transmission/cmake/LargeFileSupport.cmake

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# Based on AC_SYS_LARGEFILE
if(NOT DEFINED NO_LFS_MACROS_REQUIRED)
include(CheckCSourceCompiles)
# Check that off_t can represent 2**63 - 1 correctly.
# We can't simply define LARGE_OFF_T to be 9223372036854775807,
# since some C++ compilers masquerading as C compilers
# incorrectly reject 9223372036854775807.
set(LFS_TEST_PROGRAM "
#include <sys/types.h>
#define LARGE_OFF_T (((off_t) 1 << 62) - 1 + ((off_t) 1 << 62))
int off_t_is_large[(LARGE_OFF_T % 2147483629 == 721 && LARGE_OFF_T % 2147483647 == 1) ? 1 : -1];
int main() { return 0; }
")
check_c_source_compiles("${LFS_TEST_PROGRAM}" NO_LFS_MACROS_REQUIRED)
if(NOT NO_LFS_MACROS_REQUIRED)
if(NOT DEFINED FILE_OFFSET_BITS_LFS_MACRO_REQUIRED)
check_c_source_compiles("#define _FILE_OFFSET_BITS 64 ${LFS_TEST_PROGRAM}" FILE_OFFSET_BITS_LFS_MACRO_REQUIRED)
if(FILE_OFFSET_BITS_LFS_MACRO_REQUIRED)
add_definitions(-D_FILE_OFFSET_BITS=64)
elseif(NOT DEFINED LARGE_FILES_LFS_MACRO_REQUIRED)
check_c_source_compiles("#define _LARGE_FILES 1 ${LFS_TEST_PROGRAM}" LARGE_FILES_LFS_MACRO_REQUIRED)
if(LARGE_FILES_LFS_MACRO_REQUIRED)
add_definitions(-D_LARGE_FILES=1)
endif()
endif()
endif()
endif()
unset(LFS_TEST_PROGRAM)
endif()