Stash some notes and tests on update checking

We ideally want to trigger configure updates, patching repeats, etc.
when git repository updates are pulled down, but because most of our
builds make src copies and apply patches an update into the src git
tree doesn't automatically trigger rebuilding.

Investigating whether a custom update step can be made to do the steps
for us automatically.  The addition of patching makes what needs to
happen for this a bit involved - what's being committed here is just the
beginnings of thinking about how to do what's needed, and is not
functional.

CMake/UpdateSync.cmake.in

@@ -0,0 +1,149 @@
+cmake_policy(SET CMP0007 NEW)
+
+if (NOT EXISTS "@SRC_DIR@")
+	message(FATAL_ERROR "@SRC_DIR@ not found on filesystem")
+endif (NOT EXISTS "@SRC_DIR@")
+file(GLOB_RECURSE SRC_FILES LIST_DIRECTORIES false RELATIVE "@SRC_DIR@" "@SRC_DIR@/*")
+list(FILTER SRC_FILES EXCLUDE REGEX ".*[.]git.*")
+list(SORT SRC_FILES)
+
+# If we have a prior existing source directory state, read it in
+set(prev_md5)
+set(prev_files)
+if (EXISTS "@MD5_SUMMARY@")
+	# Read each line in to make two lists - files and MD5 hashes.  First entry
+	# is MD5.  Will use file list to get the index to use to get the MD5 hash
+	# for each file in subsequent lookups
+	file(STRINGS "@MD5_SUMMARY@" hash_strings)
+	foreach(hs ${hash_strings})
+		set(hlist ${hs})
+		list(POP_FRONT hlist pmd5)
+		list(APPEND prev_md5 "${pmd5}")
+		list(APPEND prev_files "${hlist}")
+	endforeach(hs ${hash_strings})
+	file(REMOVE "@MD5_SUMMARY@")
+endif (EXISTS "@MD5_SUMMARY@")
+
+message("prev_files: ${prev_files}")
+
+# Generate an MD5 summary for the current source dir state
+set(curr_md5)
+set(curr_files)
+foreach(S ${SRC_FILES})
+	file(MD5 "@SRC_DIR@/${S}" md5_hash)
+	file(APPEND "@MD5_SUMMARY@" "${md5_hash};${S}\n")
+	list(APPEND curr_md5 "${md5_hash}")
+	list(APPEND curr_files "${S}")
+endforeach(S ${SRC_FILES})
+
+message("curr_files: ${curr_files}")
+
+# Check if we have any changed files.  If so, update the src copy
+set(updated_files)
+foreach(S ${SRC_FILES})
+	list(FIND prev_files "${S}" prev_ind)
+	if ("${prev_ind}" EQUAL -1)
+		# New file
+		message("New file: ${S}")
+		list(APPEND update_files ${S})
+		continue()
+	endif ("${prev_ind}" EQUAL -1)
+	# Check file contents
+	list(GET prev_md5 ${prev_ind} pmd5)
+	list(FIND curr_files "${S}" curr_ind)
+	list(GET curr_md5 ${curr_ind} cmd5)
+	if (NOT "${pmd5}" STREQUAL "${cmd5}")
+		list(APPEND update_files ${S})
+		message("File changed: ${S}")
+	endif (NOT "${pmd5}" STREQUAL "${cmd5}")
+endforeach(S ${SRC_FILES})
+# Copy any changed files from the src directory to the build directory
+foreach(CF ${updated_files})
+	execute_process(COMMAND "@CMAKE_COMMAND@" -E copy "@SRC_DIR@/${CF}" "@BLD_DIR@/${CF}")
+endforeach(S ${SRC_FILES})
+
+
+# If we have previously applied patches, read in that information.  We will need:
+#
+# md5 of previously applied patch file.  If that's changed, we need to remove all
+# added files from the previous patch and re-apply
+#
+# list of files changed by the patch.  If any of the updated files were also
+# patch targets, we need to reset all files involved with the patch and
+# re-apply.  To that end, we also need a separate list of files added by the
+# patch so we can remove them. (Unless a file created by patch is already part
+# of the update list - in that case leave the file from the update - the patch
+# will need to be corrected.)
+set(patch_changed_files)
+if (EXISTS "@PATCH_CHANGED_SUMMARY@")
+	file(STRINGS "@PATCH_CHANGED_SUMMARY@" patch_changed_files)
+	file(REMOVE "@PATCH_CHANGED_SUMMARY@")
+endif (EXISTS "@PATCH_CHANGED_SUMMARY@")
+set(patch_added_files)
+if (EXISTS "@PATCH_ADDED_SUMMARY@")
+	file(STRINGS "@PATCH_ADDED_SUMMARY@" patch_added_files)
+	file(REMOVE "@PATCH_ADDED_SUMMARY@")
+endif (EXISTS "@PATCH_ADDED_SUMMARY@")
+
+# First check for changed files
+set(changed_patch FALSE)
+foreach(pcf ${patch_changed_files})
+	list(FIND updated_files "${pcf}" pcf_ind)
+	if (NOT "${pcf_ind}" EQUAL -1)
+		set(changed_patch TRUE)
+	endif (NOT "${pcf_ind}" EQUAL -1)
+endforeach(pcf ${patch_changed_files})
+
+
+
+
+# Remove files present only in the build dir
+# TODO - this needs to be more nuanced - files may be added by patching, and we don't
+# want to remove those
+if (NOT EXISTS "@BLD_DIR@")
+	message(FATAL_ERROR "@BLD_DIR@ not found on filesystem")
+endif (NOT EXISTS "@BLD_DIR@")
+file(GLOB_RECURSE BLD_FILES LIST_DIRECTORIES false RELATIVE "@BLD_DIR@" "@BLD_DIR@/*")
+list(FILTER BLD_FILES EXCLUDE REGEX ".*[.]git.*")
+set(BLD_ONLY ${BLD_FILES})
+list(REMOVE_ITEM BLD_ONLY ${SRC_FILES})
+foreach(B ${BLD_ONLY})
+	message("Removing: ${B}")
+	file(REMOVE "@BLD_DIR@/${B}")
+endforeach(B ${BLD_ONLY})
+
+# If any previously patched files are present in the updated
+# files list (or if we have never applied patches before)
+# we need to proceed with patching.
+set(prev_files)
+if (EXISTS "@PATCH_SUMMARY@")
+	# Read each line in to make two lists - files and MD5 hashes.  First entry
+	# is MD5.  Will use file list to get the index to use to get the MD5 hash
+	# for each file in subsequent lookups
+	file(STRINGS "@MD5_SUMMARY@" hash_strings)
+	foreach(hs ${hash_strings})
+		set(hlist ${hs})
+		list(POP_FRONT hlist pmd5)
+		list(APPEND prev_md5 "${pmd5}")
+		list(APPEND prev_files "${hlist}")
+	endforeach(hs ${hash_strings})
+	file(REMOVE "@MD5_SUMMARY@")
+endif (EXISTS "@MD5_SUMMARY@")
+
+
+
+
+# Copy any changed files from the src directory to the build directory
+foreach(S ${SRC_FILES})
+	execute_process(COMMAND "@CMAKE_COMMAND@" -E compare_files "@SRC_DIR@/${S}" "@BLD_DIR@/${S}" RESULT_VARIABLE FILES_DIFFER)
+	if (FILES_DIFFER)
+		execute_process(COMMAND "@CMAKE_COMMAND@" -E copy "@SRC_DIR@/${S}" "@BLD_DIR@/${S}")
+		set(HAVE_DIFFERENCE TRUE)
+	endif (FILES_DIFFER)
+endforeach(S ${SRC_FILES})
+
+set(PFILES @PATCH_FILES@)
+foreach(PF ${PFILES})
+	# Ignore whitespace, don't attempt reverse patching
+	execute_process(COMMAND "@PATCH_EXECUTABLE@" -E -p1 --ignore-whitespace -N -i "@CMAKE_CURRENT_SOURCE_DIR@/${PF}")
+endforeach(PF ${PFILES})

itcl/CMakeLists.txt

@@ -83,11 +83,17 @@ if (ENABLE_ITCL)
   # in which we are storing the library.
   set(RPATH_SUFFIX itcl3.4)
 
+  set(SRC_DIR "${CMAKE_CURRENT_SOURCE_DIR}/itcl")
+  set(BLD_DIR "${CMAKE_CURRENT_BINARY_DIR}/ITCL_BLD-prefix/src/ITCL_BLD")
+  file(MAKE_DIRECTORY ${BLD_DIR})
+  set(MD5_SUMMARY "${BLD_DIR}/../md5_summary.txt")
+  set(PATCH_FILES itcl.patch ${TCL_HDRS_PATCH})
+  configure_file(${CMAKE_SOURCE_DIR}/CMake/UpdateSync.cmake.in ${CMAKE_CURRENT_BINARY_DIR}/UpdateSync.cmake @ONLY)
+
   ExternalProject_Add(ITCL_BLD
     URL "${CMAKE_CURRENT_SOURCE_DIR}/itcl"
     BUILD_ALWAYS ${EXT_BUILD_ALWAYS} ${LOG_OPTS}
-    PATCH_COMMAND ${PATCH_EXECUTABLE};-E;-p1;${PATCH_OPTIONS};-i;${CMAKE_CURRENT_SOURCE_DIR}/itcl.patch
-    COMMAND ${TCL_HDRS_PATCH_CMD}
+    UPDATE_COMMAND ${CMAKE_COMMAND} -P ${CMAKE_CURRENT_BINARY_DIR}/UpdateSync.cmake
     CMAKE_ARGS
     ${BUILD_TYPE_SPECIFIER}
     -DBIN_DIR=$<IF:$<BOOL:${WIN32}>,${LIB_DIR},${BIN_DIR}>