Utilities/Release: Pass pre-built docs tarball

Avoid requiring all build machines for the upstream packaging process to
have Python and Sphinx installed.  Instead create a way to build the
documentation once on the host machine and copy it to each build machine
as a tarball with content to include in the installation tree for
packaging.

1 files changed, 22 insertions, 1 deletions

diff --git a/Utilities/CMakeLists.txt b/Utilities/CMakeLists.txt
index 410f37a23b..8b3e325fa0 100644
--- a/Utilities/CMakeLists.txt
+++ b/Utilities/CMakeLists.txt
@@ -11,4 +11,25 @@
 #=============================================================================
 subdirs(Doxygen KWStyle)
 
-add_subdirectory(Sphinx)
+if(CMAKE_DOC_TARBALL)
+  # Undocumented option to extract and install pre-built documentation.
+  # This is intended for use during packaging of CMake itself.
+  if(CMAKE_DOC_TARBALL MATCHES "/([^/]+)\\.tar\\.gz$")
+    set(dir "${CMAKE_MATCH_1}")
+  else()
+    message(FATAL_ERROR "CMAKE_DOC_TARBALL must end in .tar.gz")
+  endif()
+  add_custom_command(
+    OUTPUT ${dir}.stamp
+    COMMAND cmake -E remove_directory ${dir}
+    COMMAND cmake -E tar xf ${CMAKE_DOC_TARBALL}
+    COMMAND cmake -E touch ${dir}.stamp
+    DEPENDS ${CMAKE_DOC_TARBALL}
+    )
+  add_custom_target(documentation ALL DEPENDS ${dir}.stamp)
+  install(DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/${dir}/
+          DESTINATION . USE_SOURCE_PERMISSIONS)
+else()
+  # Normal documentation build.
+  add_subdirectory(Sphinx)
+endif()