util.h

控制CPU的linux程序cpud、cpuctl

/*
 * Copyright (c) 2005 Alf Schlichting
 * All rights reserved.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */


#include <stdio.h>
#include <errno.h>

int		read_sock(int, char *, int);
int		write_sock(int, char *, int);

/* Helper functions to handle EINTR and EAGAIN */
int
read_sock(int fd, char *buf, int len)
{
	int n, pos;
	char *p;

	p = buf;
	n = pos = 0;

	while (len > pos) {
		n = read(fd, p + pos, len - pos);
		switch (n) {
			case -1:
				if (errno != EINTR && errno != EAGAIN)
					return(-1);
				else
					continue;
			case 0:
				return(0);
			default:
				pos += n;
		}
	}
	return pos;
}

int
write_sock(int fd, char *buf, int len)
{
	int n, pos;
	char *p;

	p = buf;
	n = pos = 0;

	while (len > pos) {
		n = write(fd, p + pos, len - pos);
		switch (n) {
			case -1:
				if (errno != EINTR && errno != EAGAIN)
					return(-1);
				else
					continue;
			case 0:
				return(0);
			default:
				pos += n;
		}
	}
	return pos;
}