CMake: Add Large File Support

This module should cover all sorts of large file supports, as long
as they either support the getconf LFS_CFLAGS command; or the
_FILE_OFFSET_BITS=64 or _LARGE_FILES macros.

Closes: #834767

1 files changed, 148 insertions, 0 deletions

diff --git a/CMake/FindLFS.cmake b/CMake/FindLFS.cmake
new file mode 100644
index 000000000..e1fcf964c
--- /dev/null
+++ b/CMake/FindLFS.cmake
@@ -0,0 +1,148 @@
+# CMake support for large files
+#
+# Copyright (C) 2016 Julian Andres Klode <jak@debian.org>.
+#
+# Permission is hereby granted, free of charge, to any person
+# obtaining a copy of this software and associated documentation files
+# (the "Software"), to deal in the Software without restriction,
+# including without limitation the rights to use, copy, modify, merge,
+# publish, distribute, sublicense, and/or sell copies of the Software,
+# and to permit persons to whom the Software is furnished to do so,
+# subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be
+# included in all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+#
+# This defines the following variables
+#
+# LFS_DEFINITIONS - List of definitions to pass to add_definitions()
+# LFS_COMPILE_OPTIONS - List of definitions to pass to add_compile_options()
+# LFS_LIBRARIES - List of libraries and linker flags
+# LFS_FOUND - If there is Large files support
+#
+
+include(CheckCXXSourceCompiles)
+include(FindPackageHandleStandardArgs)
+
+# Test program to check for LFS. Requires that off_t has at least 8 byte large
+set(_lfs_test_source
+    "
+    #include <sys/types.h>
+    typedef char my_static_assert[sizeof(off_t) >= 8 ? 1 : -1];
+    int main(void) { return 0; }
+    "
+)
+
+# Check if the given options are needed
+#
+# This appends to the variables _lfs_cppflags, _lfs_cflags, and _lfs_ldflags,
+# it also sets LFS_FOUND to 1 if it works.
+function(_lfs_check_compiler_option var options definitions libraries)
+    set(CMAKE_REQUIRED_QUIET 1)
+    set(CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS} ${options})
+    set(CMAKE_REQUIRED_DEFINITIONS ${CMAKE_REQUIRED_DEFINITIONS} ${definitions})
+    set(CMAKE_REQUIRED_LIBRARIES ${CMAKE_REQUIRED_DEFINITIONS} ${libraries})
+
+    message(STATUS "Looking for LFS support using ${options} ${definitions} ${libraries}")
+    check_cxx_source_compiles("${_lfs_test_source}" ${var})
+
+    if(${var})
+        message(STATUS "Looking for LFS support using ${options} ${definitions} ${libraries} - found")
+        set(_lfs_cppflags ${_lfs_cppflags} ${definitions} PARENT_SCOPE)
+        set(_lfs_cflags ${_lfs_cflags} ${options} PARENT_SCOPE)
+        set(_lfs_ldflags ${_lfs_ldflags} ${libraries} PARENT_SCOPE)
+        set(LFS_FOUND TRUE PARENT_SCOPE)
+    else()
+        message(STATUS "Looking for LFS support using ${options} ${definitions} ${libraries} - not found")
+    endif()
+endfunction()
+
+# Check for the availability of LFS.
+# The cases handled are:
+#
+#  * Native LFS
+#  * Output of getconf LFS_CFLAGS; getconf LFS_LIBS; getconf LFS_LDFLAGS
+#  * Preprocessor flag -D_FILE_OFFSET_BITS=64
+#  * Preprocessor flag -D_LARGE_FILES
+#
+function(_lfs_check)
+    set(_lfs_cflags)
+    set(_lfs_cppflags)
+    set(_lfs_ldflags)
+    set(_lfs_libs)
+    set(CMAKE_REQUIRED_QUIET 1)
+    message(STATUS "Looking for native LFS support")
+    check_cxx_source_compiles("${_lfs_test_source}" lfs_native)
+    if (lfs_native)
+        message(STATUS "Looking for native LFS support - found")
+        set(LFS_FOUND TRUE)
+    else()
+        message(STATUS "Looking for native LFS support - not found")
+    endif()
+
+    if (NOT LFS_FOUND)
+        # Check using getconf. If getconf fails, don't worry, the check in
+        # _lfs_check_compiler_option will fail as well.
+        execute_process(COMMAND getconf LFS_CFLAGS
+                        OUTPUT_VARIABLE _lfs_cflags_raw
+                        OUTPUT_STRIP_TRAILING_WHITESPACE
+                        ERROR_QUIET)
+        execute_process(COMMAND getconf LFS_LIBS
+                        OUTPUT_VARIABLE _lfs_libs_tmp
+                        OUTPUT_STRIP_TRAILING_WHITESPACE
+                        ERROR_QUIET)
+        execute_process(COMMAND getconf LFS_LDFLAGS
+                        OUTPUT_VARIABLE _lfs_ldflags_tmp
+                        OUTPUT_STRIP_TRAILING_WHITESPACE
+                        ERROR_QUIET)
+
+        separate_arguments(_lfs_cflags_raw)
+        separate_arguments(_lfs_ldflags_tmp)
+        separate_arguments(_lfs_libs_tmp)
+
+        # Move -D flags to the place they are supposed to be
+        foreach(flag ${_lfs_cflags_raw})
+            if (flag MATCHES "-D.*")
+                list(APPEND _lfs_cppflags_tmp ${flag})
+            else()
+                list(APPEND _lfs_cflags_tmp ${flag})
+            endif()
+        endforeach()
+
+        # Check if the flags we received (if any) produce working LFS support
+        _lfs_check_compiler_option(lfs_getconf_works
+                                   "${_lfs_cflags_tmp}"
+                                   "${_lfs_cppflags_tmp}"
+                                   "${_lfs_libs_tmp};${_lfs_ldflags_tmp}")
+    endif()
+
+    if(NOT LFS_FOUND)  # IRIX stuff
+        _lfs_check_compiler_option(lfs_need_n32 "-n32" "" "")
+    endif()
+    if(NOT LFS_FOUND)  # Linux and friends
+        _lfs_check_compiler_option(lfs_need_file_offset_bits "" "-D_FILE_OFFSET_BITS=64" "")
+    endif()
+    if(NOT LFS_FOUND)  # AIX
+        _lfs_check_compiler_option(lfs_need_large_files "" "-D_LARGE_FILES=1" "")
+    endif()
+
+    set(LFS_DEFINITIONS ${_lfs_cppflags} CACHE STRING "Extra definitions for large file support")
+    set(LFS_COMPILE_OPTIONS ${_lfs_cflags} CACHE STRING "Extra definitions for large file support")
+    set(LFS_LIBRARIES ${_lfs_libs} ${_lfs_ldflags} CACHE STRING "Extra definitions for large file support")
+    set(LFS_FOUND ${LFS_FOUND} CACHE INTERNAL "Found LFS")
+endfunction()
+
+if (NOT LFS_FOUND)
+    _lfs_check()
+endif()
+
+find_package_handle_standard_args(LFS "Could not find LFS. Set LFS_DEFINITIONS, LFS_COMPILE_OPTIONS, LFS_LIBRARIES." LFS_FOUND)