Update CMake build to define RUNPREFIX different than CMAKE_INSTALL_PREFIX for package building compatibility

[amessina]

Is your feature request related to a problem? Please describe.
The CMake build assumes write access to CMAKE_INSTALL_PREFIX. Packages are typically built for redistribution and prepend DESTDIR to CMAKE_INSTALL_PREFIX. In that way, the package can be "installed" in a temporary buildroot while maintaining the runtime prefix of CMAKE_INSTALL_PREFIX after they are packaged and installed on other systems.

Describe the solution you'd like
The CMake system needs to be updated to install to ${DESTDIR}${CMAKE_INSTALL_PREFIX} during the build so it can be packaged properly.

Describe alternatives you've considered
I've tried setting CMAKE_INSTALL_PREFIX to a place in the builddir (/builddir/build/BUILD/mythtv-34.0-build/install) then moving that install location to /usr which fails at runtime (on another computer) as the runtime prefix is also set to /builddir/build/BUILD/mythtv-34.0-build/install and I get errors like the following as of course it should be looking in /usr/lib64/mythtv/plugins:

mythfrontend[1320]: No plugins directory /builddir/build/BUILD/mythtv-34.0-build/install/lib64/mythtv/plugins

[amessina]

I was able to "resolve" this challenge by updating the RUNPREFIX to /usr in mythtv/libs/libmythbase/CMakeLists.txt using the following patch. It would be helpful to have a CMake definition like MYTHTV_RUNPREFIX that could default to CMAKE_INSTALL_PREFIX if unset, that way MYTHTV_RUNPREFIX could be overridden (just like with the non-CMake build).

 mythtv/libs/libmythbase/CMakeLists.txt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mythtv/libs/libmythbase/CMakeLists.txt b/mythtv/libs/libmythbase/CMakeLists.txt
index b5976ff5f1..3b652d18f4 100644
--- a/mythtv/libs/libmythbase/CMakeLists.txt
+++ b/mythtv/libs/libmythbase/CMakeLists.txt
@@ -266,7 +266,7 @@ set_source_files_properties(
   mythdirs.cpp
   PROPERTIES
     COMPILE_DEFINITIONS
-    "RUNPREFIX=\"${CMAKE_INSTALL_PREFIX}\";LIBDIRNAME=\"${CMAKE_INSTALL_LIBDIR}\""
+    "RUNPREFIX=\"/usr\";LIBDIRNAME=\"${CMAKE_INSTALL_LIBDIR}\""
 )
 target_include_directories(
   mythbase

[linuxdude42]

How about this? Does this give you the control you need?

index 1dfac3b601..ebf22af5ee 100644
--- a/cmake/MythOptions.cmake
+++ b/cmake/MythOptions.cmake
@@ -21,6 +21,11 @@ set(MYTH_DEFAULT_LIBS_PREFIX
     CACHE PATH
           "Default library install prefix if not specified on the command line."
 )
+set(MYTH_RUN_PREFIX
+    ""
+    CACHE PATH
+          "The prefix where MythTV is expected to be at runtime.  This may differ from MYTH_DEFAULT_PREFIX or CMAKE_INSTALL_PREFIX for packagers."
+)
 
 # Location for downloaded tarballs.
 #
diff --git a/mythtv/libs/libmythbase/CMakeLists.txt b/mythtv/libs/libmythbase/CMakeLists.txt
index c51e056175..5bde73d5b9 100644
--- a/mythtv/libs/libmythbase/CMakeLists.txt
+++ b/mythtv/libs/libmythbase/CMakeLists.txt
@@ -261,11 +261,15 @@ target_compile_definitions(mythbase PRIVATE MBASE_API)
 set_source_files_properties(mythcdrom.cpp PROPERTIES COMPILE_DEFINITIONS
                                                      HAVE_LIBUDFREAD)
 
+if(NOT MYTH_RUN_PREFIX)
+  message(VERBOSE "Setting MYTH_RUN_PREFIX to ${CMAKE_INSTALL_PREFIX}")
+  set(MYTH_RUN_PREFIX ${CMAKE_INSTALL_PREFIX})
+endif()
 set_source_files_properties(
   mythdirs.cpp
   PROPERTIES
     COMPILE_DEFINITIONS
-    "RUNPREFIX=\"${CMAKE_INSTALL_PREFIX}\";LIBDIRNAME=\"${CMAKE_INSTALL_LIBDIR}\""
+    "RUNPREFIX=\"${MYTH_RUN_PREFIX}\";LIBDIRNAME=\"${CMAKE_INSTALL_LIBDIR}\""
 )
 target_include_directories(
   mythbase

[amessina]

How about this? Does this give you the control you need?

index 1dfac3b601..ebf22af5ee 100644
--- a/cmake/MythOptions.cmake
+++ b/cmake/MythOptions.cmake
@@ -21,6 +21,11 @@ set(MYTH_DEFAULT_LIBS_PREFIX
     CACHE PATH
           "Default library install prefix if not specified on the command line."
 )
+set(MYTH_RUN_PREFIX
+    ""
+    CACHE PATH
+          "The prefix where MythTV is expected to be at runtime.  This may differ from MYTH_DEFAULT_PREFIX or CMAKE_INSTALL_PREFIX for packagers."
+)
 
 # Location for downloaded tarballs.
 #
diff --git a/mythtv/libs/libmythbase/CMakeLists.txt b/mythtv/libs/libmythbase/CMakeLists.txt
index c51e056175..5bde73d5b9 100644
--- a/mythtv/libs/libmythbase/CMakeLists.txt
+++ b/mythtv/libs/libmythbase/CMakeLists.txt
@@ -261,11 +261,15 @@ target_compile_definitions(mythbase PRIVATE MBASE_API)
 set_source_files_properties(mythcdrom.cpp PROPERTIES COMPILE_DEFINITIONS
                                                      HAVE_LIBUDFREAD)
 
+if(NOT MYTH_RUN_PREFIX)
+  message(VERBOSE "Setting MYTH_RUN_PREFIX to ${CMAKE_INSTALL_PREFIX}")
+  set(MYTH_RUN_PREFIX ${CMAKE_INSTALL_PREFIX})
+endif()
 set_source_files_properties(
   mythdirs.cpp
   PROPERTIES
     COMPILE_DEFINITIONS
-    "RUNPREFIX=\"${CMAKE_INSTALL_PREFIX}\";LIBDIRNAME=\"${CMAKE_INSTALL_LIBDIR}\""
+    "RUNPREFIX=\"${MYTH_RUN_PREFIX}\";LIBDIRNAME=\"${CMAKE_INSTALL_LIBDIR}\""
 )
 target_include_directories(
   mythbase

I think that would work, though I'll need to wait until this weekend to try it. The following also references the resulting run prefix so that may be another place to use MYTH_RUN_PREFIX when set.

mythtv/mythtv/cmake/PrintConfig.cmake

Line 63 in 683d1a4

message("runtime prefix ${CMAKE_INSTALL_PREFIX}")

[linuxdude42]

Let me know how the testing goes. I'll leave the issue open for now in case you need further tweaks.

[amessina]

Let me know how the testing goes. I'll leave the issue open for now in case you need further tweaks.

I was able to rebuild with 31ea30c atop fixes/34 and the patch works beautifully. If this qualifies for backport, I'd appreciate it.

Thank you @linuxdude42.