Problem report #76

[Dan Nicolaescu <dann@ics.uci.edu>]

CID: 76
Checker: FORWARD_NULL (help)
File: base/src/emacs/src/xdisp.c
Function: x_produce_glyphs
Description: Variable "font_info" tracked as NULL was dereferenced.

20490		  /* Draw the first glyph at the normal position.  It may be
20491		     shifted to right later if some other glyphs are drawn at
20492		     the left.  */
20493		  cmp->offsets[0] = 0;
20494		  cmp->offsets[1] = boff;
20495	
20496		  /* Set cmp->offsets for the remaining glyphs.  */

At conditional (13): "i < (cmp)->glyph_len" taking true path

20497		  for (i = 1; i < cmp->glyph_len; i++)
20498		    {
20499		      int left, right, btm, top;

At conditional (14): "(cmp)->method == 5" taking true path

20500		      int ch = COMPOSITION_GLYPH (cmp, i);

At conditional (15): "ch & 255 == ch" taking true path

20501		      int face_id = FACE_FOR_CHAR (it->f, face, ch);
20502	

At conditional (16): "face_id < (((it)->f)->face_cache)->used" taking true path

20503		      face = FACE_FROM_ID (it->f, face_id);
20504		      get_char_face_and_encoding (it->f, ch, face->id,
20505						  &char2b, it->multibyte_p, 0);
20506		      font = face->font;

At conditional (17): "font == 0" taking false path

20507		      if (font == NULL)
20508			{
20509			  font = FRAME_FONT (it->f);
20510			  boff = FRAME_BASELINE_OFFSET (it->f);

Event assign_zero: Variable "font_info" assigned value 0.
Also see events: [var_deref_op]

20511			  font_info = NULL;
20512			}
20513		      else
20514			{

At conditional (18): "(face)->font_info_id >= 0" taking true path
At conditional (19): "(face)->font_info_id < (((((it)->f)->output_data).x)->display_info)->font_table_size" taking false path

20515			  font_info
20516			    = FONT_INFO_FROM_ID (it->f, face->font_info_id);

Event var_deref_op: Variable "font_info" tracked as NULL was dereferenced.
Also see events: [assign_zero]

20517			  boff = font_info->baseline_offset;
20518			  if (font_info->vertical_centering)
20519			    boff = VCENTER_BASELINE_OFFSET (font, it->f) - boff;
20520			}
20521	

At conditional (1): "font_info != 0" taking false path

20522		      if (font_info
20523			  && (pcm = rif->per_char_metric (font, &char2b,
20524							  FONT_TYPE_FOR_MULTIBYTE (font, ch))))
20525			{
20526			  width = pcm->width;
20527			  ascent = pcm->ascent;
20528			  descent = pcm->descent;
20529			}
20530		      else
20531			{
20532			  width = FONT_WIDTH (font);
20533			  ascent = 1;
20534			  descent = 0;
20535			}
20536	

At conditional (2): "(cmp)->method != 5" taking false path

20537		      if (cmp->method != COMPOSITION_WITH_RULE_ALTCHARS)
20538			{
20539			  /* Relative composition with or without
20540			     alternate chars.  */
20541			  left = (leftmost + rightmost - width) / 2;
20542			  btm = - descent + boff;
20543			  if (font_info && font_info->relative_compose
20544			      && (! CHAR_TABLE_P (Vignore_relative_composition)
20545				  || NILP (Faref (Vignore_relative_composition,
20546						  make_number (ch)))))
20547			    {
20548	
20549			      if (- descent >= font_info->relative_compose)
20550				/* One extra pixel between two glyphs.  */
20551				btm = highest + 1;
20552			      else if (ascent <= 0)
20553				/* One extra pixel between two glyphs.  */
20554				btm = lowest - 1 - ascent - descent;
20555			    }
20556			}
20557		      else
20558			{
20559			  /* A composition rule is specified by an integer
20560			     value that encodes global and new reference
20561			     points (GREF and NREF).  GREF and NREF are
20562			     specified by numbers as below:
20563	
20564				0---1---2 -- ascent
20565				|       |
20566				|       |
20567				|       |
20568				9--10--11 -- center
20569				|       |
20570			     ---3---4---5--- baseline
20571				|       |
20572				6---7---8 -- descent
20573			  */
20574			  int rule = COMPOSITION_RULE (cmp, i);
20575			  int gref, nref, grefx, grefy, nrefx, nrefy;
20576	

At conditional (3): "gref > 12" taking false path
At conditional (4): "0" taking false path

20577			  COMPOSITION_DECODE_RULE (rule, gref, nref);
20578			  grefx = gref % 3, nrefx = nref % 3;
20579			  grefy = gref / 3, nrefy = nref / 3;
20580	
20581			  left = (leftmost
20582				  + grefx * (rightmost - leftmost) / 2
20583				  - nrefx * width / 2);

At conditional (5): "grefy == 0" taking true path
At conditional (6): "nrefy == 0" taking false path
At conditional (7): "nrefy == 1" taking false path
At conditional (8): "nrefy == 2" taking false path

20584			  btm = ((grefy == 0 ? highest
20585				  : grefy == 1 ? 0
20586				  : grefy == 2 ? lowest
20587				  : (highest + lowest) / 2)
20588				 - (nrefy == 0 ? ascent + descent
20589				    : nrefy == 1 ? descent - boff
20590				    : nrefy == 2 ? 0
20591				    : (ascent + descent) / 2));
20592			}
20593	
20594		      cmp->offsets[i * 2] = left;
20595		      cmp->offsets[i * 2 + 1] = btm + descent;
20596	
20597		      /* Update the bounding box of the overall glyphs. */
20598		      right = left + width;
20599		      top = btm + descent + ascent;

At conditional (9): "left < leftmost" taking true path

20600		      if (left < leftmost)
20601			leftmost = left;

At conditional (10): "right > rightmost" taking true path

20602		      if (right > rightmost)
20603			rightmost = right;

At conditional (11): "top > highest" taking true path

20604		      if (top > highest)
20605			highest = top;

At conditional (12): "btm < lowest" taking true path

20606		      if (btm < lowest)
20607			lowest = btm;
20608		    }
20609	
20610		  /* If there are glyphs whose x-offsets are negative,
20611		     shift all glyphs to the right and make all x-offsets
20612		     non-negative.  */