Problem report #76

[Dan Nicolaescu]

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.  */