Add variable 'wbufsize' to track window buffer including padding, to allow

Dead2 · Dead2 · commit a5c20ed67e0f · 2024-10-08T15:51:12.000+02:00
the chunkset code to spill garbage data into the padding area if available.
diff --git a/infback.c b/infback.c
@@ -55,6 +55,7 @@ int32_t ZNG_CONDEXPORT PREFIX(inflateBackInit)(PREFIX3(stream) *strm, int32_t wi
     strm->state = (struct internal_state *)state;
     state->wbits = (unsigned int)windowBits;
     state->wsize = 1U << windowBits;
+    state->wbufsize = 1U << windowBits;
     state->window = window;
     state->wnext = 0;
     state->whave = 0;
diff --git a/inffast_tpl.h b/inffast_tpl.h
@@ -137,7 +137,7 @@ void Z_INTERNAL INFLATE_FAST(PREFIX3(stream) *strm, uint32_t start) {
     /* Detect if out and window point to the same memory allocation. In this instance it is
        necessary to use safe chunk copy functions to prevent overwriting the window. If the
        window is overwritten then future matches with far distances will fail to copy correctly. */
-    extra_safe = (wsize != 0 && out >= window && out + INFLATE_FAST_MIN_LEFT <= window + wsize);
+    extra_safe = (wsize != 0 && out >= window && out + INFLATE_FAST_MIN_LEFT <= window + state->wbufsize);
 
 #define REFILL() do { \
         hold |= load_64_bits(in, bits); \
diff --git a/inflate.c b/inflate.c
@@ -240,6 +240,7 @@ int32_t ZNG_CONDEXPORT PREFIX(inflateInit2)(PREFIX3(stream) *strm, int32_t windo
     state = alloc_bufs->state;
     state->window = alloc_bufs->window;
     state->alloc_bufs = alloc_bufs;
+    state->wbufsize = INFLATE_ADJUST_WINDOW_SIZE((1 << MAX_WBITS) + 64);
     Tracev((stderr, "inflate: allocated\n"));
 
     strm->state = (struct internal_state *)state;
diff --git a/inflate.h b/inflate.h
@@ -111,6 +111,7 @@ struct ALIGNED_(64) inflate_state {
         /* sliding window */
     unsigned wbits;             /* log base 2 of requested window size */
     uint32_t wsize;             /* window size or zero if not using window */
+    uint32_t wbufsize;          /* real size of the allocated window buffer, including padding */
     uint32_t whave;             /* valid bytes in the window */
     uint32_t wnext;             /* window write index */
     unsigned char *window;      /* allocated sliding window, if needed */
