[cups.bugs] [LOW] STR #3868: cups: GIF reader incorrect initialization of LZW decoder table

[Tomas Hoger]

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[STR New]

I've noticed following in the code initializing LZW decoding table in the
GIF reader code:

584    /*
585     * Wipe the decompressor table...
586     */
587 
588     fresh = 1;
589 
590     for (i = 0; i < clear_code; i ++)
591     {
592       table[0][i] = 0;
593       table[1][i] = i;
594     }
595 
596     for (; i < 4096; i ++)
597       table[0][i] = table[1][0] = 0;

It seems line 597 is supposed to be doing table[1][i], just as is done
when re-initializing table after seeing clear_code:

621     if (code == clear_code)
622     {
623       for (i = 0; i < clear_code; i ++)
624       {
625         table[0][i] = 0;
626         table[1][i] = i;
627       }
628 
629       for (; i < 4096; i ++)
630         table[0][i] = table[1][i] = 0;

This bug is rather cosmetic one, as table[][] is calloc()ed shortly before
being initialized.  Given that, initialization can be reduced to omit line
592 and the whole second loop, probably at some code readability cost.

Link: http://www.cups.org/str.php?L3868
Version: 1.4.6