/*
* iread - insistent read. Same usage as read, but will always return
* either the exact number of bytes requested, 0, or -1, unless a call
* to read gets some data and a subsequent call returns 0.
*/
int
iread (fd, buf, n)
int fd, n;
register char *buf;
{
register int r, offset;
r = read (fd, buf, n);
if (r <= 0)
return r;
offset = 0;
while (r != n - offset && r > 0) {
offset += r;
r = read (fd, buf + offset, n - offset);
}
return r < 0? r: r + offset;
}