From a9ac4bbf41aa1d7f4f25f45ea5cc237894e1fb56 Mon Sep 17 00:00:00 2001
From: Felix Geyer <debfx@fobos.de>
Date: Fri, 24 Sep 2010 13:32:05 +0200
Subject: [PATCH] Add cmake check to verify that zlib supports the gzip format.

---
 CMakeLists.txt | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 29e47ff2d..f3c662518 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -53,6 +53,20 @@ find_package(Libgcrypt REQUIRED)
 
 find_package(ZLIB REQUIRED)
 
+include(CheckCXXSourceCompiles)
+check_cxx_source_compiles("
+    #include <zlib.h>
+
+    #if !defined(ZLIB_VERNUM) || (ZLIB_VERNUM < 0x1200)
+        #error zlib 1.2.x or higher is required to use the gzip format
+    #endif
+
+    int main() { return 0; }" ZLIB_SUPPORTS_GZIP)
+
+if(NOT ZLIB_SUPPORTS_GZIP)
+    message(FATAL_ERROR "zlib 1.2.x or higher is required to use the gzip format")
+endif(NOT ZLIB_SUPPORTS_GZIP)
+
 add_subdirectory(src)
 if( WITH_TESTS )
     add_subdirectory(tests)