Add a CMake build alongside autotools

CMake >= 3.18, coexisting with the autotools build; both read the
package version from the shared VERSION file. Linux is fully wired
(libltfs, the ltfs/mkltfs/ltfsck executables, the sg/file/itdtimg tape
backends, both I/O schedulers, both key managers); macOS builds the
iokit tape backend; the FreeBSD/NetBSD backends are skipped with a
notice and remain autotools-only. The build targets libfuse 2, like
autotools; the FUSE 3 selection arrives with the FUSE 3 port.

Notable differences from the autotools implementation:
- ICU is found through CMake's ICU module instead of the icu-config
  tool that ICU removed in 2018, and ICU6x is defined automatically
  for ICU >= 60. libxml2 uses find_package(LibXml2); fuse/uuid/
  net-snmp have no CMake packages and use pkg-config imported targets.
- config.h is generated from cmake/config.h.in, covering the subset
  of macros the sources use; feature toggles are passed on the
  command line, as in the autotools build.
- The message bundles are compiled by the same shared
  messages/make_message_src.sh, invoked with explicit source/output
  directories and the discovered genrb/pkgdata.
- The per-backend source symlinks and the CRC_OPTIMIZE compile rule
  are replaced by direct source paths and one SSE4.2-flagged OBJECT
  library linked into every tape backend.
- Plugins are MODULE libraries named exactly as ltfs.conf expects
  (libtape-sg.so etc.), installed to <libdir>/ltfs.
- ctest registers tests/t/*.sh by glob via the shared harness
  (SKIP_RETURN_CODE 77 outside Linux/fuse hosts), so the build works
  with or without the integration test suite.

A CI workflow configures, builds, and runs ctest on ubuntu.

Verified in an Ubuntu VM: the build and all 14 tests pass via ctest
with the test suite present; the install tree matches autotools (bin,
lib, lib/ltfs plugins, etc/ltfs.conf{,.local}, pkgconfig, man,
headers); ltfs --version reports the identical version string; the
autotools build and make check stay green. On macOS 26 (arm64,
macFUSE SDK) the CMake build produces libltfs, the executables, and
all plugins including libtape-iokit.so.

Author: matejk

.github/workflows/cmake.yml

@@ -0,0 +1,30 @@
+name: CMake Build
+
+on: [push, pull_request]
+
+jobs:
+  build:
+    name: Build and test with CMake
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Set up Git repository
+        uses: actions/checkout@v6
+        with:
+          submodules: recursive
+
+      - name: Install dependencies
+        run: |
+          sudo apt-get -q update
+          sudo apt-get -q -y install --no-install-recommends \
+            build-essential cmake pkg-config \
+            icu-devtools libicu-dev libxml2-dev uuid-dev libsnmp-dev \
+            libfuse-dev attr
+
+      - name: Build
+        run: |
+          cmake -S . -B build
+          cmake --build build -j"$(nproc)"
+
+      - name: Run tests
+        run: ctest --test-dir build --output-on-failure

.gitignore

@@ -4,7 +4,7 @@ aclocal.m4
 autom4te.cache/
 build-aux/
 m4/
-config.h.in
+/config.h.in
 configure
 # Files generated by ./configure
 config.h

CMakeLists.txt

@@ -0,0 +1,235 @@
+#
+# CMake build for LTFS. Coexists with the autotools build; both are
+# maintained. The package version is read from the top-level VERSION file
+# (the single source of truth shared with configure.ac).
+#
+cmake_minimum_required(VERSION 3.18)
+
+# --- Version (single source of truth: ./VERSION) -----------------------------
+file(STRINGS "${CMAKE_CURRENT_SOURCE_DIR}/VERSION" _ltfs_ver_lines)
+list(GET _ltfs_ver_lines 0 LTFS_VERSION_NUM)
+list(LENGTH _ltfs_ver_lines _ltfs_ver_n)
+set(LTFS_VERSION_SUFFIX "")
+if(_ltfs_ver_n GREATER 1)
+    list(GET _ltfs_ver_lines 1 LTFS_VERSION_SUFFIX)
+endif()
+if(LTFS_VERSION_SUFFIX STREQUAL "")
+    set(LTFS_VERSION_FULL "${LTFS_VERSION_NUM}")
+else()
+    set(LTFS_VERSION_FULL "${LTFS_VERSION_NUM} ${LTFS_VERSION_SUFFIX}")
+endif()
+
+project(ltfs VERSION ${LTFS_VERSION_NUM} LANGUAGES C)
+
+set(LTFS_PACKAGE_NAME "LTFS")
+set(LTFS_PACKAGE_TARNAME "ltfs")
+set(LTFS_BUGREPORT "IBM corporation.")
+
+set(CMAKE_C_STANDARD 99)
+set(CMAKE_C_STANDARD_REQUIRED ON)
+if(NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)
+    set(CMAKE_BUILD_TYPE "RelWithDebInfo" CACHE STRING "" FORCE)
+endif()
+
+include(GNUInstallDirs)
+include(CheckIncludeFile)
+include(CheckSymbolExists)
+include(CheckTypeSize)
+include(CheckCCompilerFlag)
+
+# --- Options (mirror the autotools --enable/--with switches) ------------------
+option(LTFS_ENABLE_SNMP "Build with SNMP support" ON)
+option(LTFS_ENABLE_LINTAPE "Build the IBM lin_tape backend (Linux only)" OFF)
+option(LTFS_SUPPORT_BUGGY_IFS "Work around buggy tape interfaces" OFF)
+option(LTFS_LIVELINK "Enable livelink symlink mode" ON)
+option(LTFS_MESSAGE_CHECK "Compile in message-checking mode" OFF)
+option(LTFS_WERROR "Treat warnings as errors" OFF)
+option(LTFS_DEBUG "Compile with extra debugging output" OFF)
+
+# New locking defaults ON for NetBSD (its old locking is broken), OFF elsewhere.
+if(CMAKE_SYSTEM_NAME STREQUAL "NetBSD")
+    option(LTFS_NEW_LOCKING "Use the new locking implementation" ON)
+else()
+    option(LTFS_NEW_LOCKING "Use the new locking implementation" OFF)
+endif()
+
+# Default plugin selection, matching configure.ac.
+if(CMAKE_SYSTEM_NAME STREQUAL "Linux")
+    set(_default_tape "sg")
+elseif(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
+    set(_default_tape "iokit")
+elseif(CMAKE_SYSTEM_NAME STREQUAL "FreeBSD")
+    set(_default_tape "cam")
+elseif(CMAKE_SYSTEM_NAME STREQUAL "NetBSD")
+    set(_default_tape "scsipi-ibmtape")
+endif()
+set(DEFAULT_TAPE "${_default_tape}" CACHE STRING "Default tape backend plugin")
+set(DEFAULT_IOSCHED "unified" CACHE STRING "Default I/O scheduler plugin")
+set(DEFAULT_KMI "none" CACHE STRING "Default key manager plugin")
+
+# --- Dependencies ------------------------------------------------------------
+# find_package is used wherever a CMake package exists (LibXml2, ICU, Threads).
+# libfuse, libuuid, and net-snmp ship no CMake config; pkg-config is their
+# canonical interface, wrapped as IMPORTED_TARGETs (PkgConfig::*).
+find_package(PkgConfig REQUIRED)
+
+pkg_check_modules(FUSE REQUIRED IMPORTED_TARGET fuse>=2.6.0)
+
+find_package(LibXml2 2.6.16 REQUIRED)
+
+if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
+    pkg_check_modules(UUID REQUIRED IMPORTED_TARGET uuid>=1.6)
+else()
+    pkg_check_modules(UUID REQUIRED IMPORTED_TARGET uuid>=1.36)
+endif()
+
+# ICU via the CMake module (replaces the removed icu-config).
+find_package(ICU REQUIRED COMPONENTS uc i18n io data)
+set(LTFS_ICU6X OFF)
+if(ICU_VERSION VERSION_GREATER_EQUAL "60")
+    set(LTFS_ICU6X ON)
+endif()
+
+find_package(Threads REQUIRED)
+if(NOT CMAKE_SYSTEM_NAME STREQUAL "Darwin")
+    find_library(RT_LIBRARY rt)
+endif()
+
+# SNMP (optional).
+if(LTFS_ENABLE_SNMP)
+    pkg_check_modules(NETSNMP IMPORTED_TARGET net-snmp>=5.3)
+    if(NOT NETSNMP_FOUND)
+        message(WARNING "net-snmp not found via pkg-config; disabling SNMP")
+        set(LTFS_ENABLE_SNMP OFF)
+    endif()
+endif()
+
+# Platform-specific libraries (declared for all platforms; used where built).
+# backtrace() has a CMake module (libc on glibc, libexecinfo on the BSDs);
+# cam/bsdxml/mt and the Apple frameworks ship neither CMake configs nor
+# pkg-config files, so find_library is the canonical way to locate them.
+if(CMAKE_SYSTEM_NAME STREQUAL "FreeBSD")
+    find_library(CAM_LIBRARY cam REQUIRED)
+    find_library(BSDXML_LIBRARY bsdxml REQUIRED)
+    find_library(MT_LIBRARY mt REQUIRED)
+    find_package(Backtrace REQUIRED)
+elseif(CMAKE_SYSTEM_NAME STREQUAL "NetBSD")
+    find_package(Backtrace REQUIRED)
+elseif(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
+    find_library(IOKIT_FRAMEWORK IOKit REQUIRED)
+    find_library(COREFOUNDATION_FRAMEWORK CoreFoundation REQUIRED)
+endif()
+
+# ICU host tools for the message bundles.
+find_program(GENRB genrb REQUIRED)
+find_program(PKGDATA pkgdata REQUIRED)
+
+# --- Feature checks for config.h ---------------------------------------------
+check_include_file("sys/sysctl.h" HAVE_SYS_SYSCTL_H)
+check_include_file("fcntl.h"      HAVE_FCNTL_H)
+check_include_file("limits.h"     HAVE_LIMITS_H)
+check_include_file("stddef.h"     HAVE_STDDEF_H)
+check_include_file("stdint.h"     HAVE_STDINT_H)
+check_include_file("stdlib.h"     HAVE_STDLIB_H)
+check_include_file("string.h"     HAVE_STRING_H)
+check_include_file("sys/ioctl.h"  HAVE_SYS_IOCTL_H)
+check_include_file("sys/mount.h"  HAVE_SYS_MOUNT_H)
+check_include_file("sys/time.h"   HAVE_SYS_TIME_H)
+check_include_file("termios.h"    HAVE_TERMIOS_H)
+check_include_file("unistd.h"     HAVE_UNISTD_H)
+check_type_size("time_t" SIZEOF_TIME_T)
+
+# xmlTextReaderSetup and XML_PARSE_HUGE (need libxml2 flags in scope).
+# XML_PARSE_HUGE is an enumerator, not a macro, so it needs a compile test.
+include(CheckCSourceCompiles)
+set(CMAKE_REQUIRED_INCLUDES ${LIBXML2_INCLUDE_DIRS})
+set(CMAKE_REQUIRED_LIBRARIES ${LIBXML2_LIBRARIES})
+check_symbol_exists(xmlTextReaderSetup "libxml/xmlreader.h" HAVE_XML_READER_SETUP)
+check_c_source_compiles("
+#include <libxml/parser.h>
+int main(void) { int foo = XML_PARSE_HUGE; (void)foo; return 0; }"
+    HAVE_XML_PARSE_HUGE)
+unset(CMAKE_REQUIRED_INCLUDES)
+unset(CMAKE_REQUIRED_LIBRARIES)
+
+configure_file(${CMAKE_CURRENT_SOURCE_DIR}/cmake/config.h.in
+               ${CMAKE_CURRENT_BINARY_DIR}/config.h @ONLY)
+
+# --- Common compile settings -------------------------------------------------
+# Definitions every translation unit gets, mirroring AM_CPPFLAGS/AM_CFLAGS.
+add_compile_definitions(
+    _GNU_SOURCE
+    LTFS_CONFIG_FILE="${CMAKE_INSTALL_FULL_SYSCONFDIR}/ltfs.conf"
+    LTFS_BASE_DIR="${CMAKE_INSTALL_PREFIX}"
+)
+if(LTFS_ENABLE_SNMP)
+    add_compile_definitions(ENABLE_SNMP)
+endif()
+if(LTFS_NEW_LOCKING)
+    add_compile_definitions(USE_NEW_LOCKING)
+endif()
+if(NOT LTFS_LIVELINK)
+    add_compile_definitions(POSIXLINK_ONLY)
+endif()
+if(LTFS_MESSAGE_CHECK)
+    add_compile_definitions(MSG_CHECK)
+endif()
+if(LTFS_DEBUG)
+    add_compile_definitions(DEBUG TRACE)
+endif()
+if(LTFS_ICU6X)
+    add_compile_definitions(ICU6x)
+endif()
+if(LTFS_SUPPORT_BUGGY_IFS AND (CMAKE_SYSTEM_NAME STREQUAL "Linux" OR CMAKE_SYSTEM_NAME STREQUAL "Darwin"))
+    add_compile_definitions(SUPPORT_BUGGY_IFS)
+endif()
+
+# -Wno-unused-parameter: callback signatures (FUSE operations, plugin ops)
+# must keep parameters they do not use.
+# -Wno-missing-field-initializers: designated initializers of operation and
+# option tables intentionally leave the remaining members zeroed.
+add_compile_options(-Wall -Wextra -Wno-unused-parameter
+                    -Wno-missing-field-initializers -Wsign-compare -fsigned-char)
+if(LTFS_WERROR)
+    add_compile_options(-Werror -Wno-deprecated-declarations)
+endif()
+
+# config.h (binary dir) and the src tree on the include path for every target.
+include_directories(${CMAKE_CURRENT_BINARY_DIR} ${CMAKE_CURRENT_SOURCE_DIR}/src)
+
+# CRC files need SSE4.2 on capable x86; detected once, applied to the ltfs_crc
+# object library (see src/tape_drivers).
+set(LTFS_CRC_OPTIONS "")
+if(CMAKE_SYSTEM_PROCESSOR MATCHES "x86_64|amd64|i[3-6]86")
+    check_c_compiler_flag("-msse4.2" LTFS_HAVE_MSSE42)
+    if(LTFS_HAVE_MSSE42)
+        set(LTFS_CRC_OPTIONS -msse4.2 -D__SSE42__)
+    endif()
+endif()
+
+# Helper modules.
+list(APPEND CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/cmake)
+include(LtfsMessages)
+include(LtfsPlugin)
+
+enable_testing()
+
+# --- Subprojects -------------------------------------------------------------
+add_subdirectory(messages)
+add_subdirectory(src)
+add_subdirectory(conf)
+add_subdirectory(man)
+add_subdirectory(init.d)
+add_subdirectory(tests)
+
+# pkg-config file (reuse the autotools template).
+set(prefix "${CMAKE_INSTALL_PREFIX}")
+set(exec_prefix "\${prefix}")
+set(libdir "${CMAKE_INSTALL_FULL_LIBDIR}")
+set(includedir "${CMAKE_INSTALL_FULL_INCLUDEDIR}")
+set(PACKAGE "ltfs")
+set(VERSION "${LTFS_VERSION_FULL}")
+configure_file(${CMAKE_CURRENT_SOURCE_DIR}/ltfs.pc.in
+               ${CMAKE_CURRENT_BINARY_DIR}/ltfs.pc @ONLY)
+install(FILES ${CMAKE_CURRENT_BINARY_DIR}/ltfs.pc
+        DESTINATION ${CMAKE_INSTALL_LIBDIR}/pkgconfig)

cmake/LtfsMessages.cmake

@@ -0,0 +1,39 @@
+# ICU message-bundle compilation for the CMake build. Reuses the shared
+# messages/make_message_src.sh so the genrb/pkgdata logic lives in one place.
+
+# ltfs_add_message_bundle(<name>)
+#   Compiles messages/<name>/*.txt into <build>/messages/lib<name>_dat.a and
+#   registers a build target msg_<name>. Link it into a consumer with
+#   ltfs_link_message().
+function(ltfs_add_message_bundle name)
+    set(_src_dir "${CMAKE_SOURCE_DIR}/messages/${name}")
+    set(_out_dir "${CMAKE_BINARY_DIR}/messages")
+    set(_archive "${_out_dir}/lib${name}_dat.a")
+    file(GLOB _txt "${_src_dir}/*.txt")
+
+    add_custom_command(
+        OUTPUT "${_archive}"
+        COMMAND ${CMAKE_COMMAND} -E make_directory "${_out_dir}"
+        COMMAND ${CMAKE_COMMAND} -E env "GENRB=${GENRB}" "PKGDATA=${PKGDATA}"
+                sh "${CMAKE_SOURCE_DIR}/messages/make_message_src.sh"
+                "lib${name}_dat.a" "${_src_dir}" "${_out_dir}"
+        DEPENDS ${_txt} "${CMAKE_SOURCE_DIR}/messages/make_message_src.sh"
+        COMMENT "Compiling message bundle ${name}"
+        VERBATIM)
+
+    add_custom_target(msg_${name} DEPENDS "${_archive}")
+    # Record the archive path for ltfs_link_message().
+    set_property(GLOBAL PROPERTY ltfs_msg_archive_${name} "${_archive}")
+endfunction()
+
+# ltfs_link_message(<target> <name>)
+#   Links message bundle <name> into <target> (as a plain archive input, the
+#   way the autotools build put it on LDFLAGS) and orders the build after it.
+function(ltfs_link_message target name)
+    get_property(_archive GLOBAL PROPERTY ltfs_msg_archive_${name})
+    if(NOT _archive)
+        message(FATAL_ERROR "Unknown message bundle '${name}'")
+    endif()
+    target_link_libraries(${target} PRIVATE "${_archive}")
+    add_dependencies(${target} msg_${name})
+endfunction()

cmake/LtfsPlugin.cmake

@@ -0,0 +1,36 @@
+# Helper for LTFS runtime plugins (tape backends, I/O schedulers, key managers).
+# Reproduces the autotools "-module -avoid-version" behavior: an unversioned
+# shared module named lib<x>.so, installed under <libdir>/ltfs.
+
+# ltfs_add_plugin(<target>
+#     SOURCES <files...>
+#     [MSG <message-bundle-name>]
+#     [CRC]                       # link the SSE-optimized CRC objects
+#     [INCLUDES <dirs...>]
+#     [DEFINES <defs...>]
+#     [LIBS <libs...>])
+function(ltfs_add_plugin target)
+    cmake_parse_arguments(P "CRC" "MSG" "SOURCES;INCLUDES;DEFINES;LIBS" ${ARGN})
+
+    add_library(${target} MODULE ${P_SOURCES})
+    set_target_properties(${target} PROPERTIES
+        PREFIX ""            # name is exactly <target>.so, no extra lib prefix
+        SUFFIX ".so"         # plugins are .so even on macOS (loader expects it)
+        OUTPUT_NAME "${target}")
+
+    target_link_libraries(${target} PRIVATE ltfs ${P_LIBS})
+    if(P_CRC)
+        target_link_libraries(${target} PRIVATE ltfs_crc)
+    endif()
+    if(P_INCLUDES)
+        target_include_directories(${target} PRIVATE ${P_INCLUDES})
+    endif()
+    if(P_DEFINES)
+        target_compile_definitions(${target} PRIVATE ${P_DEFINES})
+    endif()
+    if(P_MSG)
+        ltfs_link_message(${target} ${P_MSG})
+    endif()
+
+    install(TARGETS ${target} LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}/ltfs)
+endfunction()

cmake/config.h.in

@@ -0,0 +1,36 @@
+/* config.h generated by CMake. Parity with the autotools config.h for the
+ * subset of macros the LTFS sources actually use. Feature toggles such as
+ * HAVE_FUSE3, ICU6x, USE_NEW_LOCKING are passed on the command line (see the
+ * top-level CMakeLists.txt), exactly as the autotools build does. */
+#ifndef LTFS_CMAKE_CONFIG_H
+#define LTFS_CMAKE_CONFIG_H
+
+#define PACKAGE         "@LTFS_PACKAGE_TARNAME@"
+#define PACKAGE_NAME    "@LTFS_PACKAGE_NAME@"
+#define PACKAGE_TARNAME "@LTFS_PACKAGE_TARNAME@"
+#define PACKAGE_VERSION "@LTFS_VERSION_FULL@"
+#define PACKAGE_STRING  "@LTFS_PACKAGE_NAME@ @LTFS_VERSION_FULL@"
+#define PACKAGE_BUGREPORT "@LTFS_BUGREPORT@"
+#define PACKAGE_URL     ""
+#define VERSION         "@LTFS_VERSION_FULL@"
+
+/* Referenced by the sources */
+#cmakedefine HAVE_SYS_SYSCTL_H 1
+#cmakedefine HAVE_XML_PARSE_HUGE 1
+#cmakedefine HAVE_XML_READER_SETUP 1
+#define SIZEOF_TIME_T @SIZEOF_TIME_T@
+
+/* Header availability (parity with autotools; mostly unreferenced) */
+#cmakedefine HAVE_FCNTL_H 1
+#cmakedefine HAVE_LIMITS_H 1
+#cmakedefine HAVE_STDDEF_H 1
+#cmakedefine HAVE_STDINT_H 1
+#cmakedefine HAVE_STDLIB_H 1
+#cmakedefine HAVE_STRING_H 1
+#cmakedefine HAVE_SYS_IOCTL_H 1
+#cmakedefine HAVE_SYS_MOUNT_H 1
+#cmakedefine HAVE_SYS_TIME_H 1
+#cmakedefine HAVE_TERMIOS_H 1
+#cmakedefine HAVE_UNISTD_H 1
+
+#endif /* LTFS_CMAKE_CONFIG_H */