dvd-sector-copy.c: Check `n' nonnegative before comparing with unsigned.

Otherwise it might be coerced to unsigned, at which point the comparison
means something completely different.

diff --git a/dvd-sector-copy.c b/dvd-sector-copy.c
index c336d3d..177ce94 100644 (file)
--- a/dvd-sector-copy.c
+++ b/dvd-sector-copy.c
@@ -595,7 +595,7 @@ static ssize_t recovery_read(struct recoverybuf *r,
     printf(" -> %zd\n", n);
 #endif
     if (n != nn) {
-      if (n > want) n = want;
+      if (n >= 0 && n > want) n = want;
       goto end;
     }
     r->start = pp;