From 2d80d3f6b52f9fa454c26c89d2d6a1790e1cecb0 Mon Sep 17 00:00:00 2001

From: Mark Adler <madler@alumni.caltech.edu>

Date: Sat, 21 Jan 2017 01:50:26 -0800

Subject: [PATCH] Limit hash table inserts after switch from stored deflate.

This limits hash table inserts to the available data in the window

and to the sliding window size in deflate_stored(). The hash table

inserts are deferred until deflateParams() switches to a non-zero

compression level.

---

 deflate.c | 10 +++++++++-

 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/deflate.c b/deflate.c

index 20bda4f..d368b25 100644

--- a/deflate.c

+++ b/deflate.c

@@ -1513,6 +1513,8 @@ local void fill_window(s)

             s->match_start -= wsize;

             s->strstart    -= wsize; /* we now have strstart >= MAX_DIST */

             s->block_start -= (long) wsize;

+            if (s->insert > s->strstart)

+                s->insert = s->strstart;

             slide_hash(s);

             more += wsize;

         }

@@ -1742,6 +1744,7 @@ local block_state deflate_stored(s, flush)

             s->matches = 2;         /* clear hash */

             zmemcpy(s->window, s->strm->next_in - s->w_size, s->w_size);

             s->strstart = s->w_size;

+            s->insert = s->strstart;

         }

         else {

             if (s->window_size - s->strstart <= used) {

@@ -1750,12 +1753,14 @@ local block_state deflate_stored(s, flush)

                 zmemcpy(s->window, s->window + s->w_size, s->strstart);

                 if (s->matches < 2)

                     s->matches++;   /* add a pending slide_hash() */

+                if (s->insert > s->strstart)

+                    s->insert = s->strstart;

             }

             zmemcpy(s->window + s->strstart, s->strm->next_in - used, used);

             s->strstart += used;

+            s->insert += MIN(used, s->w_size - s->insert);

         }

         s->block_start = s->strstart;

-        s->insert += MIN(used, s->w_size - s->insert);

     }

     if (s->high_water < s->strstart)

         s->high_water = s->strstart;

@@ -1779,12 +1784,15 @@ local block_state deflate_stored(s, flush)

         if (s->matches < 2)

             s->matches++;           /* add a pending slide_hash() */

         have += s->w_size;          /* more space now */

+        if (s->insert > s->strstart)

+            s->insert = s->strstart;

     }

     if (have > s->strm->avail_in)

         have = s->strm->avail_in;

     if (have) {

         read_buf(s->strm, s->window + s->strstart, have);

         s->strstart += have;

+        s->insert += MIN(have, s->w_size - s->insert);

     }

     if (s->high_water < s->strstart)

         s->high_water = s->strstart;

-- 

2.39.1