Add undocumented inflateResetKeep() function for CAB file decoding.

The Microsoft CAB file format compresses each block with completed
deflate streams that depend on the sliding window history of the
previous block in order to decode.  inflateResetKeep() does what
inflateReset() does, except the sliding window history from the
previous inflate operation is retained.

as400/bndsrc

@@ -180,5 +180,6 @@ STRPGMEXP PGMLVL(*CURRENT) SIGNATURE('ZLIB')
   EXPORT SYMBOL("inflatePrime")
   EXPORT SYMBOL("inflateReset2")
   EXPORT SYMBOL("inflateUndermine")
+  EXPORT SYMBOL("inflateResetKeep")
 
 ENDPGMEXP

as400/zlib.inc

@@ -431,6 +431,10 @@
      D  strm                               like(z_stream)                       Expansion stream
      D  arg                          10I 0 value                                Error code
       *
+     D inflateResetKeep...
+     D                 PR            10I 0 extproc('inflateResetKeep')          End and init. stream
+     D  strm                               like(z_stream)                       Expansion stream
+      *
      D gzflags         PR            10U 0 extproc('gzflags')
       *
       /endif

contrib/vstudio/vc10/zlibvc.def

@@ -128,7 +128,8 @@ EXPORTS
         inflatePrime                            @158
         inflateReset2                           @159
         inflateUndermine                        @160
-
-; zlib1 v1.2.6 added:
-        gzgetc_                                 @30
-        gzflags                                 @162
+
+; zlib1 v1.2.6 added:
+        gzgetc_                                 @30
+        gzflags                                 @162
+        inflateResetKeep                        @163

contrib/vstudio/vc9/zlibvc.def

@@ -128,7 +128,8 @@ EXPORTS
         inflatePrime                            @158
         inflateReset2                           @159
         inflateUndermine                        @160
-
-; zlib1 v1.2.6 added:
-        gzgetc_                                 @30
-        gzflags                                 @162
+
+; zlib1 v1.2.6 added:
+        gzgetc_                                 @30
+        gzflags                                 @162
+        inflateResetKeep                        @163

inflate.c

@@ -100,7 +100,7 @@ local int updatewindow OF((z_streamp strm, unsigned out));
 local unsigned syncsearch OF((unsigned FAR *have, unsigned char FAR *buf,
                               unsigned len));
 
-int ZEXPORT inflateReset(strm)
+int ZEXPORT inflateResetKeep(strm)
 z_streamp strm;
 {
     struct inflate_state FAR *state;
@@ -115,9 +115,6 @@ z_streamp strm;
     state->havedict = 0;
     state->dmax = 32768U;
     state->head = Z_NULL;
-    state->wsize = 0;
-    state->whave = 0;
-    state->wnext = 0;
     state->hold = 0;
     state->bits = 0;
     state->lencode = state->distcode = state->next = state->codes;
@@ -127,6 +124,19 @@ z_streamp strm;
     return Z_OK;
 }
 
+int ZEXPORT inflateReset(strm)
+z_streamp strm;
+{
+    struct inflate_state FAR *state;
+
+    if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
+    state = (struct inflate_state FAR *)strm->state;
+    state->wsize = 0;
+    state->whave = 0;
+    state->wnext = 0;
+    return inflateResetKeep(strm);
+}
+
 int ZEXPORT inflateReset2(strm, windowBits)
 z_streamp strm;
 int windowBits;

win32/zlib.def

@@ -77,5 +77,6 @@ EXPORTS
     inflateSyncPoint
     get_crc_table
     inflateUndermine
+    inflateResetKeep
     gzgetc_
     gzflags

zconf.h

@@ -103,6 +103,7 @@
 #  define inflateSync           z_inflateSync
 #  define inflateSyncPoint      z_inflateSyncPoint
 #  define inflateUndermine      z_inflateUndermine
+#  define inflateResetKeep      z_inflateResetKeep
 #  define inflate_copyright     z_inflate_copyright
 #  define inflate_fast          z_inflate_fast
 #  define inflate_table         z_inflate_table

zconf.h.cmakein

@@ -105,6 +105,7 @@
 #  define inflateSync           z_inflateSync
 #  define inflateSyncPoint      z_inflateSyncPoint
 #  define inflateUndermine      z_inflateUndermine
+#  define inflateResetKeep      z_inflateResetKeep
 #  define inflate_copyright     z_inflate_copyright
 #  define inflate_fast          z_inflate_fast
 #  define inflate_table         z_inflate_table

zconf.h.in

@@ -103,6 +103,7 @@
 #  define inflateSync           z_inflateSync
 #  define inflateSyncPoint      z_inflateSyncPoint
 #  define inflateUndermine      z_inflateUndermine
+#  define inflateResetKeep      z_inflateResetKeep
 #  define inflate_copyright     z_inflate_copyright
 #  define inflate_fast          z_inflate_fast
 #  define inflate_table         z_inflate_table

zlib.h

@@ -1687,6 +1687,7 @@ ZEXTERN const char   * ZEXPORT zError           OF((int));
 ZEXTERN int            ZEXPORT inflateSyncPoint OF((z_streamp));
 ZEXTERN const uLongf * ZEXPORT get_crc_table    OF((void));
 ZEXTERN int            ZEXPORT inflateUndermine OF((z_streamp, int));
+ZEXTERN int            ZEXPORT inflateResetKeep OF((z_streamp));
 #ifndef Z_SOLO
   ZEXTERN unsigned long  ZEXPORT gzflags          OF((void));
 #endif

zlib.map

@@ -74,4 +74,5 @@ ZLIB_1.2.5.1 {
 ZLIB_1.2.5.2 {
     gzflags;
     gzgetc_;
+    inflateResetKeep;
 } ZLIB_1.2.5.1;