Fix access to single-byte characters in buffer text

* src/xdisp.c (get_visually_first_element)
(Fbidi_find_overridden_directionality):
* src/cmds.c (Fend_of_line): Use FETCH_BYTE instead of FETCH_CHAR,
and byte position instead of character position, to access
individual bytes of buffer text.  This avoids producing invalid
characters and accessing wrong buffer positions.  (Bug#41520)

1 files changed, 2 insertions, 2 deletions

diff --git a/src/cmds.c b/src/cmds.c
index 5d7a45e65f6..9914b7a01f7 100644
--- a/src/cmds.c
+++ b/src/cmds.c
@@ -203,7 +203,7 @@ to t.  */)
       SET_PT (newpos);
 
       if (PT > newpos
-          && FETCH_CHAR (PT - 1) == '\n')
+          && FETCH_BYTE (PT_BYTE - 1) == '\n')
         {
           /* If we skipped over a newline that follows
              an invisible intangible run,
@@ -214,7 +214,7 @@ to t.  */)
           break;
         }
       else if (PT > newpos && PT < ZV
-               && FETCH_CHAR (PT) != '\n')
+               && FETCH_BYTE (PT_BYTE) != '\n')
         /* If we skipped something intangible
            and now we're not really at eol,
            keep going.  */