From: David Herrmann <dh.herrmann@gmail.com>
Date: Tue, 23 Sep 2014 11:38:09 +0000 (+0200)
Subject: terminal: fix tile-offset calculation
X-Git-Tag: v217~450
X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=commitdiff_plain;h=b4170aed36e667e52ce4a353bda1964e3872ab34

terminal: fix tile-offset calculation

Binary operators with two pointers as arguments always operate on
object-size, not bytes. That is, "int *a, *b", (a - b) calculates the
number of integers between b and a, not the number of bytes.

Fix our cache-offset calculation to not use sizeof() with full-ptr
arithmetic.
---

diff --git a/src/libsystemd-terminal/grdev.c b/src/libsystemd-terminal/grdev.c
index c5ea524c6..80a71beeb 100644
--- a/src/libsystemd-terminal/grdev.c
+++ b/src/libsystemd-terminal/grdev.c
@@ -345,7 +345,7 @@ const grdev_display_target *grdev_display_next_target(grdev_display *display, co
                 assert(cache->pipe->tile->display == display);
                 assert(display->pipes >= cache);
 
-                idx = (cache - display->pipes) / sizeof(*cache) + 1;
+                idx = cache - display->pipes + 1;
         } else {
                 idx = 0;
         }