Be nice with the CPU in fd_{read,write}_all()

glorytun.c

@@ -263,7 +263,14 @@ static ssize_t fd_read_all (int fd, void *data, size_t size)
 {
     size_t done = 0;
 
+    struct pollfd pollfd = {
+        .fd = fd,
+        .events = POLLIN,
+    };
+
     while (done<size) {
+        poll(&pollfd, 1, -1);
+
         ssize_t ret = fd_read(fd, data+done, size-done);
 
         if (!ret)
@@ -280,7 +287,14 @@ static ssize_t fd_write_all (int fd, const void *data, size_t size)
 {
     size_t done = 0;
 
+    struct pollfd pollfd = {
+        .fd = fd,
+        .events = POLLOUT,
+    };
+
     while (done<size) {
+        poll(&pollfd, 1, -1);
+
         ssize_t ret = fd_write(fd, data+done, size-done);
 
         if (!ret)