Fix checksummed manifest when DESTDIR is set

 - Fixes #665

Author: zbeekman

cmake/InstallFileManifest.cmake

@@ -1,3 +1,4 @@
+
 # This script will create and install an install manifest, including SHA256 hashes of each installed file
 # Variables passed from CMake must be set with `install(CODE "set(...)")`
 
@@ -6,7 +7,7 @@ message(STATUS "Generating SHA256 checksumed receipt for all installed assets")
 # Set receipt install destination
 set(RECEIPT_INSTALL_DIR "${CMAKE_INSTALL_PREFIX}/${CMAKE_INSTALL_DATADIR}/${PROJECT_NAME}")
 
-# Mimic cmake_install.cmake's handlin of components
+# Mimic cmake_install.cmake's handling of components
 if(CMAKE_INSTALL_COMPONENT)
   set(HASHED_INSTALL_MANIFEST "install_manifest_${CMAKE_INSTALL_COMPONENT}.SHA256.txt")
 else()
@@ -16,10 +17,15 @@ endif()
 # Clean out any old install manifest on re-installation, if it exists
 file(REMOVE "${CMAKE_BINARY_DIR}/${HASHED_INSTALL_MANIFEST}")
 
+if(DEFINED ENV{DESTDIR})
+  get_filename_component(ABS_DESTDIR "$ENV{DESTDIR}" ABSOLUTE)
+else()
+  set(ABS_DESTDIR "")
+endif()
 # Loop over files computing hashes
 foreach(file IN LISTS CMAKE_INSTALL_MANIFEST_FILES)
-  file(SHA256 "${file}" _file_sha256)
-  file(RELATIVE_PATH FILE_REL_PATH "${RECEIPT_INSTALL_DIR}" "${file}")
+  file(SHA256 "$ENV{DESTDIR}${file}" _file_sha256)
+  file(RELATIVE_PATH FILE_REL_PATH "${ABS_DESTDIR}${RECEIPT_INSTALL_DIR}" "${ABS_DESTDIR}${file}")
   file(APPEND "${CMAKE_BINARY_DIR}/${HASHED_INSTALL_MANIFEST}" "${_file_sha256}  ${FILE_REL_PATH}\n")
 endforeach()
 file(APPEND "${CMAKE_BINARY_DIR}/${HASHED_INSTALL_MANIFEST}"