/usr/src/gnu/usr.bin/texinfo/info/display.c

Bug Summary

File:	src/gnu/usr.bin/texinfo/info/display.c
Warning:	line 303, column 37 Access to field 'text' results in a dereference of a null pointer (loaded from variable 'entry')

Annotated Source Code

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clang -cc1 -cc1 -triple amd64-unknown-openbsd7.0 -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name display.c -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -mrelocation-model pic -pic-level 1 -pic-is-pie -mframe-pointer=all -relaxed-aliasing -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -target-feature +retpoline-indirect-calls -target-feature +retpoline-indirect-branches -tune-cpu generic -debugger-tuning=gdb -fcoverage-compilation-dir=/usr/src/gnu/usr.bin/texinfo/obj/info -resource-dir /usr/local/lib/clang/13.0.0 -D HAVE_CONFIG_H -D LOCALEDIR="/usr/share/locale" -D INFODIR="/usr/share/info" -D INFODIR2="/usr/share/info" -I . -I /usr/src/gnu/usr.bin/texinfo/info -I .. -I . -I /usr/src/gnu/usr.bin/texinfo/lib -I ../intl -I .. -I /usr/src/gnu/usr.bin/texinfo/info -internal-isystem /usr/local/lib/clang/13.0.0/include -internal-externc-isystem /usr/include -O2 -fdebug-compilation-dir=/usr/src/gnu/usr.bin/texinfo/obj/info -ferror-limit 19 -fwrapv -D_RET_PROTECTOR -ret-protector -fgnuc-version=4.2.1 -vectorize-loops -vectorize-slp -fno-builtin-malloc -fno-builtin-calloc -fno-builtin-realloc -fno-builtin-valloc -fno-builtin-free -fno-builtin-strdup -fno-builtin-strndup -analyzer-output=html -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /home/ben/Projects/vmm/scan-build/2022-01-12-194120-40624-1 -x c /usr/src/gnu/usr.bin/texinfo/info/display.c

1/* display.c -- How to display Info windows.
 $Id: display.c,v 1.4 2006/07/17 16:12:36 espie Exp $

 Copyright (C) 1993, 1997, 2003, 2004 Free Software Foundation, Inc.

 This program is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation; either version 2, or (at your option)
 any later version.

 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with this program; if not, write to the Free Software
 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

 Originally written by Brian Fox (bfox@ai.mit.edu). */

22#include "info.h"
23#include "display.h"

25extern int info_any_buffered_input_p (void); /* Found in session.c. */

27static void free_display (DISPLAY_LINE **display);
28static DISPLAY_LINE **make_display (int width, int height);

30void handle_tag (char *tag);
31void handle_tag_start (char *tag);
32void handle_tag_end (char *tag);

34/* An array of display lines which tell us what is currently visible on
 the display.  */
36DISPLAY_LINE **the_display = (DISPLAY_LINE **)NULL((void *)0);

38/* Non-zero means do no output. */
39int display_inhibited = 0;

41/* Initialize THE_DISPLAY to WIDTH and HEIGHT, with nothing in it. */
42void
43display_initialize_display (int width, int height)
44{
free_display (the_display);
the_display = make_display (width, height);
display_clear_display (the_display);
48}

50/* Clear all of the lines in DISPLAY making the screen blank. */
51void
52display_clear_display (DISPLAY_LINE **display)
53{
register int i;

for (i = 0; display[i]; i++)
  {
    display[i]->text[0] = '\0';
    display[i]->textlen = 0;
    display[i]->inverse = 0;
  }
62}

64/* Non-zero if we didn't completely redisplay a window. */
65int display_was_interrupted_p = 0;

67/* Update the windows pointed to by WINDOW in the_display.  This actually
 writes the text on the screen. */
69void
70display_update_display (WINDOW *window)
71{
register WINDOW *win;

display_was_interrupted_p = 0;

/* For every window in the list, check contents against the display. */
for (win = window; win; win = win->next)
  {
    /* Only re-display visible windows which need updating. */
    if (((win->flags & W_WindowVisible0x04) == 0) ||
        ((win->flags & W_UpdateWindow0x01) == 0) ||
        (win->height == 0))
      continue;

    display_update_one_window (win);
    if (display_was_interrupted_p)
      break;
  }

/* Always update the echo area. */
display_update_one_window (the_echo_area);
92}

94void
95handle_tag_start (char *tag)
96{
/* TODO really handle this tag.  */
return;
99}

101void
102handle_tag_end (char *tag)
103{
/* TODO really handle this tag.  */
return;
106}

108void
109handle_tag (char *tag)
110{
  if (tag[0] == '/')
    {
tag++;
handle_tag_end (tag);
    }
  else
    handle_tag_start (tag);
118}

120/* Display WIN on the_display.  Unlike display_update_display (), this
 function only does one window. */
122void
123display_update_one_window (WINDOW *win)
124{
register char *nodetext;      /* Current character to display. */
register char *last_node_char; /* Position of the last character in node. */
register int i;               /* General use index. */
char *printed_line;           /* Buffer for a printed line. */
int pl_index = 0;             /* Index into PRINTED_LINE. */
int line_index = 0;           /* Number of lines done so far. */
int pl_ignore = 0;		/* How many chars use zero width on screen. */
int allocated_win_width;
DISPLAY_LINE **display = the_display;

/* If display is inhibited, that counts as an interrupted display. */
if (display_inhibited)
1
Assuming 'display_inhibited' is 0→
2
←
Taking false branch→
  display_was_interrupted_p = 1;

/* If the window has no height, or display is inhibited, quit now. */
if (!win->height || display_inhibited3.1
'display_inhibited' is 0
)
3
←
Assuming field 'height' is not equal to 0→
4
←
Taking false branch→
  return;

/* If the window's first row doesn't appear in the_screen, then it
   cannot be displayed.  This can happen when the_echo_area is the
   window to be displayed, and the screen has shrunk to less than one
   line. */
if ((win->first_row < 0) || (win->first_row > the_screen->height))
5
←
Assuming field 'first_row' is >= 0→
6
←
Assuming field 'first_row' is <= field 'height'→
7
←
Taking false branch→
  return;

/* Print each line in the window into our local buffer, and then
   check the contents of that buffer against the display.  If they
   differ, update the display. */
allocated_win_width = win->width + 1;
printed_line = (char *)xmalloc (allocated_win_width);

if (!win->node || !win->line_starts)
8
←
Assuming field 'node' is non-null→
9
←
Assuming field 'line_starts' is non-null→
10
←
Taking false branch→
  goto done_with_node_display;

nodetext = win->line_starts[win->pagetop];
last_node_char = win->node->contents + win->node->nodelen;

for (; nodetext < last_node_char; nodetext++)
11
←
Loop condition is true.  Entering loop body→
  {
    char *rep = NULL((void *)0), *rep_carried_over, rep_temp[2];
    int replen;

    if (isprint (*nodetext))
12
←
Taking false branch→
      {
        rep_temp[0] = *nodetext;
        replen = 1;
        rep_temp[1] = '\0';
        rep = rep_temp;
      }
    else
      {
        if (*nodetext == '\r' || *nodetext == '\n')
13
←
Assuming the condition is true→
          {
            replen = win->width - pl_index + pl_ignore;
          }
 else if (*nodetext == '\0'
   && (nodetext + 2) < last_node_char
   && *(nodetext + 1) == '\b'
   && *(nodetext + 2) == '[')
   {
     /* Found new style tag/cookie \0\b[
 Read until the closing tag \0\b] */
     int element_len = 0;
     char *element;

     /* Skip the escapes.  */
     nodetext += 3;

     while (!(*nodetext == '\0'
    && *(nodetext + 1) == '\b'
    && *(nodetext + 2) == ']'))
{
  nodetext++;
  element_len++;
}

     element = (char *) malloc (element_len + 1);
     strncpy (element, nodetext - element_len, element_len);

     /* Skip the escapes.  */
     nodetext += 2;
     pl_ignore += element_len + 5;
     /* Append string terminator.  */
     element[element_len] = '\0';

     handle_tag (element);

     /* Over and out */
     free (element);

     continue;
   }
        else
          {
            rep = printed_representation (*nodetext, pl_index);
            replen = strlen (rep);
          }
      }

    /* Support ANSI escape sequences under -R.  */
    if (raw_escapes_p
14
←
Assuming 'raw_escapes_p' is not equal to 0→
 && *nodetext == '\033'
 && nodetext[1] == '['
 && isdigit (nodetext[2]))
{
 if (nodetext[3] == 'm')
   pl_ignore += 4;
 else if (isdigit (nodetext[3]) && nodetext[4] == 'm')
   pl_ignore += 5;
}
    while (pl_index + 2 >= allocated_win_width - 1)
15
←
Assuming the condition is false→
16
←
Loop condition is false. Execution continues on line 243→
{
 allocated_win_width *= 2;
 printed_line = (char *)xrealloc (printed_line, allocated_win_width);
}

    /* If this character can be printed without passing the width of
       the line, then stuff it into the line. */
    if (replen + pl_index < win->width + pl_ignore)
17
←
Taking false branch→
      {
        /* Optimize if possible. */
        if (replen == 1)
          {
            printed_line[pl_index++] = *rep;
          }
        else
          {
            for (i = 0; i < replen; i++)
              printed_line[pl_index++] = rep[i];
          }
      }
    else
      {
        DISPLAY_LINE *entry;

        /* If this character cannot be printed in this line, we have
           found the end of this line as it would appear on the screen.
           Carefully print the end of the line, and then compare. */
        if (*nodetext == '\n' || *nodetext == '\r' || *nodetext == '\t')
          {
            printed_line[pl_index] = '\0';
            rep_carried_over = (char *)NULL((void *)0);
          }
        else
          {
            /* The printed representation of this character extends into
               the next line.  Remember the offset of the last character
               printed out of REP so that we can carry the character over
               to the next line. */
            for (i = 0; pl_index < (win->width + pl_ignore - 1);)
              printed_line[pl_index++] = rep[i++];

            rep_carried_over = rep + i;

            /* If printing the last character in this window couldn't
               possibly cause the screen to scroll, place a backslash
               in the rightmost column. */
            if (1 + line_index + win->first_row < the_screen->height)
              {
                if (win->flags & W_NoWrap0x10)
                  printed_line[pl_index++] = '$';
                else
                  printed_line[pl_index++] = '\\';
              }
            printed_line[pl_index] = '\0';
          }

        /* We have the exact line as it should appear on the screen.
           Check to see if this line matches the one already appearing
           on the screen. */
        entry = display[line_index + win->first_row];
18
←
Value assigned to 'entry'→

        /* If the screen line is inversed, then we have to clear
           the line from the screen first.  Why, I don't know.
           (But don't do this if we have no visible entries, as can
           happen if the window is shrunk very small.)  */
        if ((entry && entry->inverse)
19
←
Assuming 'entry' is null→
     /* Need to erase the line if it has escape sequences.  */
     || (raw_escapes_p19.1
'raw_escapes_p' is not equal to 0
 && strchr (entry->text, '\033') != 0))
20
←
Access to field 'text' results in a dereference of a null pointer (loaded from variable 'entry')
          {
            terminal_goto_xy (0, line_index + win->first_row);
            terminal_clear_to_eol ();
            entry->inverse = 0;
            entry->text[0] = '\0';
            entry->textlen = 0;
          }

        /* Find the offset where these lines differ. */
        for (i = 0; i < pl_index; i++)
          if (printed_line[i] != entry->text[i])
            break;

        /* If the lines are not the same length, or if they differed
           at all, we must do some redrawing. */
        if ((i != pl_index) || (pl_index != entry->textlen))
          {
            /* Move to the proper point on the terminal. */
            terminal_goto_xy (i, line_index + win->first_row);

            /* If there is any text to print, print it. */
            if (i != pl_index)
              terminal_put_text (printed_line + i);

            /* If the printed text didn't extend all the way to the edge
               of the window, and text was appearing between here and the
               edge of the window, clear from here to the end of the line. */
            if ((pl_index < win->width + pl_ignore
   && pl_index < entry->textlen)
  || (entry->inverse))
              terminal_clear_to_eol ();

            fflush (stdout(&__sF[1]));

            /* Update the display text buffer. */
     if (strlen (printed_line) > (unsigned int) screenwidth)
/* printed_line[] can include more than screenwidth
   characters if we are under -R and there are escape
   sequences in it.  However, entry->text was
   allocated (in display_initialize_display) for
   screenwidth characters only.  */
entry->text = xrealloc (entry->text, strlen (printed_line)+1);
            strcpy (entry->text + i, printed_line + i);
            entry->textlen = pl_index;

            /* Lines showing node text are not in inverse.  Only modelines
               have that distinction. */
            entry->inverse = 0;
          }

        /* We have done at least one line.  Increment our screen line
           index, and check against the bottom of the window. */
        if (++line_index == win->height)
          break;

        /* A line has been displayed, and the screen reflects that state.
           If there is typeahead pending, then let that typeahead be read
           now, instead of continuing with the display. */
        if (info_any_buffered_input_p ())
          {
            free (printed_line);
            display_was_interrupted_p = 1;
            return;
          }

        /* Reset PL_INDEX to the start of the line. */
        pl_index = 0;
 pl_ignore = 0;	/* this is computed per line */

        /* If there are characters from REP left to print, stuff them
           into the buffer now. */
        if (rep_carried_over)
          for (; rep[pl_index]; pl_index++)
            printed_line[pl_index] = rep[pl_index];

        /* If this window has chosen not to wrap lines, skip to the end
           of the physical line in the buffer, and start a new line here. */
        if (pl_index && (win->flags & W_NoWrap0x10))
          {
            char *begin;

            pl_index = 0;
            printed_line[0] = '\0';

            begin = nodetext;

            while ((nodetext < last_node_char) && (*nodetext != '\n'))
              nodetext++;
          }
      }
  }

done_with_node_display:
/* We have reached the end of the node or the end of the window.  If it
   is the end of the node, then clear the lines of the window from here
   to the end of the window. */
for (; line_index < win->height; line_index++)
  {
    DISPLAY_LINE *entry = display[line_index + win->first_row];

    /* If this line has text on it then make it go away. */
    if (entry && entry->textlen)
      {
        entry->textlen = 0;
        entry->text[0] = '\0';

        terminal_goto_xy (0, line_index + win->first_row);
        terminal_clear_to_eol ();
      }
  }

/* Finally, if this window has a modeline it might need to be redisplayed.
   Check the window's modeline against the one in the display, and update
   if necessary. */
if ((win->flags & W_InhibitMode0x08) == 0)
  {
    window_make_modeline (win);
    line_index = win->first_row + win->height;

    /* This display line must both be in inverse, and have the same
       contents. */
    if ((!display[line_index]->inverse) ||
        (strcmp (display[line_index]->text, win->modeline) != 0))
      {
        terminal_goto_xy (0, line_index);
        terminal_begin_inverse ();
        terminal_put_text (win->modeline);
        terminal_end_inverse ();
        strcpy (display[line_index]->text, win->modeline);
        display[line_index]->inverse = 1;
        display[line_index]->textlen = strlen (win->modeline);
        fflush (stdout(&__sF[1]));
      }
  }

/* Okay, this window doesn't need updating anymore. */
win->flags &= ~W_UpdateWindow0x01;
free (printed_line);
fflush (stdout(&__sF[1]));
443}

445/* Scroll the region of the_display starting at START, ending at END, and
 moving the lines AMOUNT lines.  If AMOUNT is less than zero, the lines
 are moved up in the screen, otherwise down.  Actually, it is possible
 for no scrolling to take place in the case that the terminal doesn't
 support it.  This doesn't matter to us. */
450void
451display_scroll_display (int start, int end, int amount)
452{
register int i, last;
DISPLAY_LINE *temp;

/* If this terminal cannot do scrolling, give up now. */
if (!terminal_can_scroll)
  return;

/* If there isn't anything displayed on the screen because it is too
   small, quit now. */
if (!the_display[0])
  return;

/* If there is typeahead pending, then don't actually do any scrolling. */
if (info_any_buffered_input_p ())
  return;

/* Do it on the screen. */
terminal_scroll_terminal (start, end, amount);

/* Now do it in the display buffer so our contents match the screen. */
if (amount > 0)
  {
    last = end + amount;

    /* Shift the lines to scroll right into place. */
    for (i = 0; i < (end - start); i++)
      {
        temp = the_display[last - i];
        the_display[last - i] = the_display[end - i];
        the_display[end - i] = temp;
      }

    /* The lines have been shifted down in the buffer.  Clear all of the
       lines that were vacated. */
    for (i = start; i != (start + amount); i++)
      {
        the_display[i]->text[0] = '\0';
        the_display[i]->textlen = 0;
        the_display[i]->inverse = 0;
      }
  }

if (amount < 0)
  {
    last = start + amount;
    for (i = 0; i < (end - start); i++)
      {
        temp = the_display[last + i];
        the_display[last + i] = the_display[start + i];
        the_display[start + i] = temp;
      }

    /* The lines have been shifted up in the buffer.  Clear all of the
       lines that are left over. */
    for (i = end + amount; i != end; i++)
      {
        the_display[i]->text[0] = '\0';
        the_display[i]->textlen = 0;
        the_display[i]->inverse = 0;
      }
  }
514}

516/* Try to scroll lines in WINDOW.  OLD_PAGETOP is the pagetop of WINDOW before
 having had its line starts recalculated.  OLD_STARTS is the list of line
 starts that used to appear in this window.  OLD_COUNT is the number of lines
 that appear in the OLD_STARTS array. */
520void
521display_scroll_line_starts (WINDOW *window, int old_pagetop,
  char **old_starts, int old_count)
523{
register int i, old, new;     /* Indices into the line starts arrays. */
int last_new, last_old;       /* Index of the last visible line. */
int old_first, new_first;     /* Index of the first changed line. */
int unchanged_at_top = 0;
int already_scrolled = 0;

/* Locate the first line which was displayed on the old window. */
old_first = old_pagetop;
new_first = window->pagetop;

/* Find the last line currently visible in this window. */
last_new = window->pagetop + (window->height - 1);
if (last_new > window->line_count)
  last_new = window->line_count - 1;

/* Find the last line which used to be currently visible in this window. */
last_old = old_pagetop + (window->height - 1);
if (last_old > old_count)
  last_old = old_count - 1;

for (old = old_first, new = new_first;
     old < last_old && new < last_new;
     old++, new++)
  if (old_starts[old] != window->line_starts[new])
    break;
  else
    unchanged_at_top++;

/* Loop through the old lines looking for a match in the new lines. */
for (old = old_first + unchanged_at_top; old < last_old; old++)
  {
    for (new = new_first; new < last_new; new++)
      if (old_starts[old] == window->line_starts[new])
        {
          /* Find the extent of the matching lines. */
          for (i = 0; (old + i) < last_old; i++)
            if (old_starts[old + i] != window->line_starts[new + i])
              break;

          /* Scroll these lines if there are enough of them. */
          {
            int start, end, amount;

            start = (window->first_row
                     + ((old + already_scrolled) - old_pagetop));
            amount = new - (old + already_scrolled);
            end = window->first_row + window->height;

            /* If we are shifting the block of lines down, then the last
               AMOUNT lines will become invisible.  Thus, don't bother
               scrolling them. */
            if (amount > 0)
              end -= amount;

            if ((end - start) > 0)
              {
                display_scroll_display (start, end, amount);

                /* Some lines have been scrolled.  Simulate the scrolling
                   by offsetting the value of the old index. */
                old += i;
                already_scrolled += amount;
              }
          }
        }
  }
590}

592/* Move the screen cursor to directly over the current character in WINDOW. */
593void
594display_cursor_at_point (WINDOW *window)
595{
int vpos, hpos;

vpos = window_line_of_point (window) - window->pagetop + window->first_row;
hpos = window_get_cursor_column (window);
terminal_goto_xy (hpos, vpos);
fflush (stdout(&__sF[1]));
602}
603
604/* **************************************************************** */
605/*                                                                  */
606/*                   Functions Static to this File                  */
607/*                                                                  */
608/* **************************************************************** */

610/* Make a DISPLAY_LINE ** with width and height. */
611static DISPLAY_LINE **
612make_display (int width, int height)
613{
register int i;
DISPLAY_LINE **display;

display = (DISPLAY_LINE **)xmalloc ((1 + height) * sizeof (DISPLAY_LINE *));

for (i = 0; i < height; i++)
  {
    display[i] = (DISPLAY_LINE *)xmalloc (sizeof (DISPLAY_LINE));
    display[i]->text = (char *)xmalloc (1 + width);
    display[i]->textlen = 0;
    display[i]->inverse = 0;
  }
display[i] = (DISPLAY_LINE *)NULL((void *)0);
return (display);
628}

630/* Free the storage allocated to DISPLAY. */
631static void
632free_display (DISPLAY_LINE **display)
633{
register int i;
register DISPLAY_LINE *display_line;

if (!display)
  return;

for (i = 0; (display_line = display[i]); i++)
  {
    free (display_line->text);
    free (display_line);
  }
free (display);
646}