master 0f5f2af51e 1/2: Fix off-by-one errors in caret position application

[Po Lu]

branch: master
commit 0f5f2af51ecc4a67c1b4875d2af4dc19fdb8e392
Author: Po Lu <luangruo@yahoo.com>
Commit: Po Lu <luangruo@yahoo.com>

    Fix off-by-one errors in caret position application
    
    * src/gtkutil.c (xg_im_context_preedit_changed):
    * src/xfns.c (xic_preedit_caret_callback):
    (xic_preedit_draw_callback): Constrain caret position to
    SCHARS (arg) - 1.
---
 src/gtkutil.c | 11 ++++++-----
 src/xfns.c    | 22 ++++++++++++----------
 2 files changed, 18 insertions(+), 15 deletions(-)

diff --git a/src/gtkutil.c b/src/gtkutil.c
index c47386dae0..8eab6ee723 100644
--- a/src/gtkutil.c
+++ b/src/gtkutil.c
@@ -6090,11 +6090,12 @@ xg_im_context_preedit_changed (GtkIMContext *imc, 
gpointer user_data)
   inev.kind = PREEDIT_TEXT_EVENT;
   inev.arg = build_string_from_utf8 (str);
 
-  Fput_text_property (make_fixnum (min (SCHARS (inev.arg),
-                                       max (0, cursor))),
-                     make_fixnum (min (SCHARS (inev.arg),
-                                       max (0, cursor) + 1)),
-                     Qcursor, Qt, inev.arg);
+  if (SCHARS (inev.arg))
+    Fput_text_property (make_fixnum (min (SCHARS (inev.arg) - 1,
+                                         max (0, cursor))),
+                       make_fixnum (min (SCHARS (inev.arg),
+                                         max (0, cursor) + 1)),
+                       Qcursor, Qt, inev.arg);
 
   kbd_buffer_store_event (&inev);
 
diff --git a/src/xfns.c b/src/xfns.c
index 7540816416..9cf6f52819 100644
--- a/src/xfns.c
+++ b/src/xfns.c
@@ -2973,11 +2973,12 @@ xic_preedit_caret_callback (XIC xic, XPointer 
client_data,
          ie.arg = make_string_from_utf8 (output->preedit_chars,
                                          output->preedit_size);
 
-         Fput_text_property (make_fixnum (min (SCHARS (ie.arg),
-                                               max (0, 
output->preedit_caret))),
-                             make_fixnum (max (SCHARS (ie.arg),
-                                               max (0, output->preedit_caret) 
+ 1)),
-                             Qcursor, Qt, ie.arg);
+         if (SCHARS (ie.arg))
+           Fput_text_property (make_fixnum (min (SCHARS (ie.arg) - 1,
+                                                 max (0, 
output->preedit_caret))),
+                               make_fixnum (max (SCHARS (ie.arg),
+                                                 max (0, 
output->preedit_caret) + 1)),
+                               Qcursor, Qt, ie.arg);
 
          XSETINT (ie.x, 0);
          XSETINT (ie.y, 0);
@@ -3196,11 +3197,12 @@ xic_preedit_draw_callback (XIC xic, XPointer 
client_data,
       ie.arg = make_string_from_utf8 (output->preedit_chars,
                                      output->preedit_size);
 
-      Fput_text_property (make_fixnum (min (SCHARS (ie.arg),
-                                           max (0, output->preedit_caret))),
-                         make_fixnum (min (SCHARS (ie.arg),
-                                           max (0, output->preedit_caret) + 
1)),
-                         Qcursor, Qt, ie.arg);
+      if (SCHARS (ie.arg))
+       Fput_text_property (make_fixnum (min (SCHARS (ie.arg) - 1,
+                                             max (0, output->preedit_caret))),
+                           make_fixnum (min (SCHARS (ie.arg),
+                                             max (0, output->preedit_caret) + 
1)),
+                           Qcursor, Qt, ie.arg);
 
       XSETINT (ie.x, 0);
       XSETINT (ie.y, 0);