server: fread() - check <= 0 return value

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/server.c b/server.c
index 4f9c023..5506ca9 100644
--- a/server.c
+++ b/server.c
@@ -938,7 +938,7 @@
 	if (!f)
 		return 0;
 
-	if (fread(buf, sb.st_size, 1, f) < 0) {
+	if (fread(buf, sb.st_size, 1, f) <= 0) {
 		fclose(f);
 		return 1;
 	}