
			         fd_set       *fds,
			         unsigned int *max_fd)
{
	if(!(fds && max_fd)) return;
	
	FD_CLR(fd, fds);
	if(fd == *max_fd)
		for(; !FD_ISSET(*max_fd, fds); *max_fd--);
}

void select_v2(unsigned int nfds,
			         fd_set       *readfds,
			         fd_set 	    *writefds,
			         fd_set       *exceptfds,
			         unsigned int timeout_ms,
			         select_cb_t  callback)
{
	struct timeval ttl;
	
	if(timeout_ms != 0)
	{
		ttl.tv_sec  = timeout_ms / 1000;
		ttl.tv_usec = (timeout_ms - ((timeout_ms / 1000) * 1000)) * 1000;
	}
	else
	{
		ttl = NULL;
	}
	
	int rv = select(nfds + 1, readfds, writefds, exceptfds, &ttl);
	
	if(rv < 0)
	{
		perror("select()"); return;
	}
	if(rv == 0)
	{
		printf("select(): timeout.\n"); return;
	}
	
	int rdyfds = rv;
	
	for(unsigned int i = 0; i < nfds && rdyfds > 0; i++)
	{
		fd_set *cbset = NULL;
		
		if(FD_ISSET(i, readfds))
			cbset = readfds;
			
		else if(FD_ISSET(i, writefds))
			cbset = writefds;
			
		else if(FD_ISSET(i, exceptfds))
			cbset = exceptfds;
		
		if(cbset)
		{
			--rdyfds;
			if(callback)
				callback(i, cbset);
		}
	}
}