CMake: Use -D_FILE_OFFSET_BITS=64 if (and only if) needed.

A CMake option LARGE_FILE_SUPPORT is created if and only if
-D_FILE_OFFSET_BITS=64 affects sizeof(off_t).

This is needed on many 32-bit platforms and even with 64-bit builds
with MinGW-w64 to get support for files larger than 2 GiB.

1 files changed, 6 insertions, 1 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index f8eeebd3..b214d71d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -9,7 +9,6 @@
 #
 # On some platforms this builds also xz and xzdec, but these are
 # highly experimental and meant for testing only:
-#   - No large file support on those 32-bit platforms that need it
 #   - No replacement getopt_long(), libc must have it
 #   - No sandboxing support
 #   - No translations
@@ -53,6 +52,7 @@ include(CheckIncludeFile)
 include(CheckSymbolExists)
 include(CheckStructHasMember)
 include(CheckCSourceCompiles)
+include(cmake/tuklib_large_file_support.cmake)
 include(cmake/tuklib_integer.cmake)
 include(cmake/tuklib_cpucores.cmake)
 include(cmake/tuklib_physmem.cmake)
@@ -152,6 +152,11 @@ add_compile_definitions(
 # it also adds the definitions to CMAKE_REQUIRED_DEFINITIONS.
 tuklib_use_system_extensions(ALL)
 
+# Check for large file support. It's required on some 32-bit platforms and
+# even on 64-bit MinGW-w64 to get 64-bit off_t. This can be forced off on
+# the CMake command line if needed: -DLARGE_FILE_SUPPORT=OFF
+tuklib_large_file_support(ALL)
+
 # This is needed by liblzma and xz.
 tuklib_integer(ALL)