From 6df5cb464b1e3814f8615e3d794b51e694ff8ced Mon Sep 17 00:00:00 2001
From: Mostyn Bramley-Moore <mostyn@antipode.se>
Date: Thu, 12 Sep 2024 23:56:34 +0200
Subject: [PATCH] cmake: look for zlib >= 1.2.1 (#2318)

zlib 1.2.0 added this improvement for inflate:
"Raw inflate no longer needs an extra dummy byte at end"

libarchive does not feed zlib extra data beyond end of stream, so it
does not work with zlib < 1.2.0.
---
 CMakeLists.txt |  5 ++++-
 configure.ac   | 19 +++++++++++++++++--
 2 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7bfaf4cfa..70d0db43e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -443,7 +443,10 @@ SET(ADDITIONAL_LIBS "")
 # Find ZLIB
 #
 IF(ENABLE_ZLIB)
-  FIND_PACKAGE(ZLIB)
+  # Require zlib >= 1.2.1, see: https://github.com/libarchive/libarchive/issues/615
+  # zlib 1.2.0 should also work, but it is difficult to test for. Let's require
+  # zlib >= 1.2.1 for consistency with the autoconf build.
+  FIND_PACKAGE(ZLIB 1.2.1 REQUIRED)
 ELSE()
   SET(ZLIB_FOUND FALSE) # Override cached value
 ENDIF()
diff --git a/configure.ac b/configure.ac
index 75c71d5c4..a76aaab20 100644
--- a/configure.ac
+++ b/configure.ac
@@ -380,8 +380,23 @@ AC_ARG_WITH([zlib],
   AS_HELP_STRING([--without-zlib], [Don't build support for gzip through zlib]))
 
 if test "x$with_zlib" != "xno"; then
-  AC_CHECK_HEADERS([zlib.h])
-  AC_CHECK_LIB(z,inflate)
+  old_LIBS="$LIBS"
+  LIBS="$LIBS -lz"
+  AC_LINK_IFELSE([AC_LANG_SOURCE([[
+      #include <zlib.h>
+      #if !defined(ZLIB_VERNUM)
+      // zlib 1.2.0 should work too, but it's difficult to test for.
+      // zlib 1.2.1 onwards have ZLIB_VERNUM, which is easy to check.
+      #error zlib >= 1.2.1 is required.
+      #endif
+      // Check that there's an inflate function.
+      int main(int argc, char **argv) { inflate(NULL, 0); return 0; }
+    ]])],
+    [AC_DEFINE([HAVE_ZLIB_H], [1], [Define to 1 if you have zlib >= 1.2.1])
+      AC_MSG_RESULT([found a suitable version of zlib (>= 1.2.1)])
+    ],
+    [AC_MSG_RESULT([could not find a suitable version of zlib (>= 1.2.1)])
+      LIBS="$old_LIBS"])
 fi
 
 AC_ARG_WITH([bz2lib],
-- 
2.47.2