From 1e4ee94f073c21476a9626c9c7d457a001d23373 Mon Sep 17 00:00:00 2001
From: Markus Frosch <markus.frosch@icinga.com>
Date: Tue, 31 Jul 2018 16:46:11 +0200
Subject: [PATCH] cmake: Improve InstallConfig for stable path handling

* similar to install() a non absolute path is prefixed with CMAKE_INSTALL_PREFIX on runtime
* in case of CPack path with be prefixed with share/skel/
* DESTDIR is prefixed as well

Also see https://cmake.org/cmake/help/latest/command/install.html
---
 cmake/InstallConfig.cmake | 45 +++++++++++++++++++++++----------------
 1 file changed, 27 insertions(+), 18 deletions(-)

diff --git a/cmake/InstallConfig.cmake b/cmake/InstallConfig.cmake
index f01357c79..aa39b9dfb 100644
--- a/cmake/InstallConfig.cmake
+++ b/cmake/InstallConfig.cmake
@@ -15,38 +15,47 @@
 # along with this program; if not, write to the Free Software Foundation
 # Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
 
+# Install $src into directory $dest - usually only used for config files
+#
+# * similar to install() a non absolute path is prefixed with CMAKE_INSTALL_PREFIX on runtime
+# * in case of CPack path with be prefixed with share/skel/
+# * DESTDIR is prefixed as well
+#
+# also see https://cmake.org/cmake/help/latest/command/install.html
 function(install_if_not_exists src dest)
-  set(real_dest "${dest}")
   if(NOT IS_ABSOLUTE "${src}")
     set(src "${CMAKE_CURRENT_SOURCE_DIR}/${src}")
   endif()
+
   get_filename_component(src_name "${src}" NAME)
-  get_filename_component(basename_dest "${src}" NAME)
-  string(REPLACE "/" "\\\\" nsis_src "${src}")
-  string(REPLACE "/" "\\\\" nsis_dest_dir "${real_dest}")
-  string(REPLACE "/" "\\\\" nsis_dest "${real_dest}/${basename_dest}")
+
   install(CODE "
-   if(\"\$ENV{DESTDIR}\" STREQUAL \"\")
-      set(target_dir \${CMAKE_INSTALL_PREFIX})
+    set(dest \"${dest}\")
+
+    if (\"\${CMAKE_INSTALL_PREFIX}\" MATCHES .*/_CPack_Packages/.*)
+      set(dest \"share/skel/\${dest}\")
+      set(force_overwrite TRUE)
     else()
-      set(target_dir \$ENV{DESTDIR})
+      set(force_overwrite FALSE)
     endif()
-    if(\${CMAKE_INSTALL_PREFIX} MATCHES .*/_CPack_Packages/.* OR NOT EXISTS \"\$ENV{DESTDIR}\${CMAKE_INSTALL_PREFIX}/\${skel_prefix}${dest}/${src_name}\")
-      message(STATUS \"Installing: \$ENV{DESTDIR}${dest}/${src_name}\")
-      if(\${CMAKE_INSTALL_PREFIX} MATCHES .*/_CPack_Packages/.*)
-        set(skel_prefix \"share/skel/\")
-      else()
-        set(skel_prefix \"\")
-      endif()
-      execute_process(COMMAND \${CMAKE_COMMAND} -E copy \"${src}\"
-                      \"\${target_dir}/\${skel_prefix}${dest}/${src_name}\"
+
+    if(NOT IS_ABSOLUTE \"\${dest}\")
+      set(dest \"\${CMAKE_INSTALL_PREFIX}/\${dest}\")
+    endif()
+
+    set(full_dest \"\$ENV{DESTDIR}\${dest}/${src_name}\")
+
+    if(force_overwrite OR NOT EXISTS \"\${full_dest}\")
+      message(STATUS \"Installing: ${src} into \${full_dest}\")
+
+      execute_process(COMMAND \${CMAKE_COMMAND} -E copy \"${src}\" \"\${full_dest}\"
                       RESULT_VARIABLE copy_result
                       ERROR_VARIABLE error_output)
       if(copy_result)
         message(FATAL_ERROR \${error_output})
       endif()
     else()
-      message(STATUS \"Skipping  : \${target_dir}/${dest}/${src_name}\")
+      message(STATUS \"Skipping  : \${full_dest}\")
     endif()
   ")
 endfunction(install_if_not_exists)