>From 5ed21000b29bda8ee6adbfdfea008ca9fba6cba8 Mon Sep 17 00:00:00 2001
From: John Reiser <address@hidden>
Date: Tue, 18 Jun 2013 07:59:48 -0700
Subject: [PATCH 2/2] Use MAX() for array overlays.  Prefer {prev,head,window}
 as base names.

---
 deflate.c | 10 ----------
 gzip.c    | 29 ++++++++++++++++++-----------
 gzip.h    | 34 ++++++++++++++++++++++------------
 trees.c   |  3 ---
 unlzw.c   |  1 +
 5 files changed, 41 insertions(+), 36 deletions(-)

diff --git a/deflate.c b/deflate.c
index 31c81db..7fb6ed2 100644
--- a/deflate.c
+++ b/deflate.c
@@ -86,16 +86,6 @@
  */
 
 #include "deflate.h"
-/* To save space (see unlzw.c), we overlay prev+head with tab_prefix and
- * window with tab_suffix. Check that we can do this:
- */
-#if (WSIZE<<1) > (1<<LZW_BITS)
-   error: cannot overlay window with tab_suffix and prev with tab_prefix0
-#endif
-#if HASH_BITS > LZW_BITS-1
-   error: cannot overlay head with tab_prefix1
-#endif
-
 #define HASH_SIZE (unsigned)(1<<HASH_BITS)
 #define HASH_MASK (HASH_SIZE-1)
 #define WMASK     (WSIZE-1)
diff --git a/gzip.c b/gzip.c
index 7da26ec..7309e84 100644
--- a/gzip.c
+++ b/gzip.c
@@ -149,12 +149,19 @@ static char const *const license_msg[] = {
 DECLARE(uch, inbuf,  INBUFSIZ +INBUF_EXTRA);
 DECLARE(uch, outbuf, OUTBUFSIZ+OUTBUF_EXTRA);
 DECLARE(ush, d_buf,  DIST_BUFSIZE);
-DECLARE(uch, window, 2L*WSIZE);
+#define LEN_window (2L*WSIZE)
+#define LEN_tab_suffix (1L<<LZW_BITS)
+DECLARE(uch, window, MAX(LEN_window, LEN_tab_suffix));
+#define LEN_prev        WSIZE
+#define LEN_head       (1L<<HASH_BITS)
 #ifndef MAXSEG_64K
-    DECLARE(ush, tab_prefix, 1L<<LZW_BITS);
+#   define LEN_tab_prefix   (1L<< LZW_BITS   )
+    DECLARE(ush, prev, MAX((LEN_prev + LEN_head), LEN_tab_prefix));
 #else
-    DECLARE(ush, tab_prefix0, 1L<<(LZW_BITS-1));
-    DECLARE(ush, tab_prefix1, 1L<<(LZW_BITS-1));
+#   define LEN_tab_prefix_0 (1L<<(LZW_BITS-1))
+#   define LEN_tab_prefix_1 (1L<<(LZW_BITS-1))
+    DECLARE(ush, prev, MAX(LEN_prev, LEN_tab_prefix0));
+    DECLARE(ush, head, MAX(LEN_head, LEN_tab_prefix1));
 #endif
 
                 /* local variables */
@@ -549,12 +556,12 @@ int main (int argc, char **argv)
     ALLOC(uch, inbuf,  INBUFSIZ +INBUF_EXTRA);
     ALLOC(uch, outbuf, OUTBUFSIZ+OUTBUF_EXTRA);
     ALLOC(ush, d_buf,  DIST_BUFSIZE);
-    ALLOC(uch, window, 2L*WSIZE);
+    ALLOC(uch, window, MAX(LEN_window, LEN_tab_suffix));
 #ifndef MAXSEG_64K
-    ALLOC(ush, tab_prefix, 1L<<LZW_BITS);
+    ALLOC(ush, prev, MAX((LEN_prev + LEN_head), LEN_tab_prefix));
 #else
-    ALLOC(ush, tab_prefix0, 1L<<(LZW_BITS-1));
-    ALLOC(ush, tab_prefix1, 1L<<(LZW_BITS-1));
+    ALLOC(ush, prev, MAX(LEN_prev, LEN_tab_prefix0));
+    ALLOC(ush, head, MAX(LEN_head, LEN_tab_prefix1));
 #endif
 
     exiting_signal = quiet ? SIGPIPE : 0;
@@ -1880,10 +1887,10 @@ local void do_exit(exitcode)
     FREE(d_buf);
     FREE(window);
 #ifndef MAXSEG_64K
-    FREE(tab_prefix);
+    FREE(prev);
 #else
-    FREE(tab_prefix0);
-    FREE(tab_prefix1);
+    FREE(prev);
+    FREE(head);
 #endif
     exit(exitcode);
 }
diff --git a/gzip.h b/gzip.h
index 648073e..acbaf55 100644
--- a/gzip.h
+++ b/gzip.h
@@ -124,17 +124,28 @@ extern int method;         /* compression method */
 EXTERN(uch, inbuf);          /* input buffer */
 EXTERN(uch, outbuf);         /* output buffer */
 EXTERN(ush, d_buf);          /* buffer for distances, see trees.c */
-EXTERN(uch, window);         /* Sliding window and suffix table (unlzw) */
-#define tab_suffix window
+
+#ifndef WSIZE
+#  define WSIZE 0x8000     /* window size--must be at least 32K for zip's deflate method */
+#endif                     /* Code is slightly faster if WSIZE is a power of 2. */
+
+#include "deflate.h"
+#ifndef LZW_BITS
+#  define LZW_BITS 16
+#endif
+
+EXTERN(uch, window);         /* Sliding window */
+#define tab_suffix window    /* Suffix table (unlzw) */
+
 #ifndef MAXSEG_64K
-#  define tab_prefix prev    /* hash link (see deflate.c) */
+   EXTERN(ush, prev);        /* hash link (see deflate.c) */
+#  define tab_prefix prev    /* prefix code (see unlzw.c) */
 #  define head (prev+WSIZE)  /* hash head (see deflate.c) */
-   EXTERN(ush, tab_prefix);  /* prefix code (see unlzw.c) */
 #else
-#  define tab_prefix0 prev
-#  define head tab_prefix1
-   EXTERN(ush, tab_prefix0); /* prefix for even codes */
-   EXTERN(ush, tab_prefix1); /* prefix for odd  codes */
+   EXTERN(ush, prev);        /* hash link (see deflate.c) */
+#  define tab_prefix0 prev   /* prefix for even codes */
+   EXTERN(ush, head);
+#  define tab_prefix1 head   /* prefix for odd codes */
 #endif
 
 extern unsigned insize; /* valid bytes in inbuf */
@@ -178,10 +189,6 @@ typedef int file_t;     /* Do not use stdio */
 #define BINARY  0
 #define ASCII   1
 
-#ifndef WSIZE
-#  define WSIZE 0x8000     /* window size--must be a power of two, and */
-#endif                     /*  at least 32K for zip's deflate method */
-
 #define MIN_MATCH  3
 #define MAX_MATCH  258
 /* The minimum and maximum match lengths */
@@ -207,6 +214,9 @@ extern int save_orig_name; /* set if original name must be saved */
 #define get_byte()  (inptr < insize ? inbuf[inptr++] : fill_inbuf(0))
 #define try_byte()  (inptr < insize ? inbuf[inptr++] : fill_inbuf(1))
 
+#define MIN(a,b) ((a) <= (b) ? (a) : (b)) /* XXX bug if arg has side effect */
+#define MAX(a,b) ((a) <= (b) ? (b) : (a)) /* XXX bug if arg has side effect */
+
 /* put_byte is used for the compressed output, put_ubyte for the
  * uncompressed output. However unlzw() uses window for its
  * suffix table instead of its output buffer, so it does not use put_ubyte
diff --git a/trees.c b/trees.c
index f2ad360..d14348a 100644
--- a/trees.c
+++ b/trees.c
@@ -330,9 +330,6 @@ local void set_file_type  (void);
  * used.
  */
 
-#define MAX(a,b) (a >= b ? a : b)
-/* the arguments must not have side effects */
-
 /* ===========================================================================
  * Allocate the match buffer, initialize the various tables and save the
  * location of the internal file attribute (ascii/binary) and method
diff --git a/unlzw.c b/unlzw.c
index 3390440..7bdf417 100644
--- a/unlzw.c
+++ b/unlzw.c
@@ -83,6 +83,7 @@ union	bytes {
       memzero(tab_prefix1, 128);
 #endif
 #define de_stack        ((char_type *)(&d_buf[DIST_BUFSIZE-1]))
+   /* DECLARE(uch, tab_suffix, (1<<LZW_BITS)); -- suffix code */
 #define tab_suffixof(i) tab_suffix[i]
 
 int block_mode = BLOCK_MODE; /* block compress mode -C compatible with 2.0 */
-- 
1.7.11.7