(update_text_area): Avoid looping due to large glyph

overhangs (bug#1070).

diff --git a/src/dispnew.c b/src/dispnew.c
index 45b5756665ceb7e04b87c0f64d77749fdfd2cc7a..9c810a53e691e4d7a4fc01e7a89c4b0da48eb877 100644 (file)
--- 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);
                }
            }