From: Richard M. Stallman <rms@gnu.org>
Date: Fri, 6 Mar 1998 21:57:04 +0000 (+0000)
Subject: (advance_to_char_boundary): Handle the case the code
X-Git-Tag: emacs-20.3~1989
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=f8449323058067b822415b4821e2eb66effe0ecb;p=emacs.git

(advance_to_char_boundary): Handle the case the code
0240..0377 is not a constituent of a multibyte sequence.
---

diff --git a/src/buffer.c b/src/buffer.c
index 9879e8520bf..9fcae96e8b2 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -1683,12 +1683,22 @@ static int
 advance_to_char_boundary (byte_pos)
      int byte_pos;
 {
-  int c = FETCH_BYTE (byte_pos);
+  int c;
 
-  while (! CHAR_HEAD_P (c))
+  if (byte_pos == BEG)
+    /* Beginning of buffer is always a character boundary.  */
+    return 1;
+
+  c = FETCH_BYTE (byte_pos);
+  if (! CHAR_HEAD_P (c))
     {
-      byte_pos++;
-      c = FETCH_BYTE (byte_pos);
+      /* We should advance BYTE_POS only when C is a constituen of a
+         multibyte sequence.  */
+      DEC_POS (byte_pos);
+      INC_POS (byte_pos);
+      /* If C is a constituent of a multibyte sequence, BYTE_POS was
+         surely advance to the correct character boundary.  If C is
+         not, BYTE_POS was unchanged.  */
     }
 
   return byte_pos;