Initial support for lhc4codec

builtins/lhc4codec/CMakeLists.txt

@@ -0,0 +1,144 @@
+# Copyright (C) 1995-2026, Rene Brun and Fons Rademakers.
+# All rights reserved.
+#
+# For the licensing terms see $ROOTSYS/LICENSE.
+# For the list of contributors see $ROOTSYS/README/CREDITS.
+
+# Build lhc4codec as part of ROOT. Upstream:
+#   https://gitlab.cern.ch/apeters/lhc4codec.git
+#
+# If LHC4CODEC_SOURCE_DIR is set, that checkout is built via add_subdirectory
+# (offline / development). Otherwise the source is fetched with ExternalProject
+# (clad-style git clone; requires network and GitLab credentials).
+
+include(ExternalProject)
+
+# **PLEASE UPDATE ALSO THE FOLLOWING LINE WHEN UPDATING THE VERSION**
+# 19 Oct 2026, https://gitlab.cern.ch/apeters/lhc4codec.git @ c433157 (Flash/Mosaic/Oracle docs, Crystal design note, RNTuple tools chapter)
+set(ROOT_LHC4CODEC_VERSION 2.5.0)
+set(ROOT_LHC4CODEC_GIT_REPOSITORY "https://gitlab.cern.ch/apeters/lhc4codec.git")
+set(ROOT_LHC4CODEC_GIT_TAG "c433157729d96b4e15cd29971d9f88a25eb43496")
+
+set(_lhc4codec_build_args
+  -DLHC4CODEC_BUILD_CLI=OFF
+  -DLHC4CODEC_BUILD_TESTS=OFF
+  -DLHC4CODEC_METAL=OFF
+  -DLHC4CODEC_HIP=OFF
+  -DLHC4CODEC_NATIVE=OFF
+  -DLHC4CODEC_LTO=OFF
+  -DLHC4CODEC_ZSTD=AUTO
+  -DLHC4CODEC_LZMA=AUTO
+  -DLHC4CODEC_BZIP3=BUNDLED
+  -DCMAKE_CXX_STANDARD=20
+  -DCMAKE_POSITION_INDEPENDENT_CODE=ON
+)
+
+if(LHC4CODEC_SOURCE_DIR)
+  if(NOT EXISTS "${LHC4CODEC_SOURCE_DIR}/CMakeLists.txt")
+    message(FATAL_ERROR "LHC4CODEC_SOURCE_DIR=\"${LHC4CODEC_SOURCE_DIR}\" does not contain a CMake project")
+  endif()
+
+  message(STATUS "Building builtin lhc4codec from ${LHC4CODEC_SOURCE_DIR}")
+
+  set(LHC4CODEC_BUILD_CLI OFF CACHE BOOL "" FORCE)
+  set(LHC4CODEC_BUILD_TESTS OFF CACHE BOOL "" FORCE)
+  set(LHC4CODEC_METAL OFF CACHE BOOL "" FORCE)
+  set(LHC4CODEC_HIP OFF CACHE BOOL "" FORCE)
+  set(LHC4CODEC_NATIVE OFF CACHE BOOL "" FORCE)
+  set(LHC4CODEC_LTO OFF CACHE BOOL "" FORCE)
+  set(LHC4CODEC_ZSTD AUTO CACHE STRING "" FORCE)
+  set(LHC4CODEC_LZMA AUTO CACHE STRING "" FORCE)
+  set(LHC4CODEC_BZIP3 BUNDLED CACHE STRING "" FORCE)
+  set(CMAKE_POSITION_INDEPENDENT_CODE ON)
+
+  add_subdirectory(${LHC4CODEC_SOURCE_DIR} ${CMAKE_BINARY_DIR}/builtins/lhc4codec-build EXCLUDE_FROM_ALL)
+
+  set(LHC4CODEC_INCLUDE_DIRS ${LHC4CODEC_SOURCE_DIR}/include)
+  set(LHC4CODEC_LIBRARIES lhc4codec_static)
+
+  if(NOT TARGET LHC4CODEC::LHC4CODEC)
+    add_library(LHC4CODEC::LHC4CODEC ALIAS lhc4codec_static)
+  endif()
+else()
+  message(STATUS "Downloading and building lhc4codec ${ROOT_LHC4CODEC_VERSION} from "
+                  "${ROOT_LHC4CODEC_GIT_REPOSITORY} (${ROOT_LHC4CODEC_GIT_TAG})")
+
+  set(ROOT_LHC4CODEC_PREFIX ${CMAKE_BINARY_DIR}/builtins/lhc4codec-prefix)
+  set(ROOT_LHC4CODEC_SOURCE_DIR ${ROOT_LHC4CODEC_PREFIX}/src/BUILTIN_LHC4CODEC)
+  set(ROOT_LHC4CODEC_BUILD_DIR ${ROOT_LHC4CODEC_PREFIX}/src/BUILTIN_LHC4CODEC-build)
+  # Staged headers live outside the git tree so the path exists at configure time
+  # (CMake validates INTERFACE_INCLUDE_DIRECTORIES on imported targets).
+  set(ROOT_LHC4CODEC_INCLUDE_DIR ${ROOT_LHC4CODEC_PREFIX}/include)
+  set(ROOT_LHC4CODEC_LIBRARY
+      ${ROOT_LHC4CODEC_BUILD_DIR}/${CMAKE_STATIC_LIBRARY_PREFIX}lhc4codec${CMAKE_STATIC_LIBRARY_SUFFIX})
+  set(ROOT_LHC4CODEC_BZIP3_LIBRARY
+      ${ROOT_LHC4CODEC_BUILD_DIR}/${CMAKE_STATIC_LIBRARY_PREFIX}lhc4_bzip3_bundled${CMAKE_STATIC_LIBRARY_SUFFIX})
+  file(MAKE_DIRECTORY ${ROOT_LHC4CODEC_INCLUDE_DIR})
+
+  if(MSVC)
+    set(_lhc4codec_build_type Release)
+    if(winrtdebug)
+      set(_lhc4codec_build_type Debug)
+    endif()
+    if(NOT CMAKE_GENERATOR MATCHES Ninja)
+      set(_lhc4codec_build_flags --config ${_lhc4codec_build_type})
+    endif()
+    set(_lhc4codec_extra_cmake_args
+      -DCMAKE_CXX_FLAGS_RELWITHDEBINFO=${CMAKE_CXX_FLAGS_RELWITHDEBINFO}
+      -DCMAKE_CXX_FLAGS_RELEASE=${CMAKE_CXX_FLAGS_RELEASE}
+      -DCMAKE_CXX_FLAGS_DEBUG=${CMAKE_CXX_FLAGS_DEBUG})
+  else()
+    set(_lhc4codec_build_type Release)
+    set(_lhc4codec_build_flags "")
+    set(_lhc4codec_extra_cmake_args "")
+  endif()
+
+  ExternalProject_Add(
+    BUILTIN_LHC4CODEC
+    GIT_REPOSITORY ${ROOT_LHC4CODEC_GIT_REPOSITORY}
+    GIT_TAG ${ROOT_LHC4CODEC_GIT_TAG}
+    GIT_SUBMODULES third_party/bzip3
+    PREFIX ${ROOT_LHC4CODEC_PREFIX}
+    UPDATE_COMMAND ""
+    CMAKE_ARGS -G ${CMAKE_GENERATOR}
+      -DCMAKE_INSTALL_PREFIX=<INSTALL_DIR>
+      -DCMAKE_BUILD_TYPE=${_lhc4codec_build_type}
+      ${_lhc4codec_build_args}
+      ${_lhc4codec_extra_cmake_args}
+    BUILD_COMMAND ${CMAKE_COMMAND} --build <BINARY_DIR> ${_lhc4codec_build_flags}
+                  --target lhc4codec_static lhc4_bzip3_bundled
+    INSTALL_COMMAND ""
+    LOG_DOWNLOAD 1 LOG_CONFIGURE 1 LOG_BUILD 1 LOG_OUTPUT_ON_FAILURE 1
+    BUILD_BYPRODUCTS ${ROOT_LHC4CODEC_LIBRARY} ${ROOT_LHC4CODEC_BZIP3_LIBRARY}
+    TIMEOUT 600
+  )
+
+  # Copy public headers after the git clone, before the nested configure/build.
+  ExternalProject_Add_Step(BUILTIN_LHC4CODEC stage-headers
+    COMMAND ${CMAKE_COMMAND} -E rm -rf ${ROOT_LHC4CODEC_INCLUDE_DIR}/lhc4codec
+    COMMAND ${CMAKE_COMMAND} -E copy_directory
+            <SOURCE_DIR>/include/lhc4codec
+            ${ROOT_LHC4CODEC_INCLUDE_DIR}/lhc4codec
+    DEPENDEES download
+    DEPENDERS configure
+  )
+
+  add_library(LHC4CODEC::LHC4CODEC IMPORTED STATIC GLOBAL)
+  add_dependencies(LHC4CODEC::LHC4CODEC BUILTIN_LHC4CODEC)
+  set_target_properties(LHC4CODEC::LHC4CODEC PROPERTIES
+    IMPORTED_LOCATION ${ROOT_LHC4CODEC_LIBRARY}
+    INTERFACE_INCLUDE_DIRECTORIES ${ROOT_LHC4CODEC_INCLUDE_DIR}
+    INTERFACE_LINK_LIBRARIES ${ROOT_LHC4CODEC_BZIP3_LIBRARY}
+  )
+
+  set(LHC4CODEC_INCLUDE_DIRS ${ROOT_LHC4CODEC_INCLUDE_DIR})
+  set(LHC4CODEC_LIBRARIES ${ROOT_LHC4CODEC_LIBRARY})
+endif()
+
+set(LHC4CODEC_FOUND TRUE)
+set(LHC4CODEC_VERSION ${ROOT_LHC4CODEC_VERSION})
+
+set(LHC4CODEC_INCLUDE_DIRS ${LHC4CODEC_INCLUDE_DIRS} PARENT_SCOPE)
+set(LHC4CODEC_LIBRARIES ${LHC4CODEC_LIBRARIES} PARENT_SCOPE)
+set(LHC4CODEC_FOUND ${LHC4CODEC_FOUND} PARENT_SCOPE)
+set(LHC4CODEC_VERSION ${LHC4CODEC_VERSION} PARENT_SCOPE)

cmake/modules/FindLHC4CODEC.cmake

@@ -0,0 +1,124 @@
+# Copyright (C) 1995-2026, Rene Brun and Fons Rademakers.
+# All rights reserved.
+#
+# For the licensing terms see $ROOTSYS/LICENSE.
+# For the list of contributors see $ROOTSYS/README/CREDITS.
+
+#.rst:
+# FindLHC4CODEC
+# -------------
+#
+# Find the lhc4codec library header and define variables.
+#
+# Imported Targets
+# ^^^^^^^^^^^^^^^^
+#
+# This module defines :prop_tgt:`IMPORTED` target ``LHC4CODEC::LHC4CODEC``,
+# if lhc4codec has been found.
+#
+# Result Variables
+# ^^^^^^^^^^^^^^^^
+#
+# This module defines the following variables:
+#
+# ::
+#
+#   LHC4CODEC_FOUND          - True if lhc4codec is found.
+#   LHC4CODEC_INCLUDE_DIRS   - Where to find lhc4codec/lhc4codec_c.h
+#   LHC4CODEC_LIBRARIES      - The lhc4codec library path
+#   LHC4CODEC_VERSION        - The lhc4codec version string, if available
+#   LHC4CODEC_INSTALL_HELP   - How to install a missing package (always set)
+
+# Prebuilt packages: https://gitlab.cern.ch/apeters/lhc4codec-bin
+set(LHC4CODEC_INSTALL_HELP [=[
+lhc4codec was not found (need lhc4codec/lhc4codec_c.h and liblhc4codec).
+
+Install a prebuilt package from https://gitlab.cern.ch/apeters/lhc4codec-bin :
+
+  # AlmaLinux 9 / 10 (x86_64)
+  sudo curl -fsSL -o /etc/yum.repos.d/lhc4codec.repo \
+    https://gitlab.cern.ch/apeters/lhc4codec-bin/-/raw/master/lhc4codec-el9.repo   # or -el10
+  sudo dnf install lhc4codec lhc4codec-devel
+
+  # macOS, Apple silicon (macOS 13+)
+  brew tap apeters/lhc4codec https://gitlab.cern.ch/apeters/lhc4codec-bin.git
+  brew install apeters/lhc4codec/lhc4codec
+
+Or point CMake at an existing prefix:  -DLHC4CODEC_ROOT=/path/to/prefix
+Or let ROOT clone and build it:        -Dbuiltin_lhc4codec=ON
+  (fetches https://gitlab.cern.ch/apeters/lhc4codec.git)
+]=])
+
+set(_lhc4codec_hints)
+if(LHC4CODEC_ROOT)
+  list(APPEND _lhc4codec_hints "${LHC4CODEC_ROOT}")
+endif()
+if(DEFINED ENV{LHC4CODEC_ROOT})
+  list(APPEND _lhc4codec_hints "$ENV{LHC4CODEC_ROOT}")
+endif()
+
+if(APPLE)
+  # Homebrew: arm64 default is /opt/homebrew, Intel is /usr/local.
+  list(APPEND _lhc4codec_hints /opt/homebrew /usr/local)
+  find_program(_lhc4codec_brew brew)
+  if(_lhc4codec_brew)
+    execute_process(COMMAND "${_lhc4codec_brew}" --prefix lhc4codec
+                    OUTPUT_VARIABLE _lhc4codec_brew_formula
+                    OUTPUT_STRIP_TRAILING_WHITESPACE
+                    ERROR_QUIET)
+    if(_lhc4codec_brew_formula)
+      list(APPEND _lhc4codec_hints "${_lhc4codec_brew_formula}")
+    endif()
+    execute_process(COMMAND "${_lhc4codec_brew}" --prefix
+                    OUTPUT_VARIABLE _lhc4codec_brew_prefix
+                    OUTPUT_STRIP_TRAILING_WHITESPACE
+                    ERROR_QUIET)
+    if(_lhc4codec_brew_prefix)
+      list(APPEND _lhc4codec_hints "${_lhc4codec_brew_prefix}")
+    endif()
+  endif()
+  unset(_lhc4codec_brew CACHE)
+endif()
+
+find_path(LHC4CODEC_INCLUDE_DIR lhc4codec/lhc4codec_c.h
+  HINTS ${_lhc4codec_hints}
+  PATH_SUFFIXES include
+)
+
+find_library(LHC4CODEC_LIBRARY
+  NAMES lhc4codec lhc4codec_static
+  HINTS ${_lhc4codec_hints}
+  PATH_SUFFIXES lib lib64
+)
+
+if(LHC4CODEC_INCLUDE_DIR AND EXISTS "${LHC4CODEC_INCLUDE_DIR}/lhc4codec/lhc4codec_c.h")
+  file(READ "${LHC4CODEC_INCLUDE_DIR}/lhc4codec/lhc4codec_c.h" _lhc4codec_header)
+  string(REGEX MATCH "#define LHC4CODEC_VERSION \"([^\"]+)\"" _lhc4codec_version_match "${_lhc4codec_header}")
+  if(CMAKE_MATCH_1)
+    set(LHC4CODEC_VERSION "${CMAKE_MATCH_1}")
+  endif()
+  unset(_lhc4codec_header)
+  unset(_lhc4codec_version_match)
+endif()
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(LHC4CODEC
+  REQUIRED_VARS LHC4CODEC_LIBRARY LHC4CODEC_INCLUDE_DIR
+  VERSION_VAR LHC4CODEC_VERSION
+)
+
+if(LHC4CODEC_FOUND)
+  set(LHC4CODEC_INCLUDE_DIRS "${LHC4CODEC_INCLUDE_DIR}")
+  set(LHC4CODEC_LIBRARIES "${LHC4CODEC_LIBRARY}")
+
+  if(NOT TARGET LHC4CODEC::LHC4CODEC)
+    add_library(LHC4CODEC::LHC4CODEC UNKNOWN IMPORTED)
+    set_target_properties(LHC4CODEC::LHC4CODEC PROPERTIES
+      IMPORTED_LOCATION "${LHC4CODEC_LIBRARIES}"
+      INTERFACE_INCLUDE_DIRECTORIES "${LHC4CODEC_INCLUDE_DIRS}")
+  endif()
+endif()
+
+unset(_lhc4codec_hints)
+unset(_lhc4codec_brew_formula)
+unset(_lhc4codec_brew_prefix)

cmake/modules/RootBuildOptions.cmake

@@ -95,6 +95,7 @@ ROOT_BUILD_OPTION(builtin_glu OFF "Build libtess-GLU from an internal source tar
 ROOT_BUILD_OPTION(builtin_gsl OFF "Build GSL from an automatically downloaded source tarball (requires network) [GPL]")
 ROOT_BUILD_OPTION(builtin_gtest OFF "Build googletest from an automatically downloaded source tarball (requires network)")
 ROOT_BUILD_OPTION(builtin_jpeg OFF "Build libjpeg from an automatically downloaded source tarball (requires network)")
+ROOT_BUILD_OPTION(builtin_lhc4codec OFF "Build bundled copy of lhc4codec (git clone or LHC4CODEC_SOURCE_DIR)")
 ROOT_BUILD_OPTION(builtin_llvm ON "Build bundled copy of LLVM (advanced option)")
 MARK_AS_ADVANCED(builtin_llvm)
 ROOT_BUILD_OPTION(builtin_lz4 OFF "Build lz4 from an automatically downloaded source tarball (requires network)")
@@ -123,6 +124,7 @@ ROOT_BUILD_OPTION(coverage OFF "Enable compile flags for coverage testing")
 ROOT_BUILD_OPTION(cuda OFF "Enable support for CUDA (requires CUDA toolkit >= 7.5)")
 ROOT_BUILD_OPTION(curl ON "Enable support for HTTP(S) through libcurl")
 ROOT_BUILD_OPTION(daos OFF "Enable RNTuple support for Intel DAOS")
+ROOT_BUILD_OPTION(lhc4codec OFF "Enable LHC4 compression for RNTuple/TFile (requires lhc4codec library)")
 ROOT_BUILD_OPTION(dataframe ON "Enable ROOT RDataFrame")
 ROOT_BUILD_OPTION(davix ON "Enable support for Davix (HTTP/WebDAV access)")
 ROOT_BUILD_OPTION(dcache OFF "Enable support for dCache (requires libdcap from DESY)")

cmake/modules/RootConfiguration.cmake

@@ -363,6 +363,11 @@ if(clad)
 else()
   set(hasclad undef)
 endif()
+if(lhc4codec)
+  set(haslhc4codec define)
+else()
+  set(haslhc4codec undef)
+endif()
 if(cocoa)
   set(hascocoa define)
 else()

cmake/modules/SearchInstalledSoftware.cmake

@@ -404,6 +404,31 @@ if(builtin_lz4)
   add_subdirectory(builtins/lz4)
 endif()
 
+#---Check for LHC4CODEC--------------------------------------------------------------
+set(LHC4CODEC_SOURCE_DIR "" CACHE PATH
+    "Optional path to an lhc4codec checkout; if empty and builtin_lhc4codec=ON, the source is git-cloned")
+
+if(lhc4codec)
+  if(builtin_lhc4codec)
+    list(APPEND ROOT_BUILTINS LHC4CODEC)
+    add_subdirectory(builtins/lhc4codec)
+  else()
+    find_package(LHC4CODEC QUIET)
+    if(NOT LHC4CODEC_FOUND)
+      if(NOT LHC4CODEC_INSTALL_HELP)
+        set(LHC4CODEC_INSTALL_HELP
+            "lhc4codec was not found. Install lhc4codec-devel / brew tap apeters/lhc4codec, set -DLHC4CODEC_ROOT, or use -Dbuiltin_lhc4codec=ON.")
+      endif()
+      message(FATAL_ERROR "${LHC4CODEC_INSTALL_HELP}")
+    endif()
+    if(LHC4CODEC_VERSION)
+      message(STATUS "Found LHC4CODEC: ${LHC4CODEC_LIBRARIES} (version ${LHC4CODEC_VERSION})")
+    else()
+      message(STATUS "Found LHC4CODEC: ${LHC4CODEC_LIBRARIES}")
+    endif()
+  endif()
+endif()
+
 #---Check for X11 which is mandatory lib on Unix--------------------------------------
 if(x11)
   message(STATUS "Looking for X11")

config/RConfigure.in

@@ -65,4 +65,6 @@
 
 #@hasgeom@ R__HAS_GEOM /**/
 
+#@haslhc4codec@ R__HAS_LHC4CODEC /**/
+
 #endif

core/CMakeLists.txt

@@ -81,6 +81,9 @@ add_subdirectory(zip)
 add_subdirectory(lzma)
 add_subdirectory(lz4)
 add_subdirectory(zstd)
+if(lhc4codec)
+  add_subdirectory(lhc4codec)
+endif()
 
 add_subdirectory(macosx)
 add_subdirectory(unix)

core/lhc4codec/CMakeLists.txt

@@ -0,0 +1,29 @@
+############################################################################
+# CMakeLists.txt file for building ROOT core/lhc4codec package
+############################################################################
+
+add_library(ROOTLHC4Zip OBJECT src/ZipLHC4.cxx)
+set_target_properties(ROOTLHC4Zip PROPERTIES
+  CXX_STANDARD 20 CXX_STANDARD_REQUIRED ON CXX_EXTENSIONS OFF
+  POSITION_INDEPENDENT_CODE ON)
+target_link_libraries(ROOTLHC4Zip PRIVATE LHC4CODEC::LHC4CODEC)
+target_include_directories(ROOTLHC4Zip
+  PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/inc>
+)
+# Compile with -DR__LHC4_FAILURE_DUMP (or uncomment below) to write failed
+# zip/unzip frames under /tmp/root-lhc4-failure-<pid>/.
+# target_compile_definitions(ROOTLHC4Zip PRIVATE R__LHC4_FAILURE_DUMP)
+
+target_sources(Core PRIVATE $<TARGET_OBJECTS:ROOTLHC4Zip>)
+
+target_link_libraries(Core PRIVATE LHC4CODEC::LHC4CODEC)
+
+# Bundled bzip3 is a separate static lib in the lhc4codec build; propagate it when
+# built via add_subdirectory (ExternalProject uses INTERFACE_LINK_LIBRARIES).
+if(TARGET lhc4_bzip3_bundled)
+  target_link_libraries(Core PRIVATE lhc4_bzip3_bundled)
+endif()
+
+target_include_directories(Core PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/inc>)
+
+ROOT_INSTALL_HEADERS()