Clean up the usage of z_const and respect const usage within zlib.

This patch allows zlib to compile cleanly with the -Wcast-qual gcc
warning enabled, but only if ZLIB_CONST is defined, which adds
const to next_in and msg in z_stream and in the in_func prototype.
A --const option is added to ./configure which adds -DZLIB_CONST
to the compile flags, and adds -Wcast-qual to the compile flags
when ZLIBGCCWARN is set in the environment.

1 files changed, 17 insertions, 24 deletions

diff --git a/inflate.c b/inflate.c
index d1efdb8..870f89b 100644
--- a/inflate.c
+++ b/inflate.c
@@ -93,11 +93,12 @@
 
 /* function prototypes */
 local void fixedtables OF((struct inflate_state FAR *state));
-local int updatewindow OF((z_streamp strm, unsigned out));
+local int updatewindow OF((z_streamp strm, const unsigned char FAR *end,
+                           unsigned copy));
 #ifdef BUILDFIXED
    void makefixed OF((void));
 #endif
-local unsigned syncsearch OF((unsigned FAR *have, unsigned char FAR *buf,
+local unsigned syncsearch OF((unsigned FAR *have, const unsigned char FAR *buf,
                               unsigned len));
 
 int ZEXPORT inflateResetKeep(strm)
@@ -375,12 +376,13 @@ void makefixed()
    output will fall in the output data, making match copies simpler and faster.
    The advantage may be dependent on the size of the processor's data caches.
  */
-local int updatewindow(strm, out)
+local int updatewindow(strm, end, copy)
 z_streamp strm;
-unsigned out;
+const Bytef *end;
+unsigned copy;
 {
     struct inflate_state FAR *state;
-    unsigned copy, dist;
+    unsigned dist;
 
     state = (struct inflate_state FAR *)strm->state;
 
@@ -400,19 +402,18 @@ unsigned out;
     }
 
     /* copy state->wsize or less output bytes into the circular window */
-    copy = out - strm->avail_out;
     if (copy >= state->wsize) {
-        zmemcpy(state->window, strm->next_out - state->wsize, state->wsize);
+        zmemcpy(state->window, end - state->wsize, state->wsize);
         state->wnext = 0;
         state->whave = state->wsize;
     }
     else {
         dist = state->wsize - state->wnext;
         if (dist > copy) dist = copy;
-        zmemcpy(state->window + state->wnext, strm->next_out - copy, dist);
+        zmemcpy(state->window + state->wnext, end - copy, dist);
         copy -= dist;
         if (copy) {
-            zmemcpy(state->window, strm->next_out - copy, copy);
+            zmemcpy(state->window, end - copy, copy);
             state->wnext = copy;
             state->whave = state->wsize;
         }
@@ -606,7 +607,7 @@ z_streamp strm;
 int flush;
 {
     struct inflate_state FAR *state;
-    unsigned char FAR *next;    /* next input */
+    z_const unsigned char FAR *next;    /* next input */
     unsigned char FAR *put;     /* next output */
     unsigned have, left;        /* available input and output */
     unsigned long hold;         /* bit buffer */
@@ -920,7 +921,7 @@ int flush;
             while (state->have < 19)
                 state->lens[order[state->have++]] = 0;
             state->next = state->codes;
-            state->lencode = (code const FAR *)(state->next);
+            state->lencode = (const code FAR *)(state->next);
             state->lenbits = 7;
             ret = inflate_table(CODES, state->lens, 19, &(state->next),
                                 &(state->lenbits), state->work);
@@ -994,7 +995,7 @@ int flush;
                values here (9 and 6) without reading the comments in inftrees.h
                concerning the ENOUGH constants, which depend on those values */
             state->next = state->codes;
-            state->lencode = (code const FAR *)(state->next);
+            state->lencode = (const code FAR *)(state->next);
             state->lenbits = 9;
             ret = inflate_table(LENS, state->lens, state->nlen, &(state->next),
                                 &(state->lenbits), state->work);
@@ -1003,7 +1004,7 @@ int flush;
                 state->mode = BAD;
                 break;
             }
-            state->distcode = (code const FAR *)(state->next);
+            state->distcode = (const code FAR *)(state->next);
             state->distbits = 6;
             ret = inflate_table(DISTS, state->lens + state->nlen, state->ndist,
                             &(state->next), &(state->distbits), state->work);
@@ -1230,7 +1231,7 @@ int flush;
     RESTORE();
     if (state->wsize || (out != strm->avail_out && state->mode < BAD &&
             (state->mode < CHECK || flush != Z_FINISH)))
-        if (updatewindow(strm, out)) {
+        if (updatewindow(strm, strm->next_out, out - strm->avail_out)) {
             state->mode = MEM;
             return Z_MEM_ERROR;
         }
@@ -1294,8 +1295,6 @@ uInt dictLength;
 {
     struct inflate_state FAR *state;
     unsigned long dictid;
-    unsigned char *next;
-    unsigned avail;
     int ret;
 
     /* check state */
@@ -1314,13 +1313,7 @@ uInt dictLength;
 
     /* copy dictionary to window using updatewindow(), which will amend the
        existing dictionary if appropriate */
-    next = strm->next_out;
-    avail = strm->avail_out;
-    strm->next_out = (Bytef *)dictionary + dictLength;
-    strm->avail_out = 0;
-    ret = updatewindow(strm, dictLength);
-    strm->avail_out = avail;
-    strm->next_out = next;
+    ret = updatewindow(strm, dictionary + dictLength, dictLength);
     if (ret) {
         state->mode = MEM;
         return Z_MEM_ERROR;
@@ -1360,7 +1353,7 @@ gz_headerp head;
  */
 local unsigned syncsearch(have, buf, len)
 unsigned FAR *have;
-unsigned char FAR *buf;
+const unsigned char FAR *buf;
 unsigned len;
 {
     unsigned got;