From: Nathan Moinvaziri <nathan@nathanm.com>
Date: Tue, 20 Jan 2026 00:45:53 +0000 (-0800)
Subject: Simplify logic in INFLATE_ALLOW_INVALID_DISTANCE_TOOFAR_ARRR
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3d9dbe97c308930a7fb339c38e581a8059d36175;p=thirdparty%2Fzlib-ng.git

Simplify logic in INFLATE_ALLOW_INVALID_DISTANCE_TOOFAR_ARRR
---

diff --git a/inffast_tpl.h b/inffast_tpl.h
index 8247b833d..6918ec194 100644
--- a/inffast_tpl.h
+++ b/inffast_tpl.h
@@ -200,21 +200,16 @@ void Z_INTERNAL INFLATE_FAST(PREFIX3(stream) *strm, uint32_t start) {
                             SET_BAD("invalid distance too far back");
                             break;
                         }
-                        if (len <= op - whave) {
-                            do {
-                                *out++ = 0;
-                            } while (--len);
+                        unsigned gap = op - whave;
+                        unsigned zeros = MIN(len, gap);
+                        memset(out, 0, zeros);  /* fill missing bytes with zeros */
+                        out += zeros;
+                        len -= zeros;
+                        if (len == 0)
                             continue;
-                        }
-                        len -= op - whave;
-                        do {
-                            *out++ = 0;
-                        } while (--op > whave);
-                        if (op == 0) {
-                            from = out - dist;
-                            do {
-                                *out++ = *from++;
-                            } while (--len);
+                        op = whave;
+                        if (op == 0) {          /* copy from already-decoded output */
+                            out = chunkcopy_safe(out, out - dist, len, safe);
                             continue;
                         }
 #else