From 59001c6acd157e52f3c4970ccc6fe3c3676590ab Mon Sep 17 00:00:00 2001
From: tb <tb@openbsd.org>
Date: Sun, 21 Jan 2024 07:46:16 +0000
Subject: [PATCH] Sync with upstream as of Jan 20

No change of compiled code: the bug fix in check_match() affects ZLIB_DEBUG
builds only and the Z_ARG macro is unused.
---
 lib/libz/deflate.c | 20 ++++++++++++++------
 lib/libz/zconf.h   |  8 --------
 2 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/lib/libz/deflate.c b/lib/libz/deflate.c
index 8cfe4471295..a29653e6b67 100644
--- a/lib/libz/deflate.c
+++ b/lib/libz/deflate.c
@@ -1552,13 +1552,21 @@ local uInt longest_match(deflate_state *s, IPos cur_match) {
  */
 local void check_match(deflate_state *s, IPos start, IPos match, int length) {
     /* check that the match is indeed a match */
-    if (zmemcmp(s->window + match,
-                s->window + start, length) != EQUAL) {
-        fprintf(stderr, " start %u, match %u, length %d\n",
-                start, match, length);
+    Bytef *back = s->window + (int)match, *here = s->window + start;
+    IPos len = length;
+    if (match == (IPos)-1) {
+        /* match starts one byte before the current window -- just compare the
+           subsequent length-1 bytes */
+        back++;
+        here++;
+        len--;
+    }
+    if (zmemcmp(back, here, len) != EQUAL) {
+        fprintf(stderr, " start %u, match %d, length %d\n",
+                start, (int)match, length);
         do {
-            fprintf(stderr, "%c%c", s->window[match++], s->window[start++]);
-        } while (--length != 0);
+            fprintf(stderr, "(%02x %02x)", *back++, *here++);
+        } while (--len != 0);
         z_error("invalid match");
     }
     if (z_verbose > 1) {
diff --git a/lib/libz/zconf.h b/lib/libz/zconf.h
index 7c1dc4fc61d..5b8331ab89b 100644
--- a/lib/libz/zconf.h
+++ b/lib/libz/zconf.h
@@ -298,14 +298,6 @@
 #  endif
 #endif
 
-#ifndef Z_ARG /* function prototypes for stdarg */
-#  if defined(STDC) || defined(Z_HAVE_STDARG_H)
-#    define Z_ARG(args)  args
-#  else
-#    define Z_ARG(args)  ()
-#  endif
-#endif
-
 /* The following definitions for FAR are needed only for MSDOS mixed
  * model programming (small or medium model with some far allocations).
  * This was tested only with MSC; for other MSDOS compilers you may have
-- 
2.20.1