gzdoom/tools/updaterevision/UpdateRevision.cmake

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#!/usr/bin/cmake -P
# UpdateRevision.cmake
#
# Public domain. This program uses git commands command to get
# various bits of repository status for a particular directory
# and writes it into a header file so that it can be used for a
# project's versioning.
# Boilerplate to return a variable from a function.
macro(ret_var VAR)
set(${VAR} "${${VAR}}" PARENT_SCOPE)
endmacro()
# Populate variables "Hash", "Tag", and "Timestamp" with relevant information
# from source repository. If anything goes wrong return something in "Error."
function(query_repo_info)
execute_process(
COMMAND git describe --tags --dirty=-m
RESULT_VARIABLE Error
OUTPUT_VARIABLE Tag
ERROR_QUIET
OUTPUT_STRIP_TRAILING_WHITESPACE
)
if(NOT "${Error}" STREQUAL "0")
ret_var(Error)
return()
endif()
execute_process(
COMMAND git log -1 "--format=%ai;%H"
RESULT_VARIABLE Error
OUTPUT_VARIABLE CommitInfo
ERROR_QUIET
OUTPUT_STRIP_TRAILING_WHITESPACE
)
if(NOT "${Error}" STREQUAL "0")
ret_var(Error)
return()
endif()
list(GET CommitInfo 0 Timestamp)
list(GET CommitInfo 1 Hash)
ret_var(Tag)
ret_var(Timestamp)
ret_var(Hash)
endfunction()
# Although configure_file doesn't overwrite the file if the contents are the
# same we can't easily observe that to change the status message. This
# function parses the existing file (if it exists) and puts the hash in
# variable "OldHash"
function(get_existing_hash File)
if(EXISTS "${File}")
file(STRINGS "${File}" OldHash LIMIT_COUNT 1)
if(OldHash)
string(SUBSTRING "${OldHash}" 3 -1 OldHash)
ret_var(OldHash)
endif()
endif()
endfunction()
function(main)
if(NOT CMAKE_ARGC EQUAL 4) # cmake -P UpdateRevision.cmake <OutputFile>
message("Usage: ${CMAKE_ARGV2} <path to gitinfo.h>")
return()
endif()
set(OutputFile "${CMAKE_ARGV3}")
get_filename_component(ScriptDir "${CMAKE_SCRIPT_MODE_FILE}" DIRECTORY)
query_repo_info()
if(NOT Hash)
message("Failed to get commit info: ${Error}")
set(Hash "0")
set(Tag "<unknown version>")
set(Timestamp "")
endif()
get_existing_hash("${OutputFile}")
if(Hash STREQUAL OldHash)
message("${OutputFile} is up to date at commit ${Tag}.")
return()
endif()
configure_file("${ScriptDir}/gitinfo.h.in" "${OutputFile}")
message("${OutputFile} updated to commit ${Tag}.")
endfunction()
main()