[Zlib-devel] error when uncompressing in 16 bits compile (Bug in zLib 1.14 only !)

[Mark Adler]

On Monday, May 5, 2003, at 03:53  AM, Gilles Vollant wrote:
> John Sørensen [john at barcode.dk]wrote me about a problem :
> When he uncompress a large file (bigger than 32.950 bytes) he get CRC 
> error in uncompressing.
>  
> He had the problem while compile minizip code or minigzip (to 
> uncompress a .zip or a .gz)
>  
> I send him several zLib version (1.04, 1.13 and latest beta 1.2.0.1), 
> and he has the bug only in 1.14
>  
> 1.14 is the actual official version, so I want inform the list about 
> the problem

This is a known problem.  The patch to fix this is below.

mark


*** infcodes.114.c      Mon Mar 11 05:16:01 2002
--- infcodes.c  Fri Mar 15 01:59:28 2002
***************
*** 197,204 ****
         c->mode = COPY;
       case COPY:          /* o: copying bytes in window, waiting for 
space */
         f = q - c->sub.copy.dist;
!       while (f < s->window)             /* modulo window size-"while" 
instead */
!         f += s->end - s->window;        /* of "if" handles invalid 
distances */
         while (c->len)
         {
           NEEDOUT
--- 197,204 ----
         c->mode = COPY;
       case COPY:          /* o: copying bytes in window, waiting for 
space */
         f = q - c->sub.copy.dist;
!       while (f < s->window || f >= s->end)      /* get pointer in 
window */
!         f += s->end - s->window;
         while (c->len)
         {
           NEEDOUT
*** inffast.114.c       Mon Mar 11 05:16:01 2002
--- inffast.c   Fri Mar 15 01:58:46 2002
***************
*** 94,104 ****
               /* do the copy */
               m -= c;
               r = q - d;
!             if (r < s->window)                  /* wrap if needed */
               {
                 do {
                   r += s->end - s->window;        /* force pointer in 
window */
!               } while (r < s->window);          /* covers invalid 
distances */
                 e = s->end - r;
                 if (c > e)
                 {
--- 94,104 ----
               /* do the copy */
               m -= c;
               r = q - d;
!             if ((uInt)(q - s->window) < d)      /* wrap if needed */
               {
                 do {
                   r += s->end - s->window;        /* force pointer in 
window */
!               } while (r < s->window || r >= s->end);
                 e = s->end - r;
                 if (c > e)
                 {