From a2b61271a362d4881b9f67fb92455f4fbbab06df Mon Sep 17 00:00:00 2001
From: Mark Adler <madler@alumni.caltech.edu>
Date: Mon, 12 May 2025 10:06:03 -0700
Subject: Allow gzflush() to write empty gzip members.

Before this, a gzflush() with Z_FINISH and no data to write would
do nothing. Now it will write an empty gzip member.
---
 gzwrite.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/gzwrite.c b/gzwrite.c
index ef9ffee5..1fd2046f 100644
--- a/gzwrite.c
+++ b/gzwrite.c
@@ -88,8 +88,9 @@ local int gz_comp(gz_statep state, int flush) {
 
     /* check for a pending reset */
     if (state->reset) {
-        /* don't start a new gzip member unless there is data to write */
-        if (strm->avail_in == 0)
+        /* don't start a new gzip member unless there is data to write and
+           we're not flushing */
+        if (strm->avail_in == 0 && flush == Z_NO_FLUSH)
             return 0;
         deflateReset(strm);
         state->reset = 0;
-- 
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