1# CMake support for large files
2#
3# Copyright (C) 2016 Julian Andres Klode <jak@debian.org>.
4#
5# Permission is hereby granted, free of charge, to any person
6# obtaining a copy of this software and associated documentation files
7# (the "Software"), to deal in the Software without restriction,
8# including without limitation the rights to use, copy, modify, merge,
9# publish, distribute, sublicense, and/or sell copies of the Software,
10# and to permit persons to whom the Software is furnished to do so,
11# subject to the following conditions:
12#
13# The above copyright notice and this permission notice shall be
14# included in all copies or substantial portions of the Software.
15#
16# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
17# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
18# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
19# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
20# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
21# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
22# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
23# SOFTWARE.
24#
25# This defines the following variables
26#
27# LFS_DEFINITIONS - List of definitions to pass to add_definitions()
28# LFS_COMPILE_OPTIONS - List of definitions to pass to add_compile_options()
29# LFS_LIBRARIES - List of libraries and linker flags
30# LFS_FOUND - If there is Large files support
31#
32
33include(CheckCSourceCompiles)
34include(FindPackageHandleStandardArgs)
35include(CMakePushCheckState)
36
37# Test program to check for LFS. Requires that off_t has at least 8 byte large
38set(_lfs_test_source
39    "
40    #include <sys/types.h>
41    typedef char my_static_assert[sizeof(off_t) >= 8 ? 1 : -1];
42    int main(void) { return 0; }
43    "
44)
45
46# Check if the given options are needed
47#
48# This appends to the variables _lfs_cppflags, _lfs_cflags, and _lfs_ldflags,
49# it also sets LFS_FOUND to 1 if it works.
50function(_lfs_check_compiler_option var options definitions libraries)
51    cmake_push_check_state()
52    set(CMAKE_REQUIRED_QUIET 1)
53    set(CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS} ${options})
54    set(CMAKE_REQUIRED_DEFINITIONS ${CMAKE_REQUIRED_DEFINITIONS} ${definitions})
55    set(CMAKE_REQUIRED_LIBRARIES ${CMAKE_REQUIRED_DEFINITIONS} ${libraries})
56
57    message(STATUS "Looking for LFS support using ${options} ${definitions} ${libraries}")
58    check_c_source_compiles("${_lfs_test_source}" ${var})
59    cmake_pop_check_state()
60
61    if(${var})
62        message(STATUS "Looking for LFS support using ${options} ${definitions} ${libraries} - found")
63        set(_lfs_cppflags ${_lfs_cppflags} ${definitions} PARENT_SCOPE)
64        set(_lfs_cflags ${_lfs_cflags} ${options} PARENT_SCOPE)
65        set(_lfs_ldflags ${_lfs_ldflags} ${libraries} PARENT_SCOPE)
66        set(LFS_FOUND TRUE PARENT_SCOPE)
67    else()
68        message(STATUS "Looking for LFS support using ${options} ${definitions} ${libraries} - not found")
69    endif()
70endfunction()
71
72# Check for the availability of LFS.
73# The cases handled are:
74#
75#  * Native LFS
76#  * Output of getconf LFS_CFLAGS; getconf LFS_LIBS; getconf LFS_LDFLAGS
77#  * Preprocessor flag -D_FILE_OFFSET_BITS=64
78#  * Preprocessor flag -D_LARGE_FILES
79#
80function(_lfs_check)
81    set(_lfs_cflags)
82    set(_lfs_cppflags)
83    set(_lfs_ldflags)
84    set(_lfs_libs)
85    cmake_push_check_state()
86    set(CMAKE_REQUIRED_QUIET 1)
87    message(STATUS "Looking for native LFS support")
88    check_c_source_compiles("${_lfs_test_source}" lfs_native)
89    cmake_pop_check_state()
90    if (lfs_native)
91        message(STATUS "Looking for native LFS support - found")
92        set(LFS_FOUND TRUE)
93    else()
94        message(STATUS "Looking for native LFS support - not found")
95    endif()
96
97    if (NOT LFS_FOUND)
98        # Check using getconf. If getconf fails, don't worry, the check in
99        # _lfs_check_compiler_option will fail as well.
100        execute_process(COMMAND getconf LFS_CFLAGS
101                        OUTPUT_VARIABLE _lfs_cflags_raw
102                        OUTPUT_STRIP_TRAILING_WHITESPACE
103                        ERROR_QUIET)
104        execute_process(COMMAND getconf LFS_LIBS
105                        OUTPUT_VARIABLE _lfs_libs_tmp
106                        OUTPUT_STRIP_TRAILING_WHITESPACE
107                        ERROR_QUIET)
108        execute_process(COMMAND getconf LFS_LDFLAGS
109                        OUTPUT_VARIABLE _lfs_ldflags_tmp
110                        OUTPUT_STRIP_TRAILING_WHITESPACE
111                        ERROR_QUIET)
112
113        separate_arguments(_lfs_cflags_raw)
114        separate_arguments(_lfs_ldflags_tmp)
115        separate_arguments(_lfs_libs_tmp)
116
117        # Move -D flags to the place they are supposed to be
118        foreach(flag ${_lfs_cflags_raw})
119            if (flag MATCHES "-D.*")
120                list(APPEND _lfs_cppflags_tmp ${flag})
121            else()
122                list(APPEND _lfs_cflags_tmp ${flag})
123            endif()
124        endforeach()
125
126        # Check if the flags we received (if any) produce working LFS support
127        _lfs_check_compiler_option(lfs_getconf_works
128                                   "${_lfs_cflags_tmp}"
129                                   "${_lfs_cppflags_tmp}"
130                                   "${_lfs_libs_tmp};${_lfs_ldflags_tmp}")
131    endif()
132
133    if(NOT LFS_FOUND)  # IRIX stuff
134        _lfs_check_compiler_option(lfs_need_n32 "-n32" "" "")
135    endif()
136    if(NOT LFS_FOUND)  # Linux and friends
137        _lfs_check_compiler_option(lfs_need_file_offset_bits "" "-D_FILE_OFFSET_BITS=64" "")
138    endif()
139    if(NOT LFS_FOUND)  # AIX
140        _lfs_check_compiler_option(lfs_need_large_files "" "-D_LARGE_FILES=1" "")
141    endif()
142
143    set(LFS_DEFINITIONS ${_lfs_cppflags} CACHE STRING "Extra definitions for large file support")
144    set(LFS_COMPILE_OPTIONS ${_lfs_cflags} CACHE STRING "Extra definitions for large file support")
145    set(LFS_LIBRARIES ${_lfs_libs} ${_lfs_ldflags} CACHE STRING "Extra definitions for large file support")
146    set(LFS_FOUND ${LFS_FOUND} CACHE INTERNAL "Found LFS")
147endfunction()
148
149if (NOT LFS_FOUND)
150    _lfs_check()
151endif()
152
153find_package_handle_standard_args(LFS "Could not find LFS. Set LFS_DEFINITIONS, LFS_COMPILE_OPTIONS, LFS_LIBRARIES." LFS_FOUND)
154