fix nonblock_read errno setting

nonblock_read() relies errno being 0 upon entering, and also does
not want to return -EINTR.

Signed-off-by: Peng Tao <bergwolf@gmail.com>

Author: bergwolf

src/init.c

@@ -1019,8 +1019,10 @@ static ssize_t hyper_channel_read(struct hyper_event *he, int efd, int len, int
 	ssize_t size;
 
 	size = nonblock_read(he->fd, buf->data + buf->get, len);
-	if (size < 0)
+	if (size < 0) {
+		fprintf(stderr, "%s failed with %d\n", __func__, (int)size);
 		goto out;
+	}
 
 	// check if peer is dissapeared
 	if ((size == 0) && (events & EPOLLHUP)) {

src/util.c

@@ -699,10 +699,12 @@ ssize_t nonblock_read(int fd, void *buf, size_t count)
 {
 	ssize_t len = 0, ret = 0;
 
+	errno = 0;
 	while (len < count) {
 		ret = read(fd, buf + len, count - len);
 		if (ret <= 0) {
 			if (errno == EINTR) {
+				errno = 0;
 				continue;
 			}
 			if (errno == EAGAIN) {