include(CheckCCompilerFlag)
include(CheckCSourceCompiles)
include(CheckIncludeFile)
include(CheckIncludeFiles)
include(CheckLibraryExists)
include(CheckSymbolExists)
include(TestBigEndian)

check_include_file("dlfcn.h" HAVE_DLFCN_H)
check_include_file("fcntl.h" HAVE_FCNTL_H)
check_include_file("inttypes.h" HAVE_INTTYPES_H)
check_include_file("memory.h" HAVE_MEMORY_H)
check_include_file("stdint.h" HAVE_STDINT_H)
check_include_file("stdlib.h" HAVE_STDLIB_H)
check_include_file("strings.h" HAVE_STRINGS_H)
check_include_file("string.h" HAVE_STRING_H)
check_include_file("sys/stat.h" HAVE_SYS_STAT_H)
check_include_file("sys/types.h" HAVE_SYS_TYPES_H)
check_include_file("unistd.h" HAVE_UNISTD_H)

check_symbol_exists("getpagesize" "unistd.h" HAVE_GETPAGESIZE)
check_symbol_exists("mmap" "sys/mman.h" HAVE_MMAP)
check_symbol_exists("getrandom" "sys/random.h" HAVE_GETRANDOM)

if(EXPAT_WITH_LIBBSD)
    set(CMAKE_REQUIRED_LIBRARIES "${LIB_BSD}")
    set(_bsd "bsd/")
else()
    set(_bsd "")
endif()
check_symbol_exists("arc4random_buf" "${_bsd}stdlib.h" HAVE_ARC4RANDOM_BUF)
if(NOT HAVE_ARC4RANDOM_BUF)
    check_symbol_exists("arc4random" "${_bsd}stdlib.h" HAVE_ARC4RANDOM)
endif()
set(CMAKE_REQUIRED_LIBRARIES)

#/* Define to 1 if you have the ANSI C header files. */
check_include_files("stdlib.h;stdarg.h;string.h;float.h" STDC_HEADERS)

test_big_endian(WORDS_BIGENDIAN)
#/* 1234 = LIL_ENDIAN, 4321 = BIGENDIAN */
if(WORDS_BIGENDIAN)
    set(BYTEORDER 4321)
else(WORDS_BIGENDIAN)
    set(BYTEORDER 1234)
endif(WORDS_BIGENDIAN)

if(HAVE_SYS_TYPES_H)
    check_c_source_compiles("
        #include <sys/types.h>
        int main(void) {
            const off_t offset = -123;
            (void)offset;
            return 0;
        }"
        HAVE_OFF_T)
endif()

if(NOT HAVE_OFF_T)
    set(off_t "long")
endif()

check_c_source_compiles("
        #define _GNU_SOURCE
        #include <stdlib.h>  /* for NULL */
        #include <unistd.h>  /* for syscall */
        #include <sys/syscall.h>  /* for SYS_getrandom */
        int main(void) {
            syscall(SYS_getrandom, NULL, 0, 0);
            return 0;
        }"
    HAVE_SYSCALL_GETRANDOM)

check_c_compiler_flag("-fno-strict-aliasing" FLAG_NO_STRICT_ALIASING)
check_c_compiler_flag("-fvisibility=hidden" FLAG_VISIBILITY)

check_library_exists(m cos "" _EXPAT_LIBM_FOUND)
