(update_text_area): Avoid looping due to large glyph

overhangs (bug#1070).

1 files changed, 11 insertions, 2 deletions

diff --git a/src/dispnew.c b/src/dispnew.c
index 45b5756665c..9c810a53e69 100644
--- a/src/dispnew.c
+++ b/src/dispnew.c
@@ -4475,6 +4475,7 @@ update_text_area (w, vpos)
       struct glyph *desired_glyph = desired_row->glyphs[TEXT_AREA];
       int overlapping_glyphs_p = current_row->contains_overlapping_glyphs_p;
       int desired_stop_pos = desired_row->used[TEXT_AREA];
+      int abort_skipping = 0;
 
       /* If the desired row extends its face to the text area end, and
          unless the current row also does so at the same position,
@@ -4494,7 +4495,7 @@ update_text_area (w, vpos)
          in common.  */
       while (i < stop)
         {
-          int can_skip_p = 1;
+          int can_skip_p = !abort_skipping;
 
           /* Skip over glyphs that both rows have in common.  These
              don't have to be written.  We can't skip if the last
@@ -4511,11 +4512,13 @@ update_text_area (w, vpos)
 
               rif->get_glyph_overhangs (glyph, XFRAME (w->frame),
                                         &left, &right);
-              can_skip_p = right == 0;
+              can_skip_p = (right == 0 && !abort_skipping);
             }
 
           if (can_skip_p)
             {
+              int start_hpos = i;
+
               while (i < stop
                      && GLYPH_EQUAL_P (desired_glyph, current_glyph))
                 {
@@ -4547,6 +4550,12 @@ update_text_area (w, vpos)
                       x -= desired_glyph->pixel_width;
                       left -= desired_glyph->pixel_width;
                     }
+
+                  /* Abort the skipping algorithm if we end up before
+                     our starting point, to avoid looping (bug#1070).
+                     This can happen when the lbearing is larger than
+                     the pixel width.  */
+                  abort_skipping = (i < start_hpos);
                 }
             }